JP2004246118A - Liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that noise becomes conspicuous as the result of improvement of the response speed of liquid crystal in a liquid crystal display. <P>SOLUTION: This liquid crystal display is constituted of a circuit which calculates the difference of an input video signal and an input video signal which is one field before, a circuit which selects one coefficient of a plurality of coefficients according to the difference and calculates the first amount of compensation by multiplying the selected coefficient to the difference, a noise detecting part which detects noise of the input video signal, a circuit which calculates a second amount of compensation by performing multiplication of the output of the noise detecting part and the first amount of compensation, a circuit which calculates a compensation video signal by adding the second amount of compensation to the input video signal, and a circuit which displays pictures on the basis of the compensation video signal. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device that displays an image based on an input video signal.
[0002]
[Prior art]
In recent years, liquid crystal displays have been remarkably developed to be large-sized and high-definition, and accordingly, the use thereof has been expanded to display not only a still image but also a moving image as a display for a personal computer. Conventionally, when displaying a moving image on a liquid crystal display, there has been a problem that image quality degradation such as tailing occurs due to a response of transmittance of a liquid crystal material being slower than a change in a display signal. In particular, an in-plane switch type (hereinafter referred to as IPS) liquid crystal characterized by a wide viewing angle characteristic has a remarkable long time required for response (hereinafter referred to as response time).
[0003]
Then, as a liquid crystal display device for solving the above-mentioned problem, there is a liquid crystal display device disclosed in JP-A-2001-331154. Hereinafter, this conventional liquid crystal display device will be described with reference to FIGS.
[0004]
FIG. 8 is a block diagram showing the configuration of this conventional liquid crystal display device. 8, the conventional liquid crystal display device includes a field memory 10, an operation unit 50, a coefficient determination unit 51, an overflow correction unit 12, a drive unit 13, and a liquid crystal panel 14.
[0005]
Hereinafter, the operation of the conventional liquid crystal display device will be described with reference to FIG. The grayscale data is input to the field memory 10 and the grayscale data one field before is output. The difference value between the grayscale data and the output of the field memory 10 is input to the arithmetic unit 50, and a correction amount corresponding to the difference value is output.
[0006]
The gradation data to which the correction amount is added is input to the overflow correction unit 12, and when an overflow occurs due to the addition of the correction amount (for example, when the gradation data exceeds the maximum value or falls below the minimum value), The input is corrected and output. If no overflow occurs, the input is output as it is. The drive unit 13 drives the liquid crystal panel 14 with an applied voltage based on the output of the overflow correction unit 12. The liquid crystal panel 14 displays an image based on the control of the drive unit 13.
Next, the configuration and operation of the arithmetic unit 50 will be described in more detail. FIG. 5 is a block diagram showing a configuration of a calculation unit 50 in a conventional example. In FIG. 5, the operation unit 50 includes a coefficient register 60, a coefficient register 61, the selector 22, and the multiplier 23. Hereinafter, the operations of the calculation unit 50 and the coefficient determination unit 51 will be described.
[0007]
The difference value between the gradation data and the output of the field memory 10 is input to the arithmetic unit 50 with a sign. This difference value indicates the increase amount of the current gradation data with respect to the gradation data one field before. The coefficient register 60 stores in advance a coefficient A indicating the degree of correction when the gradation data increases, and the coefficient register 61 stores in advance a coefficient B indicating the degree of correction when the gradation data decreases. I have. Then, only one sign bit is extracted from the difference value of, for example, 9 bits input to the arithmetic unit 50 and input to the selector 22. Then, according to the value of the sign bit, the selector 22 selects the coefficient register 60 if it is, for example, “0”, and selects the coefficient register 61 if it is “1”, and selects the selected coefficient. The coefficient stored in the register is output. The multiplier 23 multiplies the signed 9-bit difference value input to the arithmetic unit 50 by the output of the selector 22, and outputs the result as a correction amount.
[0008]
In addition, the coefficient determination unit 51 allows the user to select a degree of correction, and outputs two coefficient data corresponding to the degree of correction selected by the user. These two coefficient data are supplied to the coefficient register 60 and the coefficient register 61 of the operation unit 50, respectively. The coefficient A and the coefficient B stored in the coefficient register 60 and the coefficient register 61 are the coefficient A and the coefficient B supplied from the coefficient determination unit 51. Updated as needed with data.
