KR20190079859A - Subpixel, driving circuit and display device - Google Patents

Abstract

Embodiments of the present invention relate to a sub-pixel structure, to a driving circuit, and to a display device for fingerprint sensing. By connecting an optical sensor to a transistor connected to a reference voltage line disposed in a sub-pixel, and sensing a voltage fluctuation depending on whether the optical sensor is exposed to light, floors and valleys of a fingerprint touched in an active area of a display panel are disassembled and the fingerprint of the user can be sensed. In addition, by disposing a transistor which is turned off during a fingerprint sensing period between a transistor connected to the optical sensor and an anode electrode of an organic light emitting diode, fingerprint sensing can be performed while preventing luminance deterioration due to leakage of currents flowing to the organic light emitting diode during the fingerprint sensing period.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a sub-

Embodiments of the present invention are directed to subpixels, driver circuits, and display devices.

BACKGROUND ART [0002] As an information society develops, various demands for a display device for displaying an image have been increasing, and a variety of display devices such as a liquid crystal display device, a plasma display device, an organic light emitting display device ) Are being utilized in various types of display devices.

In order to provide a variety of functions to the user, such a display device provides various functions such as a function of recognizing a user's touch on a display panel and performing an input process in addition to a basic function of displaying an image through a display panel.

Further, in order to provide an input processing function using biometric information of a user, a function of recognizing biometric information of a user such as a fingerprint, iris, or face of a user and performing input processing is provided in a display device.

As a method of recognizing a fingerprint of a user among the biometric information of the user, for example, a fingerprint sensor may be disposed in a region (non-active region) where no image is displayed on the front face of the display panel or on the side or rear face of the display device, A fingerprint of a user who is in contact with the fingerprint is recognized.

Here, the structure in which the fingerprint sensor is disposed on the side surface or the rear surface of the display device has a problem that the user's convenience is deteriorated because the fingerprint sensor is disposed at a position where it is difficult for the user to visually recognize.

In addition, the structure of disposing the fingerprint sensor in the non-active area of the display panel has a problem that the area (active area) where the image is displayed becomes relatively narrow as the non-active area increases due to the fingerprint sensor.

Accordingly, there is a need for a method of improving user convenience and providing a fingerprint sensing function in a structure of a display device that maximizes the active area and minimizes the non-active area.

It is an object of embodiments of the present invention to provide a sub-pixel structure and a driving circuit and a display device that enable a fingerprint of a user to be sensed in an active area of a display panel.

It is an object of embodiments of the present invention to provide a sub-pixel structure, a driving circuit, and a display device that enable a user's fingerprint to be sensed in an active area of a display panel without deteriorating the image display function of the display panel .

In one aspect, embodiments of the present invention include a display panel in which a plurality of gate lines, a plurality of data lines, a plurality of reference voltage lines, and a plurality of subpixels are arranged, And a driving circuit for detecting a signal using at least one reference voltage line among the reference voltage lines of the display device.

In such a display device, at least one subpixel of the plurality of subpixels includes an organic light emitting diode, a driving transistor connected to the first electrode of the organic light emitting diode, and a driving transistor connected between the gate node of the driving transistor and the data line, A third transistor electrically connected between the second transistor and a second node (e.g., a source node) of the driving transistor; and a third transistor electrically connected between the first node of the second transistor (E.g., a drain node) and a second node (e.g., a source node), and a storage capacitor electrically coupled between a gate node of the drive transistor and a second node (e.g., a source node) have.

According to another aspect of the present invention, there is provided a display device comprising: a reference voltage output unit for outputting a reference voltage to a reference voltage line arranged in a subpixel during a display driving period; A sensing voltage output unit outputting a sensing driving voltage as a reference voltage line and outputting a sensing reference voltage as a reference voltage line in a second period of the fingerprint sensing period, And a fingerprint sensing unit for sensing the fingerprint based on the sensed voltage.

According to embodiments of the present invention, a sensing signal can be detected when a user's fingerprint is touched in an active area of a display panel through a structure in which an optical sensor is connected to a transistor connected to a reference voltage line in a subpixel of a display panel .

According to embodiments of the present invention, detection of a sensing signal by a fingerprint touch in units of subpixels in a display panel enables disassembly of ridges and valleys of the fingerprint, So that the fingerprint of the user can be recognized.

