KR100705622B1 - LCD comprising optical sensor unit - Google Patents

Abstract

The present invention is to maintain a constant brightness of the display by adjusting the current or voltage of the light sensing element for sensing the brightness of the liquid crystal display device, and the inverter to control the brightness of the backlight by sensing the intensity of light emitted from the backlight with the light sensing element The present invention relates to a liquid crystal display device, which provides a light sensing element for measuring the brightness of a liquid crystal display device at an edge portion of a liquid crystal panel of the liquid crystal display device. By detecting in advance, it is possible to maintain stable luminance efficiently.

In particular, in the present invention, by integrating a photosensitive device at the edge of the liquid crystal panel through the same production line and manufacturing process as the liquid crystal panel, there is an effect of reducing the manufacturing time, cost, and improved characteristics.

Description

Liquid crystal display device comprising a light sensing element {LCD comprising optical sensor unit}

1 is an example of a conventional photosensitive device.

2 is an example of a circuit diagram of a conventional photosensitive device shown in FIG.

3 is an example of a photosensitive device according to the present invention.

4 is another example of a photosensitive device according to the present invention.

5 is a view for explaining a liquid crystal display device having a light sensing element according to the present invention;

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device having an optical sensing element. In particular, an optical sensing element for sensing the brightness of the liquid crystal display and an inverter for sensing the intensity of light emitted from the backlight with the optical sensing element to control the brightness of the backlight. The present invention relates to a liquid crystal display device which maintains a constant brightness of a display by adjusting a current or a voltage thereof.

In recent years, there is an increasing demand for a product (display used in a hospital, airport search station, non-destructive inspection device, etc.) having a constant front luminance of a display in a high brightness liquid crystal display device.

By the way, the backlight, which is a light source used for the display of a liquid crystal display device, gradually decreases as the use time of the light becomes longer. Generally, when the light is used for about 10,000 hours, the amount of light decreases to about 10% or less compared with the initial stage. to be.

For this reason, when the liquid crystal display is used for a long time, the brightness of the display is lowered due to deterioration of the backlight, thereby causing a problem in that the front luminance of the display is not kept constant.

In order to solve this problem, conventionally, a device for sensing the brightness, i.e., a light sensing element, etc. is installed outside the liquid crystal display to detect the brightness of the display at a predetermined level. The brightness of the display can be kept constant by connecting a liquid crystal display device and a separate device connected to an optical sensing element.

FIG. 1 shows an example of such a conventional light sensing element, and FIG. 2 shows an example of a circuit diagram of the conventional light sensing element shown in FIG.

As can be seen in FIG. 1, the photosensitive device is largely composed of a sensor transistor, a charging and transmitting portion, and a switch transistor. Here, the sensor transistor has a function of generating a photocurrent by sensing the amount of light, and the charging and transmitting part transmits light and charges a current (that is, a charge) transmitted from the sensor transistor, and the switch transistor transmits an external control signal. (Not shown) has a function of outputting the charge stored in the charging unit. In relation to the operation, it can be seen that the light of the backlight is reflected from the subject and applied to the sensor transistor.

However, such a conventional photosensitive device is installed outside the liquid crystal display device, and therefore, separate devices are required to connect them in order to control the liquid crystal display device by sensing the amount of current or voltage output from the switch transistor. This has the disadvantage of requiring additional cost and additional space.

FIG. 2 is a circuit diagram of the photosensitive device shown in FIG. 1.

As shown, it can be seen that the sensor transistor functions to convert light into a current and then store it in an adjacent storage means capacitor, and then transfer the charge stored in the capacitor to the signal line when the switch transistor is turned on. Here, the signal line is transmitted to the above-described equipment for controlling the liquid crystal display.

However, as described above, in the related art, the photosensitive device for measuring the brightness of the display is generally installed outside the liquid crystal display device, for example, around the display unit. In order to control the brightness of the display, It was necessary to provide a separate equipment for interlocking the light sensing element.

For this reason, in the related art, there is a problem in that additional space is required as well as additional cost for installing individual equipment.

SUMMARY OF THE INVENTION The present invention has been proposed to solve the above-mentioned problems, and an object thereof is to form a photosensitive device integrally on a substrate of a liquid crystal display device to more efficiently correct luminance of the liquid crystal display device.                         

In addition, the present invention proposes a structure of a new light sensing element formed integrally with the liquid crystal display.

