JP2000131666A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device suppressing a flicker occurring when a specified pattern is displayed, preventing deterioration in picture quality and reducing power consumption regardless of a display pattern. SOLUTION: This device is provided with a liquid crystal panel 1 arranging display pixels in matrix, a data driver 2 supplying the image data in pixel, a gate driver 3 synchronized with a horizontal synchronizing signal and successively making respective pixels an operation state, an input control part 5 fetching display control information from a personal computer 4, etc., and display controlling a required pattern on the liquid crystal panel 1 and a reference source generation part 6 generating a reference voltage applied to the display pixel of the liquid crystal panel 1. At this time, the input control part 5 always monitors a correlation between the change of the display pattern and the polarity reverse period of the reference voltage, and when the control part 5 detects synchronism between both, switches to an optional reverse period to apply the reference voltage to the data driver 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device which applies a reference voltage having a predetermined polarity inversion cycle to display pixels to display a desired display pattern on a liquid crystal panel.

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices have rapidly become widespread as displays for various devices such as digital video cameras and telephones, including OA devices such as notebook personal computers. The liquid crystal display device has a large screen and display quality (image quality),
Although it is still inferior to display means such as CRT in terms of price, etc.,
Attention has been paid to excellent features such as low power consumption, light weight, and space saving.

[0003] A conventional liquid crystal display device will be described with reference to FIGS. 9 and 10. As shown in FIG. 9, a conventional liquid crystal display device includes a liquid crystal panel 1 having liquid crystal pixels (display pixels) arranged in a matrix at each intersection of a plurality of data lines 2a and gate lines 3a, and a liquid crystal panel. 1, a data driver 2 provided in the vertical (vertical) direction to supply image display data in pixel units to a data line 2a connected to each display pixel, and a data driver 2 provided in the horizontal (horizontal) direction of the liquid crystal panel 1. A gate driver 3 for sequentially turning on (ON) each display pixel in synchronization with a horizontal synchronizing signal with a gate line 3a connected to the display pixel; and a display control information source 4 such as a personal computer
An input control unit 5 ′ that takes in image data, a synchronization signal, an operation clock, and the like from the CPU and controls the data driver 2 and the gate driver 3 to display desired image data on the liquid crystal panel 1; And a reference power supply 6 ′ for supplying a reference voltage to be applied to the data driver 2.

Further, as shown in FIG. 10, the input control unit 5 'receives display control information (image data, a horizontal synchronizing signal, an operation control signal, etc.) from a personal computer or the like, and receives a subsequent input data latch unit. 12, an input interface (I / F) unit 11 for transmitting a predetermined signal to a data output circuit 13 and the like, an input data latch circuit 12 for temporarily holding each image data (R, G, B), And a data output circuit 13 that performs timing adjustment, waveform shaping, and the like, and outputs the data to the data driver 2.

In such a configuration, the input I / F unit 1
1 is output to the data driver 2 at a predetermined timing through an input data latch circuit 12 and a data output circuit 13 and inverted by a reference power supply to the data driver 2. A driving method is adopted in which the polarity of the data voltage applied to the display pixels is inverted at a constant cycle based on the cycle.

Here, the inversion period of the reference voltage means that the reference voltage applied between the pixel electrode and the counter electrode of the liquid crystal panel alternately repeats a positive voltage state and a negative voltage state with respect to the common voltage. This refers to the inversion cycle, and is usually set to a constant inversion cycle.

[0007]

In the above-described liquid crystal display device, a driving method for displaying image data by inverting the polarity of a reference voltage (data voltage) with respect to a counter electrode voltage at a predetermined cycle set in advance. Has been adopted. As such a method of inverting the polarity of the data voltage, there are known a method of inverting every frame, a method of inverting every horizontal line or vertical line, and a method of inverting each display pixel. In any of the inversion methods, it is known that when a pattern having a specific relationship with the inversion cycle of the data voltage is displayed, flickering of the display screen becomes remarkable or power consumption increases. .