1 is a diagram showing a schematic configuration of a display device according to embodiments of the present invention.
2A and 2B are diagrams illustrating an example of a circuit structure of a subpixel arranged in a display panel of a display device according to embodiments of the present invention.
3 is a diagram illustrating an exemplary structure of a sub-pixel in which a fingerprint sensor is disposed in a display device according to embodiments of the present invention.
4 is a diagram illustrating an example of a circuit structure of a subpixel in which a fingerprint sensing function is implemented in a display device according to embodiments of the present invention.
5 is a view for explaining a principle of sensing a fingerprint using an optical sensor disposed in a subpixel in a display device according to embodiments of the present invention.
6 to 9 are views illustrating an example of a driving method of a sub-pixel during a fingerprint sensing period in a display device according to embodiments of the present invention.
10 is a diagram showing an example of a schematic configuration of a driving circuit for sensing a fingerprint in a display device according to embodiments of the present invention.
11 is a diagram illustrating an example of a process of a fingerprint sensing method of a display device according to embodiments of the present invention.
12 is a diagram illustrating the effect of the fingerprint sensing function provided by the display device according to the embodiments of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. In the drawings, like reference numerals are used to denote like elements throughout the drawings, even if they are shown on different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

In describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended to distinguish the components from other components, and the terms do not limit the nature, order, order, or number of the components. When a component is described as being "connected", "coupled", or "connected" to another component, the component may be directly connected or connected to the other component, Quot; intervening "or that each component may be" connected, "" coupled, "or " connected" through other components.

1 shows a schematic configuration of a display device 100 according to embodiments of the present invention.

1, a display device 100 according to embodiments of the present invention includes a display panel 110 in which a plurality of sub-pixels SP including a light emitting device are arranged, A gate driving circuit 120, a data driving circuit 130, a controller 140, and the like.

A plurality of gate lines GL and a plurality of data lines DL are arranged in the display panel 110 and sub pixels SP are arranged in a region where the gate lines GL and the data lines DL intersect each other . Each of the subpixels SP may include a light emitting element, and two or more subpixels SP may constitute one pixel.

The gate driving circuit 120 is controlled by the controller 140 and sequentially outputs scan signals to a plurality of gate lines GL disposed on the display panel 110 to sequentially output driving timing of a plurality of sub- .

The gate driving circuit 120 may include one or more gate driver integrated circuits (GDICs), and may be located only on one side of the display panel 110 or on both sides of the display panel 110 It is possible.

The data driving circuit 130 receives the video data from the controller 140 and converts the video data into an analog data voltage. The data voltages are outputted to the respective data lines DL in accordance with the timing of applying the scan signals through the gate lines GL so that each subpixel SP expresses the brightness according to the image data.

The data driving circuit 130 may include one or more source driver integrated circuits (SDICs).

The controller 140 supplies various control signals to the gate driving circuit 120 and the data driving circuit 130 and controls the operations of the gate driving circuit 120 and the data driving circuit 130.

The controller 140 causes the gate driving circuit 120 to output a scan signal according to the timing to be implemented in each frame and converts the image data received from the outside into a data signal format used in the data driving circuit 130 And outputs the converted image data to the data driving circuit 130.

The controller 140 outputs various timing signals including the vertical synchronization signal Vsync, the horizontal synchronization signal Hsync, the input data enable signal DE, and the clock signal CLK, (E.g., a host system).

The controller 140 can generate various control signals using various timing signals received from the outside and output them to the gate driving circuit 120 and the data driving circuit 130. [

For example, in order to control the gate driving circuit 120, the controller 140 generates a gate start pulse (GSP), a gate shift clock (GSC), a gate output enable signal GOE, Gate Output Enable) and the like.

Here, the gate start pulse GSP controls the operation start timing of one or more gate driver integrated circuits constituting the gate driving circuit 120. The gate shift clock GSC is a clock signal commonly input to one or more gate driver ICs, and controls the shift timing of the scan signal. The gate output enable signal GOE specifies the timing information of one or more gate driver ICs.

In order to control the data driving circuit 130, the controller 140 generates a source start pulse (SSP), a source sampling clock (SSC), a source output enable signal (SOE, Source Output Enable) and the like.

Here, the source start pulse SSP controls the data sampling start timing of one or more source driver integrated circuits constituting the data driving circuit 130. The source sampling clock SSC is a clock signal for controlling sampling timing of data in each of the source driver integrated circuits. The source output enable signal SOE controls the output timing of the data driving circuit 130.

The display device 100 includes a power management integrated circuit for supplying various voltages or currents to the display panel 110, the gate driving circuit 120, the data driving circuit 130, etc., or for controlling various voltages or currents to be supplied .

In the display panel 110, voltage lines to which various signals and voltages are supplied may be arranged in addition to the gate lines GL and the data lines DL. In each sub-pixel SP, a light emitting element and a transistor Etc. may be disposed.

2A and 2B illustrate an example of the circuit structure of a sub-pixel SP arranged in the display panel 110 of the display device 100 according to the embodiments of the present invention. And the display device 100 is an organic light emitting display device.

2A, a subpixel SP according to embodiments of the present invention includes an organic light emitting diode OLED and includes a driving transistor DRT for driving the organic light emitting diode OLED, A first transistor T1, a second transistor T2, a storage capacitor Cstg, and the like. That is, it may be a 3T1C structure including three transistors and one capacitor.

