TWI383372B - Liquid crystal display and method of adjusting luminance of liquid crystal display - Google Patents

Description

Liquid crystal display device and display brightness adjustment method thereof

The present invention relates to a liquid crystal display device and a display luminance adjusting method thereof.

Due to its low radiation, short size and low power consumption, liquid crystal display devices are widely used in mobile phones, personal digital assistants, notebook computers, personal computers and televisions. As a display device, a liquid crystal display device displays a main performance parameter of luminance. In order to meet the display luminance requirements of different situations, it is necessary to adjust the luminance of the liquid crystal display device. For example, in a dark room, the liquid crystal display device should be adjusted to a relatively low display brightness to avoid excessive brightness to the viewer's eyes. Generally, an amorphous germanium thin film transistor exposed to ambient light is driven to generate a photocurrent corresponding to ambient light intensity, and the photocurrent is received by a processing unit, and the processed output corresponds to the photocurrent intensity. The ambient light intensity signal is sent to a brightness adjustment unit, and the brightness adjustment unit appropriately adjusts the brightness of the liquid crystal display device according to the ambient light intensity signal.

However, the liquid crystal display device senses ambient light of various illuminances by a single amorphous germanium film transistor, which is easily exposed to ambient light for a long time and is driven to cause internal structural defects of the amorphous germanium film transistor. The photoelectric conversion efficiency is lowered, and the photocurrent outputted by the same ambient light is attenuated, so that the reliability of adjusting the luminance of the liquid crystal display device is lowered according to the photocurrent.

In view of this, it is necessary to provide a liquid crystal display device with high reliability.

In view of the above, it is also necessary to provide a display luminance adjustment method for a highly reliable liquid crystal display device.

A liquid crystal display device includes a photosensitive device, a processing unit and a brightness adjustment unit. The photosensitive device includes at least two photosensitive units. The processing unit selectively drives one of the photosensitive cells according to the ambient light level, so that the photosensitive cell outputs a sensing signal, and the processing unit outputs a brightness adjusting signal according to the sensing signal. The brightness adjustment unit adjusts the display brightness of the liquid crystal display device according to the brightness adjustment signal.

A display brightness adjustment method for a liquid crystal display device, wherein the liquid crystal display device using the display brightness adjustment method comprises a photosensitive device, a processing unit and a brightness adjustment unit, the photosensitive device comprising at least two photosensitive units, the brightness adjustment method comprising the following steps The processing unit selectively drives one of the photosensitive units according to the ambient light level to cause the photosensitive unit to output a sensing signal; the processing unit outputs a brightness adjusting signal according to the sensing signal; the brightness adjusting unit adjusts the signal according to the brightness The display luminance of the liquid crystal display device is adjusted.

The liquid crystal display device of the present invention and the display brightness adjusting method thereof adopt a processing unit to selectively drive one of the at least two photosensitive units according to the ambient light degree. When the liquid crystal display device is respectively placed in an environment with different ambient light levels, the driving can be selected differently. The photosensitive unit, thereby reducing the time for driving a single photosensitive unit to a certain extent, reducing the probability that the photoelectric conversion efficiency of the photosensitive unit is lowered due to long-time driving, so that the liquid crystal display device that adjusts the display brightness according to the sensing signal outputted by the photosensitive device is reliable. Higher sex.

1 is a schematic structural view of a first embodiment of a liquid crystal display device of the present invention. The liquid crystal display device 2 includes a photosensitive device 20, a display area 25, a frame 22, a supporting device 26, and a control circuit (not shown). The display area 25 is a rectangular area for displaying a picture. The photosensitive device 20 is adjacent to the display area 25 for sensing the illuminance of the ambient light and outputting the light sensing signal. The control circuit outputs a corresponding ambient illuminance according to the light sensing signal outputted by the photosensitive device 20, and adjusts the display luminance of the display area 25 according to the ambient illuminance. The frame 22 houses the photosensitive device 20, the display area 25, and the control circuit. The support device 26 supports the frame 22.

