KR20080040102A - Liquid crystal device - Google Patents

Abstract

An LCD(Liquid Crystal Display) is provided to reduce manufacturing costs by including a camera driving unit in an integration chip and improve image quality by mounting a camera in a display panel unit. A driving circuit chip(700) drives a display panel unit. A camera(900) photographs an object and transmits the photographed image to the driving circuit chip. In a display panel unit(300), the driving circuit chip and the camera are mounted. The driving circuit chip comprises a voltage generator for generating a plurality of first voltages, and a camera driving unit(750) for generating a second voltage based on at least one of the plural first voltages and applying the generated second voltage to the camera.

Description

Liquid crystal display {LIQUID CRYSTAL DEVICE}

With reference to the accompanying drawings will be described in detail the embodiments of the present invention to make the present invention clear.

1 is a block diagram of a liquid crystal display according to an exemplary embodiment of the present invention.

2 is an equivalent circuit diagram of one pixel of a liquid crystal display according to an exemplary embodiment of the present invention.

3 is a schematic diagram of a liquid crystal display according to an exemplary embodiment of the present invention.

4 is a diagram illustrating a voltage generated by a camera driver.

FIG. 5 is an example of a circuit diagram of the camera driver shown in FIG. 4.

<Description of Drawing>

3: liquid crystal layer 100: lower display panel

191: pixel electrode 200: upper display panel

230: color filter 270: common electrode

300: liquid crystal panel assembly, display panel portion

400: gate driver

500: data driver 600: signal controller

700: driving chip 750: camera driver

800: gray voltage generator 900: camera

R, G, B: Input image data DE: Data enable signal

MCLK: Main Clock Hsync: Horizontal Sync Signal

Vsync: Vertical Sync Signal CONT1: Gate Control Signal

CONT2: data control signal DAT: digital video signal

Clc: Liquid Crystal Capacitor Cst: Keeping Capacitor

Q: switching device

The present invention relates to a liquid crystal display device.

A typical liquid crystal display (LCD) includes two display panels provided with pixel electrodes and a common electrode, and a liquid crystal layer having dielectric anisotropy interposed therebetween. The pixel electrodes are arranged in a matrix and connected to switching elements such as thin film transistors (TFTs) to receive data voltages one by one in sequence. The common electrode is formed over the entire surface of the display panel and receives a common voltage. The pixel electrode, the common electrode, and the liquid crystal layer therebetween form a liquid crystal capacitor, and the liquid crystal capacitor becomes a basic unit that forms a pixel together with a switching element connected thereto.

In such a liquid crystal display, a voltage is applied to two electrodes to generate an electric field in the liquid crystal layer, and the intensity of the electric field is adjusted to adjust the transmittance of light passing through the liquid crystal layer to obtain a desired image. In this case, in order to prevent degradation caused by an electric field applied to the liquid crystal layer for a long time, the polarity of the data voltage with respect to the common voltage is inverted frame by frame, row by pixel, or pixel by pixel.

Such liquid crystal displays have been widely applied to small and medium sized display devices such as mobile phones.

Small and medium sized display devices include so-called integration chips that integrate several driving devices.

The integrated chip generates a plurality of driving signals for controlling the display panel, and is mainly mounted on the display panel in the form of a chip on glass (COG).

On the other hand, such a small and medium-sized liquid crystal display device is a trend that is gradually spreading products equipped with a camera basically, and requires a separate camera driver for driving the camera.

At this time, the camera driver for driving the camera is usually mounted on a flexible printed circuit board (FPC).

In other words, this means that a separate camera driver increases manufacturing costs and requires space for mounting the camera driver.

In addition, in the process of sending a signal from the camera to the integrated chip, a delay or loss of the signal may occur, thereby degrading the image quality.

Therefore, the technical problem to be achieved by the present invention is to provide a liquid crystal display device that can solve the problems of the prior art.

According to an exemplary embodiment of the present invention, a liquid crystal display device includes a display panel unit, a driving circuit chip for driving the display panel unit, and a camera for photographing a subject and transmitting the object to the driving circuit chip. The drive circuit chip and the camera are mounted to the unit.

In this case, the driving circuit chip may include a signal controller to selectively send data from the outside and data from the camera to the display panel according to a predetermined control signal.

The driving circuit chip may include a voltage generator configured to generate a plurality of first voltages, and a camera driver configured to generate a second voltage based on at least one of the plurality of first voltages and apply the generated voltage to the camera. have.