A driving voltage line DVL to which the driving voltage Vdd is applied and a reference voltage line Vdd to which the reference voltage Vref is applied are arranged in the subpixel SP, (RVL) may be disposed. Here, the driving voltage line DVL and the reference voltage line RVL may be arranged one by one for two or more sub-pixels SP.

The first transistor T1 is electrically connected between the data line DL and the first node N1 of the driving transistor DRT. The gate node of the first transistor T1 may be electrically connected to the first gate line GL1 or formed integrally with the first gate line GL1.

The first transistor T1 is turned on and off by a scan signal applied to the first gate line GL1 and the data voltage Vdata supplied through the data line DL is supplied to the driving transistor DRT To the first node N1, which is a gate node of the first transistor N1. The first transistor T1 is also referred to as a switching transistor.

The second transistor T2 is electrically connected between the reference voltage line RVL and the second node N2 of the driving transistor DRT. The gate node of the second transistor T2 may be electrically connected to the second gate line GL2 or formed integrally with the second gate line GL2.

The second transistor T2 is turned on and off by a scan signal applied to the second gate line GL2 so that the reference voltage Vref supplied through the reference voltage line RVL is applied to the driving transistor DRT to the second node N2.

The driving transistor DRT is electrically connected between the driving voltage line DVL and the organic light emitting diode OLED.

The driving transistor DRT is turned on by the data voltage Vdata applied to the first node N1 so that the driving voltage Vdd is applied to the organic light emitting diode OLED according to the data voltage Vdata .

The storage capacitor Cstg is electrically connected between a first node N1 which is a gate node of the driving transistor DRT and a second node N2 which is a source node. Such a storage capacitor Cstg can maintain the data voltage Vdata applied to the gate node of the driving transistor DRT for one frame.

The organic light emitting diode OLED displays the brightness according to the difference between the voltage applied to the anode electrode by the driving transistor DRT and the base voltage Vss so that each subpixel SP can display an image .

These subpixels SP can be designed in various structures other than the 3T1C structure described above.

2B shows another example of the circuit structure of the subpixel SP according to the embodiments of the present invention. An example of a 4T1C structure in which four transistors and one capacitor are arranged in one subpixel SP .

2B, each sub-pixel SP includes an organic light emitting diode (OLED), a driving transistor DRT and a first transistor T1 for driving the organic light emitting diode OLED, a second transistor T2 ), A light emitting transistor (EMT), and a storage capacitor (Cstg).

A first gate line GL1 for applying a scan signal to the first transistor T1, a second gate line GL2 for applying a scan signal to the second transistor T2, A light emission scan line (ESL) for applying a scan signal may be disposed.

The data line DL, the driving voltage line DVL, and the reference voltage line RVL may be arranged.

2A, the light emitting transistor EMT is electrically connected between the driving voltage line DVL and the third node N3 of the driving transistor DRT. It is turned on and off by the light emitting signal applied through the light emission scan line ESL.

The first transistor T1 and the second transistor T2 are turned on while the light emitting transistor EMT is turned off during the display driving and the data voltage Vdata is applied to the gate node of the driving transistor DRT And the reference voltage Vref is applied to the source node of the driving transistor DRT to charge the storage capacitor Cstg.

When the light emitting transistor EMT is turned on, a voltage is applied to the anode electrode of the organic light emitting diode OLED according to the voltage charged in the storage capacitor Cstg, and the organic light emitting diode OLED emits light.

Thus, by disposing the light emitting transistor EMT between the driving transistor DRT and the driving voltage line DVL, the emission timing of each subpixel SP can be controlled. Further, after the charging of the storage capacitor Cstg of each subpixel SP is completed, the light emitting transistor EMT disposed in each subpixel SP is simultaneously turned on, and the subpixel SP charges the storage capacitor Cstg It may be displayed.

Embodiments of the present invention provide a sub-pixel (SP) including a sensor capable of sensing a fingerprint and minimizing the influence on the display drive in such a sub-pixel (SP) structure and a display device .

3 shows an example of a schematic structure of a subpixel SP in which a fingerprint sensor is disposed in the display device 100 according to the embodiments of the present invention.

Referring to FIG. 3, the subpixels SP arranged in the display panel 110 in the display device 100 according to the embodiments of the present invention may be divided into a light emitting region and a region in which circuit elements are arranged. 3 shows a structure in which a red subpixel SP, a green subpixel SP and a blue subpixel SP are arranged in each subpixel SP. One example is shown.

Each of the sub-pixels SP may be provided with a fingerprint sensor FS for sensing a fingerprint of a user to be touched on the display panel 110. Such a fingerprint sensor FS may be arranged for each subpixel SP, or one for each of two or more subpixels SP. That is, the reduction of the emission region of the subpixel SP can be minimized and the sensing signal for fingerprint sensing can be variously arranged.

