CN110709994A - Optical sensor and organic light emitting diode display screen - Google Patents

Optical sensor and organic light emitting diode display screen Download PDF

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Publication number
CN110709994A
CN110709994A CN201780091760.XA CN201780091760A CN110709994A CN 110709994 A CN110709994 A CN 110709994A CN 201780091760 A CN201780091760 A CN 201780091760A CN 110709994 A CN110709994 A CN 110709994A
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China
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light emitting
organic light
emitting diode
voltage
thin film
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CN201780091760.XA
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Chinese (zh)
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陈小明
赵晓辉
曹慧敏
刘鹏
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Shenzhen Royole Technologies Co Ltd
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Shenzhen Royole Technologies Co Ltd
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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00

Abstract

The invention discloses a light sensor (10). The light sensor (10) is used for an organic light emitting diode display screen (100). An organic light emitting diode display screen (100) includes an organic light emitting diode layer (20). The light sensor (10) is arranged on the organic light-emitting diode layer (20). The light sensor (10) comprises a first thin film transistor (T)P) And a second thin film transistor (T)R). A first thin film transistor (T)P) Is connected to the first node (N). A second thin film transistor (T)R) Is connected to the first node (N). The organic light emitting diode layer (20) includes a plurality of organic light emitting diodes (22). The light sensor (10) is used for detecting the brightness of one organic light emitting diode (22) corresponding to the light sensor (10) according to the voltage change of the first node (N). In addition, the invention also discloses an organic light emitting diode display screen (100).

Description

Optical sensor and organic light emitting diode display screen Technical Field
The invention relates to the field of brightness detection, in particular to an optical sensor and an organic light emitting diode display screen.
Background
During the use of an Organic Light-Emitting Diode (OLED) display, the luminance of the OLED may change due to the degradation of the OLED material. In order to restore its brightness to normal, the brightness of the OLED may be compensated according to its aging characteristics. However, this approach is too dependent on the aging characteristics of the OLED. If the actual aging of the OLED is different from expected, the compensation effect is limited.
Disclosure of Invention
The embodiment of the invention provides an optical sensor and an organic light emitting diode display screen.
The optical sensor of the embodiment of the invention is used for an organic light-emitting diode display screen, the organic light-emitting diode display screen comprises an organic light-emitting diode layer, the optical sensor is arranged on the organic light-emitting diode layer, and the optical sensor comprises:
the grid electrode of the first thin film transistor is connected with a first voltage input end, the source electrode of the first thin film transistor is connected with a first preset voltage, and the drain electrode of the first thin film transistor is connected with a first node; and
a second thin film transistor, wherein a gate of the second thin film transistor is connected to a second voltage input terminal, a source of the second thin film transistor is connected to the first node, and a drain of the second thin film transistor is connected to a second predetermined voltage;
the organic light emitting diode layer comprises a plurality of organic light emitting diodes, and the light sensor is used for detecting the brightness of one organic light emitting diode corresponding to the light sensor according to the voltage change of the first node.
An organic light emitting diode display panel according to an embodiment of the present invention includes:
an organic light emitting diode layer comprising a plurality of organic light emitting diodes; and
a plurality of the photo sensors according to the above embodiments, the plurality of the photo sensors being disposed on the organic light emitting diode layer, the plurality of the photo sensors corresponding to the plurality of organic light emitting diodes, each of the photo sensors being configured to detect a luminance of one of the organic light emitting diodes corresponding to the photo sensor according to a voltage variation of the first node.
In the optical sensor and the organic light emitting diode display screen of the embodiment of the invention, the optical sensor is arranged on the organic light emitting diode layer and detects the brightness of the organic light emitting diode according to the voltage change of the first node, so that the detection result is accurate, and the brightness of the organic light emitting diode can be compensated according to the detection result.