[0008] More specifically, this is generated when the inversion cycle of the reference voltage and the change of the display pattern coincide (synchronize). For example, a specific horizontal line is formed on a checkered pattern or a green background. This is particularly noticeable in a displayed pattern. The flickering of the screen and the increase in power consumption in such a specific display pattern are inevitable problems in a driving method using a reference voltage having a polarity inversion cycle fixed in advance.

As described above, it is possible to solve the problems of image quality deterioration, operator fatigue, and increased stress due to the occurrence of flickers peculiar to the liquid crystal display device, and to reduce the power consumption regardless of the display pattern from the viewpoint of portability. It is desired to realize a liquid crystal display device that achieves the above. The present invention provides a liquid crystal display device that solves the above-described problems, suppresses flicker that occurs when a specific pattern is displayed, prevents image quality from deteriorating, and can reduce power consumption regardless of the display pattern. It is intended to do so.

[0010]

According to a first aspect of the present invention, there is provided a liquid crystal panel having display pixels arranged in a matrix at each intersection of a plurality of data lines and gate lines. A data driver for supplying the image data of the display pixel unit to the data line, a gate driver for sequentially activating each display pixel via the gate line in synchronization with a horizontal synchronization signal, and at least the image data An input control unit that supplies a display control signal including the horizontal synchronization signal to the data driver and the gate driver to control image data displayed on the liquid crystal panel; and the liquid crystal panel based on the image data. And a reference power generation unit that generates a reference voltage to be applied to a display pixel having a predetermined polarity. The correlation between the change cycle of the data display pattern and the polarity inversion cycle of the reference voltage is monitored, and when it is determined that the change cycle and the polarity inversion cycle are synchronized, the polarity inversion cycle is arbitrarily set. It is characterized by doing.

According to a second aspect of the present invention, in the liquid crystal display device according to the first aspect, the input control section includes an image data extracting means for sequentially extracting the image data, and a change in the extracted image data. A pattern determining unit that counts the amount and compares the amount with a predetermined value to determine a specific display pattern; and an inversion cycle control unit that generates a reference voltage having a different polarity inversion cycle. Means, based on a result of the determination by the pattern determination means,
The polarity inversion cycle is arbitrarily switched and set, and the reference power generation unit generates a reference voltage having the switched polarity inversion cycle and supplies the reference voltage to the data driver.

According to a third aspect of the present invention, in the liquid crystal display device according to the first or second aspect, the input control unit includes:
Input data latch means having a plurality of flip-flops for temporarily holding the image data, wherein the image data extraction means outputs a predetermined logic with the input and output data of the flip-flop of the input data latch means as input And a logic gate for extracting a change state between adjacent pixel data.

Further, according to a fourth aspect of the present invention, in the liquid crystal display device according to the first, second or third aspect, the reference power supply generation section normally selects a predetermined polarity inversion cycle, and selects the specific display pattern. Alternatively, when a state in which the cycles are synchronized is determined, an inversion cycle is randomly selected from another inversion cycle group prepared in advance. According to a fifth aspect of the present invention, in the liquid crystal display device according to the first, second, third or fourth aspect, the inversion cycle control means includes:
The polarity inversion method of the reference voltage applied to the display pixels includes at least an inversion method in units of dots, an inversion method in units of data lines and gate lines, and a state in which the specific display pattern or the period is synchronized. When the determination is made, the polarity inversion method is arbitrarily switched and set.

That is, according to the present invention, the image data extracting means and the pattern judging means sequentially extract and monitor the image data displayed adjacent to each other, and judge a specific display pattern causing flickering or an increase in power consumption. Then, the reference voltage is supplied by the inversion cycle control means at a different polarity inversion cycle prepared in advance. Therefore, according to the liquid crystal display device of the present invention, when the polarity of the data voltage applied to the display pixel is inverted based on the polarity inversion cycle set as the initial state, the display screen flickers or consumes. When image data that displays a specific pattern that causes an increase in power is input, the polarity can be switched to a different polarity inversion cycle. It is possible to suppress flicker specific to the display device or increase in power consumption.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (Basic Configuration) First, a basic configuration of a liquid crystal display device according to the present invention will be described with reference to FIGS. The same components as those of the above-described conventional liquid crystal display device will be described with the same reference numerals.