[0009]
In the conventional example, the degree of correction to be selected by the user in the coefficient determining unit 51 may be, for example, the degree of correction selected from five levels, or the coefficient set in the coefficient register 60 and the coefficient register 61 itself. May be input by the user. In the coefficient determination unit 51, the coefficient data to be output corresponding to the degree of correction may be output by referring to a data table based on the degree of correction, or may be calculated and output by calculation. No problem.
[0010]
Here, the coefficient A and the coefficient B will be described. As described above, when the sign bit is “0”, that is, when the difference value is positive, the coefficient A is multiplied by the difference value, and the result is added to the gradation data as a correction amount. In other words, the coefficient A is a coefficient that indicates, when the gradation data is increased, how many times the correction amount is added to the gradation data to perform the correction. Therefore, when the coefficient A is set to 0, no correction is performed. When the coefficient A is set to 0.5, a correction amount that is half of the increase amount of the gradation data is added to the gradation data. The correction amount corresponding to the data increase amount is added to the gradation data.
[0011]
On the other hand, when the sign bit is "1", that is, when the difference value is negative, the coefficient B is multiplied by the difference value, and the result is added to the gradation data as a correction amount. In other words, the coefficient B is a coefficient indicating how many times the correction amount is to be subtracted from the gradation data for correction when the gradation data is reduced. Therefore, when the coefficient B is set to 0, no correction is performed. When the coefficient B is set to 0.5, a correction amount that is half of the reduction amount of the gradation data is subtracted from the gradation data. The correction amount corresponding to the data reduction amount is subtracted from the gradation data.
[0012]
Here, the difference value is multiplied by a different coefficient (coefficient A and coefficient B) when the gradation data increases and when the gradation data decreases, and the correction amount is calculated. The reason for this will be described. In the liquid crystal panel, the voltage applied to the liquid crystal is changed to cause a change in the arrangement of liquid crystal molecules. As a result, the transmittance of the liquid crystal is changed, and a predetermined gradation display is performed. At this time, when the applied voltage is increased, the arrangement of the liquid crystal molecules is changed by the applied electric field. On the other hand, when the applied voltage is decreased, the arrangement of the liquid crystal molecules is changed by the intermolecular force.
[0013]
By the way, generally, the speed of the arrangement change of the liquid crystal molecules due to the applied electric field is faster than the speed of the arrangement change of the liquid crystal molecules due to the intermolecular force. Therefore, the response speed when the gradation data increases (when the applied voltage increases) is faster than the response speed when the gradation data decreases (when the applied voltage decreases). As described above, there is a difference in the response speed of the liquid crystal between when the gradation data is increased and when the gradation data is decreased. Therefore, it is preferable that the coefficients can be set separately according to the respective cases, as described above. In general, for the above reason, it is preferable to set the coefficient B when the gradation data decreases to a value larger than the coefficient A when the gradation data increases.
[0014]
There are two types of liquid crystal panels: a normally white type in which the transmittance is maximum (white display) when no voltage is applied, and a normally black type in which the transmittance is black (black display). The changing directions of the white display and the black display corresponding to the increase and decrease of the tone data are different from each other. However, it is common that the response speed when the gradation data is increased is faster than the response speed when the gradation data is decreased, and the above-described content is that the liquid crystal panel is a normally white type. It applies to both, regardless of whether it is of the normally black type.
[0015]
As described above, as shown in the conventional example, without performing complicated arithmetic processing and storing a large amount of data in the reference data table, the difference value between the pixel data of one field before and the pixel data is stored in the pixel data. The response speed of the liquid crystal can be improved by a simple operation and configuration that simply adds a correction amount obtained by multiplying the liquid crystal by a predetermined coefficient. In particular, since the difference is multiplied by the difference coefficient value between when the gradation data increases and when the gradation data decreases, the correction amount is obtained, so that the response speed can be more optimally improved in accordance with the characteristics of the liquid crystal.
[0016]
Further, according to this conventional example, the degree of correction of the response speed of the liquid crystal can be arbitrarily changed at any time according to the user's preference, and the change can be easily made only by selecting the degree of correction. It can be carried out. Therefore, it is not necessary to rewrite data or store a large amount of data in advance in order to cope with such a change, and the degree of correction can be easily changed with a simple configuration.