Additional aspects and advantages of embodiments of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a schematic diagram of a circuit configuration of a light sensor according to an embodiment of the present invention;
FIG. 2 is a cross-sectional view of an organic light emitting diode display panel according to an embodiment of the present invention;
FIG. 3 is a graph of threshold voltage of a thin film transistor over time at different illumination intensities;
FIG. 4 is a graph of threshold voltage of a thin film transistor over time under different wavelengths of light;
description of the main elements and symbols:
a light sensor 10;
a first thin film transistor TPA second thin film transistor TRA first voltage input terminal VGPA second voltage input terminal VGRA first predetermined voltage VCOMA second predetermined voltage VDA first node N, a voltage Vn of the first node, a first negative bias NBIS, a second negative biasPressing NBS, a first positive bias PBIS and a second positive bias PBS;
the display panel comprises an organic light emitting diode display screen 100, an organic light emitting diode display layer 20, an organic light emitting diode 22, packaging glass 30, a polarizer 40 and a cover plate 50.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
In the description of the embodiments of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of describing the embodiments of the present invention and simplifying the description, but do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the embodiments of the present invention. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", may explicitly or implicitly include one or more of the described features. In the description of the embodiments of the present invention, "a plurality" means two or more unless specifically limited otherwise.
In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as being fixedly connected, detachably connected, or integrally connected; may be mechanically connected, may be electrically connected or may be in communication with each other; either directly or indirectly through intervening media, either internally or in any other relationship. Specific meanings of the above terms in the embodiments of the present invention can be understood by those of ordinary skill in the art according to specific situations.
In embodiments of the invention, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may comprise the first and second features being in direct contact, or the first and second features being in contact, not directly, but via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.
The following disclosure provides many different embodiments or examples for implementing different configurations of embodiments of the invention. In order to simplify the disclosure of embodiments of the invention, the components and arrangements of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. Furthermore, embodiments of the invention may repeat reference numerals and/or reference letters in the various examples, which have been repeated for purposes of simplicity and clarity and do not in themselves dictate a relationship between the various embodiments and/or arrangements discussed. In addition, embodiments of the present invention provide examples of various specific processes and materials, but one of ordinary skill in the art may recognize applications of other processes and/or use of other materials.
Referring to fig. 1 and 2, a light sensor 10 according to an embodiment of the present invention is used for an organic light emitting diode display panel 100. The organic light emitting diode display screen 100 includes an organic light emitting diode layer 20. The light sensor 10 is arranged on an organic light emitting diodeOn the tube layer 20. The light sensor 10 includes a first thin film transistor TPAnd a second thin film transistor TR. A first thin film transistor TPIs connected with a first voltage input terminal VGPFirst thin film transistor TPIs connected to a first predetermined voltage VCOMFirst thin film transistor TPIs connected to the first node N. A second thin film transistor TRIs connected with a second voltage input terminal VGRA second thin film transistor TRIs connected to a first node N, a second thin film transistor TRIs connected to a second predetermined voltage VD. The organic light emitting diode layer 20 includes a plurality of organic light emitting diodes 22, and the light sensor 10 is configured to detect a luminance of one organic light emitting diode 22 corresponding to the light sensor 10 according to a voltage variation of the first node N.
It is understood that the luminance of the organic light emitting diode display screen may vary during use due to the degradation of the material of the organic light emitting diode. In order to restore its brightness to normal, the brightness of the organic light emitting diode may be compensated according to its aging characteristics. However, this approach is too dependent on the aging characteristics of the organic light emitting diode. If the actual aging degree of the organic light emitting diode is different from the expected aging degree, the compensation effect is limited. If the luminance of the organic light emitting diode is detected by the optical sensor by using the principle of photo-generated carriers, the detection result is often inaccurate. Specifically, referring to fig. 3 and 4, in the case where light is applied to a gate electrode of a Thin Film Transistor (TFT) and a positive bias or a negative bias is applied to the gate electrode, a threshold voltage V of the TFT is setthDrift will occur and the wavelength, intensity, and bias time of the illumination will affect the threshold voltage VthDrift of (2). If the light sensor detects the brightness of the organic light emitting diode by utilizing the principle of photo-generated carriers, the brightness is easily influenced by V in the organic light emitting diode display screenthNon-uniformity, degradation of the thin film transistor, and noise, thereby causing stability of the detection result to be affected.
The optical sensor 10 of the present embodiment is based on a thin film crystalThe light sensor 10 is disposed on the organic light emitting diode layer 20 and is located on the first thin film transistor TPAnd a second thin film transistor TRThe voltage variation of the first node N therebetween detects the brightness of the organic light emitting diode 22, which reduces the voltage variation due to V in the organic light emitting diode display panel 100thThe detection result is accurate due to the influence of factors such as unevenness of the organic light emitting diode, deterioration of the thin film transistor, and noise on the detection result, so that the luminance of the organic light emitting diode 22 can be compensated according to the detection result.