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A liquid crystal display device having a light sensing element according to the present invention includes a top plate including a color filter unit, a bottom plate including a liquid crystal panel array unit, and a backlight for providing light from the bottom plate to the top plate. At least one light including a sensor transistor for sensing, a charging and transmitting portion for charging the charge according to the amount of light sensed by the sensor transistor and transmitting the light of the backlight, and a switching transistor for switching the output of the charge stored in the charging and transmitting portion A sensing element is integrally formed on the lower plate, and a reflective layer is formed on the upper plate region corresponding to an upper portion of the region where at least one light sensing element is formed to reflect light passing through the charging and transmitting unit to the sensor transistor. The photosensitive device is connected to the liquid crystal panel array unit. W being placed at a predetermined position on the outside of the active area on the lower plate to be formed, characterized by at least one supplied from the photo-sensing device output is provided on the lower panel for the control of the drive voltage supplied to the backlight.
A reader IC configured to provide a control signal to the photosensitive device to operate the switching transistor, and to input a signal output according to the switching of the switching transistor; And a controller configured to receive the output of the photosensitive device through the reader IC to adjust the driving voltage provided to the backlight.
In addition, the sensor transistor and the switch transistor of the photosensitive device may be configured in the singular or plural, respectively, to share one of the charging and transmitting units.
(Example)

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

3 is an example of a photosensitive device according to the present invention.

As shown in the drawing, the photosensitive device includes a sensor transistor 330 which is a sensing transistor, a charging unit 340, and a switch transistor 350. Here, the sensor transistor 330 has a function of generating a photo current by sensing the amount of light, and the charging unit 340 transmits light and charges the current (ie, charge) transmitted from the sensor transistor 330. The switch transistor 350 has a function of outputting charges stored in the charging unit by an external control signal (not shown). For reference, since the basic circuit of FIG. 3 is substantially the same as that of FIG. 2, no further description will be provided in this regard.

Hereinafter, an example of the manufacturing method of the photosensitive device will be described.

In the first step of the first step, a gate thin film is deposited on a transparent substrate 300 representing a window through which light from a backlight, a light source of a liquid crystal display, is transmitted, and then patterned to form a gate electrode 304 of the sensor transistor 330. The gate electrode 302 of the switch transistor 350 is formed.

In the second step, after depositing ITO or the like in the region of the charging unit 340, the transparent electrode 306 is formed by patterning.

Next, in a third step, the insulating film 308 is entirely deposited.

In a fourth step, amorphous silicon or the like is deposited and patterned to form the active region 310 of the sensor transistor and the active region 312 of the switch transistor.

In a fifth step, a transparent conductive material such as ITO is deposited and patterned to form another transparent electrode 315.

In a sixth step, the conductive material is deposited and patterned to form the drain electrode 314 and the source electrode 317 of the sensor transistor 330, and also the drain electrode 316 and the source electrode 319 of the switch transistor 350. ).

Next, in a seventh step, the first insulating protective film 318 is deposited and patterned to form a contact region.

Next, in an eighth step, a shield bar 311 is deposited and patterned.

Next, in step 9, the second insulating protective film 320 is deposited and patterned as shown.

Thereafter, a reflective layer 322 is finally provided on these to serve to reflect light from the backlight and to shield external light. The reflective layer 322 is shown spaced apart from other components of the light sensing element, because it is preferably disposed at a corresponding position on the color filter substrate (corresponding to FIG. 5) of the liquid crystal display device.

Here, it is preferable that the first step and the third to seventh steps proceed simultaneously with the formation of the LCD-TFT for display of the liquid crystal display.

Hereinafter, the overall configuration and operation will be described in more detail.

The transparent substrate 300 has a window function for transmitting light from a backlight which is a light source of the liquid crystal display device.

The sensor transistor 330 basically includes a gate electrode 304, an insulating film 308, an active region 310, a drain electrode 314, and a source electrode 317. The sensor transistor 330 receives a light amount of the backlight reflected from the reflective layer 322 to generate a photocurrent.

In the charging unit 340, the capacitor includes a transparent electrode 306, a transparent electrode 315, and an insulating film 308 therebetween. The charging unit 340 stores the photocurrent transferred from the sensor transistor 330 in the form of a charge.

