KR100927709B1 - Display device and driving device thereof - Google Patents

Abstract

The present invention relates to a display device and a drive device thereof.

In the present invention, a plurality of first electrodes and a plurality of second electrodes are formed in row and column directions, respectively, and data pulses are applied to a display panel in which a plurality of pixels are formed in an area defined by the intersection of the gate line and the data line. In particular, gamma correction is performed by changing the interval of the data pulse for each gray level. The interval between the data pulses is widened at a portion where the change of the emission current of the display device is small for each gray level, and the interval between the data pulses is narrowed at a portion where the change amount of the emission current of the display device is large for each gray level, and the display is performed for each gray level. In the part where the emission current of the device changes proportionally, the intervals of the data pulses are equally spaced.

According to the present invention, gamma correction is performed according to the luminance of the surrounding environment, thereby further improving visibility of the display device.

Description

Display and driving device thereof

1 is a graph showing general gamma characteristics.

2 is a plan view of a field emission display device according to an exemplary embodiment of the present invention.

3 is a cross-sectional view of a field emission display device according to an exemplary embodiment of the present invention.

4 is a graph illustrating a relationship between a voltage applied to a panel and emission current in the field emission display device according to an exemplary embodiment of the present invention.

5 is a structural diagram of a driving device of a field emission display device according to an exemplary embodiment of the present invention.

FIG. 6 is a detailed structural diagram of the panel controller shown in FIG. 5.

7 is an exemplary view showing an output of a data pulse according to an embodiment of the present invention.

8 is a graph illustrating voltage-current characteristics according to an embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display, and more particularly, to a display having a gamma-correction function and a driving device thereof.                         

Recently, display devices are also required to be lighter and thinner in accordance with the light weight and thickness of personal computers and televisions, and according to such demands, instead of cathode ray tubes (CRTs), such as field emission displays (FEDs), etc. Flat panel display devices are being developed.

In such a display device, gamma correction is performed to express various colors. Gamma correction is an image enhancement technology that matches the difference between the display device and human visual perception by adjusting the image to the most suitable contrast and color. In order to express a natural screen, it is possible to set a constant gray-scale level by dividing the amount of light felt by human vision.However, in a dark screen, the brightness difference is easily distinguished. The brightness difference on the bright screen is adjusted in consideration of the difficulty of distinguishing the brightness level. This method is called gamma correction.

The commonly used gamma correction uses a method of adjusting linearity by converting a VT-curve into a logarithmic function in that human visual characteristics are similar to a logarithmic function. A typical VT curve is shown in FIG. The slope of the logarithmic function of the VT curve mainly used a value between 1.5 and 3.

However, as a result of displaying the image by applying the gamma curve values used in the prior art to the display device, the difference between the display device and the human visual perception characteristics cannot be matched properly, so that delicate gray scale display is not possible and the distribution of brightness Was uneven, resulting in a rough image.

Therefore, the technical problem to be achieved by the present invention is to solve the conventional problem, and to match the difference between the human visual perception characteristics and the display device in a display device driven by a pulse width modulation (PWM) method.

According to an aspect of the present invention, a driving device of a display device includes a plurality of first electrodes and a plurality of second electrodes formed in rows and columns, respectively, and define intersections of the gate lines and data lines. A driving device of a display device including a display panel in which a plurality of pixels are formed in a region, the driving device comprising: a first driver supplying a scan signal to the first electrode; A second driver supplying a data pulse signal to the second electrode; And a panel controller which generates and supplies the scan signal and converts the interval of the data pulse based on the luminance value of each gray level to output the scan signal to the second driver.

Here, the panel control unit generates a number setting signal for determining the multiplication number of the reference clock signal based on the luminance value of each gray level, a start signal and an end signal for respectively indicating a start position and an end position of a section to which the multiplication number is applied. Comparator; A reference clock converter for multiplying a reference clock signal input according to the multiplication number setting signal and outputting the reference clock signal for a period defined by the start signal and an end signal, and outputting a data pulse whose interval is changed based on the multiplied reference clock signal And a PWM generator including a signal output unit.                     