Referring to FIG. 2 together, a cross-sectional enlarged view of the photosensitive device 20 shown in FIG. 1 is shown. The photosensitive device 20 includes a first substrate 23 and a second substrate 24 opposite to the first substrate 23. The surface of the first substrate 23 facing the second substrate 24 includes a first photosensitive element 260, a second photosensitive element 262, a third photosensitive element 264, a fourth photosensitive element 266, and a fifth photosensitive element 267. A compensating element 27. The surface of the second substrate 24 facing the first substrate 23 includes a black matrix 240 and a first light transmissive element 245, a second light transmissive element 246, and a third light transmissive element 247 spaced apart from the black matrix 240. And a fourth light transmitting element 248. A liquid crystal layer (not shown) is filled between the first substrate 23 and the second substrate 24.

The plurality of light transmissive elements are a color photoresist layer formed by mixing a pigment, a sensitizer, or the like into the resin, and the first light transmissive element 245, the second light transmissive element 246, the third light transmissive element 247, and the fourth The light transmittance of the light transmitting member 248 is sequentially increased and smaller than the light transmittance of the second substrate 24. For example, the transmittance of the first light transmissive element 245, the second light transmissive element 246, the third light transmissive element 247, and the fourth light transmissive element 248 and the second substrate 24 are respectively 20%. 40%, 60%, 80% and 100%. The light transmittance of each of the light-transmitting elements can be controlled by adjusting the concentration of the pigment, the color, or the thickness of the light-transmitting member.

The compensating element 27 is an amorphous germanium thin film transistor corresponding to the black matrix 240 such that it is unable to receive ambient light illumination due to the blockage of the black matrix 240. The first photosensitive element 260, the second photosensitive element 262, the third photosensitive element 264, the fourth photosensitive element 266 and the fifth photosensitive element 267 are respectively an amorphous germanium film transistor, which respectively correspond to the first The light transmissive element 245, the second light transmissive element 246, the third light transmissive element 247, the fourth light transmissive element 248, and the second substrate 24 located between the black matrixes 240, so that the photosensitive device 20 is in the same illumination In ambient light, the light passes through the first light transmissive element 245, the second light transmissive element 246, the third light transmissive element 247, the fourth light transmissive element 248, and the second substrate 24 to illuminate the first The photosensitive element 260, the second photosensitive element 262, the third photosensitive element 264, the fourth photosensitive element 266, and the fifth photosensitive element 267, the first photosensitive element 260, the second photosensitive element 262, and the third The amount of light received by the photosensitive element 264, the fourth photosensitive element 266, and the fifth photosensitive element 267 is sequentially increased. Each of the photosensitive elements and the corresponding light transmissive elements constitute a photosensitive unit.

The display area 25 includes a plurality of amorphous germanium thin film transistors (not shown) for controlling the display of the screen and a color filter layer (not shown) corresponding thereto, which are respectively disposed on the first substrate 23 and the second The surface of the substrate 24 is formed together with the photosensitive element and the light transmitting element of the display area 25.

Please refer to FIG. 3 and FIG. 4 together. FIG. 3 is a schematic diagram showing the circuit structure of the photosensitive device 20 shown in FIG. 2, and FIG. 4 is a block diagram of the control circuit of the liquid crystal display device. The first photosensitive element 260, the second photosensitive element 262, the third photosensitive element 264, the fourth photosensitive element 266 and the fifth photosensitive element 267 are connected to each other and grounded via a first resistor 268. The common bungee can measure the photovoltage Vp. The compensating element 27 is used to generate a comparison reference value. The gate and the source of the compensating element 27 are respectively connected to a fixed gate voltage Vg and a fixed source voltage Vs, and the drain is grounded via a second resistor 269. The compensating element 27 generates a conductive channel between the source and the drain thereof under the action of the gate voltage Vg, and the source voltage drives the electrons in the conductive channel to generate a current toward the drain, and the current flows through the The second resistor 269 outputs the reference voltage Vr at the drain. The resistance of the second resistor 269 is equal to the resistance of the first resistor 268.

The control circuit 28 includes a processing unit 280 and a luminance adjustment unit 288. The processing unit 280 includes a differential amplifier 281, an analog/digital converter 282, a microprocessor 284, and a memory unit 286. The input terminals of the differential amplifier 281 receive the photovoltage Vp and the reference voltage Vr, respectively, and output a difference voltage ΔV (not labeled) between the photovoltage Vp and the reference voltage Vr. The analog/digital converter converts the difference voltage ΔV into a corresponding digital signal.