As shown in FIG. 1, a liquid crystal display device according to the present invention comprises a liquid crystal panel 1 having display pixels arranged in a matrix at each intersection of a plurality of data lines and gate lines, and a pixel unit. A data driver 2 for supplying image data to the data line group 2a, a gate driver 3 for sequentially activating each pixel via a gate line group 3a in synchronization with a horizontal synchronization signal, and a display control information source 4 such as a personal computer An input control unit 5 that takes in image data, a horizontal synchronization signal, an operation control signal, and the like, and controls display of a desired pattern on the liquid crystal panel 1 via a data driver 2 and a gate driver 3. And a reference power supply generating unit 6 for supplying a reference voltage to be applied to the data driver 2. In particular, the input control unit 5 controls the change cycle of the display pattern and the polarity inversion cycle of the reference voltage. Is constantly monitored, and when the synchronization between the two is detected and it is determined that the display pattern is a specific display pattern set in advance, a polarity inversion cycle different from the original reference voltage is output to the reference power generation unit 6. , The reference voltage is supplied to the data driver 2 at an arbitrary inversion cycle.

Here, as shown in FIG. 2, the input control unit 5 has an input I / F unit 11, an input data latch unit 12, and a data output circuit 13 as in the conventional configuration, and The output timing of the image data output to the data driver 2 is set based on the synchronization signal and the operation clock CLK input via the / F unit 11 and the image data extraction signal extracted by the input data latch circuit 12. Operation clock CLK2 of data output circuit 13
And the operation clock of the data driver 2, the data start pulse and the latch pulse, the operation clock of the gate driver 3, the gate start pulse and the output enable signal, and the polarity inversion of the reference voltage supplied from the reference power generation unit 6. It has a timing control circuit 14 that outputs a polarity inversion signal for controlling the cycle.

Further, the main configuration of the timing control circuit 14 will be described with reference to FIG. As shown in FIG. 3, the timing control circuit 14 includes an image data extraction unit 12a that forms the image data extraction unit, a display pattern determination unit 14a that forms the pattern determination unit, and an inversion cycle circuit that configures the inversion cycle control unit. It has a group 14b and switch means 14c.

The image data extracting section 12a is provided in a part of the input data latch circuit 12, and sequentially extracts continuously adjacent image data. The display pattern determination unit 14a
A change between the extracted adjacent image data, for example, a change amount from white to black and the number of changes are counted, and a specific display pattern is determined. Here, the specific display pattern is a pattern in which the display flickers or the power consumption increases remarkably with respect to the polarity inversion cycle of the reference voltage in the initial state, and a horizontal line is formed on a checkered or green background. Refers to a pattern such as display.

Inverting periodic circuit group 14b and switch means 1
4c switches the polarity inversion signal (polarity inversion cycle) output to the reference power generation unit 6 when a specific display pattern is detected based on the determination result from the display pattern determination unit 14a. As shown in FIG. 3, for example, two inversion cycle circuits (A) and (B) having two different polarity inversion cycles are provided, and usually one of the inversion cycle circuits (A) is provided.
When a specific display pattern is detected based on the polarity inversion cycle of (i), the switching means 14c is switched and controlled to select the other inversion cycle circuit (B), and to use a different polarity inversion cycle. Perform display operation.

The reference power supply generator 6 supplies a reference voltage to the data driver 2 based on the inversion cycle of the polarity inversion signal. In addition, as a configuration of the inversion cycle control means, a pair of switch means SW1-SW1 is configured to select one of the plurality of inversion cycle circuits (A) and (B) based on the determination result by the display pattern determination unit 14a.
, SW2-SW2 'is controlled. However, as long as the polarity inversion cycle can be arbitrarily changed and output to the reference power generation unit 6, the invention is not limited thereto. Absent.