The fingerprint sensor FS may be configured such that a transistor disposed in the subpixel SP, a capacitor, or the like is connected to a sensor responsive to light.

The fingerprint sensor FS may be driven using one or more lines to which a scan signal to be applied to the subpixel SP is applied and a voltage line.

For example, the fingerprint sensor FS may be configured such that a sensor responsive to light is connected to the second transistor T2 disposed in the subpixel SP. In this case, the fingerprint sensor FS may be driven by the second gate line GL2 connected to the second transistor T2 and the reference voltage line RVL.

Therefore, the reference voltage line RVL is arranged for each subpixel SP for fingerprint sensing, and the reference voltage line RVL disposed in each subpixel SP can be dividedly driven.

In addition, a transistor that prevents the current from flowing between the second transistor T2 and the anode electrode of the organic light emitting diode OLED during the fingerprint sensing period by performing the fingerprint sensing using the second transistor T2, A gate line GL for driving the gate line GL is additionally disposed.

As described above, by connecting the optical sensor PS to the second transistor T2 of the sub-pixel SP and further arranging the transistor and the gate line GL for fingerprint sensing, So that the sensor can be configured.

4 shows an example of a circuit structure of a subpixel SP in which a fingerprint sensor FS is disposed in a display device 100 according to an embodiment of the present invention. The 4T1C subpixel (SP) structure is shown as an example will be.

4, each sub-pixel SP includes an organic light emitting diode OLED and includes a driving transistor DRT, a first transistor T1, a second transistor T2, and a light emitting transistor EMT. And a storage capacitor Cstg. The organic light emitting diode OLED may further include a third transistor T3 electrically connected between the second transistor T2 and the anode electrode of the organic light emitting diode OLED.

And an optical sensor PS electrically connected between the drain node and the source node of the second transistor T2.

Such a photosensor PS may have photosensitivity in which electrical characteristics are changed when exposed to light of a specific wavelength.

For example, the photosensor (PS) acts as a non-conductor before being exposed to light, and when exposed to light, the electrical characteristics change so that both ends are electrically connected and can act as conductors. Here, the optical sensor PS is also referred to as a photosensor, and FIG. 4 shows an example in which a bi-directional diode is used as the optical sensor PS.

That is, in the structure in which the optical sensor PS is electrically connected between the drain node and the source node of the second transistor T2, when the optical sensor PS is exposed to light when the second transistor T2 is off, A current flowing through the sensor PS may occur. Therefore, a current flows between the drain node and the source node of the second transistor T2.

Since the storage capacitor Cstg is connected to the source node of the second transistor T2, when a leakage current due to light exposure occurs in a state where the storage capacitor Cstg is charged, the voltage charged in the storage capacitor Cstg .

By sensing the amount of change in the charging voltage of the storage capacitor Cstg, it is possible to detect a sensing signal generated depending on whether the photosensor PS is exposed or not. In addition, by using the sensing signal, the ridge and valley of the fingerprint touched on the display panel 110 can be disassembled and the fingerprint can be sensed.

Since the second transistor T2 is connected to the second gate line GL2 and the reference voltage line RVL, the second gate line GL2 can be used as a line to which a scan signal for fingerprint sensing is applied have.

The reference voltage line RVL may be used as a line to which a driving voltage for fingerprint sensing is applied and which detects a sensing signal.

That is, the reference voltage line RVL is connected to a circuit for outputting a reference voltage Vref for driving the display during a display driving period, a circuit for outputting a driving voltage for fingerprint sensing and detecting a sensing signal during a fingerprint sensing period, So that the display driving and the fingerprint sensing can be performed.

Here, there may be a period during which the second transistor T2 is turned on during the fingerprint sensing period by performing the fingerprint sensing using the second transistor T2. At this time, since the reference voltage line RVL and the second node N2 are electrically connected, current leakage to the organic light emitting diode OLED may occur.

The third transistor T3 may be disposed between the second transistor T2 and the second node N2 and the third transistor T3 may be turned on during the fingerprint sensing period, Off to prevent leakage of a current flowing to the organic light emitting diode (OLED).

That is, in the fingerprint sensing period, when the third transistor T3 is turned off, a voltage is applied to the fourth node N4 to charge the storage capacitor Cstg, and the voltage of the fourth node N4 is sensed So that the variation amount of the charging voltage can be sensed.

In addition, a third gate line GL3 for controlling the third transistor T3 may be further disposed in the fingerprint sensing period.

Accordingly, the sub-pixel SP capable of fingerprint sensing is provided with a first transistor T1 and a second transistor T2, which are connected to the first and third transistors T3 and T4, respectively, in addition to the first and second gate lines GL1 and GL2, And a third gate line GL3 connected to the third gate line GL2.