[0017]
In the conventional example, the sign of the difference value input to the calculation unit 50 is described as being positive when the gradation data increases, but this can be changed according to the design of the entire apparatus. . Further, in the conventional example, in the arithmetic unit 50, a signed difference value is input to the multiplier 23, and a value having no sign is set for the coefficient A and the coefficient B. It can be changed according to. For example, only the absolute value of the difference excluding the sign bit may be input to the multiplier 23, and a signed value may be set for the coefficient A and the coefficient B.
[0018]
Here, with reference to FIG. 9, an operation when the gradation data is corrected by the correction value will be described in more detail. Here, the value of a certain gradation data is Dx, the liquid crystal application voltage corresponding to this data is Vx, and the liquid crystal state which is a gradation when the voltage of Vx is sufficiently stabilized is Sx. I do. Now, as shown in FIG. 9A, when the gradation data changes from D1 to D2 (D1 <D2), if no correction is performed, the voltage applied to the liquid crystal is as shown in FIG. 9B. Thus, the voltage changes from the voltage V1 to the voltage V2. However, the liquid crystal cannot follow the change in the voltage, and the transmittance of the liquid crystal changes as shown in FIG. That is, the state of the liquid crystal becomes S2 several frames after the gradation data changes from D1 to D2. As described above, when the correction is not performed, a response time corresponding to several frames occurs from S1 to S2.
[0019]
By the way, a liquid crystal material generally has a property that the greater the degree of change when the applied voltage changes, the higher the change speed. Therefore, as shown in FIG. 9E, the voltage V3 which is larger than the voltage V2 such that the liquid crystal enters the state of S2 one frame after the change of the gradation data (the state of the state of S3 if sufficient time elapses) Is applied only for one frame after the change of the gradation data (FIG. 9D). Thereafter, when the applied voltage is set to V2, the state of the liquid crystal is stabilized at S2. As described above, when the gradation data changes, the applied voltage is temporarily corrected so as to increase the liquid crystal change speed, thereby increasing the liquid crystal change speed and shortening the liquid crystal response time to, for example, one frame. can do.
[0020]
[Patent Document 1]
JP 2001-331154 A
[0021]
[Problems to be solved by the invention]
However, when the correction processing as disclosed in JP-A-2001-331154 is performed, the response time of the liquid crystal can be reduced. This caused a problem that the noise was more noticeable than before.
[0022]
Therefore, an object of the present invention is to realize a noise reduction by using a characteristic of a response speed of a liquid crystal positively and adding a small-scale circuit even in a liquid crystal display device having a high response speed. Another object of the present invention is to provide a liquid crystal display device that realizes optimum noise reduction in each display area in a situation where a plurality of input signals are displayed as in a multi-screen display. That is.
[0023]
[Means for Solving the Problems]
A first invention is a circuit for calculating a difference between an input video signal and an input video signal one field before, selecting one of a plurality of coefficients according to the difference, and multiplying the difference by the selected coefficient. A circuit for obtaining a first correction amount, a noise detection unit for detecting noise of the input video signal, a circuit for multiplying the output of the noise detection unit by the first correction amount to obtain a second correction amount, The liquid crystal display device includes a circuit for obtaining a corrected video signal by adding a second correction amount to a video signal, and a circuit for displaying an image based on the corrected video signal.
[0024]
As described above, according to the first aspect, even in a liquid crystal display device having a high response speed, a circuit that increases the response speed of the liquid crystal is positively used, and a small circuit is added. Noise reduction can be realized.
[0025]
According to a second aspect of the present invention, there is provided a multi-screen combining circuit for combining two input video signals, a circuit for calculating a difference between an input video signal one field before the output of the multi-screen combining circuit, and a plurality of coefficients corresponding to the difference. A circuit for selecting one of the differences and multiplying the difference by the selected coefficient to obtain a first correction amount; a multi-screen noise detection unit for detecting noise of the input video signal; and an output of the multi-screen noise detection unit A circuit for obtaining a second correction amount by multiplying the output of the multi-screen combining circuit by a second correction amount to obtain a corrected video signal; This is a liquid crystal display device including a circuit for displaying an image.
[0026]
As described above, according to the second aspect, in a situation where a plurality of input signals are displayed as in a multi-screen display, optimal noise reduction can be realized in each display area.