Referring to fig. 1 and 2, an oled display panel 100 according to an embodiment of the present invention includes an oled layer 20 and a plurality of photosensors 10. The organic light emitting diode layer 20 includes a plurality of organic light emitting diodes 22. A plurality of photosensors 10 is disposed on the organic light emitting diode layer 20. The plurality of photo sensors 10 correspond to the plurality of organic light emitting diodes 22, and each of the photo sensors 10 is configured to detect the luminance of one of the organic light emitting diodes 22 corresponding to the photo sensor 10 according to a voltage variation of the first node N.
In this way, by disposing the plurality of photosensors 10 on the organic light emitting diode layer 20 and detecting the luminance of the corresponding plurality of organic light emitting diodes 22 by the plurality of photosensors 10, respectively, the detection result is accurate, so that the luminance of each organic light emitting diode 22 can be compensated and corrected according to the detection result.
It should be noted that, in the embodiment of the present invention, the disposing of the light sensor 10 on the organic light emitting diode layer 20 may be: the light sensor 10 is integrated on the organic light emitting diode layer 20 or the light sensor 10 is integrated within the organic light emitting diode layer 20.
Referring to fig. 1 and 2, in some embodiments, the oled display 100 includes an oled layer 20, a package glass 30, a polarizer 40, and a cover plate 50, which are sequentially disposed along a light emitting direction of the oled display 100. When the light sensor 10 is integrated on the organic light emitting diode layer 20, the light sensor 10 may be integrated on the surface of the organic light emitting diode layer 20 close to the package glass 30, or the light sensor 10 may be integrated on the surface of the organic light emitting diode 22 far from the package glass 30. Preferably, the light sensor 10 may be integrated on the surface of the organic light emitting diode layer 20 near the package glass 30. In this way, the light sensor 10 is disposed in the light emitting direction of the organic light emitting diode 22, which is advantageous for the light sensor 10 to detect the brightness of the organic light emitting diode 22.
In some embodiments, the light sensor 10 is integrated within the organic light emitting diode layer 20. Thus, on the one hand, the light sensor 10 facilitates detecting the brightness of the organic light emitting diodes 22 in the organic light emitting diode layer 20; on the other hand, when the optical sensor 10 is applied to the organic light emitting diode display panel 100, the thickness of the organic light emitting diode display panel 100 is thin as a whole.
In some embodiments, the first thin film transistor TPExposed to the illumination of the organic light emitting diode 22, and a second thin film transistor TRAvoiding illumination of the organic light emitting diode 22; or a second thin film transistor TRExposed to the illumination of the organic light emitting diode 22, the first thin film transistor TPAvoiding the illumination of the organic light emitting diode 22.
That is, the first thin film transistor TPAnd a second thin film transistor TROne exposed to the illumination of the organic light emitting diode 22 and the other shielded from the illumination of the organic light emitting diode 22 (i.e., not exposed to the illumination of the organic light emitting diode 22). The threshold voltage V of the thin film transistor is obtained under the conditions of light irradiation and no light irradiationthHas different offset (specifically, the threshold voltage V of the thin film transistor under the condition of applying illuminationthWill be reduced; the stronger the illumination intensity is, the threshold voltage V of the thin film transistorthThe faster the reduction speed is), and thus, the first thin film transistor TPAnd a second thin film transistor TRA control can be formed. A first thin film transistor TPAnd a second thin film transistor TRThreshold voltage V ofthWill result in the first thin film transistor TPAnd a second thin film transistor TRIs different in resistance variation amount and is located in the first thin film transistor TPAnd a second thin film transistor TRBetweenThe voltage of the first node N is changed, and the illumination intensity of the organic light emitting diode 22, that is, the brightness of the organic light emitting diode 22, can be detected according to the voltage change of the first node N.
In the embodiment of the invention, the first thin film transistor TPAnd a second thin film transistor TRAre located adjacently. A first thin film transistor TPOr a second thin film transistor TRMethods of avoiding illumination by the organic light emitting diode 22 include, but are not limited to: an opaque film is provided between the thin film transistor to be shielded from light and the organic light emitting diode 22. The opaque film may be in a block shape, and a plurality of block-shaped opaque films are respectively disposed between each of the tfts and the oled 22. The opaque film may also be a monolithic structure, and holes are cut in the opaque film at locations corresponding to the tfts that do not need to be shielded, so that the tfts that do not need to be shielded are exposed to the light of the oled 22.