Since the second transistor T2 and the third transistor T3 used for fingerprint sensing must be independently driven, each transistor may be connected to a different gate line GL.

As described above, the light sensor PS is connected to the second transistor T2 disposed in the sub-pixel SP, and the sub-pixel SP (SP) is connected to the third transistor T3 through the additional arrangement of the third transistor T3 and the third gate line GL3. So that a sensing signal corresponding to the touched fingerprint can be detected.

By allowing the sensing signal to be detected for each subpixel SP disposed in the area where the fingerprint is touched, it is possible to decompose the ridge and valley of the fingerprint based on the sensing signal and to sense the fingerprint do.

Since the second transistor T2 is disposed for each of the subpixels SP, it is possible to perform fingerprint sensing in all areas of the display panel 110, PS) may be disposed to enable fingerprint sensing.

Hereinafter, the principle of fingerprint sensing using the optical sensor PS will be described with reference to FIG. 5, and a driving method for fingerprint sensing will be described in detail with reference to FIG. 6 to FIG.

FIG. 5 shows a principle of sensing a fingerprint using a photosensor PS disposed in a sub-pixel SP in a display device 100 according to an embodiment of the present invention.

5, a display device 100 according to embodiments of the present invention may be disposed on a substrate 530 in all areas of a display panel 110 or in a subpixel SP of an area set for fingerprint sensing The optical sensor PS is located.

The display device 100 may include a light source device 510 for emitting light in a fingerprint sensing period and a light guide plate 520 for guiding light emitted from the light source device 510. Such a light guide plate 520 may be one in which a light guide panel or a light guide device is additionally arranged or a configuration included in the display device 100 such as a cover glass of the display panel 110 may be utilized .

When the light source device 510 irradiates light having a specific wavelength in the fingerprint sensing period, the light emitted from the light source device 510 can be emitted along the light guide plate 520.

At this time, when a fingerprint is touched on the surface of the display panel 110, light may be transmitted or reflected depending on a ridge protruding from the fingerprint and a valley being a recessed portion.

For example, the light reaching the portion where the ridge of the fingerprint and the light guide plate 520 are contacted is substantially the same as the refractive index of the finger and the glass, so that light is transmitted. Since the light is transmitted and emitted to the outside, the optical sensor PS disposed in the region corresponding to the ridge of the fingerprint is not exposed to light (light blocking area).

In the portion where the valley of the fingerprint is located, the valley of the fingerprint and the light guide plate 520 are not in contact with each other and the air is positioned therebetween. Since the refractive index of the air differs from the refractive index of the glass, the light is not transmitted through the portion where the valleys of the fingerprint are located and is reflected. Therefore, the light sensor PS disposed in the region corresponding to the valley of the fingerprint is exposed to light (light-exposed region).

That is, the light sensor PS disposed in the region corresponding to the ridge of the fingerprint is blocked, and the light sensor PS disposed in the region corresponding to the valley of the fingerprint can be exposed to light have.

In addition, the electrical characteristics of the optical sensor PS may vary depending on light interception or light exposure.

By using such a change in electrical characteristic of the photosensor PS due to the light interception or the light exposure, it corresponds to the subpixel SP located in the region corresponding to the ridge of the fingerprint and the valley of the fingerprint It is possible to detect another sensing signal from the sub-pixel SP located in the region where the sub-pixel SP is located.

A ridge and a valley of the fingerprint are decomposed using the difference of the sensing signal detected from the sub pixel SP so that the fingerprint touched on the display panel 110 can be sensed.

FIGS. 6 to 9 show examples of how the display device 100 according to the embodiments of the present invention drives the sub-pixels SP during the fingerprint sensing period.

Such fingerprint sensing can be performed in the display driving period and the time division period since the reference voltage line RVL arranged in the subpixel SP is used as the sensing line.

Accordingly, fingerprint sensing can be performed by allocating a part of the display driving period or a part of the touch sensing period when the touch sensing function is provided. Alternatively, the fingerprint sensing may be performed only when fingerprint sensing is requested by an application executed in the display device 100 or the like.

6, an optical sensor PS electrically connected between the drain node and the source node of the second transistor T2 is connected to the subpixel SP of the display device 100 according to the embodiments of the present invention. . A third transistor T3 electrically connected between the second transistor T2 and the second node N2 and a third gate line GL3 connected to the third transistor T3 may be disposed.

The reference voltage line RVL may be controlled such that a voltage for display driving or a voltage for fingerprint sensing is applied by the first switch SW1 included in the data driving circuit 130. [

The reference voltage line RVL may be connected to the sensing circuit 150.

The sensing circuit 150 may include a second switch SW2 electrically connected to the reference voltage line RVL, and an amplifier and a feedback capacitor Cfb.