In the display device according to another aspect of the present invention, a plurality of first electrodes and a plurality of second electrodes are formed in rows and columns, respectively, and a plurality of pixels are formed in an area defined by the intersection of the gate line and the data line. Display panel; A first driver supplying a scan signal to the first electrode; A second driver supplying a data pulse signal to the second electrode; And a panel controller which generates and supplies the scan signal and converts the interval of the data pulse based on the luminance value of each gray level to output the scan signal to the second driver.

According to another aspect of the present invention, a display device includes a first substrate and a second substrate that are disposed to face each other at a predetermined interval, and are formed on opposite surfaces of the first substrate and are formed in one direction. A first electrode, a plurality of second electrodes formed on the opposite surface of the second substrate and formed to intersect the first electrode, and the first electrode corresponding to an intersection region of the first electrode and the second electrode. A display panel including an electron emission source respectively formed on the display panel; A first driver supplying a scan signal to the first electrode; A second driver supplying a data pulse signal to the second electrode; And a panel controller which generates and supplies the scan signal and converts the interval of the data pulse based on the luminance value of each gray level to output the scan signal to the second driver.

According to the present invention having the above characteristics, the interval between the data pulses is widened at a portion where the change of the emission current of the display device is small for each gray level, and the interval between the data pulses is at a portion where the change amount of the emission current of the display device is large for each gray level. The data pulses are narrowed and the data pulses are equally spaced at portions where the emission current of the display device is proportionally changed for each gray level.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

In the following embodiment, the difference between the visual perception characteristic of the human being and the field emission display device is matched in the field emission display device, but the display device according to the present invention is not limited to the field emission display device. Applicable to all display devices driven.

A field emission display (FED) is a display device that forms an image using cold cathode electrons as an electron emission source.

FIG. 2 is a schematic plan view of a lower substrate of a field emission display device according to an exemplary embodiment of the present invention, and FIG. 3 is a schematic cross-sectional view of the field emission display device.

As illustrated in FIGS. 2 and 3, the field emission display device includes two glass substrates 1 and 2 facing each other and separated from each other. On the glass substrate (lower substrate) 1, the plurality of gate electrodes 10 extend in the vertical direction at regular intervals. The gate electrode 10 is covered with the insulating film 20, and the insulating film 20 may be formed of glass, SiO ₂ , polyimide, nitride, a combination thereof, or a stacked structure thereof.

On the insulating film 20, the plurality of cathode electrodes 30 extend in the horizontal direction at regular intervals. One pixel region is formed in a region where the cathode electrode 30 and the gate electrode 10 which are perpendicular to each other meet. An electron emission layer 40 is formed on the cathode electrode 30 positioned in each pixel region so that electrons are emitted through the electron emission layer 40. 2 and 3, the electron emission layer 40 is formed to cover the edge of the cathode electrode 30 and the insulating film 20. However, the position at which the electron emission pieces 40 are formed is not limited thereto. For example, the electron emission layer 40 may be formed only at the center of the cathode electrode 30 or at one edge of the cathode electrode 30, or It may be formed at both edges of the cathode electrode 30. In addition, the electron emission layer 40 may be formed of a carbon-based material, such as carbon natonoube, C ₆₀ (fulleren), diamond, diamond like carbon (DLC), graphite, or a combination thereof.

On the other hand, unlike the present embodiment, the insulating film 20 may include a contact hole for exposing the gate electrode, in this case, a counter electrode made of a conductive material is formed on the portion where the contact hole is formed, the counter electrode It is preferable to connect with the gate electrode through the silver contact hole.

On the glass substrate (upper substrate) 2, a plurality of anode electrodes 50 made of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO) extend in the vertical direction at regular intervals.

The fluorescent film 60 is formed on the anode electrode 50, and R, G, and B fluorescent materials are formed in the fluorescent film 60 corresponding to the pixel region, respectively. A pixel region composed of R, G, and B fluorescent materials forms one R, G, B pixel.

A grid electrode 70 or a mesh electrode is formed between the glass substrates 1 and 2, and the grid electrode 70 is formed in an aperture at a position corresponding to the pixel area on a thin metal sheet. It is made in the form that is formed. That is, the openings correspond one-to-one to one pixel region, and R, G, and B phosphors are formed in the fluorescent film 60 corresponding to the pixel region.