The memory unit 286 is a read-only memory that stores a first lookup table, a second lookup table, and a third lookup table. The first lookup table establishes a relationship between the digital signal corresponding to the photovoltage Vp and the ambient illuminance for each photosensitive element. The second lookup table establishes a correspondence between the ambient illuminance range and the switching signal, and the switching signal selects and drives one of the photosensitive elements corresponding to the ambient illuminance range. The first photosensitive element 260, the second photosensitive element 262, the third photosensitive element 264, the fourth photosensitive element 266, and the fifth photosensitive element 267 respectively correspond to a first illuminance range, a second illuminance range, and The third illuminance range, the fourth illuminance range, and the fifth illuminance range are sequentially continuous and constitute a sensible range of the photo sensing circuit. For example, if the ambient illuminance range that can be sensed is set to 0 Lux-1000000 Lux, the first illuminance range, the second illuminance range, the third illuminance range, the fourth illuminance range, and the fifth illuminance range are respectively divided into 20001 Lux-10000 lux, 2001 Lux-20000 Lux, 501 Lux-2000 Lux, 11 Lux-500 Lux and 0 Lux-10 Lux. The third lookup table establishes a relationship between ambient illuminance and display luminance adjustment signals.

The microprocessor 284 searches for the ambient illuminance corresponding to the digital signal according to the received digital signal and the first lookup table, and determines the ambient illuminance range to which the digital signal belongs according to the ambient illuminance, and then searches for and outputs the corresponding corresponding finder in the second lookup table. The switching signal is used to drive one of the photosensitive elements corresponding to the ambient illuminance range to turn off the other photosensitive elements. The switching signal includes a first switching signal Vc1 and a second switching signal Vc2, wherein Vc1 is a digital sequence outputted by the microprocessor 284 to the gates of the five photosensitive elements, such as “10000”, which is expressed as the first A photosensitive element 260 provides a gate driving voltage, and the second switching signal Vc2 outputs a digit sequence identical to the first switching signal Vc1 to the sources of the five photosensitive elements, indicating that the first driving element 260 is simultaneously supplied with a source driving voltage. The first photosensitive element 260 is driven to output a sensing signal under ambient light illumination.

When the ambient illuminance is within the first ambient illuminance range of the illuminance, the first switching signal Vc1 outputted by the microprocessor 284 is level-converted to apply a high level equal to the gate voltage Vg to the first photosensitive element. The gate of 260 creates a conductive channel between the drain and the source. Since the first photosensitive element 260 can generate photogenerated electrons when it is irradiated with light, the number of electrons in the conductive channel is larger than the number of electrons in the conductive channel of the compensating element 27, and the number of electrons increases as the illumination intensity increases. At the same time, the second switching signal Vc2 outputted by the microprocessor 284 is level-converted to apply a high level equal to the source voltage Vs to the source of the first photosensitive element 260 to drive the electrons in the conductive channel. Moving to the drain and forming a photocurrent, because the electrons in the conductive channel are more, the photocurrent is greater than the drain current generated by the compensating element 27, so that the photovoltage Vp outputted through the first resistor 268 is greater than the reference voltage. Vr, the difference ΔV between the photovoltage Vp and the reference voltage Vr increases as the illumination illuminance increases.

Because the plurality of photosensitive elements are respectively driven in different ambient light ranges to output a photovoltage corresponding to the ambient light, the processing unit 280 can selectively drive different photosensitive elements according to changes in the ambient light level, thereby avoiding a single sensitivity to a certain extent. The component is exposed and driven for a long time. In addition, since the first photosensitive element 260 is corresponding to the first light-transmitting element 245 having the lowest light transmittance, and ambient light is irradiated to the first photosensitive element 260, only the percent of the first light-transmitting element 245 is The illumination amount of twenty passes, so that the illumination illuminance received by the first photosensitive element 260 is largely reduced to protect the first photosensitive element 260 from strong light, so that the first photosensitive element 260 generates internal structural defects. The probability is reduced and its stability is good. At this time, the other photosensitive elements are in a closed state, and the probability of causing internal structural defects can also be lowered.