One end of the second switch SW2 of the sensing circuit 150 may be electrically connected to the reference voltage line RVL and the other end may be electrically connected to the negative input terminal of the amplifier. A feedback capacitor (Cfb) may be electrically connected between the (-) input terminal and the output terminal of the amplifier. The amplifier can output a signal detected through the reference voltage line RVL when the second switch SW2 is turned on in the fingerprint sensing period.

The sensing circuit 150 may be disposed separately from the data driving circuit 130, or may be disposed inside the data driving circuit 130. Also, the configuration of the sensing circuit 150 is an example, and various types of circuits capable of detecting a signal through the reference voltage line RVL may be applied.

6 illustrates the driving of the sub-pixel SP during the driving period during the fingerprint sensing period. The fingerprint sensing according to the embodiments of the present invention includes a driving period, a lighting period, a reset period ③ Reset) and sensing period (④ Sensing).

In the fingerprint sensing period, the first switch SW1 included in the data driving circuit 130 is connected to a circuit for outputting a voltage for fingerprint sensing. Therefore, a voltage for fingerprint sensing can be applied through the reference voltage line RVL.

The scan signal is applied through the second gate line GL2 during the driving period of the fingerprint sensing period to turn on the second transistor T2. Then, the data driving circuit 130 outputs the sensing driving voltage Vdrv through the reference voltage line RVL.

Here, a scan signal for turning off the third transistor T3 is applied through the third gate line GL3. The third transistor T3 maintains the turn-off state during the fingerprint sensing period. Accordingly, during the fingerprint sensing period, no current flows between the second transistor T2 and the anode electrode of the organic light emitting diode OLED, thereby preventing current leakage to the organic light emitting diode OLED.

When the sensing driving voltage Vdrv is applied through the reference voltage line RVL, since the second transistor T2 is turned on, the sensing driving voltage Vdrv is applied to the fourth node N4, Cstg) is charged.

When the period for applying the sensing driving voltage Vdrv to the fourth node N4 is completed, an operation for generating a voltage leakage through the optical sensor PS is performed.

7 shows driving of the sub-pixel SP during the light irradiation period during the fingerprint sensing period.

7, when the application of the sensing driving voltage Vdrv to the fourth node N4 is completed, the second transistor T2 is turned off in the light irradiation period, and light is emitted from the light source device 510 do. The third transistor T3 maintains the turn-off state during the fingerprint sensing period.

The light is irradiated in a state where the second transistor T2 is turned off so that a leakage voltage Vleak may be generated depending on whether the photosensor PS connected to the second transistor T2 is exposed to light. The larger the difference in the leakage voltage Vleak is, the larger the difference in the sensing signal occurs, so that the light irradiation period can be set to be sufficiently long during the fingerprint sensing period.

Here, the data driving circuit 130 outputs the reference voltage Vref or the sensing reference voltage on the reference voltage line RVL during the light irradiation period.

This sensing reference voltage is for generating a leakage voltage Vleak through the optical sensor PS and may be a voltage capable of generating a voltage difference between the fourth node N4 and the reference voltage line RVL . For example, the sensing reference voltage may be a reference voltage (Vref), a common voltage or a ground voltage, and may be a separately set voltage for fingerprint sensing.

That is, in the light irradiation period, a sensing reference voltage having a level different from the sensing driving voltage Vdrv supplied through the reference voltage line RVL during the driving period of the fingerprint sensing period may be supplied to the reference voltage line RVL.

Since the second transistor T2 is in the OFF state and the voltage difference exists between the drain node and the source node of the second transistor T2, the light sensor PS is turned on, depending on whether the light sensor PS is exposed to light. A leakage voltage Vleak may be generated.

For example, the area corresponding to the ridge of the fingerprint corresponds to the light blocking area, so that the photosensor PS of the sub pixel SP located in the area may not be exposed to light. Therefore, the optical sensor PS maintains the non-conductive state, so that the leakage voltage Vleak through the optical sensor PS is not generated.

Since the region corresponding to the valley of the fingerprint corresponds to the light-exposed region, the photosensor PS of the sub-pixel SP located in the corresponding region is exposed to light. The optical sensor PS exposed to light changes its electrical characteristics like a conductor, so that a leakage voltage Vleak through the optical sensor PS may occur. When the leakage voltage Vleak is generated, the voltage charged in the fourth node N4 may change.

Therefore, by sensing the voltage of the fourth node N4 after the light irradiation period, the subpixel SP corresponding to the ridge of the fingerprint and the subpixel SP corresponding to the valley of the fingerprint are distinguished . Then, fingerprints can be sensed by disassembling the ridges and valleys of the fingerprints.

Here, after the light irradiation period, the voltage of the fourth node N4 may be sensed through the reference voltage line RVL. At this time, the voltage state of the reference voltage line RVL may be different for each subpixel SP, so that the voltage of the fourth node N4 may not be accurately sensed.

