KR20090007169A - Liquid crystal display device having photo sensor, fabricating method of the same, and controling method of the same - Google Patents

Liquid crystal display device having photo sensor, fabricating method of the same, and controling method of the same Download PDF

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Publication number
KR20090007169A
KR20090007169A KR1020070070869A KR20070070869A KR20090007169A KR 20090007169 A KR20090007169 A KR 20090007169A KR 1020070070869 A KR1020070070869 A KR 1020070070869A KR 20070070869 A KR20070070869 A KR 20070070869A KR 20090007169 A KR20090007169 A KR 20090007169A
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KR
South Korea
Prior art keywords
liquid crystal
optical sensor
crystal panel
crystal display
light source
Prior art date
Application number
KR1020070070869A
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Korean (ko)
Inventor
최상호
Original Assignee
엘지디스플레이 주식회사
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Priority to KR1020070070869A priority Critical patent/KR20090007169A/en
Publication of KR20090007169A publication Critical patent/KR20090007169A/en

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    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1343—Electrodes
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/3406—Control of illumination source
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/02—Improving the quality of display appearance
    • G09G2320/0233—Improving the luminance or brightness uniformity across the screen

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  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Liquid Crystal (AREA)
  • Mathematical Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Optics & Photonics (AREA)
  • Computer Hardware Design (AREA)
  • Theoretical Computer Science (AREA)

Abstract

The present invention discloses a liquid crystal display device having an optical sensor, a manufacturing method thereof, and a brightness control method of the liquid crystal display device. The disclosed liquid crystal display device includes a light source and a current supply unit supplying a driving current to the light source. The liquid crystal display according to the present invention includes a liquid crystal panel having a screen display area, a current formed on the liquid crystal panel to at least one optical pulse, and a current applied to the light source by a sinking signal of the optical pulse. And a control unit for controlling the supply amount.

According to the above configuration, the present invention can control the amount of current supplied to the light source by the matching signal of the optical sensor, thereby maintaining the initial bright brightness to implement a uniform brightness.

Description

Liquid crystal display device with optical sensor and manufacturing method thereof, brightness control method of liquid crystal display device. {LIQUID CRYSTAL DISPLAY DEVICE HAVING PHOTO SENSOR, FABRICATING METHOD OF THE SAME, AND CONTROLING METHOD OF THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, a manufacturing method thereof, and a brightness control method. More particularly, the present invention relates to a liquid crystal display device, a manufacturing method, and a brightness control method capable of improving luminance uniformity using an optical sensor.

In general, the liquid crystal display device has a trend that the application range is gradually widened due to the characteristics such as light weight, thin, low power consumption. In accordance with this trend, liquid crystal displays are used in office automation equipment, audio / video equipment, and the like. In such a liquid crystal display, a transmission amount of a light beam is adjusted according to a signal applied to a plurality of control switches arranged in a matrix to display a desired image on a screen.

Since the liquid crystal display is not a self-luminous display, a separate light source such as a back light is required. The backlight includes a direct type and an edge type according to the position of the light source. An edge type backlight is provided with a light source at one edge of the liquid crystal display, and irradiates the liquid crystal display panel with light incident from the light source through the light guide plate and the plurality of optical sheets. In the direct type backlight, a plurality of light sources are disposed directly below the liquid crystal display, and light incident from the light sources is irradiated onto the liquid crystal display panel through the diffusion plate and the plurality of optical sheets.

Recently, the direct type backlight having higher luminance, light uniformity and color purity than the edge type has been used more mainly in LCD TVs.

1 is a view showing a conventional liquid crystal display device to which a direct type backlight is applied.

As shown in FIG. 1, a conventional liquid crystal display device includes a liquid crystal display panel 11 for displaying an image and a backlight unit 10 for irradiating light to the liquid crystal display panel 11.

In the liquid crystal display panel 11, a plurality of data lines and a plurality of gate lines are arranged to cross each other, and liquid crystal cells are arranged in an active matrix form between the upper substrate and the lower substrate. Further, pixel electrodes and common electrodes for applying an electric field to each of the liquid crystal cells are formed in the liquid crystal display panel. Thin film transistors (TFTs) for switching data voltages to be applied to the pixel electrodes are formed at intersections of the plurality of data lines and the gate lines. Gate drive integrated circuits and data drive integrated circuits are electrically connected to the liquid crystal display panel through a tape carrier package (TCP).

The backlight unit 10 includes a plurality of lamps 15, a cover bottom 12, a diffusion plate 13, and a plurality of optical sheets 14.