The camera driver is connected to an operational amplifier having a non-inverting terminal and an inverting terminal connected to a predetermined voltage, an input terminal connected to a variable resistor, a control terminal connected to the control signal, and the non-inverting terminal. And a transistor having an output terminal, wherein the variable resistor may be connected between any one of the first voltage and a ground voltage.

The display panel may include a plurality of pixels each including a switching element and first and second signal lines connected to the switching element.

The liquid crystal display may further include a gate driver configured to generate a gate signal and apply it to the first signal line, and a data driver generate a data voltage and apply the data signal to the second signal line, wherein the driving circuit chip includes the gate driver. And the data driver.

DETAILED DESCRIPTION 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.

In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. Like parts are designated by like reference numerals throughout the specification. When a portion of a layer, film, region, plate, etc. is said to be "on top" of another part, this includes not only when the other part is "right on" but also another part in the middle. On the contrary, when a part is "just above" another part, there is no other part in the middle.

A liquid crystal display according to an exemplary embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

1 is a block diagram of a liquid crystal display according to an embodiment of the present invention, FIG. 2 is an equivalent circuit diagram of one pixel of the liquid crystal display according to an embodiment of the present invention, and FIG. 3 is an embodiment of the present invention. It is a schematic diagram of a liquid crystal display device which concerns on an example. 4 is a diagram illustrating a voltage generated by the camera driver, and FIG. 5 is a circuit diagram illustrating an example of the camera driver illustrated in FIG. 4.

In the following, the liquid crystal panel assembly is also used as a display panel portion.

As shown in FIG. 1, a liquid crystal display according to an exemplary embodiment of the present invention includes a liquid crystal panel assembly 300, a gate driver 400, and a data driver ( 500, a gray voltage generator 800 connected to the data driver 500, a signal controller 600 and a camera 900 for controlling the gray voltage generator 800. In addition, the liquid crystal display according to the exemplary embodiment may further include a DC / DC converter 710 for generating driving voltages Von and Voff and a camera driver 750 connected thereto.

The signal lines G ₁ -G _n and D ₁ -D _m are a plurality of gate lines G ₁ -G _n for transmitting a gate signal (also called a “scan signal”) and a plurality of data lines for transmitting a data voltage ( D ₁ -D _m ). The gate lines G ₁ -G _n extend substantially in the row direction and are substantially parallel to each other, and the data lines D ₁ -D _m extend substantially in the column direction and are substantially parallel to each other.

Pixels connected to each pixel PX, for example, the i-th (i = 1, 2,, n) gate line G _i and the j-th (j = 1, 2,, m) data line D _j ( PX includes a switching element Q connected to the signal lines G _i and D _j , a liquid crystal capacitor Clc and a storage capacitor Cst connected thereto. Holding capacitor Cst can be omitted as needed.

The switching element Q is a three-terminal element of a thin film transistor or the like provided in the lower panel 100, the control terminal of which is connected to the gate line G _i , and the input terminal of which is connected to the data line D _j . The output terminal is connected to the liquid crystal capacitor Clc and the storage capacitor Cst.

The liquid crystal capacitor Clc has two terminals, the pixel electrode 191 of the lower panel 100 and the common electrode 270 of the upper panel 200, and the liquid crystal layer 3 between the two electrodes 191 and 270 is a dielectric material. Function as. The pixel electrode 191 is connected to the switching element Q, and the common electrode 270 is formed on the front surface of the upper panel 200 and receives the common voltage Vcom. Unlike in FIG. 2, the common electrode 270 may be provided in the lower panel 100. In this case, at least one of the two electrodes 191 and 270 may be formed in a linear or bar shape.

The storage capacitor Cst, which serves as an auxiliary part of the liquid crystal capacitor Clc, is formed by overlapping a separate signal line (not shown) and the pixel electrode 191 provided on the lower panel 100 with an insulator interposed therebetween. A predetermined voltage such as the common voltage Vcom is applied to the separate signal line. However, the storage capacitor Cst may be formed such that the pixel electrode 191 overlaps the front gate line G _i-1 directly above the insulator.

On the other hand, in order to implement color display, each pixel PX uniquely displays one of the primary colors (spatial division) or each pixel PX alternately displays the primary colors over time (time division). The desired color is recognized by the spatial and temporal sum of these primary colors. Examples of the primary colors include three primary colors such as red, green, and blue. FIG. 2 illustrates that each pixel PX includes a color filter 230 representing one of the primary colors in an area of the upper panel 200 corresponding to the pixel electrode 191 as an example of spatial division. Unlike in FIG. 2, the color filter 230 may be disposed above or below the pixel electrode 191 of the lower panel 100.

