KR20030075317A - device for calibrating illumination and device for driving liquid crystal device using the same - Google Patents

Abstract

PURPOSE: A device for measuring the intensity of illumination and an LCD driving device using the same are provided to construct a light sensor formed of two transistors inside a black matrix of an LCD panel not to be exposed to the outside, thereby simplifying the fabrication of the LCD. CONSTITUTION: A device for measuring the intensity of illumination includes first and second transistors(M1,M2) connected to each other in serial. Each of the transistors is formed in the shape of thin film transistor to serve as a photo-transistor by the characteristics of the TFT in which carriers increase in response to light radiation. A source of the first transistor is connected to a drain of the second transistor. An input voltage(Vin) is applied between a gate and a drain of the first transistor. A voltage between a gate and the drain of the second transistor is output as an output voltage(Vout).

Description

Apparatus for calibrating illumination and device for driving liquid crystal device using the same}

The present invention relates to an illuminance measuring device and a driving device of a liquid crystal display device using the same.

Among display elements for displaying various types of information, liquid crystal displays are used as monitors of notebook PCs, and camcorders, automotive LCDs, and the like.

Generally, amorphous silicon is mainly used in the process of integrating a thin film transistor on a liquid crystal display substrate. Since amorphous silicon has a threshold voltage of about 1.7 eV and an adsorption constant is larger than that of crystallized silicon, it is widely used in optoelectronics or optoelectronic devices. Can be. In addition, the large area can be made inexpensive, and the deposition can be performed at a low temperature. In addition, since amorphous silicon effectively generates holes and electrons by visible light, the amount of light current generated can be changed according to the amount of light felt by the human eye. This characteristic can be used to adjust the image according to the amount of external light.

Conventionally, due to the characteristics of such amorphous silicon, a thin film transistor is used as an optical sensor to control illuminance. As a method of using a thin film transistor as an optical sensor, a single thin film transistor is mounted in a top chassis hole of a liquid crystal display and connected to an external illumination control circuit to control an image. This is used as an illuminance control signal by using the absolute amount of the photo current flowing through the thin film transistor forming the optical sensor for each liquid crystal display.

However, the optical sensor according to the related art has a problem in that it is disadvantageous in terms of assembly and is also exposed. In addition, since the conventional thin film transistor detects illuminance as one optical sensor using an absolute amount of photo current, there is a problem in that inconvenience and productivity have to be separately tuned according to component distribution of the optical sensor.

Accordingly, an object of the present invention is to provide an illuminance measuring device for a liquid crystal display device which is easy to manufacture.

Another object of the present invention is to provide an illuminance measuring device capable of measuring illuminance reliably without performing a separate tuning process for each liquid crystal display and a driving device of the liquid crystal display device using the same.

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

2 is a diagram showing an equivalent circuit of the illuminance measuring apparatus according to the first embodiment of the present invention.

3 is a diagram in which an illuminance measuring apparatus according to a first exemplary embodiment of the present invention is disposed on a liquid crystal panel.

4 is a diagram illustrating a result of changing an input voltage Vin versus an output voltage Vout of the illuminance measuring apparatus according to the first exemplary embodiment of the present invention according to the illuminance.

5 is a circuit diagram of an illuminance measuring apparatus according to a second embodiment of the present invention.

6 is a circuit diagram of an illuminance measuring apparatus according to a third embodiment of the present invention.

FIG. 7 is a simulation result illustrating voltages of respective parts according to the timing design of Vin and V2 of FIG. 6.

In the illuminance measuring device of the liquid crystal display device including a display area in which a plurality of pixels are formed and a black matrix area formed around the display area, the illuminance measuring device of the present invention is formed in the black matrix area, The black matrix is removed, is exposed to light, is driven by a first voltage applied, and operates in conjunction with the first transistor, the first transistor having a variable resistance value according to the amount of light, and a black matrix formed thereon. And a second transistor to block light, and the output voltage is changed according to a split resistance ratio between the first transistor and the second transistor.

In addition, a first amplifier for amplifying and outputting the output voltage; A first switch, a capacitor for charging the output voltage applied according to the operation of the first switch, and a second switch for discharging the voltage charged in the capacitor, wherein the second switch is configured according to the operation of the first and second switches. Preferably, the voltage charged in the capacitor is provided to the first amplifier, and the first switch and the second switch further include a switch unit which does not operate at the same time.