Referring to FIG. 1, in some embodiments, the optical sensor 10 has a first voltage input VGPA first negative bias voltage NBIS is applied to the first input terminal and a second voltage input terminal V is applied to the second input terminalGRAfter the second negative bias NBS is applied for a predetermined time, the luminance of the organic light emitting diode 22 is detected according to the voltage variation of the first node N.
That is, the first thin film transistor TPA first negative bias voltage NBIS is applied to the gate electrode of the first thin film transistor TRThe gate of (b) is applied with a second negative bias NBS. It can be understood that when a negative bias is applied to the gate of the thin film transistor, the threshold voltage V of the thin film transistorthWill be reduced. When the negative bias voltage and the light act simultaneously, the threshold voltage V of the thin film transistor is acceleratedthIs reduced, so that the first thin film transistor TPAnd a second thin film transistor TRThe voltage of the first node N will change according to the variation of the resistance, and the brightness of the organic light emitting diode 22 can be detected according to the voltage variation of the first node N. In the embodiment of the invention, a negative bias is applied to the organic light emitting diode 22 due to the thin film transistor exposed to lightThreshold voltage V of voltage-driven thin film transistorthDecrease faster, after a predetermined length of time (e.g. 1000 seconds), VthThe offset can reach more than 15V, and the offset can cover V in the organic light emitting diode display screen 100thNon-uniformity of (A), deterioration of thin film transistor, and noisethThe accuracy of the detection result is improved.
In some embodiments, the first negative bias NBIS is equal to the second negative bias NBS. Thus, the first thin film transistor TPAnd a second thin film transistor TRThe negative bias voltage of the same magnitude is applied, and the voltage variation of the first node N is only affected by the illumination intensity, so that the light sensor 10 can detect the brightness of the organic light emitting diode 22 according to the voltage variation of the first node N.
In some embodiments, when the first thin film transistor TPExposed to the illumination of the organic light emitting diode 22, and a second thin film transistor TRWhen the illumination of the organic light emitting diode 22 is avoided, the light sensor 10 detects the brightness of the organic light emitting diode 22 according to the voltage variation of the first node N, and then applies the first voltage input terminal VGPApplying a positive bias to restore the voltage at the first node N to the first voltage input terminal VGPApplying a first negative bias NBIS to a second voltage input terminal VGRBefore applying the second negative bias NBS.
It is understood that when the first thin film transistor T is formedPWhen a positive bias is applied to the gate of (1), the first thin film transistor TPThreshold voltage V ofthA forward shift will occur due to the first thin film transistor TPExposed to the illumination of the OLED 22, the illumination will offset V to some extentthBut eventually the voltage at the first node N can be restored to the first voltage input terminal VGPApplying a first negative bias voltage NBIS and a second voltage input terminal VGRBefore the second negative bias NBS is applied.
In some embodiments, when the second thin film transistor T is usedRExposed to the illumination of the organic light emitting diode 22, the first thin film transistor TPWhen the illumination of the organic light emitting diode 22 is avoided,the light sensor 10 detects the brightness of the organic light emitting diode 22 according to the voltage variation of the first node N, and then inputs the detected brightness to the second voltage input terminal VGRApplying a positive bias to restore the voltage at the first node N to the first voltage input terminal VGPApplying a first negative bias NBIS to a second voltage input terminal VGRBefore applying the second negative bias NBS.
It is understood that when the second thin film transistor T is usedRWhen a positive bias is applied to the gate electrode of the second thin film transistor TRThreshold voltage V ofthA forward shift will occur and since the second thin film transistor TR is exposed to the illumination of the organic light emitting diode 22, the illumination will cancel V to some extentthBut eventually the voltage at the first node N can be restored to the first voltage input terminal VGPApplying a first negative bias voltage NBIS and a second voltage input terminal VGRBefore the second negative bias NBS is applied.
In some embodiments, the light sensor 10 has a first voltage input VGPA first positive bias voltage PBIS and a second voltage input terminal V are appliedGRAfter the second forward bias PBS is applied for a predetermined time, the brightness of the organic light emitting diode 22 is detected according to the voltage change of the first node N.