The switch transistor 350 basically includes a gate electrode 302, an insulating film 308, an active region 312, a drain electrode 316, and a source electrode 319. The switch transistor 350 functions to output the charge information stored in the capacitor of the charging unit to the outside.

The reflective layer 322 positioned on the sensor transistor 330, the charging unit 340, and the switch transistor 350 reflects the backlight light incident through the transparent substrate to the sensor transistor, and at the same time, may be reflected from the external light source. It also serves as a shield to prevent light from entering the photosensitive layer of the sensor transistor.

In addition, although not shown (see FIG. 5 to be described later), a driving IC for driving the sensor transistor, a reader IC for outputting charge information stored from the switch transistor, an electric signal output from the reader IC, and then a backlight are read. A control unit is provided to control the voltage or current of the drive inverter, as well as to control the on / off of the drive IC and the reader IC.

As described above, when the backlight is used for a long time, the amount of light of the backlight is generally reduced. When the amount of light in the backlight is reduced, the photocurrent generated by the sensor transistor is correspondingly reduced, and the amount of charge stored in the capacitor of the charging unit is also reduced. This information, i.e. the reduction in the amount of light, is sent to the readout circuit (not shown) through the reader IC through the switch transistor, and the readout circuit changes the voltage or current of the backlight drive inverter based on this information to reduce the amount of light in the backlight. Readjust.

Therefore, when the feedback operation is continuously performed, the brightness of the LCD of the liquid crystal display may be maintained relatively constant. As a result, when the predetermined image information is displayed, the image having the same white color coordinate characteristic may be realized. have.

4 is another example of the photosensitive device according to the present invention.

In the first step of the first step, the gate metal of the sensor transistor 430 is deposited by patterning and depositing a first metal thin film for a gate on a transparent substrate 400 representing a window through which light from a backlight, which is a light source of a liquid crystal display, is transmitted. 402 and a gate electrode 401 of the switch transistor 450 are formed.

In the second step, after depositing ITO or the like in the region of the charging unit 440, the transparent electrode 404 is formed by patterning.

Then, in a third step, the insulating protective film 406 is entirely deposited.

In the next fourth step, an amorphous silicon or the like used as the active layers 408 and 409 is deposited, and an etch stopper 414 is formed by back exposure.

In the next fifth step, the second metal thin film is deposited and patterned to form a source, a drain electrode, and the like of the transistor, and the etch stopper of the sensor transistor is etched.

In a sixth step, a transparent conductive material such as ITO is deposited and patterned to form another transparent electrode 412.

Next, in step 7, an insulating protective film 415 is deposited and patterned as shown. By depositing the insulating protective film 412 on the transparent electrode 412, it is possible to protect the device from external impurities and moisture.

Thereafter, a reflective layer 416 is finally installed on these to serve to reflect light from the backlight and shield external light.

5 is a view for explaining a liquid crystal display device having a light sensing element according to the present invention.

As shown, the light sensing element 500 is arranged on the upper right side of the periphery in the liquid crystal display device, which is distinguished from the display area of the liquid crystal panel array unit, preferably in the region where no gate or data pad is disposed. The arrangement position of the light sensing element can be arbitrarily changed. For example, if it is arranged in the peripheral portion corresponding to a partial region (region where the black matrix BM is formed) of the color filter portion of the liquid crystal display device, it is possible anywhere. For reference, in the drawings, the upper plate represents the color filter unit, and the lower plate represents the liquid crystal panel array unit. Sensor transistors and switch transistors constituting the photosensitive device may be configured in the singular or plural to share one charging and transmitting unit. In addition, by arranging a plurality of the above-described photosensitive device, it is possible to provide more accuracy in the photosensitive efficiency.

In addition, the gate of the sensing transistor in the photosensitive device 500 is connected to the gate pad 510 for the sensor transistor, and the gate of the switch transistor is connected to the gate pad 520 for the switch transistor. These pads are provided in the liquid crystal panel array portion where the gate pads and the data pads are provided.

As described above, the reader IC 530 outputs the stored charge information through the switch transistor, and the controller 540 reads the electric signal output from the reader IC 530, and then the voltage of the inverter for driving the backlight. Or by controlling the current to provide a stable brightness.

As can be seen from the above, in the case of using the photosensitive device and the liquid crystal display device having the same according to the present invention has the following effects.