Spacers (not shown) are formed between the glass substrate 1 and the grid electrode 70 and between the glass substrate 2 and the grid electrode 70, respectively, so that the grid electrode 70 is between the glass substrates 1 and 2. It is fixed at. Such spacers (not shown) are formed in the non-pixel regions of the glass substrates 1 and 2.

In the field emission display device having such a structure, when a voltage is applied to the gate electrode 10, an electric field caused by the gate voltage penetrates the insulating layer 20, and a strong electric field is formed at the electron emission source 40, thereby preventing the field emission. Electrons are emitted.

For example, a high level of DC voltage Va is applied to the anode electrode 50 and a low level of DC voltage Vg is applied to the gate electrode 10. The voltage Vm of a level lower than the anode voltage Va and higher than the gate voltage Vg is applied to the grid electrode 70. A voltage higher than the mesh voltage Vm is applied to the unselected cathode electrode, and a negative voltage Vc is applied to the selected cathode electrode.

Then, electrons are emitted from the electron emission layer 40 by an electric field formed by the voltage difference Vg-Vc between the cathode electrode 30 and the gate electrode 10, and the voltage Vm applied to the grid electrode 70. Electrons pass through the opening formed in the grid electrode 70. The electrons passing through the opening of the grid electrode 70 reach the fluorescent film 60 on the glass substrate 2 corresponding to the opening, and the color corresponding to the phosphor formed in the fluorescent film 60 is displayed.

As described above, the emission current characteristic according to the data voltage applied to the gate electrode or the cathode electrode in the field emission display device is as shown in FIG. 4. 4 shows voltage-current characteristics of the field emission display.

As shown in FIG. 4, the voltage-current characteristic can be divided into three parts. That is, when the voltage starts to be applied for the first time (Black), there is little change in the emission current even when the voltage is changed. Then, it is divided into an intermediate portion in which the emission current changes in proportion to the applied voltage. Therefore, in order to display the gradation of the medium brightness, the middle linear section is mainly used.

In the actual image implementation, the gray level is displayed by dividing the interval in which the emission current almost linearly changes with respect to the applied voltage in several steps. However, when the voltage is divided at regular intervals, the emission currents do not become constant due to the nonlinear nature of the emission currents. That is, in order to display a delicate image, the gradation of the middle part should be finely divided. When the gradation is divided by a constant voltage, the distribution of the emission current is large at one side and the other is small, resulting in uneven luminance distribution. . If the image is displayed in this state, it is difficult to display the delicate gradation and the image becomes rough.

Therefore, in order to display a smooth image, it is necessary to maintain the emission current at regular intervals rather than voltage. To do this, it is necessary to make the gradation voltage narrower in the middle part, narrower in the white part, and wider in the black part.

Therefore, in the exemplary embodiment of the present invention, by adjusting the values of data corresponding to the image to be displayed using the PWM interval, the image is adjusted to the most comfortable contrast and color, so that the display device and human visual perception characteristics Match the differences between.

5 illustrates a structure of a driving device of a field emission display device according to an embodiment of the present invention for correcting such gamma.

As shown in FIG. 5, the driving device of the field emission display device according to an exemplary embodiment of the present invention provides data for displaying an image on the display panel 100 having a structure as shown in FIGS. 2 and 3. The processor 200 includes a panel controller 300, a first driver, and a second driver 500.

The data processor 200 may receive data (for example, R, G, and B data) from various sources or various control signals (eg, vertical and horizontal sync signals (Vsync, Hsync), reference for driving the field emission display device). A clock signal, etc.) is supplied and converted into a form that can be supplied to the display panel.

The panel controller 300 generates a timing control signal according to the signal provided from the data processor 200 and supplies the timing control signal to the first driver 400, and the first driver 400 sequentially scans the pulses according to the timing control signal. The display panel 100 is supplied to the display panel 100. The scan pulse is supplied to the gate electrode or the cathode electrode of the display panel 100. When the gate electrode is used as a scan electrode driven according to the scan pulse, the cathode electrode is used as the data electrode, and when the cathode electrode is used as the scan electrode, the gate electrode is used as the data electrode.