When the ambient illuminance belongs to the second illuminance range, the third illuminance range, the fourth illuminance range, and the fifth illuminance range, respectively, the microprocessor 284 drives the second photosensitive element 262, the third photosensitive element 264, and the fourth The photosensitive element 266 and the fifth photosensitive element 267, that is, the first photosensitive element 260, the second photosensitive element 262, the third photosensitive element 264, the fourth photosensitive element 266, and the fifth photosensitive element 267 are respectively responsible for sensing Ambient light for 20001 Lux-1000000 Lux, 2001 Lux-20000 Lux, 501 Lux-2000 Lux, 11 Lux-500 Lux and 0 Lux-10 Lux illumination range. In this way, it is possible to prevent each photosensitive element from receiving ambient light irradiation with excessive illuminance, and when the ambient light is weak, driving the photosensitive element corresponding to the light-transmitting element having a high light transmittance to ensure sufficient light amount to pass through the light-transmitting element. The photosensitive element is illuminated to produce a photocurrent that is easily identifiable.

The microprocessor 284 outputs a display brightness adjustment signal corresponding to the ambient light level to the brightness adjustment unit 288 according to the ambient light level and the third lookup table. The brightness adjustment unit 288 is a backlight adjustment unit that adjusts the display screen of the display area 25 to the brightness corresponding to the ambient light by adjusting the brightness of the backlight according to the display brightness adjustment signal.

When the microprocessor 284 does not change the first switching signal Vc1 outputted during the predetermined predetermined complex period, the liquid crystal display device 2 can be considered to be in an environment where the illuminance is relatively stable. At this time, the microprocessor 284 intermittently drives the photosensitive element until the first switching signal Vc1 changes to prevent the liquid crystal display device 2 from being in a certain illumination range for a long time. Driven to further avoid internal structural defects caused by the photosensitive element being driven for a long time.

The liquid crystal display device 2 of the present invention has a switchable light sensor. By driving the microprocessor 284 to drive different photosensitive elements in different ambient light ranges, the single photosensitive element can be prevented from being exposed to light for a long time to a certain extent. The driving, thereby reducing the probability of the photosensitive member generating internal structural defects, improving the stability of the photosensitive device, thereby making the liquid crystal display device 2 highly reliable. In addition, when the ambient light is strong, the photosensitive element under the light-transmitting element with low light transmittance is driven, the photosensitive element receives ambient light of appropriate illumination, and the display area 25 is adjusted according to the light voltage output by the photosensitive element. The brightness is displayed to avoid the internal structural defects caused by the strong ambient light irradiation of the amorphous germanium film transistor as the photosensitive element, and the stability of the amorphous germanium thin film transistor as the photosensitive element is improved, and according to the photosensor The output signal adjusts the display brightness of the liquid crystal display device 2 with high reliability.

Please refer to FIG. 5, which is a schematic diagram of a second embodiment of a liquid crystal display device of the present invention. The liquid crystal display device is substantially the same as the liquid crystal display device 2. The main difference is that the frame 32 houses the display area 35. The photosensitive device 30 is disposed on the frame 32. The display area 35 and the photosensitive device 30 are formed independently of each other. .

Please refer to FIG. 6, which is a schematic diagram of a photosensitive element of a third embodiment of the liquid crystal display device of the present invention. The liquid crystal display device is substantially the same as the liquid crystal display device 2, except that each photosensitive member is composed of n ² amorphous germanium film transistors, respectively, where n = 2, 3, 4, .... The n ² amorphous germanium thin film transistors are equally divided into n groups, and the source and the drain of the n amorphous germanium thin film transistors in each group are sequentially connected to form a series structure, and an independent source and one are retained. Independent bungee, each group of independent dipoles connected to form an equivalent dipole D, the independent source of each group is connected to an equivalent source S, the gate connection of the n ² amorphous germanium thin film transistors Become an equivalent gate G. Figure 6 is exemplified by n = 2, that is, four (2 ² ) amorphous germanium thin film transistors. The equivalent gate G, the equivalent source S and the equivalent drain D are the gate, the source and the drain of the equivalent amorphous germanium film transistor, and the single amorphous germanium film transistor The characteristics are basically the same, and because of the series-parallel structure, the amorphous germanium thin film transistors are mutually pinned, and the difference in characteristics between the individual amorphous germanium thin film transistors due to the specific structure and the process is neutralized and neutralized. The effect is that the difference in characteristics between the respective equivalent amorphous germanium thin film transistors produced in batch production is small, so that the mass productivity is better.