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0028]
(1st Embodiment)
FIG. 1 is a block diagram showing the configuration of the liquid crystal display device according to the first embodiment of the present invention. In FIG. 1, reference numeral 10 denotes a field memory, 50 denotes a calculation unit, 51 denotes a coefficient determination unit, 12 denotes an overflow correction unit, 13 denotes a drive unit, 14 denotes a liquid crystal panel, and 1 denotes a noise detection unit.
[0029]
Hereinafter, the operation of the liquid crystal display device according to the first embodiment of the present invention will be described with reference to FIG. The grayscale data is input to the field memory 10 and the grayscale data one field before is output. The difference value between the gradation data and the output of the field memory 10 is input to the arithmetic unit 50, and the arithmetic unit 50 outputs a correction amount A according to the difference value.
[0030]
The noise detection unit 1 detects a noise amount of an input video signal and outputs a value corresponding to the noise. For example, when there is no noise or very little, that is, normally, 1 is output. As a result, the correction value A is multiplied by 1, and the value of the correction value A is directly provided to the adder as the correction value B. That is, the control is performed so that the response speed of the liquid crystal is increased when the noise is small. On the other hand, when the noise is very large, a value close to 0 is output. As a result, the correction value A is multiplied by a value of 1 or less and given as a correction value B to the adder. That is, control is performed such that the response speed of the liquid crystal is reduced according to the amount of noise.
[0031]
FIG. 2 is a block diagram illustrating an example of the noise detection unit. 5 is a vertical blanking period sampling unit, 6 is a noise amount calculation unit, and 7 is a conversion table. When the video signal A is input, a period in which the video signal and the character multiplex signal in the vertical blanking period are not superimposed is extracted. The noise amount detector 6 calculates the amount of noise from the output of the vertical blanking period sampling unit 5. For example, a sum of squares of the period is used as a method of calculating the noise amount. The conversion table 7 converts the calculated noise amount from 0 to 1 and outputs it. When the noise is small, a value close to 1 is output. When the noise is large, a value close to 0 is output. The circuit configuration of the noise detection unit 1 is not limited to the configuration shown in FIG.
[0032]
The gradation data to which the correction amount B has been added is input to the overflow correction unit 12, and an overflow has occurred due to the addition of the correction amount B (for example, when the gradation data exceeds the maximum value or falls below the minimum value). , The input is corrected and output, and if no overflow occurs, the input is output as it is. The drive unit 13 drives the liquid crystal panel 14 with an applied voltage based on the output of the overflow correction unit 12. The liquid crystal panel 14 displays an image based on the control of the drive unit 13.
[0033]
Next, the configuration and operation of the arithmetic unit 50 will be described in more detail. FIG. 5 is a block diagram showing a configuration of a calculation unit 50 in a conventional example. In FIG. 5, the operation unit 50 includes a coefficient register 60, a coefficient register 61, the selector 22, and the multiplier 23. Hereinafter, the operations of the calculation unit 50 and the coefficient determination unit 51 will be described.
[0034]
The difference value between the gradation data and the output of the field memory 10 is input to the arithmetic unit 50 with a sign. This difference value indicates the increase amount of the current gradation data with respect to the gradation data one field before. The coefficient register 60 stores in advance a coefficient A indicating the degree of correction when the gradation data increases, and the coefficient register 61 stores in advance a coefficient B indicating the degree of correction when the gradation data decreases. I have. Then, only one sign bit is extracted from the difference value of, for example, 9 bits input to the arithmetic unit 50 and input to the selector 22. Then, according to the value of the sign bit, the selector 22 selects the coefficient register 60 when the value is, for example, “0”, and selects the coefficient register 61 when the value is “1”. The coefficient stored in the register is output. The multiplier 23 multiplies the signed 9-bit difference value input to the arithmetic unit 50 by the output of the selector 22 and outputs the result as a correction amount A.
[0035]
In addition, the coefficient determination unit 51 allows the user to select a degree of correction, and outputs two coefficient data corresponding to the degree of correction selected by the user. These two coefficient data are supplied to the coefficient register 60 and the coefficient register 61 of the operation unit 50, respectively. The coefficient A and the coefficient B stored in the coefficient register 60 and the coefficient register 61 are the coefficient A and the coefficient B supplied from the coefficient determination unit 51. Updated as needed with data.