Here, the lamps 15 emit light by an alternating current high voltage from an inverter (not shown) to generate light toward the diffusion plate 13.

The cover bottom 12 is manufactured in a container structure in which a plurality of lamps 15 are accommodated in an inner space, and reflecting plates (not shown) are formed on the bottom and side surfaces of the inner space.

 The diffusion plate 13 is assembled with the cover bottom 13. The diffuser plate 13 includes a plurality of beads and uses the beads

 The light incident through the lamps 15 is scattered so that the luminance difference does not occur at the position of the lamps 15 and the position between the lamps 15 on the display surface of the liquid crystal display panel 11. Since the diffuser plate 13 is manufactured in a structure in which beads are dispersed in a medium having the same refractive index, light cannot be collected.

The optical sheets 14 include one or more diffusion sheets and one or more prism sheets to uniformly irradiate the light incident from the diffusion plate 13 to the entire liquid crystal display panel 11 and to be perpendicular to the display surface. It serves to condense the light to the front of the display surface by bending the light path in the direction.

The lamp 15 includes a cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp (EEFL), a light emitting diode (LED), and the like. Among them, the external electrode fluorescent lamp can realize high brightness, and unlike the cold cathode fluorescent lamp in which the electrode is in the lamp, the electrodes are externally, so that they are generally operated in parallel to reduce the voltage deviation between the lamps. have. In addition, the use of external electrode fluorescent lamps is increasing in energy efficiency and long life.

2 is a plan view illustrating a schematic structure of a backlight unit using a conventional external electrode fluorescent lamp, and FIG. 3 is a cross-sectional view taken along line II ′ of FIG. 2.

As shown in FIGS. 2 and 3, the conventional external electrode fluorescent lamp has an external electrode 17 connected to the lamp 15 and the external electrodes 17 disposed at regular intervals on the cover bottom 12. A wire or cable for fixing the common electrode 19 and the common electrode 19 to the cover bottom 12 and electrically connecting the inverter 22 and the common electrode 19 formed under the cover bottom 12 ( And a power inlet screw 20 for connecting 24.

In the conventional backlight unit using the external electrode fluorescent lamp as described above, there is a problem that the initial increase in brightness is initially increased and then the brightness of the entire backlight unit gradually decreases and becomes uneven when a predetermined time elapses.

Since the luminance unevenness is difficult to predict the time according to the surrounding environment, light sensing of the backlight light source is required. However, attaching an optical sensor attachment to the exterior of the backlight incurs additional costs and requires some complicated procedures, such as linking the optical sensor and backlight drive.

SUMMARY OF THE INVENTION In order to solve the above problems, an object of the present invention is to compensate for a change in luminance over time of a backlight light source, thereby providing a liquid crystal display device having an optical sensor capable of improving luminance uniformity, a manufacturing method thereof, and a luminance control method. Is to provide.

In order to achieve the above object, the liquid crystal display device according to the present invention includes a light source and a current supply unit for supplying a driving current to the light source. The liquid crystal display according to the present invention includes a liquid crystal panel having a screen display area, a current formed on the liquid crystal panel to at least one optical pulse, and a current applied to the light source by a sinking signal of the optical pulse. And a control unit for controlling the supply amount.

The optical sensor is formed outside the screen display area of the liquid crystal panel. More specifically, the optical sensor is formed on the lower substrate of the liquid crystal panel.

The liquid crystal panel includes the lower substrate, an upper substrate disposed to face the lower substrate, and a black matrix covering a portion corresponding to the optical sensor on the upper substrate.

The optical sensor includes a semiconductor layer formed on a substrate, a source electrode / drain electrode formed on the substrate having the semiconductor layer, and an ohmic contact layer formed between the semiconductor layer and the source electrode / drain electrode.

It is preferable that the semiconductor layer has a thickness of 1000 to 2000 GPa.

The present invention provides a method of manufacturing a liquid crystal display device having a light source and a current supply unit for supplying a driving current to the light source, the method comprising: forming an optical sensor outside the screen display area on the liquid crystal panel and by a sensing signal of the optical sensor; Adjusting the photocurrent to the current supply unit.

The forming of the optical sensor may include providing a liquid crystal panel having a screen display area, forming a semiconductor layer outside the screen display area on the liquid crystal panel, and forming an ohmic contact layer on the substrate having the semiconductor layer. And forming a source electrode and a drain electrode at predetermined intervals on the substrate having the ohmic contact layer.

It is preferable to form the said semiconductor layer in thickness of 1000-2000 micrometers.