On the other hand, a plurality of gate lines and data lines are formed in the row and column direction, respectively, and a plurality of pixels having a switching element connected to the gate line and the data line, respectively, in a region defined by the intersection of the gate line and the data line A drive device for a liquid crystal display device comprising: a display area formed with a liquid crystal display; and a liquid crystal panel having a black matrix area formed around the display area, wherein the drive device for the liquid crystal display device according to the present invention is gated to the gate line. A gate driver supplying a voltage; A data driver supplying a corresponding gray voltage to the data line according to an applied data signal; A first transistor formed in the black matrix region, the upper black matrix being removed, exposed to light, driven by a first voltage applied thereto, and having a resistance value varied according to the amount of light, and interlocked with the first transistor And a second transistor for blocking light by forming a black matrix thereon, and an illuminance measuring unit including an optical sensor unit configured to change an output voltage according to a split resistance ratio between the first transistor and the second transistor. It is made to include.

The illuminance measuring unit may include: a first amplifier configured to amplify and output the output voltage; A first switch connected to the optical sensor unit, a capacitor charging an output voltage applied according to the first switch operation, and a second switch discharging a voltage charged in the capacitor, wherein the first switch and the first switch are discharged. According to an operation of the second switch, the voltage charged in the capacitor is provided to the first amplifier, and the first switch and the second switch preferably further include a switch unit which does not operate at the same time.

The display device may further include a second amplifier positioned between the optical sensor unit and the first switch to amplify the output voltage.

In addition, the switch unit may be composed of a diode and the first switch and the second switch, respectively.

Hereinafter, an illuminance measuring apparatus and a liquid crystal display apparatus using the same will be described with reference to the accompanying drawings.

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

As shown in FIG. 1, the liquid crystal display according to the exemplary embodiment of the present invention includes a liquid crystal panel 10, a data driver 20, a gate driver 30, a timing controller 40, and a gray voltage generator 50. And an illuminance measuring unit 60.

The liquid crystal panel 10 has a plurality of gate lines G1, G2, G3,..., Gn for transmitting a gate-on signal, and includes a data line D1, for transmitting a data voltage representing an image signal. D2, ..., Dm) are formed. Each region surrounded by the gate line and the data line constitutes a pixel, and each pixel is connected to the thin film transistor T and the drain electrode of the thin film transistor T, the gate electrode and the source electrode of which are connected to the gate line and the data line, respectively. (Cl). The pixel forms a display area of the liquid crystal panel 10, and a black matrix area is formed around the display area.

The data driver 20 is also called a source driver, and serves to lower the voltage value transmitted to each pixel in the liquid crystal panel 10 by one line. More specifically, the data driver 20 stores digital data from the timing controller 40 described later in a shift register in the data driver, and then a signal (LOAD signal) for instructing the liquid crystal panel 10 to lower the data. In this case, a voltage corresponding to each data is selected to transfer the voltage into the liquid crystal panel 10.

The gate driver 30 may also be referred to as a scan driver. The gate driver 30 opens a path for data from the data driver 20 to be transferred to the pixel. Each pixel of the liquid crystal panel 10 is turned on or off by the thin film transistor T serving as a switch.

The timing controller 40 generates a digital signal for driving the data driver 20 and the gate driver 30. Specifically, the timing controller 40 generates a signal that enters the drivers 20 and 30, adjusts timing of data, and adjusts clock. It plays a role.

The gray voltage generator 50 generates a gray voltage entering the data driver 20, and in particular, generates a gray voltage for each of the R, G, and B data, and supplies the gray voltage to the data driver 20.

The illuminance measuring unit 60 includes an optical sensor formed in the black matrix area of the liquid crystal panel 10. In detail, the illuminance measuring unit 60 converts a signal sensed by the optical sensor into an appropriate signal to adjust the timing controller 40. ) To be used as an illuminance control signal for driving the backlight to adjust the brightness of the liquid crystal display, or to the gradation voltage generator 50 to change the gamma curve according to the illuminance to increase visibility. Let's do it.

Hereinafter, the illuminance measuring unit 60, which is a main part of the present invention, will be described in detail.

The illuminance measuring unit 60 according to the present invention includes an optical sensor formed in the black matrix area of the liquid crystal panel 10. First, a first embodiment of the present invention will be described in detail with reference to FIGS. 2 and 3. Shall be.

2 is a diagram illustrating an equivalent circuit of the illuminance measuring apparatus according to the first exemplary embodiment of the present invention, and FIG. 3 is a diagram in which the illuminance measuring apparatus according to the first exemplary embodiment of the present invention is disposed in the liquid crystal panel.

As shown in FIG. 2, the illuminance measuring apparatus according to the first embodiment of the present invention is composed of two transistors M1 and M2 connected in series. Here, each of the transistors M1 and M2 is formed in the form of a thin film transistor TFT, and when light is irradiated, the transistors M1 and M2 act as phototransistors due to the characteristics of the thin film transistor in which carriers of the inside are increased.

The source of the transistor M1 and the drain of the transistor M2 are connected. An input voltage Vin is applied between the gate drains of the transistors M1, and outputs a voltage as the output voltage Vout between the gate drains of the transistors M2.