That is, the first thin film transistor TPThe gate of which is applied with a first positive bias voltage PBIS, a second thin film transistor TRThe gate of (a) is applied with a second positive bias PBS. It can be understood that when the gate of the thin film transistor is applied with a positive bias voltage, the threshold voltage V of the thin film transistorthWill increase. When the forward bias voltage and the illumination are applied simultaneously, the illumination will cancel V to some extentthSo that the first thin film transistor TPAnd a second thin film transistor TRThe voltage of the first node N will change according to the variation of the resistance, and the brightness of the organic light emitting diode 22 can be detected according to the voltage variation of the first node N. In an embodiment of the invention, after a predetermined period of time (e.g. 2000 seconds), VthThe offset can reach more than 15V, and the offset can cover V in the organic light emitting diode display screen 100thNon-uniformity of (2) and inferiority of thin film transistorConversion and noise factor pair VthThe accuracy of the detection result is improved.
In some embodiments, the first forward bias PBIS is equal to the second forward bias PBS. Thus, the first thin film transistor TPAnd a second thin film transistor TRThe voltage variation of the first node N is only affected by the illumination intensity when the positive bias voltage of the same magnitude is applied, so that the light sensor 10 can detect the brightness of the organic light emitting diode 22 according to the voltage variation of the first node N.
In some embodiments, when the first thin film transistor TPExposed to the illumination of the organic light emitting diode 22, and a second thin film transistor TRWhen the illumination of the organic light emitting diode 22 is avoided, the light sensor 10 detects the brightness of the organic light emitting diode 22 according to the voltage variation of the first node N, and then applies the first voltage input terminal VGPApplying a negative bias to restore the voltage at the first node N to the first voltage input terminal VGPApplying a first positive bias voltage PBIS to the second voltage input terminal VGRBefore applying the second positively biased PBS.
It is understood that when the first thin film transistor T is formedPWhen a negative bias is applied to the gate of the first thin film transistor TPThreshold voltage V ofthA negative shift will occur due to the first thin film transistor TPExposed to the illumination of the organic light emitting diode 22, the first thin film transistor TPThreshold voltage V ofthThe voltage at the first node N can be quickly restored to the first voltage input terminal VGPApplying a first positive bias voltage PBIS and a second voltage input terminal VGRBefore the second positively biased PBS is applied.
In some embodiments, when the second thin film transistor T is usedRExposed to the illumination of the organic light emitting diode 22, the first thin film transistor TPWhen the illumination of the organic light emitting diode 22 is avoided, the light sensor 10 detects the brightness of the organic light emitting diode 22 according to the voltage variation of the first node N, and then applies the second voltage input terminal VGRApplying a negative bias to restore the voltage at the first node N to the first voltage input terminal VGPApplying a first positive bias voltage PBIS and applying a second positive bias voltage PBISTwo voltage input terminals VGRBefore applying the second positively biased PBS.
It is understood that when the second thin film transistor T is usedRWhen a negative bias is applied to the gate electrode of the second thin film transistor TRThreshold voltage V ofthA negative shift will occur due to the second thin film transistor TRExposed to the illumination of the organic light emitting diode 22, and a second thin film transistor TRThreshold voltage V ofthThe voltage at the first node N can be quickly restored to the first voltage input terminal VGPApplying a first positive bias voltage PBIS and a second voltage input terminal VGRBefore the second positively biased PBS is applied.
The first thin film transistor T is used as the followingPExposed to the illumination of the organic light emitting diode 22, and a second thin film transistor TRThe operation principle of the optical sensor 10 according to the embodiment of the present invention will be described in detail by taking the example of avoiding the light irradiation of the organic light emitting diode 22.