Polarizers (not shown) for polarizing light emitted from a light source unit (not shown) are attached to outer surfaces of the two display panels 100 and 200 of the liquid crystal panel assembly 300.

Meanwhile, in the structure shown in FIG. 3, the camera 900 and the integrated chip 700 are mounted on the display panel 300. In the display area DA, most of the signal lines D ₁ -D _m and the pixels PX are formed.

The camera 900 captures an object and transmits the data CDAT to the integrated chip 700 through wires (not shown) provided in a peripheral area outside the display area DA. Voltage is applied).

The integrated chip 700 receives the signal EDAT from the outside and the image information CDAT from the camera 900 and receives the processed signal to the display panel 300. In addition, the integrated chip 700 includes a camera driver 750 to apply a voltage required for driving the camera 900.

The camera driver 750 starts an operation according to the camera driving signal CAEN and generates the camera driving voltages VDD1 and VDD2 using the voltage AVDD from the DC / DC converter 710, and then the camera 900. To pass on.

As illustrated in FIG. 5, the camera driver 750 may include an operational amplifier OP, a transistor TR, and a variable resistor Rv.

The transistor TR is connected to the non-inverting terminal + of the operational amplifier OP, and the voltage source Vref having a reference voltage is connected to the inverting terminal −. The input terminal of the transistor TR is connected to the variable resistor Rv, and the control terminal is connected to the camera driving signal CAEN. The variable resistor Rv is connected between the power supply voltage AVDD and the ground voltage. The transistor TR is an example of an N-type transistor.

When the camera driving signal CAEN is input, the transistor TR is turned on, and the voltage obtained by distributing the power supply voltage AVDD is transferred to the non-inverting terminal (+) of the operational amplifier OP. The voltage and the inverting terminal (-) The voltage determined by the difference between the voltages Vref is generated as the driving voltage VDD1. In other words, the operational amplifier OP is a differential amplifier.

In this case, the driving voltage VDD1 may be 1.8 V, and the driving voltage VDD2 may be 2.8 V, for example.

Referring back to FIG. 1, the DC / DC converter 710 sequentially amplifies an input voltage Vin from the outside to provide a plurality of voltages required by the driving devices 400, 500, 600, 800, and 750. do.

The gray voltage generator 800 generates a total gray voltage or a limited number of gray voltages (hereinafter, referred to as a "reference gray voltage") related to the transmittance of the pixel PX. The reference gray level voltage may include a positive value and a negative value with respect to the common voltage Vcom.

The gate driver 400 is connected to the gate lines G ₁ -G _n of the liquid crystal panel assembly 300 to form a combination of the gate on voltage Von and the gate off voltage Voff from the DC / DC converter 710. The formed gate signal is applied to the gate lines G ₁ -G _n .

Data driver 500 is connected with the data lines (D ₁ -D _m) of the liquid crystal panel assembly 300, select a gray voltage from the gray voltage generator 800 and the data lines do this as a data voltage (D ₁ -D _m ). However, when the gray voltage generator 800 does not provide all the gray voltages but provides only a limited number of reference gray voltages, the data driver 500 divides the reference gray voltages to generate a desired data voltage.

The signal controller 600 controls the gate driver 400, the data driver 500, and the like.

The signal controller 600, the gate driver 400, the data driver 500, the gray voltage generator 800, the camera driver 750, and the DC / DC converter 710 are one integrated chip as shown in FIG. 3. The display panel 300 is implemented as 700 and mounted on the display panel 300 in a chip on glass (COG) manner. In addition, as described above, the camera 900 is also mounted on the display panel 300.

Next, the operation of the liquid crystal display will be described in detail.

The signal controller 600 receives an input image signal (CDAT, EDAT) and an input control signal for controlling the display thereof from an external graphic controller (not shown) or the camera 900. The input image signals CDAT and EDAT contain luminance information of each pixel PX, and the luminance is a predetermined number, for example, 1024 (= 2 ¹⁰ ), 256 (= 2 ⁸ ), or 64 (= 2 ^6). ) Has gray levels. Examples of the input control signal include a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, a main clock signal MCLK, a data enable signal DE, and a camera driving signal CAEN.

The signal controller 600 properly processes the input image signals CDAT and EDAT according to the operating conditions of the liquid crystal panel assembly 300 based on the input image signals EDAT and CDAT and the input control signals, and controls the gate control signal CONT1. After generating the data control signal CONT2 and the like, the gate control signal CONT1 is sent to the gate driver 400, and the data control signal CONT2 and the processed image signal DAT are sent to the data driver 500. .