Embodiments of the present invention can perform a process of initializing or resetting a reference voltage line (RVL) which is a sensing line after a light irradiation period, in order to improve accuracy of a sensing voltage after a light irradiation period.

8 shows the driving of the sub-pixel SP in the reset period during the fingerprint sensing period.

Referring to FIG. 8, in the reset period of the fingerprint sensing period, the light source device 510 stops the light irradiation. The off state of the second transistor T2 and the third transistor T3 is maintained, and the sensing reset voltage Vrst is output to the reference voltage line RVL.

This sensing reset voltage Vrst is a voltage for adjusting the voltage level of the reference voltage line RVL disposed in the subpixel SP for fingerprint sensing to a constant level and may be a voltage having a constant level. For example, the sensing reset voltage Vrst may be a reference voltage Vref or a ground voltage.

In this manner, before the voltage of the fourth node N4 is sensed after the light irradiation period, the data driving circuit 130 outputs the reference of each subpixel SP so that the voltage of the fourth node N4 can be accurately sensed. And outputs the same level of the sensing reset voltage Vrst to the voltage line RVL.

Here, the sensing reset voltage Vrst may be a voltage of the same level as the voltage input to the (+) input terminal of the amplifier of the sensing circuit 150.

The amplifier of the sensing circuit 150 outputs a signal corresponding to the difference between the voltage input to the (+) input terminal and the voltage input to the (-) input terminal. Therefore, before sensing the voltage of the fourth node N4, (RVL) to the voltage level input to the (+) input of the amplifier.

Therefore, it is possible to accurately sense the voltage of the fourth node N4 in the sensing period.

9 shows the driving of the sub-pixel SP during the sensing period of the fingerprint sensing period.

Referring to FIG. 9, after the voltage level of the reference voltage line RVL, which is a sensing line, is uniformly adjusted, the second transistor T2 is turned on by the scan signal applied to the second gate line GL2 . The third transistor T3 maintains the turn-off state and turns on the second switch SW2 included in the sensing circuit 150. [

Here, sensing may be performed by turning on the second transistor T2 and the second switch SW2 after a sensing reset voltage Vrst is applied.

When the second transistor T2 and the second switch SW2 are turned on, the (-) input terminal of the amplifier of the sensing circuit 150 is connected to the reference voltage line RVL. Therefore, it becomes possible to sense the voltage of the fourth node N4 through the reference voltage line RVL.

Since the voltage of the fourth node N4 has a different voltage level depending on whether or not the photosensor PS disposed in the sub-pixel SP is exposed to light, the voltage from the sub-pixel SP located in the light- It is possible to detect different sensing signals.

For example, a voltage at a level similar to the sensing driving voltage Vdrv from the subpixel SP disposed in the light blocking area can be sensed. A voltage lower than the sensing driving voltage Vdrv can be sensed from the sub-pixel SP arranged in the light-exposing area.

Since the voltages of the different levels are sensed from the sub-pixel SP of the light blocking area and the sub-pixel SP of the light-exposed area, the sensing signal detected through the voltage sensing of the fourth node N4 is used to detect the fingerprint The touch panel 100 can distinguish the positions of the ridges and valleys of the display panel 110 and sense fingerprints touched in the active area of the display panel 110. [

Such fingerprint sensing may be performed by a circuit built in or connected to the data driving circuit 130 or the sensing circuit 150. In addition, as described above, the data driving circuit 130 and the sensing circuit 150 may be configured separately or may be constituted by one circuit.

10 shows an example of a schematic configuration of a driving circuit 1000 for sensing a fingerprint in the display device 100 according to the embodiments of the present invention.

Referring to FIG. 10, a driving circuit 1000 for providing a fingerprint sensing function according to embodiments of the present invention may include a reference voltage output unit 1010 and a fingerprint sensing driver 1020. The fingerprint sensing driver 1020 may include a sensing voltage output unit 1021 and a fingerprint sensing unit 1022.

The reference voltage output unit 1010 is connected to the reference voltage line RVL during the display driving period and outputs the reference voltage Vref to the reference voltage line RVL.

The fingerprint sensing driver 1020 is connected to the reference voltage line RVL during the fingerprint sensing period. Then, a voltage required for fingerprint sensing is output to the reference voltage line RVL, and a sensing signal is detected through the reference voltage line RVL.

Specifically, in the driving period of the fingerprint sensing period, the sensing voltage output unit 1021 of the fingerprint sensing driver 1020 outputs the sensing driving voltage Vdrv through the reference voltage line RVL. At this time, since the second transistor T2 connected to the reference voltage line RVL is in a turned-on state, the sensing driving voltage Vdrv is charged to the fourth node N4.