First, a first negative bias NBIS is applied to the gate electrode of the first thin film transistor TP, and a second negative bias NBS is applied to the gate electrode of the second thin film transistor TR. The magnitude of the first negative bias NBIS may be the same as the magnitude of the second negative bias NBS. At the same time, the first thin film transistor TPThreshold voltage V ofthWill be larger than the second thin film transistor TRThreshold voltage V ofthSo that the first thin film transistor T is formedPThe resistance reduction of (a) will be larger. In some embodiments, the first predetermined voltage VCOMMay be 0V, that is, the first thin film transistor TPIs grounded. The second predetermined voltage may be VD. A first thin film transistor TPAnd a second thin film transistor TRForming a voltage divider circuit. Since the first thin film transistor TPIs reduced by a smaller amount than the second thin film transistor TRIs more decreased, and thus, the first thin film transistor TPAnd a second thin film transistor TRThe voltage of the first node N therebetween is decreased, and the intensity of the illumination is determined according to the amount of decrease in the voltage of the first node N. For example, assume a first thin film transistor TPAnd a secondThin film transistor TRIs the same thin film transistor, after a predetermined period of time, due to the threshold voltage VthSo that the voltage V of the first node NnFrom VD2 to VD/5, 3V according to the voltage change of the first node NDThe luminance of the organic light emitting diode 22 can be calculated as/10. Then, for the first thin film transistor TPIs positively biased so that the first thin film transistor T is formedPThreshold voltage V ofthA forward shift occurs until the voltage V of the first node NnFrom VDChange from/5 to VD/2, i.e. the first thin-film transistor TPThreshold voltage V ofthAnd restoring the initial state.
Of course, the first thin film transistor T may be required to be detected while limiting the amount of change in the voltage of the first node NPApplying a first negative bias NBIS to the gate electrode and applying a second negative bias to the second thin film transistor TRFor the time of applying the second negative bias NBS. For example, the voltage V of the first node N is detectednFrom VDThe shorter the switching time, the stronger the intensity of light is. Therefore, the luminance of the organic light emitting diode 22 can be calculated from the conversion time. Then, for the first thin film transistor TPIs positively biased so that the first thin film transistor T is formedPThreshold voltage V ofthA forward shift occurs until the voltage V of the first node NnFrom 0V to VD/2, i.e. the first thin-film transistor TPThreshold voltage V ofthAnd restoring the initial state.
In some embodiments, the organic light emitting diode display panel 100 controls the magnitude of the voltage applied to the organic light emitting diode 22 according to the brightness of the organic light emitting diode 22.
Specifically, when it is detected that the luminance of the organic light emitting diode 22 is lower than a normal value, the voltage applied across the organic light emitting diode 22 is increased, and the lower the luminance of the organic light emitting diode 22, the greater the voltage applied across the organic light emitting diode 22, so that the luminance of the organic light emitting diode 22 is restored to normal, thereby preventing the organic light emitting diode display panel 100 from generating color difference.
In some embodiments, the OLED display 100 controls the amount of current applied to the OLED 22 according to the brightness of the OLED 22.
Specifically, when it is detected that the luminance of the organic light emitting diode 22 is lower than a normal value, the current applied to the organic light emitting diode 22 is increased, and the lower the luminance of the organic light emitting diode 22 is, the greater the current applied to the organic light emitting diode 22 is, so that the luminance of the organic light emitting diode 22 is restored to normal, thereby preventing the organic light emitting diode display screen 100 from generating color difference.
In the description herein, references to the description of the terms "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example" or "some examples" or the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
Any process or method descriptions in flow charts or otherwise described herein may be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps of the process, and alternate implementations are included within the scope of the preferred embodiment of the present invention in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the present invention.
The logic and/or steps represented in the flowcharts or otherwise described herein, such as an ordered listing of executable instructions that can be considered to implement logical functions, can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processing module-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. For the purposes of this description, a "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of the computer-readable medium would include the following: an electrical connection having one or more wires (control method), a portable computer diskette (magnetic device), a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium could even be paper or another suitable medium upon which the program is printed, as the program can be electronically captured, via for instance optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner if necessary, and then stored in a computer memory.
It should be understood that portions of embodiments of the present invention may be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, the various steps or methods may be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or combination of the following techniques, which are known in the art, may be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application specific integrated circuit having an appropriate combinational logic gate circuit, a Programmable Gate Array (PGA), a Field Programmable Gate Array (FPGA), or the like.
It will be understood by those skilled in the art that all or part of the steps carried by the method for implementing the above embodiments may be implemented by hardware related to instructions of a program, which may be stored in a computer readable storage medium, and when the program is executed, the program includes one or a combination of the steps of the method embodiments.
In addition, functional units in the embodiments of the present invention may be integrated into one processing module, or each unit may exist alone physically, or two or more units are integrated into one module. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode. The integrated module, if implemented in the form of a software functional module and sold or used as a stand-alone product, may also be stored in a computer readable storage medium.