However, the present invention is not limited to the above embodiments. For example, the liquid crystal display device 2 may not include the compensation component 27 and the differential amplifier 281, and the memory unit 286 stores a predetermined Vr by using the memory unit 286. The microprocessor 284 compares the Vr with the Vp converted to the digital signal; the first switching signal Vc1 can also apply a voltage equal to the gate voltage Vg of the compensation component 27 to the gate of the photosensitive element via a switching element. For example, by controlling the opening of a thin film transistor, the source voltage of the thin film transistor is turned on to the gate of the photosensitive element connected to the drain thereof; the first resistor 268 and the second resistor 269 may also be replaced by a non- Crystalline film transistor.

In summary, the present invention has indeed met the requirements of the invention patent, and has filed a patent application according to law. However, the above description is only the preferred embodiment of the present invention, and the scope of the present invention is not limited to the above-described embodiments, and equivalent modifications or variations made by those skilled in the art in light of the spirit of the present invention are It should be covered by the following patent application.

Liquid crystal display device. . . 2, 3

Photosensitive device. . . 20, 30

Display area. . . 25, 35

Control circuit. . . 28

First substrate. . . twenty three

Second substrate. . . twenty four

Black matrix. . . 240

First light transmitting element. . . 245

Second light transmitting element. . . 246

Third light transmitting element. . . 247

Fourth light transmitting element. . . 248

First photosensitive element. . . 260

Second photosensitive element. . . 262

The third photosensitive element. . . 264

Fourth photosensitive element. . . 266

Fifth photosensitive element. . . 267

First resistance. . . 268

Second resistance. . . 269

Differential amplifier. . . 281

Analog/digital converter. . . 282

microprocessor. . . 284

Memory unit. . . 286

Brightness adjustment unit. . . 288

Compensation component. . . 27

frame. . . 22,32

Support device. . . 26

Processing unit. . . 280

1 is a schematic structural view of a first embodiment of a liquid crystal display device of the present invention.

Figure 2 is an enlarged cross-sectional view showing the photosensitive device shown in Figure 1.

3 is a schematic view showing the circuit structure of the photosensitive device shown in FIG. 2.

4 is a block diagram showing a control circuit of the liquid crystal display device shown in FIG. 1.

Fig. 5 is a schematic view showing the structure of a second embodiment of the liquid crystal display device of the present invention.

Fig. 6 is a view showing a photosensitive member of a third embodiment of the liquid crystal display device of the present invention.

First substrate. . . twenty three

Second substrate. . . twenty four

Black matrix. . . 240

First light transmitting element. . . 245

Second light transmitting element. . . 246

Third light transmitting element. . . 247

Fourth light transmitting element. . . 248

First photosensitive element. . . 260

Second photosensitive element. . . 262

The third photosensitive element. . . 264

Fourth photosensitive element. . . 266

Fifth photosensitive element. . . 267

Compensation component. . . 27

Photosensitive device. . . 20

Claims (44)