[0036]
Here, the coefficient A and the coefficient B will be described. As described above, when the sign bit is “0”, that is, when the difference value is positive, the coefficient A is multiplied by the difference value, and the result is added to the gradation data as a correction amount. In other words, the coefficient A is a coefficient that indicates, when the gradation data is increased, how many times the correction amount is added to the gradation data to perform the correction. Therefore, when the coefficient A is set to 0, no correction is performed. When the coefficient A is set to 0.5, a correction amount that is half of the increase amount of the gradation data is added to the gradation data. The correction amount corresponding to the data increase amount is added to the gradation data.
[0037]
On the other hand, when the sign bit is "1", that is, when the difference value is negative, the coefficient B is multiplied by the difference value, and the result is added to the gradation data as a correction amount. In other words, the coefficient B is a coefficient indicating how many times the correction amount is to be subtracted from the gradation data for correction when the gradation data is reduced. Therefore, when the coefficient B is set to 0, no correction is performed. When the coefficient B is set to 0.5, a correction amount that is half of the reduction amount of the gradation data is subtracted from the gradation data. The correction amount corresponding to the data reduction amount is subtracted from the gradation data.
[0038]
Here, the difference value is multiplied by a different coefficient (coefficient A and coefficient B) when the gradation data increases and when the gradation data decreases, and the correction amount is calculated. The reason for this will be described. In the liquid crystal panel, the voltage applied to the liquid crystal is changed to cause a change in the arrangement of liquid crystal molecules. As a result, the transmittance of the liquid crystal is changed, and a predetermined gradation display is performed. At this time, when the applied voltage is increased, the arrangement of the liquid crystal molecules is changed by the applied electric field. On the other hand, when the applied voltage is decreased, the arrangement of the liquid crystal molecules is changed by the intermolecular force.
[0039]
By the way, generally, the speed of the arrangement change of the liquid crystal molecules due to the applied electric field is faster than the speed of the arrangement change of the liquid crystal molecules due to the intermolecular force. Therefore, the response speed when the gradation data increases (when the applied voltage increases) is faster than the response speed when the gradation data decreases (when the applied voltage decreases). As described above, there is a difference in the response speed of the liquid crystal between when the gradation data is increased and when the gradation data is decreased. Therefore, it is preferable that the coefficients can be set separately according to the respective cases, as described above. In general, for the above reason, it is preferable to set the coefficient B when the gradation data decreases to a value larger than the coefficient A when the gradation data increases.
[0040]
There are two types of liquid crystal panels: a normally white type in which the transmittance is maximum (white display) when no voltage is applied, and a normally black type in which the transmittance is black (black display). The changing directions of the white display and the black display corresponding to the increase and decrease of the tone data are different from each other. However, it is common that the response speed when the gradation data is increased is faster than the response speed when the gradation data is decreased, and the above-described content is that the liquid crystal panel is a normally white type. It applies to both, regardless of whether it is of the normally black type.
[0041]
FIG. 6 shows the response speed of the liquid crystal panel 14 when there is much noise in the present invention. FIG. 9 is a diagram showing a result of measuring a response time (a time when the light output of the liquid crystal panel 14 changes when the gradation is changed) at this time. On the other hand, FIG. 7 is a diagram showing a result of measuring a response time when there is no noise. Comparing FIG. 6 and FIG. 7, the response time of the halftone is 90 ms when there is much noise, and 30 ms or less when there is no noise. When actually viewed on a display screen, when there is no noise, the response speed is fast, and clear high image quality can be realized even in a moving image. In addition, when there is a lot of noise, the response speed becomes moderately slow, and the noise can be moderately suppressed.
[0042]
Here, with reference to FIG. 9, an operation when the gradation data is corrected by the correction value will be described in more detail. Here, the value of a certain gradation data is Dx, the liquid crystal application voltage corresponding to this data is Vx, and the liquid crystal state which is a gradation when the voltage of Vx is sufficiently stabilized is Sx. I do. Now, as shown in FIG. 9A, when the gradation data changes from D1 to D2 (D1 <D2), if no correction is performed, the voltage applied to the liquid crystal is as shown in FIG. 9B. Thus, the voltage changes from the voltage V1 to the voltage V2. However, the liquid crystal cannot follow the change in the voltage, and the transmittance of the liquid crystal changes as shown in FIG. That is, the state of the liquid crystal becomes S2 several frames after the gradation data changes from D1 to D2. As described above, when the correction is not performed, a response time corresponding to several frames occurs from S1 to S2.