The storage medium mentioned above may be a read-only memory, a magnetic or optical disk, etc.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and not to be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made in the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims (12)

  1. A light sensor for an organic light emitting diode display screen, the organic light emitting diode display screen including an organic light emitting diode layer, wherein the light sensor is disposed on the organic light emitting diode layer, the light sensor comprising:
    the grid electrode of the first thin film transistor is connected with a first voltage input end, the source electrode of the first thin film transistor is connected with a first preset voltage, and the drain electrode of the first thin film transistor is connected with a first node; and
    a second thin film transistor, wherein a gate of the second thin film transistor is connected to a second voltage input terminal, a source of the second thin film transistor is connected to the first node, and a drain of the second thin film transistor is connected to a second predetermined voltage;
    the organic light emitting diode layer comprises a plurality of organic light emitting diodes, and the light sensor is used for detecting the brightness of one organic light emitting diode corresponding to the light sensor according to the voltage change of the first node.
  2. The light sensor of claim 1, wherein the light sensor is integrated within the organic light emitting diode layer.
  3. The light sensor of claim 1, wherein the light sensor detects the brightness of the OLED according to a voltage variation of the first node after the first voltage input terminal is applied with a first negative bias and the second voltage input terminal is applied with a second negative bias for a predetermined time.
  4. The light sensor of claim 3, wherein the first negative bias is equal to the second negative bias.
  5. The light sensor of claim 3, wherein when the first thin film transistor is exposed to the light of the organic light emitting diode and the second thin film transistor is shielded from the light of the organic light emitting diode, the light sensor applies a positive bias to the first voltage input terminal after detecting the brightness of the organic light emitting diode according to the voltage variation of the first node to restore the voltage of the first node to the first negative bias applied to the first voltage input terminal and the second negative bias applied to the second voltage input terminal;
    when the second thin film transistor is exposed to the illumination of the organic light emitting diode and the first thin film transistor avoids the illumination of the organic light emitting diode, after the light sensor detects the brightness of the organic light emitting diode according to the voltage change of the first node, a positive bias is applied to the second voltage input end so that the voltage of the first node is restored to be before the first negative bias is applied to the first voltage input end and the second negative bias is applied to the second voltage input end.
  6. The light sensor of claim 1, wherein the light sensor detects the brightness of the OLED according to a voltage change of the first node after the first voltage input terminal is applied with a first positive bias and the second voltage input terminal is applied with a second positive bias for a predetermined period of time.
  7. The light sensor of claim 6, wherein the first positive bias voltage is equal to the second positive bias voltage.
  8. The light sensor of claim 6, wherein when the first thin film transistor is exposed to the light of the organic light emitting diode and the second thin film transistor is shielded from the light of the organic light emitting diode, the light sensor applies a negative bias to the first voltage input terminal after detecting the brightness of the organic light emitting diode according to the voltage variation of the first node to restore the voltage of the first node to the voltage before applying the first positive bias to the first voltage input terminal and the second positive bias to the second voltage input terminal;
    when the second thin film transistor is exposed to the illumination of the organic light emitting diode and the first thin film transistor avoids the illumination of the organic light emitting diode, after the light sensor detects the brightness of the organic light emitting diode according to the voltage change of the first node, a negative bias is applied to the second voltage input end so that the voltage of the first node is restored to be before the first positive bias is applied to the first voltage input end and the second positive bias is applied to the second voltage input end.
  9. An organic light emitting diode display panel, comprising:
    an organic light emitting diode layer comprising a plurality of organic light emitting diodes; and
    a plurality of the photo sensors of any one of claims 1-8, a plurality of the photo sensors being disposed on the organic light emitting diode layer, a plurality of the photo sensors corresponding to a plurality of the organic light emitting diodes, each of the photo sensors being configured to detect a brightness of one of the organic light emitting diodes corresponding to the photo sensor according to a voltage variation of the first node.
  10. The OLED display panel of claim 9, wherein the voltage applied to the OLED is controlled according to the brightness of the OLED.
  11. The OLED display panel of claim 9, wherein the OLED display panel controls the amount of current applied to the OLED according to the brightness of the OLED.
  12. The OLED display screen of claim 9, wherein the OLED display screen comprises the OLED layer, the packaging glass, the polarizer and the cover plate in this order along the light emitting direction of the OLED display screen.
CN201780091760.XA 2017-10-20 2017-10-20 Optical sensor and organic light emitting diode display screen Pending CN110709994A (en)

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