In particular, in an embodiment of the present invention, transistor M1 is exposed to light and transistor M2 is not exposed to light.

In the illuminance measuring apparatus according to the present invention having the above characteristics, as illustrated in FIG. 3, transistors M1 and M2 are formed in the form of thin film transistors having the same size inside the black matrix region of the liquid crystal panel 100. The black matrix BM covered over the region of one transistor M1 is removed.

Therefore, the transistor M1 positioned in the region where the black matrix BM is removed is exposed to light, and the transistor M2 positioned in the region where the black matrix BM is not removed is not exposed to light.

In addition, as shown in FIG. 3, the input voltage Vin, the output voltage Vout, and the ground GND of the illuminance measuring apparatus according to the first embodiment of the present invention are connected to the driving circuit.

Next, the operation of the illuminance measuring apparatus according to the first embodiment of the present invention will be described.

In the dark illuminance, the characteristics of the two transistors M1 and M2 are the same. That is, since light is not irradiated to each of the transistors M1 and M2, the concentration of the carrier in each transistor channel does not increase. Accordingly, the half voltage Vin / 2 is applied to each of the transistors M1 and M2 by the input voltage Vin applied thereto. On the other hand, when light caused by illuminance is irradiated to the transistor M1 from which the black matrix BM has been removed, the carrier concentration in the channel of the transistor M1 is increased to decrease the resistance at turn-on, and thus the transistor M1 has a higher density than Vin / 2. High voltage is applied.

In other words, when the two transistors M1 and M2 having the same size are turned on, the divided voltage is generated as the output voltage Vout.

The output voltage Vout is converted into an appropriate signal to be used as an illuminance control signal of the backlight to adjust luminance, and to be applied to a gray voltage generator to change the gamma curve to increase visibility.

4 is a diagram illustrating a result of changing an input voltage Vin versus an output voltage Vout of the illuminance measuring apparatus according to the first exemplary embodiment of the present invention according to the illuminance.

As shown in Fig. 4, when the illuminance is ALUX (DARK) < BLUX < CLUX, the output voltage Vout is 0 when ALUX is dark and V (ALUX) = V1 / 2 < V (BLUX) < It can be seen that V (CLUX).

Next, an illuminance measuring apparatus according to a second embodiment of the present invention will be described.

5 is a circuit diagram of an illuminance measuring apparatus according to a second embodiment of the present invention.

As shown in FIG. 5, the illuminance measuring apparatus according to the second exemplary embodiment of the present invention includes an optical sensor unit 100, a switch unit 200, and an amplifier 300.

As described above, the photosensor unit 100 includes a transistor M1 exposed to light and a transistor M2 not exposed to light connected to the transistor M1.

In this case, a pulse-shaped first voltage Vin is applied between the gate drains of the transistor M1, and a voltage between the gate drains of the transistor M2 is applied to the switch unit 200 as an output signal Vout.

The switch unit 200 includes a first switch S1 connected to a first side, a capacitor C connected to a second side, and a second switch S2 connected to a third side with the node n as the center. The fourth side is connected to the amplifier 300. At this time, the second voltage V2 is applied to the second switch S2.

The amplifier 300 includes an operational amplifier (OPA). Here, the operational amplifier OPA amplifies the voltage charged in the capacitor C to generate an illumination control voltage Vcontrol.

The first switch S1 of the switch unit 200 is turned on while the pulse-shaped first voltage Vin is applied to charge the output voltage Vout of the optical sensor unit 100 to the capacitor C. FIG. .

The voltage charged in the capacitor C is output to the amplifier 300, after which the second switch S2 is turned on to discharge the voltage of the capacitor C. In this case, the second switch S2 operates according to the second voltage V2.

Therefore, since the lowest value of the output voltage Vout of the photosensor unit 100 is Vin / 2 in the dark state, the second voltage V2 is set to maintain the Vin / 2 or less.

If the minimum amount of charge is to be introduced during charging of the capacitor C, it is preferable to set the second voltage V2 to Vin / 2.

Meanwhile, the first switch S1 and the second switch S2 are not turned on at the same time, and both the first and second switches S1 and S2 should be turned off during the display time when the gray voltage is applied to the pixel. Therefore, the turn on time of the two switches S1 and S2 must exist during the vertical blank time. In addition, since the output signal Vout of the optical sensor unit 100 needs to be recharged after the discharge of the capacitor C, the second switch S2 has a timing design such that the second switch S2 is operated just before the first switch S1 is turned on. It is desirable to.

Next, an illuminance measuring apparatus according to a third embodiment of the present invention will be described.