(Basic Operation) Next, the inversion cycle control operation of the above-described timing control circuit will be described with reference to the flowchart of FIG. Here, in the timing control circuit shown in FIG.
The switch means 14c for selecting SW4b includes SW1 and SW1.
'Are both in the ON state, and the polarity inversion cycle of the inversion cycle circuit (A) is output to the reference power generation unit 6.

First, the input data extraction unit 12a receives the input I
Input to the input data latch circuit 12 via the / F unit 11,
The stored image data is constantly monitored, and continuously adjacent image data is extracted for each of R, G, and B data (S
1). Next, the display pattern determining unit 14a counts the amount of change and the number of times of change of the image data extracted by the input data extracting unit 12a, and calculates the polarity inversion cycle of the inversion cycle circuit (A) set as an initial state. Then, a display pattern in which the flicker of the display screen becomes remarkable or the power consumption increases is detected and determined (S2).

Next, when a specific display pattern is detected, the switch means SW1 selects the other inversion cycle circuit (B) having an inversion cycle different from that of the currently selected inversion cycle circuit (A). The combination of SW2 and SW1 'is turned off, and the combination of SW2 and SW2' is turned on (S3). Next, the polarity inversion cycle of the newly selected inversion cycle circuit (B) is output to the reference power generation unit 6 as a polarity inversion signal, and a reference voltage is generated with a polarity inversion cycle different from that in the initial state. 2 (S4, S5).

On the other hand, when the image data extracted by the input data extracting section 12a is no longer determined to be a specific display pattern preset in the display pattern determining section 14a, the switched inversion cycle circuit (B) In the case where the display screen flickers remarkably with respect to the polarity inversion cycle of the above or a display pattern that causes an increase in power consumption is detected, the switching to the inversion cycle circuit (A) selected in the initial state is performed. To control the switch means 14c.

According to such a method of switching the inversion cycle, of the display pixels of the liquid crystal panel, only the display pixels having a polarity potential of either positive polarity or negative polarity are turned on (ON). By changing the polarity inversion cycle of the reference voltage applied to the display pixels when the image data of the pattern is input, the arrangement of the display pixels of the positive polarity and the negative polarity can be changed. Here, it is preferable that half of all the display pixels are in the ON state, even if the changed arrangement of the display pixels is the same display pattern.

More specifically, as shown in FIG. 5, in a normal operation state, an inversion cycle circuit (A)
Is selected, and [RGBRGB.multidot.
..] Are arranged in such a manner that data voltages of positive polarity “+” and negative polarity “−” are alternately applied as [+ − + − + −. In such a state, as shown in FIG. 5B, in the case of a display pattern in which only one polarity pixel, for example, only a pixel of positive polarity “+” is turned on, the polarity inversion cycle and the display pattern The changes are synchronized and flicker occurs.

As described above, the pattern displayed on the display screen is constantly monitored by the input data extracting section 12a and the display pattern determining section 14a. 14
The switch means 14c is controlled so as to switch the inversion cycle circuit group 14b based on the determination result from a. As a result, the other inversion cycle circuit (B) is selected, for example, a cycle in which the polarity is inverted randomly in units of horizontal lines as shown in FIG. 5C, or one horizontal cycle as shown in FIG. 5D. A cycle in which the polarity inversion is performed alternately for each line is output to the reference power generation unit 6 as a polarity inversion signal.

Therefore, when a series of image data that is a display pattern that causes flickering and an increase in power consumption is input to the display screen, the polarity inversion cycle of the reference voltage applied to the display pixels can be switched immediately. Therefore, it is possible to improve display quality and reduce power consumption. (Embodiment) An embodiment of the input data extraction unit 12a applied to the liquid crystal display device according to the present invention will be described with reference to FIGS.