[0043]
By the way, a liquid crystal material generally has a property that the greater the degree of change when the applied voltage changes, the higher the change speed. Therefore, as shown in FIG. 9E, the voltage V3 which is larger than the voltage V2 such that the liquid crystal enters the state of S2 one frame after the change of the gradation data (the state of the state of S3 if sufficient time elapses) Is applied only for one frame after the change of the gradation data (FIG. 9D). Thereafter, when the applied voltage is set to V2, the state of the liquid crystal is stabilized at S2. As described above, when the gradation data changes, the applied voltage is temporarily corrected so as to increase the liquid crystal change speed, thereby increasing the liquid crystal change speed and shortening the liquid crystal response time to, for example, one frame. can do.
[0044]
As described above, it is possible to improve both the liquid crystal response speed when the noise is small and the noise reduction using the liquid crystal response speed when the noise is large.
[0045]
(Second embodiment)
FIG. 3 is a block diagram illustrating a configuration of a liquid crystal display device according to the second embodiment of the present invention. FIG. 3 is a block diagram illustrating a configuration of the liquid crystal display device according to the first embodiment of the present invention. 3, reference numeral 10 denotes a field memory, 50 denotes a calculation unit, 51 denotes a coefficient determination unit, 12 denotes an overflow correction unit, 13 denotes a drive unit, 14 denotes a liquid crystal panel, and 2 denotes a multi-screen noise detection unit. In FIG. 3, the same components as those in FIG. 1 are denoted by the same reference numerals.
[0046]
FIG. 4 is a block diagram illustrating an example of the multi-screen noise detection unit 2. Reference numerals 5 and 25 denote vertical blanking period sampling units, reference numerals 6 and 26 denote noise amount calculating units, reference numerals 7 and 27 denote conversion tables, reference numeral 28 denotes display synchronization, a clock reproducing unit, and reference numeral 29 denotes a screen switching signal generation unit. 4, the same components as those in FIG. 2 are denoted by the same reference numerals.
[0047]
Hereinafter, the operation of the second embodiment will be described. However, the second embodiment is different from the first embodiment only in the internal configuration of the multi-screen noise detection unit 2, and the detailed description of the other same configurations is omitted.
[0048]
Here, in order to simplify the description, a case of a two-screen display as shown in FIG. 10 will be described. When the video signal A is input, the vertical blanking period extracting unit 5 extracts a period in which the video signal and the character multiplex signal in the vertical blanking period are not superimposed. When the video signal B is input, the vertical blanking period extracting unit 25 extracts a period in which the video signal and the character multiplex signal in the vertical blanking period are not superimposed. The noise amount detector 6 calculates the amount of noise from the output of the vertical blanking period sampling unit 5. The noise amount detection unit 26 calculates the noise amount from the output of the vertical blanking period sampling unit 25. For example, a sum of squares of the period is used as a method of calculating the noise amount. The conversion table 7 converts the calculated noise amount from 0 to 1 and outputs it. The conversion table 27 converts the calculated noise amount from 0 to 1 and outputs it. When there is little noise, a value close to 1 is output, and when there is much noise, a value close to 0 is output. The selector 30 switches the output of the conversion table 7 and the output of the conversion table 27 according to the output of the screen display switching signal generator and outputs the same. The display synchronization / clock generation circuit 28 generates a horizontal synchronization signal HD, a vertical synchronization signal VD, and a clock pulse CK synchronized with the display of the liquid crystal panel 14. The screen switching signal generator 29 outputs a switching signal based on the output of the display synchronization and clock generation circuit 28.
[0049]
For example, in the case of the two screens shown in FIG. 10, 0 is output during the period of the video signal A, and 1 is output during the period of the video signal B. In this way, the multi-screen noise detector 2 selects and outputs a signal corresponding to the amount of noise of the video signals A and B.
[0050]
The circuit configuration of the multi-screen noise detector 2 is not limited to the configuration shown in FIG.
[0051]
As described above, in a liquid crystal display device that performs multi-screen display, by improving the liquid crystal response speed on the screen of a signal with a small amount of noise, and performing noise reduction using the liquid crystal response speed on the screen of a signal with a large amount of noise, An optimal viewing state can be provided.
[0052]
【The invention's effect】
As described above, according to the present invention, it is possible to achieve both the improvement of the liquid crystal response speed when the noise is small and the noise reduction using the liquid crystal response speed when the noise is large.