6 is a circuit diagram of an illuminance measuring apparatus according to a third exemplary embodiment of the present invention, and FIG. 7 is a simulation result showing voltages of respective parts according to the timing design of Vin and V2 of FIG. 6.

As shown in FIG. 6, the illuminance measuring apparatus according to the third embodiment of the present invention uses diodes D1 instead of the first and second switches S1 and S2 shown in FIG. 5 of the second embodiment of the present invention. , D2), and when the current driving ability of the transistors M1 and M2 is small, it is insufficient to charge the capacitor C within a short time. An OPB was added to allow voltage amplification to the voltage level required for charging C).

Operation of the illuminance measuring apparatus according to the third embodiment of the present invention is as follows.

6 and 7, after the second voltage V2 is at a low level to discharge the capacitor C, the first voltage Vin is at a high level to operate the transistors M1 and M2. . At this time, according to the amount of light sensed by the transistor M1, the divided voltages of the transistors M1 and M2 are charged to the capacitor C via the op amp OPA. The voltage charged in the capacitor C is amplified by the operational amplifier (OPB) of the amplifier 300 and then supplies the desired illuminance control voltage (Vcontrol) to the necessary circuit as the divided resistors of the resistors R3 and R4. .

Therefore, the illuminance measuring apparatus of the present invention can operate the transistors M1 and M2 of the optical sensor unit 100 only for a minimum time, thereby preventing deterioration of the transistors M1 and M2.

In the illuminance measuring apparatus according to the first to third embodiments of the present invention, an optical sensor is formed inside the black matrix of the liquid crystal display to prevent exposure to the outside. In addition, by connecting the transistor covered by the black matrix and the transistor exposed by the black matrix removal, the divided voltage by the relative resistance ratio of the two transistors is output and used as the illuminance control voltage, thereby solving the problem of reduced productivity due to the necessity of tuning. It was.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. It will be appreciated.

As described above, the illuminance measuring apparatus of the liquid crystal display according to the present invention may facilitate the manufacture of the liquid crystal display by forming an optical sensor composed of two transistors inside the black matrix of the liquid crystal panel so as not to be exposed to the outside. . In addition, the upper part of one transistor is a method of eliminating the black matrix, and uses the divided voltage value of the relative resistance ratio of the two transistors as the illuminance control voltage, thereby improving productivity by separately tuning each liquid crystal display device. Can be.

Claims (6)

In the illuminance measuring apparatus of the liquid crystal display device including a display area in which a plurality of pixels are formed, and a black matrix area formed around the display area, A first transistor formed in the black matrix region, the first black matrix being removed to be exposed to light, and driven by a first voltage applied to the black matrix to change a resistance value according to the amount of light; It operates in conjunction with the first transistor, and includes a second transistor formed on the black matrix to block the light, An illuminance measuring apparatus, the output voltage of which is varied according to a split resistance ratio between the first transistor and the second transistor. In claim 1, A first amplifier for amplifying and outputting the output voltage; A first switch, a capacitor for charging the output voltage applied according to the operation of the first switch, and a second switch for discharging the voltage charged in the capacitor, wherein the second switch is configured according to the operation of the first and second switches. A voltage charged in a capacitor is provided to the first amplifier, and the switch unit does not operate simultaneously with the first switch and the second switch. Illuminance measuring device further comprising. A plurality of gate lines and data lines are formed in the row and column directions, respectively, and a plurality of pixels having switching elements connected to the gate line and the data line are formed in an area defined by the intersection of the gate line and the data line, respectively. In the driving device of the liquid crystal display device comprising a liquid crystal panel having a display area and a black matrix area formed around the display area, A gate driver supplying a gate voltage to the gate line; A data driver supplying a corresponding gray voltage to the data line according to an applied data signal; A first transistor formed in the black matrix region, the upper black matrix being removed, exposed to light, driven by a first voltage applied thereto, and having a resistance value varied according to the amount of light, and interlocked with the first transistor And a second transistor for blocking light by forming a black matrix thereon, and an illumination sensor including an optical sensor unit configured to vary an output voltage according to a split resistance ratio between the first transistor and the second transistor. ; Driving device for a liquid crystal display comprising a. In claim 3, The illuminance measuring unit A first amplifier for amplifying and outputting the output voltage; A first switch connected to the optical sensor unit, a capacitor charging an output voltage applied according to the first switch operation, and a second switch discharging a voltage charged in the capacitor, wherein the first switch and the first switch are discharged. According to the operation of a switch, a voltage charged in the capacitor is provided to the first amplifier, and the switch unit in which the first switch and the second switch do not operate simultaneously. The driving device of the liquid crystal display device further comprising. In claim 4, And a second amplifier disposed between the optical sensor unit and the first switch to amplify the output voltage. In claim 3, The switch unit And the first and second switches are each composed of diodes.