As shown in FIGS. 6 and 7, the input data extraction unit 12a includes a plurality of stages of flip-flops (F / F) FRa, FGa, FBa and FR for each of R, G and B data.
b, FGb, FBb in the input data latch circuit provided in the subsequent flip-flops FRb, FGb, F
Bb input data and output data as input, and a predetermined logical output as extracted data,
And a logic gate for outputting the data.

Here, when extracting a checkerboard-like display pattern in which display flicker occurs remarkably, for example, as shown in FIG. 6, an exclusive NOR ( ENOR) gate, and an exclusive OR (EOR) gate for G data. Thus, the input data latch circuit 12
Of the flip-flops FRb, FGb, and FBb of the above-described manner,
The state of the change between successive image data is represented by R,
G and B data can always be extracted.

In order to increase the power consumption of the liquid crystal display device, for example, to extract a display pattern in which the black and white colors of a checkerboard pattern are exchanged, as shown in FIG. FRb, FG
By providing an exclusive OR (EOR) gate for inputting the input data and output data of b and FBb, R,
It is possible to always extract a state in which all the G and B image data fluctuate in a synchronous inversion cycle.

Next, an embodiment of a display pattern determining section applied to the liquid crystal display device according to the present invention will be described with reference to FIG. As illustrated in FIG. 8, the display pattern determination unit 14a performs a logical product (AN) using the R, G, and B logical outputs extracted by the input data extracting unit 12a as inputs.
D) a gate 15a, a counter 15b that receives the logical output as an input, and outputs a count value as a bit,
Bit output from b and a preset specified value (reference value)
And a comparison circuit 15c for comparing
And a plurality of inversion cycle circuit groups 14b which are switched and set by switch means (not shown) and have mutually different polarity inversion cycles.

Here, the inversion cycle circuit group 14b outputs a predetermined polarity inversion signal to the reference power generation unit 6 in the subsequent stage. For example, in the initial state, the inversion cycle circuit (A) is selected. When a specific display pattern that causes flickering of the display screen is detected, it is only necessary to switch to another inverting period circuit (B) (C), and as shown in FIG. What is necessary is just to have the number of inversion period circuits.

As shown in FIG. 8, in a configuration having three or more inversion periodic circuits, different polarity inversion states shown in FIGS. 5B to 5C are changed to the inversion periodic circuit (A). By setting in advance each of (B) and (C), the inversion periodic circuit (A) is usually selected, and when a specific display pattern is detected, the other inversion periodic circuit (B) is selected.
By selecting one inversion cycle circuit at random from (C), it is possible to avoid synchronization between the polarity inversion cycle of the reference voltage applied to the display pixel and the change in the display pattern.

As described above, the input data extracting unit 12a and the display pattern judging unit 14a continuously extract adjacent image data, count the amount of change and the number of changes, and compare the specified values. Thus, a specific display pattern can be monitored and determined, and the screen flicker consumption can be avoided by avoiding synchronization between the cycle of the display pattern displayed on the liquid crystal panel 1 and the polarity inversion cycle of the reference voltage applied to the display pixels. An increase in power can be suppressed.

According to such a drive control method,
Even if the polarity inversion method of the reference voltage applied to the display pixel is, for example, one dot unit, two dot units, or a horizontal line or a vertical line unit, the synchronization state with the cycle of the display pattern is avoided. The polarity inversion cycle can be set appropriately.

[0038]

As described above, according to the liquid crystal display device of the present invention, the image data displayed adjacent to each other is sequentially extracted and monitored by the image data extracting means and the pattern judging means, and the image data is flickered or consumed. When a specific display pattern that causes an increase in power is determined, the inversion cycle is switched by the inversion cycle control means so that the data voltage is applied at a different polarity inversion cycle prepared in advance. And the change of the display pattern are synchronized, avoiding the flicker unique to the liquid crystal display device,
Alternatively, an increase in power consumption can be suppressed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a liquid crystal display device according to the present invention.

FIG. 2 is a schematic configuration diagram of an input control unit applied to the present invention.