In addition, the panel controller 300 supplies a data pulse corresponding to data provided from the data processor 200 to the second driver 500, and the second driver 500 supplies the data pulse to the display panel 100. The image corresponding to the gray value of the data pulse is displayed. In particular, in the exemplary embodiment of the present invention, the panel controller 300 performs gamma correction by adjusting the interval of the data pulse by the PWM method.

6 illustrates a partial structure of the panel controller 300 according to an exemplary embodiment of the present invention for correcting such gamma. 6 illustrates only a portion for gamma correction according to an exemplary embodiment of the present invention among the components of the panel controller 300, and the remaining portions of the panel controller 300 are already known technologies, and thus, the detailed description will be provided herein. Omit.

As shown in FIG. 6, the panel controller 300 for gamma correction according to an exemplary embodiment of the present invention has a number setting signal for determining the multiplication number of the reference clock signal based on the reference clock signal Incclk and the brightness value Bright. (clknum), a comparator 310 for generating a start signal S-num and an end signal E-num, respectively, for determining a start position and an end position of each multiplication value section, and a comparator 310 And a PWM generator 320 generating a data pulse PWMMCLK whose interval is changed according to a signal output from the controller. Specifically, the PWM generator 320 may multiply and output the reference clock signal Inclk input based on the signal output from the comparator 310 and output the multiplied reference clock signal Inclk. The signal output unit 322 generates a data pulse whose interval is changed based on the.

Referring to the operation of the driving device of the field emission display according to the embodiment of the present invention having such a structure in more detail, when analog, R, G, B data provided from an external video processor (not shown) is inputted, The data processor 200 processes the R, G, and B data as digital data and outputs the digital data. The data processor 200 processes the R, G, and B data as a control signal necessary for driving the field emission display based on various control signals, and provides the same to the panel controller 300. .

The comparator 310 of the panel controller 300 is stored in a brightness value (Bright) for each gray level input according to a reference clock signal (Inclk) input from the data processor 200 and in its own LUT (look up table). By comparing the luminance value, the multiplication number of the reference clock signal for generating the PWM pulse is set. In the LUT according to an embodiment of the present invention, a signal value for setting the multiplication number of the reference clock signal corresponding to the luminance value of each gray level and a section value indicating a section to which the multiplication value is applied are stored. Accordingly, the comparator 310 checks the LUT based on the input luminance value and outputs a number setting signal clknum for determining the multiplication number of the reference clock signal according to the signal value corresponding to the luminance value. A start signal S-num and an end signal E-num are respectively determined to determine a start position and an end position of each multiplication period according to a section value corresponding to the luminance value. The signals generated in this way are input to the PWM generator 320.

The reference clock converter 321 of the PWM generator 320 multiplies the reference clock signal Inclk by the number corresponding to the number setting signal clknum output from the comparator 310, and starts the signal S-num and The reference clock signal multiplied during the period corresponding to the end signal E-num is output. Accordingly, the signal output unit 322 adjusts the interval of the data pulses according to the multiplied reference clock signal and outputs the data pulses to the second driver 500. Therefore, the data pulses whose intervals are changed according to the gradation level are applied to the display panel 100, so that the gradation display is performed. In this case, the data pulse is supplied to the gate electrode or the cathode electrode of the display panel 100.

7 illustrates an example of outputting a data pulse according to an exemplary embodiment of the present invention. As illustrated in FIG. 7, the interval of the data pulse is widened at the gradation level at which the emission current is hardly changed by adjusting the multiplication number of the reference clock signal described above, and at the gradation level at which the emission current changes rapidly. Reduce the interval of data pulses. In the gray level where the emission current is linearly generated, the data pulses are adjusted at equal intervals.

In this way, the reference clock signal for adjusting the interval of the data pulse is multiplied according to the gradation level to differentially control the period of the data pulse for each gradation level, so that the emission current can be maintained at a constant interval. 8 illustrates a characteristic curve of data voltages for each gray level according to the gamma correction.

Although the present invention has been described with reference to the most practical and preferred embodiments, the present invention is not limited to the above disclosed embodiments, but also includes various modifications and equivalents within the scope of the following claims.

As described above, according to the present invention, in a display device driven by a pulse width modulation (PWM) method, a difference between a human visual recognition characteristic and a display device may be matched. Thereby, the visibility of a display apparatus can be improved more.