The present invention provides a brightness control method of a liquid crystal display device having a light source, a current supply unit for supplying a driving current to the light source, a liquid crystal panel, and an optical signal formed on the liquid crystal panel, wherein a predetermined off current reference value is set. And calculating an off-current measurement value through the optical sensor, comparing the measured value with a reference value, calculating an optical output compensation value when the measured value is smaller than the reference value, and providing the current supply unit by the calculated compensation value. Supplying further photocurrent to the device.

According to the present invention, an optical sequence for covering the amount of light is provided outside the screen display area of the liquid crystal panel. Thus, by controlling the amount of current supplied to the light source by the fining signal of the optical sensor, the initial bright luminance is continuously maintained. As a result, uniform luminance can be realized.

In addition, the present invention has the advantage of reducing the power consumption according to the frequent on / off of the liquid crystal panel.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

4 is a schematic view of a liquid crystal display device having an optical sensor according to the present invention, and FIG. 5 is an enlarged plan view of part A of FIG. 6A and 6B are cross-sectional views of the processes taken along the line II-II ′ of FIG. 5.

7 is a cross-sectional view of a liquid crystal display device having an optical sensor according to the present invention, and FIG. 8 is a flowchart illustrating a method of realizing the luminance uniformly using the optical sensor according to the present invention.

The liquid crystal display according to the present invention constitutes an optical laser when fabricating a thin film transistor on a lower substrate. At least one optical sensor may be formed outside the screen display area of the liquid crystal panel.

As shown in FIG. 4, the liquid crystal display device according to the present invention includes a liquid crystal panel 100 having a screen display area, and formed on the liquid crystal panel 100 to sense the amount of light and at least one optical sensor 130. And a control unit for controlling the amount of current supplied to the light source by the fining signal of the optical sensor 130. Here, the liquid crystal display according to the present invention includes a light source (not shown) and a current supply unit (not shown) for supplying a driving current to the light source.

The optical sensor 130 may be formed outside the screen display area of the liquid crystal panel 100, and at least one optical sensor 130 may be disposed on the outer portion. Specifically, the optical sensor 130 is formed on the lower substrate 101 of the liquid crystal panel 100, and is simultaneously formed in the process of forming the thin film transistor on the lower substrate 101.

As shown in FIGS. 5 and 7, the optical sensor 130 includes a semiconductor layer 103 formed on the lower substrate 101 and a source electrode 107S formed on the substrate having the semiconductor layer 103. ) / Drain electrode 107D, and an ohmic contact layer 105 formed between the semiconductor layer 103 and the source electrode 107S / drain electrode 107D. The ohmic contact layer 105 has a structure of exposing a portion of the semiconductor layer. Here, it is preferable that the semiconductor layer 103 has a thickness of 1000 to 2000 GPa.

Meanwhile, as shown in FIG. 7, the liquid crystal panel 100 includes a lower substrate 101, an upper substrate 121 disposed to face the lower substrate 101, and an upper substrate 121. It includes a black matrix 123 covering a portion corresponding to the optical sensor 130. In this case, the black matrix 123 serves to prevent light leakage and block external light exposure.

Hereinafter, a method of manufacturing a liquid crystal display device according to the present invention having the above structure will be described with reference to FIGS. 6A to 6B.

As shown in FIG. 6A, a semiconductor layer 103 is formed on the lower substrate 101.

6B, an ohmic contact layer 105 is formed on the substrate having the semiconductor layer 103.

6B, a metal film is formed on the substrate having the ohmic contact layer 105, and the metal film is patterned to form a source electrode 107S and a drain electrode 107D. As a result, the optical photo sensor 130 according to the present invention is completed. In this case, fabrication of the optical sensor 130 according to the present invention proceeds simultaneously with fabrication of the thin film transistor, and proceeds in the same process except for the formation of the gate electrode.

On the other hand, the upper substrate 123 is provided on the lower substrate 101 having the optical sensor 130. The upper substrate 123 has a color filter (not shown) and a black matrix 123 covering a portion corresponding to the optical sensor 130.

Hereinafter, a luminance control method of the liquid crystal display according to the present invention will be described with reference to FIG. 8.

As shown in FIG. 8, a constant voltage is applied to the source electrode 107S while driving the screen of the optical sensor. The off current measurement value formed in the semiconductor layer 103 is determined according to the light amount of the light source disposed under the liquid crystal panel 100. At this time, electron transfer occurs in the semiconductor layer between the source electrode and the drain electrode due to the remaining amount of light, and the off current value is matched to the optical sensor by the electron transfer.