FIG. 3 is a main part configuration diagram of a timing control circuit applied to the present invention.

FIG. 4 is a flowchart illustrating an inversion cycle control operation.

FIG. 5 is a diagram illustrating a relationship between an operation state of a display pixel and a polarity inversion cycle.

FIG. 6 is an embodiment of an input data extraction unit applied to the present invention.

FIG. 7 is another embodiment of the input data extraction unit applied to the present invention.

FIG. 8 is an embodiment of a display pattern determination unit applied to the present invention.

FIG. 9 is a schematic configuration diagram of a conventional liquid crystal display device.

FIG. 10 is a main part configuration diagram of a conventional input control unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal panel 2 Data driver 2a Data line group 3 Gate driver 3a Gate line group 4 Display control information source 5 Input control unit 6 Reference power generation unit 11 Input I / F unit 12 Input data latch circuit 12a Input data extraction unit 13 Data output Circuit 14 Timing control circuit 14a Display pattern determination unit 14b Inverted periodic circuit group 14c Switch means 15a AND gate 15B Counter 15c Comparison circuit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H093 NA34 NA43 NA64 NC01 NC09 NC16 NC25 NC26 NC27 ND10 ND34 ND39 NE06 5C006 AA22 AC27 AC28 AF42 AF44 AF51 AF53 AF61 AF71 BB11 BF04 BF06 BF14 BF22 BF26 BF43 FA25 FA47 5C080 A03 DD06 DD26 EE17 FF09 JJ02 JJ03 JJ07

Claims (5)

[Claims] A liquid crystal panel having display pixels arranged in a matrix at respective intersections of a plurality of data lines and gate lines; a data driver for supplying image data in units of display pixels to the data lines; A gate driver for sequentially activating each display pixel via the gate line in synchronization with a synchronization signal; and a display control signal including at least the image data and the horizontal synchronization signal to the data driver and the gate driver. An input control unit that controls image data displayed on the liquid crystal panel; and a reference power generation unit that generates a reference voltage to be applied to a display pixel having a predetermined polarity based on the image data. In the liquid crystal display device, the input control unit includes: a change cycle of a display pattern of the image data; and a polarity inversion cycle of the reference voltage. Correlation monitoring of, when the change period and the polarity inversion cycle is determined a state of synchronization, a liquid crystal display device, characterized in that optionally switchable set the polarity inversion period. 2. The image processing apparatus according to claim 1, wherein the input control unit includes an image data extracting unit that sequentially extracts the image data, counts a change amount of the extracted image data, compares the counted amount with a predetermined value, and displays a specific display pattern. Pattern determining means for determining, and inversion cycle control means for generating a reference voltage having a different polarity inversion cycle, the inversion cycle control means based on the determination result by the pattern determination means, the polarity inversion cycle 2. The liquid crystal display device according to claim 1, wherein the reference power generation unit generates a reference voltage having the switched polarity inversion cycle and supplies the generated reference voltage to the data driver. 3. The input control section includes input data latch means having a plurality of stages of flip-flops for temporarily holding the image data, and the image data extraction means includes an input of a flip-flop of the input data latch means. 3. The liquid crystal display device according to claim 1, further comprising a logic gate that outputs a predetermined logic by using the output data as input and extracts a change state between adjacent pixel data. 4. The reference power generation unit normally selects a predetermined polarity inversion cycle and, when determining the specific display pattern or the state in which the cycle is synchronized, determines a predetermined inversion cycle of another inversion cycle group prepared in advance. 4. The liquid crystal display device according to claim 1, wherein an inversion cycle is selected at random from among them. 5. The inversion cycle control means has at least a dot inversion method and a data line and gate line inversion method as a polarity inversion method of a reference voltage applied to the display pixel. 3. The method according to claim 1, wherein when a specific display pattern or a state in which the period is synchronized is determined, the polarity inversion method is arbitrarily switched and set.
5. The liquid crystal display device according to 3 or 4.