Claims (10)

A plurality of first electrodes and a plurality of second electrodes are formed in rows and columns, respectively, and the display panel includes a display panel in which a plurality of pixels are formed in an area defined by the intersection of the gate line and the data line. In the device, A first driver supplying a scan signal to the first electrode; A second driver supplying a data pulse signal to the second electrode; And And a panel controller configured to generate and supply the scan signal, and convert the interval of the data pulse based on the luminance value of each gray level to output the scan signal to the second driver. The panel control unit A comparison unit configured to generate a number setting signal for determining the multiplication number of the reference clock signal based on the luminance value of each gray level, a start signal and an end signal indicating a start position and an end position of a section to which the multiplication number is applied; And A reference clock converter for multiplying a reference clock signal input according to the multiplication number setting signal and outputting the reference clock signal during a period defined by the start signal and the end signal, and a data pulse whose interval is changed based on the multiplied reference clock signal And a PWM generator including an output signal output unit. delete The method of claim 1 And the display device is a field emission display device. The method according to claim 1 or 3 In the characteristic curve of the voltage vs. the emission current of the display device, the interval of the data pulse is widened in the interval of the smaller slope of the two non-linear intervals of the characteristic curve. The method according to claim 1 or 3 In the characteristic curve of the voltage versus the emission current of the display device, the interval of the data pulse is narrowed in the section of the two slopes of the non-linear slope of the characteristic curve is larger. The method according to claim 1 or 3 The driving device of the display device, wherein the intervals of the data pulses are equally spaced at a portion where the emission current of the display device is proportionally changed for each gray level. A display panel in which a plurality of first electrodes and a plurality of second electrodes are formed in row and column directions, respectively, and a plurality of pixels are formed in an area defined by the intersection of the gate line and the data line; A first driver supplying a scan signal to the first electrode; A second driver supplying a data pulse signal to the second electrode; And And a panel controller configured to generate and supply the scan signal, and convert the interval of the data pulse based on the luminance value of each gray level to output the scan signal to the second driver. The panel control unit A comparison unit configured to generate a number setting signal for determining the multiplication number of the reference clock signal based on the luminance value of each gray level, a start signal and an end signal indicating a start position and an end position of a section to which the multiplication number is applied; And A reference clock converter for multiplying a reference clock signal input according to the multiplication number setting signal and outputting the reference clock signal during a period defined by the start signal and the end signal, and a data pulse whose interval is changed based on the multiplied reference clock signal A display device comprising a PWM generator including a signal output unit for outputting. A first substrate and a second substrate disposed to face each other at regular intervals, A plurality of first electrodes formed on opposite surfaces of the first substrate and formed in one direction; A plurality of second electrodes formed on opposing surfaces of the second substrate and formed to intersect the first electrode; A display panel including an electron emission source formed on each of the first electrodes corresponding to an intersection area between the first electrode and the second electrode; A first driver supplying a scan signal to the first electrode; A second driver supplying a data pulse signal to the second electrode; And And a panel controller configured to generate and supply the scan signal, and convert the interval of the data pulse based on the luminance value of each gray level to output the scan signal to the second driver. The panel control unit A comparison unit configured to generate a number setting signal for determining the multiplication number of the reference clock signal based on the luminance value of each gray level, a start signal and an end signal indicating a start position and an end position of a section to which the multiplication number is applied; And A reference clock converter for multiplying a reference clock signal input according to the multiplication number setting signal and outputting the reference clock signal during a period defined by the start signal and the end signal, and a data pulse whose interval is changed based on the multiplied reference clock signal A display device comprising a PWM generator including a signal output unit for outputting. delete The method according to claim 7 or 8 The interval between the data pulses becomes wider in a section in which the slope of the characteristic curve is less linear among two sections in which the slope of the characteristic curve is non-linear in the characteristic curve of the display device, and the characteristic of the voltage versus emission current of the display device. In the curve, the interval between the data pulses is narrowed in the section where the slope of the characteristic curve is non-linear is large, and the interval of the data pulses is equal in the portion where the emission current is proportionally changed for each gray level. Display device consisting of intervals.

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