The matched off current measurement is then compared with a predetermined reference value. As a result, when the measured value is larger than the reference value, it can be determined that the luminance has not decreased. However, when the measured value is smaller than the reference value, the light output compensation value is calculated. Thereafter, by supplying a photocurrent to the current supply unit by the calculated compensation value, the luminance can be maintained uniformly without deterioration. Here, the photocurrent may be a tube current applied to a lamp tube of a light source, for example, a light source.

In the present invention, as shown in Fig. 5, in order to improve the off current detection force, the width W between the source electrode 107S and the drain electrode 107D is widened, and the source electrode 107S and the drain electrode 107D are widened. The length L between) designs the optical sensor 103 in a decreasing direction.

The semiconductor layer 103 constituting the optical sensor 130 is formed as thick as possible. In this case, the semiconductor layer 103 is preferably formed to a thickness of 1000 ~ 2000∼.

Meanwhile, in the present invention, a plurality of optical sensors may be formed at positions outside the screen display area of the liquid crystal panel, and the sensing signals of the optical sensors may be used as averaging data.

1 is a view showing a conventional liquid crystal display device to which a direct type backlight is applied.

Figure 2 is a plan view showing a schematic structure of a backlight unit using a conventional external electrode fluorescent lamp.

3 is a cross-sectional view taken along the line II ′ of FIG. 2.

4 is a schematic view of a liquid crystal display device having an optical sensor according to the present invention;

5 is an enlarged plan view of a portion A of FIG. 4;

6A and 6B are cross-sectional views of processes taken along the line II-II ′ of FIG. 5.

7 is a cross-sectional view of a liquid crystal display device having an optical sensor according to the present invention.

8 is a flowchart illustrating a method of realizing uniformity of luminance using an optical sensor according to the present invention.

Claims (10)

A liquid crystal display device comprising a light source and a current supply unit supplying a driving current to the light source. A liquid crystal panel having a display area; Is formed on the liquid crystal panel and the amount of light, the at least one optical sensor, And a control unit for controlling an amount of current supplied to the light source by a matching signal of the optical sensor. The liquid crystal display device according to claim 1, wherein the optical sensor is formed outside the screen display area of the liquid crystal panel. The liquid crystal panel of claim 1, wherein The lower substrate, An upper substrate disposed to face the lower substrate; And a black matrix covering a portion corresponding to the optical sensor on the upper substrate. The liquid crystal display device according to claim 3, wherein the optical sensor is formed on a lower substrate of the liquid crystal panel and is formed outside the screen display area of the liquid crystal panel. The method of claim 1, wherein the optical sensor A semiconductor layer formed on the substrate, A source electrode / drain electrode formed on the substrate having the semiconductor layer; And an ohmic contact layer formed between the semiconductor layer and the source electrode / drain electrode. 6. The liquid crystal display device according to claim 5, wherein the semiconductor layer has a thickness of 1000 to 2000 kHz. In the manufacturing method of the liquid crystal display device having a light source and a current supply unit for supplying a driving current to the light source Forming an optical sensor outside the screen display area on the liquid crystal panel; And controlling a photo current in the current supply part by a sensing signal of the optical sensor. The method of claim 7, wherein forming the optical sensor Providing a liquid crystal panel having a screen display area; Forming a semiconductor layer outside the screen display area on the liquid crystal panel; Forming an ohmic contact layer on the substrate having the semiconductor layer; And forming a source electrode and a drain electrode at predetermined intervals on the substrate having the ohmic contact layer. 10. The method of claim 8, wherein the semiconductor layer is formed to a thickness of 1000 to 2000 kHz. In the brightness control method of the liquid crystal display device provided with the light source, the current supply part which supplies a drive current to the said light source, a liquid crystal panel, and the optical order formed in the said liquid crystal panel, Setting a predetermined off current reference value; Obtaining off-current measurements through the optical sensor, Comparing the measured value with a reference value and calculating a light output compensation value when the measured value is smaller than the reference value; And supplying a photocurrent to the current supply unit by the calculated compensation value.
KR1020070070869A 2007-07-13 2007-07-13 Liquid crystal display device having photo sensor, fabricating method of the same, and controling method of the same KR20090007169A (en)

Priority Applications (1)

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KR1020070070869A KR20090007169A (en) 2007-07-13 2007-07-13 Liquid crystal display device having photo sensor, fabricating method of the same, and controling method of the same

Applications Claiming Priority (1)

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KR1020070070869A KR20090007169A (en) 2007-07-13 2007-07-13 Liquid crystal display device having photo sensor, fabricating method of the same, and controling method of the same

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KR20090007169A true KR20090007169A (en) 2009-01-16

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