A liquid crystal display device comprising: a photosensitive device comprising at least two photosensitive units, each photosensitive unit respectively comprising a photosensitive element and a light transmitting element corresponding to one of the photosensitive elements, wherein the light transmitting elements have different transmittances The processing unit is configured to drive one of the photosensitive cells according to the ambient light level, so that the photosensitive unit outputs a sensing signal, and the processing unit outputs a brightness adjusting signal according to the sensing signal, when the liquid crystal display device respectively When the two different ambient illuminances belong to different preset ambient illuminance ranges, the processing unit respectively selects and drives two of the photosensitive elements, and is selected when the ambient illuminance is strong. The transmittance of the light-transmitting element corresponding to one photosensitive element is lower than the light transmittance of the light-transmitting element corresponding to the other photosensitive element; and a brightness adjustment unit that adjusts the display brightness of the liquid crystal display device according to the brightness adjustment signal. The liquid crystal display device of claim 1, wherein the at least two photosensitive units receive different amounts of illumination under the same ambient light level. The liquid crystal display device of claim 1, wherein the material of the light transmissive element is a color photoresist. The liquid crystal display device of claim 1, wherein the photosensitive element is an amorphous germanium film transistor. The liquid crystal display device of claim 4, wherein the The drains of at least two photosensitive elements are connected to each other and grounded via a resistor. The liquid crystal display device of claim 5, wherein the sensing signal is a drain voltage of the amorphous germanium film transistor. The liquid crystal display device of claim 6, wherein the gate and the source of the photosensitive element receive a driving voltage and output the sensing signal under ambient light illumination. The liquid crystal display device of claim 4, wherein the photosensitive element is equivalent to n ² amorphous germanium thin film transistors, wherein the n ² amorphous germanium thin film transistors are divided into n groups. The drains of the n amorphous bismuth thin film transistors of each group are sequentially connected to the source, and a free source and a free drain are reserved, and the free sources of the groups are respectively connected to form an equivalent source. The free bungee of each group is connected as an equivalent bungee. The liquid crystal display device of claim 8, wherein n=2. The liquid crystal display device of claim 1, further comprising a first substrate and a second substrate opposite to the first substrate, wherein the photosensitive element and the light transmissive element are respectively disposed on the first substrate and the first Two substrates. The liquid crystal display device of claim 10, wherein the second substrate further comprises a black matrix spaced apart from the light transmissive element. The liquid crystal display device of claim 11, wherein the photosensitive device further comprises a compensating element corresponding to the black matrix. The liquid crystal display device of claim 12, wherein The gate and the source of the compensation component are respectively connected to a fixed gate voltage and a fixed source voltage, and the drain is grounded via a second resistor, and a reference value is output from the drain. The liquid crystal display device of claim 13, wherein the processing unit comprises a differential amplifier that receives the sensing signal and the comparison reference value and outputs a difference signal thereof. The liquid crystal display device of claim 14, wherein the processing unit further comprises an analog/digital converter that converts the difference signal into a corresponding digital signal. The liquid crystal display device of claim 15, wherein the processing unit further comprises a memory, which stores a first lookup table, wherein the first lookup table establishes a sensing signal for the output of each photosensitive element. Correspondence between the corresponding digital signal and ambient illumination. The liquid crystal display device of claim 16, wherein the memory unit further comprises a second lookup table that establishes a correspondence between the ambient illuminance range and the switching signal. The liquid crystal display device of claim 17, wherein the processing unit further comprises a microprocessor, according to the digital signal, finding a corresponding ambient illuminance according to the first look-up table, and determining that the ambient illuminance belongs to The ambient illuminance range is further, according to the second look-up table, outputting a switching signal corresponding to the ambient illuminance range to the photosensitive device to drive one of the corresponding photosensitive elements. The liquid crystal display device of claim 18, wherein the memory unit further comprises a third lookup table that establishes ambient illumination Correspondence between the degree and the display brightness adjustment signal. The liquid crystal display device of claim 19, wherein the microprocessor outputs a corresponding display brightness adjustment signal according to the ambient light level and the third lookup table. The liquid crystal display device of claim 1, wherein the photosensitive device comprises five photosensitive elements, respectively corresponding to a transmittance of twenty percent, forty percent, sixty percent, Eighty percent and one hundred percent of the light-transmitting components are disposed such that the light-receiving quantities of the five photosensitive components in the same ambient light are respectively 20%, 40%, 60% of the ambient light. 