1. A thin-film transistor-type sensor transistor for converting optical information into an electrical signal is built and fabricated on a thin film transistor array substrate in a liquid crystal display panel. It is possible to implement an intelligent display device that maintains the same brightness characteristic regardless of the long time required for displaying images such as / airport screening station / non-destructive inspection.

2. Also, unlike the conventional case in which each production process is manufactured by different production lines. Simultaneously formed in the same production line and manufacturing process has the effect of reducing the manufacturing time and cost, improving characteristics.

3. Finally, additional costs such as the provision of a separate optical sensor device or system (eg piezoelectric sensor, optical sensor) for application of luminance correction and an application device for connection with these devices are avoided. In short, it is very economically advantageous.

Claims (6)

delete A liquid crystal display device comprising an upper plate including a color filter unit, a lower plate including a liquid crystal panel array unit, and a backlight for providing light from the lower plate to the upper plate. A sensor transistor that senses light of the backlight, a charging and transmitting unit which charges the charge according to the amount of light sensed by the sensor transistor and transmits the light of the backlight, and a switching transistor that switches the output of the charge stored in the charging and transmitting unit. At least one photosensitive device is formed integrally on the lower plate, A reflective layer is formed on the upper region corresponding to the upper portion of the region where at least one light sensing element is formed to reflect the light passing through the charging and transmitting portion to the sensor transistor. The photosensitive device is disposed at a predetermined position outside the active area on the lower plate formed by the liquid crystal panel array unit. And an output for adjusting a driving voltage provided to the backlight is provided from at least one of the photosensitive devices formed on the lower plate. The method of claim 2, A reader IC configured to provide a control signal to the photosensitive device to operate the switching transistor and to receive a signal output according to the switching of the switching transistor; And And a controller configured to receive the output of the photosensitive device through the reader IC to adjust the driving voltage provided to the backlight. 3. The liquid crystal display device according to claim 2, wherein the sensor transistors and the switch transistors of the light sensing element are each composed of a single number or a plurality of switch transistors to share one of the charging and transmitting portions. The method of claim 2, wherein the photosensitive device, A transparent substrate of the lower plate; First and second gate electrodes divided and patterned in a sensor transistor region and a switch transistor region on the transparent substrate, respectively; A first transparent electrode patterned with a transparent conductive material and partially overlapped with the first gate electrode to form a charge and a transmission portion in a region between the sensor transistor region and the switch transistor region; An insulating film formed on the first and second gate electrodes and the first transparent electrode; A first active region for forming the sensor transistor patterned on the first gate electrode and the second gate electrode and a second active region for forming the switch transistor by deposition and patterning of amorphous silicon on the insulating layer. ; A second transparent electrode patterned with the transparent conductive material in a region corresponding to the first transparent electrode on the insulating film; A drain electrode and a source electrode formed by depositing and patterning a conductive material and separated from each other and patterned to be in contact with the first active region, respectively; A drain electrode and a source electrode formed by depositing and patterning a conductive material and separated from each other and patterned to be in contact with the second active region, respectively; A first insulating protective film including a plurality of contacts in electrical contact with each of the electrodes; A shield bar formed in a region between a drain electrode and a source electrode of the switching transistor on the first insulating protective layer; And And a second insulating protective film deposited on the entire surface of the first insulating protective film and the upper portion of the shield bar. The method of claim 2, wherein the photosensitive device, A transparent substrate of the lower plate; First and second gate electrodes divided and patterned in a sensor transistor region and a switch transistor region on the transparent substrate, respectively; A first transparent electrode patterned with a transparent conductive material and partially overlapped with the first gate electrode to form a charge and a transmission portion in a region between the sensor transistor region and the switch transistor region; An insulating film formed on the first and second gate electrodes and the first transparent electrode; A first active region for forming the sensor transistor patterned on the first gate electrode and the second gate electrode and a second active region for forming the switch transistor by deposition and patterning of amorphous silicon on the insulating layer. ; A drain electrode and a source electrode formed by depositing and patterning a conductive material and separated from each other and patterned on the first active region; A drain electrode and a source electrode formed by depositing and patterning a conductive material and separated from each other and patterned on the second active region; An etch stopper formed by depositing and back etching amorphous silicon between the drain electrode and the source electrode of the switch transistor on the second active region; A second transparent electrode patterned on the insulating layer between the source of the sensor transistor and the drain of the switch transistor with the transparent conductive material; And And an insulating protective film deposited over the electrodes.

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