[0053]
In addition, in a liquid crystal display device that performs multi-screen display, the liquid crystal response speed is improved for the screen of a signal with a small noise, and the noise reduction using the liquid crystal response speed is performed for the screen of a signal with a large amount of noise, so that the optimal viewing is achieved. Can provide status.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a liquid crystal display device according to a first embodiment of the present invention.
FIG. 2 is a block diagram illustrating a configuration of a noise detection unit 1 according to the first embodiment of the present invention.
FIG. 3 is a block diagram illustrating a configuration of a liquid crystal display device according to a second embodiment of the present invention.
FIG. 4 is a block diagram illustrating a configuration of a multi-screen noise detection unit 2 according to the first embodiment of the present invention.
FIG. 5 is a block diagram showing a configuration of a calculation unit 50 in a conventional liquid crystal display device.
FIG. 6 is a diagram showing a result of measuring a response time of the liquid crystal panel 14 when there is much noise in the first embodiment.
FIG. 7 is a diagram showing a result of measuring a response time of the liquid crystal panel 14 when there is no noise in the first embodiment.
FIG. 8 is a block diagram illustrating a configuration of a conventional liquid crystal display device.
FIG. 9 is a diagram showing a correction algorithm of a liquid crystal response speed in a conventional liquid crystal display device.
FIG. 10 is an image diagram of a display screen when two screens are displayed.
[Explanation of symbols]
1 Noise detector
5, 25 Vertical flyback sampling section
6, 26 Noise amount calculation unit
7, 27 Conversion table
10 Field memory
12 Overflow correction unit
13 Driver
14 LCD panel
28 Display Synchronous Clock Regeneration Unit
29 Screen switching signal generator
30 selector
50 arithmetic unit
51 Coefficient determination unit

Claims (7)

What is claimed is: 1. A liquid crystal display device for displaying an image based on an input video signal, comprising: means for obtaining a difference between the input video signal and an input video signal one field before, and selecting one of a plurality of coefficients according to the difference. Means for multiplying the difference by the selected coefficient to obtain a first correction amount; noise detection means for detecting noise of the input video signal; output of the noise detection means and the first correction amount Means for obtaining a second correction amount by multiplying the input image signal, means for obtaining the corrected video signal by adding the second correction amount to the input video signal, and means for displaying an image based on the corrected video signal. A liquid crystal display device comprising: 2. The noise detecting means includes: a noise calculating means for calculating an amount of noise in a vertical retrace period of an input signal; and a conversion table for converting an output of the noise calculating means into a signal for limiting a first correction amount. The liquid crystal display device according to the above. 2. The liquid crystal display device according to claim 1, wherein the noise detection means operates to reduce the first correction amount when the noise amount is large. What is claimed is: 1. A liquid crystal display device for displaying an image based on an input video signal, comprising: a multi-screen synthesizing unit for synthesizing at least two input video signals; Means for determining, selecting one of a plurality of coefficients according to the difference, multiplying the difference by the selected coefficient to determine a first correction amount, and detecting noise of the input video signal Multi-screen noise detection means; means for multiplying the output of the multi-screen noise detection means by the first correction amount to obtain a second correction amount; and outputting the second correction amount to the output of the multi-screen synthesis means. A liquid crystal display device comprising: means for obtaining a corrected video signal by adding the correction signal; and means for displaying an image based on the corrected video signal. The multi-screen noise detection means calculates a noise amount of the at least two input signals during a vertical blanking period, and at least converts an output of the at least two noise calculation means into a signal for limiting a first correction amount. Two conversion tables, a display synchronization clock generating means for generating display horizontal and vertical synchronization signals and a display clock, and a signal indicating a multi-screen display area from the output of the display synchronization clock generation means 5. The liquid crystal display device according to claim 4, further comprising: a screen switching signal generating unit that outputs the conversion table; and a selector that switches an output of the at least two conversion tables in accordance with an output of the screen switching signal generating unit. 5. The liquid crystal display according to claim 4, wherein the multi-screen noise detection means calculates at least two noise amounts, and operates to reduce the first correction amount when the noise amount is large in each display area. apparatus. The step of obtaining the correction amount includes the step of storing two coefficients, the step of selecting one of the stored two coefficients according to the sign of the difference, and the step of multiplying the difference by the selected coefficient. 7. The liquid crystal display method according to claim 6, comprising:

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