80% and 100%. The liquid crystal display device of claim 21, wherein the ambient light levels of the five photosensitive elements in the environment in which the liquid crystal display device is located are respectively preset and sequentially decreasing the first ambient light range and the second ambient light range. The third ambient illuminance range, the fourth ambient illuminance range, and the fifth ambient illuminance range are respectively selected and driven. The liquid crystal display device of claim 1, wherein the liquid crystal display device further comprises a display area, wherein the brightness adjustment unit adjusts the display brightness of the display area according to the brightness adjustment signal. The liquid crystal display device of claim 23, wherein the display area comprises a plurality of amorphous germanium thin film transistors for controlling the display of the screen and a color filter unit disposed opposite the amorphous germanium thin film transistor. The liquid crystal display device of claim 24, wherein the display area and the photosensitive device are disposed on the same substrate. The liquid crystal display device of claim 24, wherein the liquid crystal display device further comprises a frame, the display area is received in the frame, and the photosensitive device is disposed on the surface of the frame. The liquid crystal display device of claim 24, wherein the liquid crystal display device further comprises a liquid crystal layer sandwiched between the amorphous germanium thin film transistor and the color filter unit. A display brightness adjustment method for a liquid crystal display device, wherein the liquid crystal display device using the display brightness adjustment method comprises a photosensitive device, a processing unit and a brightness adjustment unit, the photosensitive device comprising at least two photosensitive units, the photosensitive unit further comprising a pair The light-transmitting element of the photosensitive element should have different transmittances of light-transmitting elements. The brightness adjustment method comprises the following steps: the processing unit selectively drives one of the photosensitive units according to the ambient light level, so that the photosensitive unit outputs a sense. a measuring signal, when the liquid crystal display device is respectively placed in ambient light of two different illuminations, and the two different ambient illumination levels respectively belong to different preset ambient illumination ranges, the processing unit respectively selects and drives two of the photosensitive elements, And the light transmittance of the light-transmitting component corresponding to one of the photosensitive elements is selected to be lower than that of the light-transmitting component corresponding to the other photosensitive component when the ambient light is strong; the processing unit outputs a corresponding one according to the sensing signal. Brightness adjustment signal; a brightness adjustment unit that adjusts the signal according to the brightness adjustment Display luminance of the liquid crystal display device. The display brightness adjustment method of the liquid crystal display device according to claim 28, wherein the at least two photosensitive units are in the same ambient light The amount of light received is different from each other. The display brightness adjustment method of the liquid crystal display device according to claim 28, wherein the brightness adjustment unit is a backlight control unit that adjusts the display luminance of the liquid crystal display device by adjusting the brightness of the backlight. The method for adjusting the brightness of a liquid crystal display device according to claim 28, wherein each of the photosensitive units comprises a photosensitive element for sensitization, the photosensitive element is an amorphous germanium film transistor, and the drain is Connected to each other and grounded via a first resistor, the sense signal is the drain voltage of the photosensitive element. The display brightness adjustment method of the liquid crystal display device of claim 31, wherein the processing unit outputs a first switching signal and a second switching signal to the gate and the source of the photosensitive element to drive One of the photosensitive elements outputs a sensing signal. The display brightness adjustment method of the liquid crystal display device of claim 32, wherein the first switching signal and the second switching signal are respectively the same one-digit sequence. The display brightness adjustment method of the liquid crystal display device of claim 32, wherein the photosensitive device further comprises a compensation component that provides a comparison reference value for the sensing signal. The display brightness adjustment method of the liquid crystal display device according to claim 34, wherein the compensation component is an amorphous germanium thin film transistor, and the gate and the source thereof are respectively connected to a fixed gate voltage and a fixed source. a pole voltage whose ground is grounded via a second resistor, the comparison reference value being Compensate the sum voltage of the components. The display brightness adjustment method of the liquid crystal display device of claim 35, wherein the resistance of the first resistor is equal to the resistance of the second resistor. The display brightness adjustment method of the liquid crystal display device of claim 35, wherein the processing unit comprises a differential amplifier that receives the sensing signal and the comparison reference value and outputs a difference signal thereof. The display luminance adjustment method of the liquid crystal display device of claim 35, wherein the processing unit further comprises an analog/digital converter that converts the difference signal into a corresponding digital signal. The display brightness adjustment method of the liquid crystal display device of claim 38, wherein the processing unit further comprises a memory storing a first lookup table, the first lookup table establishing each photosensitive element Correspondence between the digital signal corresponding to the output sensing signal and the ambient illuminance. The display brightness adjustment method of the liquid crystal display device of claim 39, wherein the memory unit further comprises a second lookup table that establishes a correspondence between the ambient light range and the switching signal. The display brightness adjustment method of the liquid crystal display device of claim 40, wherein the processing unit further comprises a microprocessor, which searches for the corresponding ambient light level according to the first lookup table and the digital signal, and according to The ambient illuminance determines the ambient illuminance range to which it belongs, and then outputs a corresponding switching signal to the photosensitive device according to the second lookup table. The display brightness adjustment method of the liquid crystal display device of claim 41, wherein the memory unit further comprises a third lookup table that establishes a correspondence between the ambient light level and the display brightness adjustment signal. The display brightness adjustment method of the liquid crystal display device of claim 42, wherein the microprocessor outputs a corresponding display brightness adjustment signal according to the ambient light level and the third lookup table. The display brightness adjustment method of the liquid crystal display device according to claim 28, wherein the photosensitive device intermittently outputs the sensing signal in the same ambient light range.