The signal controller 600 processes the data CDAT from the camera 900 and, if not input, the camera driving signal CAEN, processes the data EDAT from the outside.

The gate control signal CONT1 includes a scan start signal STV indicating a scan start and at least one clock signal controlling an output period of the gate-on voltage Von. The gate control signal CONT1 may also further include an output enable signal OE that defines the duration of the gate-on voltage Von.

The data control signal CONT2 is analog to the horizontal synchronization start signal STH and the data lines D ₁ -D _m indicating the start of the transmission of the digital image signal DAT to the pixels PX in one row (bundling). A load signal LOAD and a data clock signal HCLK to apply a data voltage are included. The data control signal CONT2 also inverts the signal RVS which inverts the polarity of the data voltage with respect to the common voltage Vcom (hereinafter referred to as "polarity of the data voltage" by reducing the "polarity of the data voltage with respect to the common voltage"). It may further include.

According to the data control signal CONT2 from the signal controller 600, the data driver 500 receives the digital image signal DAT for the pixels PX in one row (bundling), and each digital image signal DAT. By converting the digital image signal DAT into an analog data voltage by selecting the gray scale voltage corresponding to), it is applied to the corresponding data lines D ₁ -D _m .

The gate driver 400 applies the gate-on voltage Von to the gate lines G ₁ -G _n in response to the gate control signal CONT1 from the signal controller 600, thereby applying the gate lines G ₁ -G _n . Turn on the switching element (Q) connected to. Then, the data voltage applied to the data lines D ₁ -D _m is applied to the pixel PX through the turned-on switching element Q.

The difference between the data voltage applied to the pixel PX and the common voltage Vcom is shown as the charging voltage of the liquid crystal capacitor Clc, that is, the pixel voltage. The arrangement of the liquid crystal molecules varies depending on the magnitude of the pixel voltage, thereby changing the polarization of light passing through the liquid crystal layer 3. This change in polarization is represented by a change in the transmittance of light by the polarizer, through which the pixel PX displays the luminance represented by the gray level of the image signal DAT.

This process is repeated in units of one horizontal period (also referred to as "1H" and equal to one period of the horizontal sync signal Hsync and the data enable signal DE), thereby all the gate lines G ₁ -G _n. ), The gate-on voltage Von is sequentially applied, and the data voltage is applied to all the pixels PX to display an image of one frame.

When one frame ends, the state of the inversion signal RVS applied to the data driver 500 is controlled so that the next frame starts and the polarity of the data voltage applied to each pixel PX is opposite to the polarity of the previous frame. "Invert frame"). At this time, even in one frame, the polarity of the data voltage flowing through one data line is periodically changed according to the characteristics of the inversion signal RVS (eg, row inversion and point inversion) or polarity of the data voltage applied to one pixel row. They can be different (eg invert columns, invert points).

As such, when the camera driver 750 driving the camera 900 is included in the integrated chip 700, the manufacturing cost may be reduced by reducing the cost of separately manufacturing the camera driver 750. In addition, when the camera 900 is mounted on the display panel 300, the transmission distance is shorter than that of the signal transmitted through the FPC, thereby preventing the delay or loss of the signal and improving the image quality.

As described above, the manufacturing cost may be further reduced by including the camera driver 750 in the integrated chip 700, and the image quality may be improved by mounting the camera 900 on the display panel 300.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

Claims (7)

Display Panel, A driving circuit chip for driving the display panel; Camera for photographing a subject and transmitting it to the driving circuit chip Including, The driving circuit chip and the camera are mounted on the display panel. Liquid crystal display. In claim 1, The driving circuit chip includes a signal controller for selectively outputting data from the outside and data from the camera to the display panel according to a predetermined control signal. In claim 2, The driving circuit chip is A voltage generator generating a plurality of first voltages, and A camera driver for generating a second voltage based on at least one of the plurality of first voltages and applying it to the camera. Containing Liquid crystal display. In claim 3, The camera driver An operational amplifier having a non-inverting terminal and an inverting terminal connected to a predetermined voltage, and A transistor having an input terminal connected to a variable resistor, a control terminal connected to the control signal, and an output terminal connected to the non-inverting terminal Including; The variable resistor is connected between any one of the first voltage and the ground voltage Liquid crystal display. In claim 1, The display panel unit includes a plurality of pixels each including a switching element and first and second signal lines connected to the switching element, respectively. In claim 5, A gate driver configured to generate a gate signal and apply the gate signal to the first signal line; A data driver which generates a data voltage and applies it to the second signal line Liquid crystal display further comprising. In claim 6, The driving circuit chip further includes the gate driver and the data driver.

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