The third transistor T3 connected between the second transistor T2 and the anode electrode of the organic light emitting diode OLED maintains a turn-off state during the fingerprint sensing period, and the current leakage to the organic light emitting diode OLED So that the luminance does not decrease.

The sensing voltage output unit 1021 outputs the sensing reference voltage through the reference voltage line RVL during the light irradiation period of the fingerprint sensing period. At this time, light is emitted from the light source device 510.

This sensing reference voltage may be a voltage having a level different from the sensing driving voltage Vdrv. Therefore, since the voltage difference exists between the reference voltage line RVL and the fourth node N4 during the light irradiation period and the second transistor T2 is turned off, A leakage voltage Vleak is generated.

The sensing voltage outputting section 1021 outputs a sensing reset voltage Vrst for constantly matching the voltage level of the reference voltage line RVL to the reference voltage line RVL in the reset period of the fingerprint sensing period.

Then, in the sensing period of the fingerprint sensing period, the fingerprint sensing unit 1022 is connected to the reference voltage line RLV.

Since the fingerprint sensing unit 1022 is connected to the reference voltage line RVL in the state that the second transistor T2 is turned on, the fingerprint sensing unit 1022 can sense the voltage of the fourth node N4 .

Since the sensing signal detected through the reference voltage line RVL is differently detected depending on whether the leakage voltage Vleak is generated through the photosensor PS disposed in the subpixel SP, The subpixels SP corresponding to the valleys can be distinguished.

The fingerprint sensing unit 1022 disassembles the ridges and valleys of the fingerprint touched in the active area of the display panel 110 using the difference of the sensing signals and senses the fingerprint of the user.

11 illustrates a process of a fingerprint sensing method of the display device 100 according to the embodiments of the present invention.

Referring to FIG. 11, in the display device 100 according to the exemplary embodiment of the present invention, when the second transistor T2 is turned on and the third transistor T3 is turned off during the driving period of the fingerprint sensing period The sensing driving voltage Vdrv is outputted from the reference voltage line RVL (S1100).

Then, the second transistor T2 is turned off to control the light source 510 to emit light (S1110). The third transistor T3 maintains the turn-off state.

At the end of the light irradiation period, the second transistor T2 and the third transistor T3 are kept off, and the sensing reset voltage Vrst is output to the reference voltage line RVL (S1120).

When the voltage level of the reference voltage line RVL is adjusted to a predetermined level by the sensing reset voltage Vrst, the third transistor T3 maintains the turn-off state and turns on the second transistor T2 The voltage of the fourth node N4 is sensed (S1130).

The positions of the ridges and valleys of the fingerprint are analyzed using the difference of the voltages sensed through the reference voltage lines RVL disposed in the respective subpixels SP, The fingerprint of the user touched in the area is sensed (S1140).

12 shows the effect of the fingerprint sensing function provided by the display device 100 according to the embodiments of the present invention.

12, by arranging a photosensor PS connected to the transistors in the sub-pixel SP and sensing the voltage fluctuation depending on whether the photosensor PS is exposed to light during the fingerprint sensing period, 110 in the active area.

Accordingly, it is possible to provide a display device 100 capable of preventing the reduction of the active area due to the arrangement of the fingerprint sensor FS, providing convenience to the user, and performing fingerprint sensing.

Embodiments of the present invention are directed to a method of driving a plasma display panel in which a photosensor PS is connected to a second transistor T2 connected to a reference voltage line RVL in a subpixel SP and a second gate line GL2 and the reference voltage line RVL to sense the voltage fluctuation depending on the light exposure of the optical sensor PS.

Then, based on the sensed voltage fluctuation, the position of the ridge and the valley of the fingerprint touched on the display panel 110 can be analyzed.

In this manner, the fingerprint of the user touched in the active area of the display panel 110 can be sensed by making it possible to distinguish the ridge and the valley of the fingerprint using signals sensed in units of subpixels (SP) .

The third transistor T3 may be disposed between the second transistor T2 and the anode electrode of the organic light emitting diode OLED and may be turned off during the fingerprint sensing period so that the organic light emitting diode OLED A display device (100) capable of preventing luminance degradation due to leakage of a flowing current and performing fingerprint sensing is provided.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. In addition, the embodiments disclosed in the present invention are not intended to limit the scope of the present invention but to limit the scope of the technical idea of the present invention. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

100: display device 110: display panel
120: Gate driving circuit 130: Data driving circuit
140: controller 150: sensing circuit
510: Light source device 520: Light guide plate
530: substrate 1000: driving circuit
1010: Reference voltage output unit 1020: Fingerprint sensing driver
1021: sensing voltage output unit 1022: fingerprint sensing unit

Claims (15)

A display panel in which a plurality of gate lines, a plurality of data lines, a plurality of reference voltage lines, and a plurality of subpixels are arranged; And
And a driving circuit for driving the plurality of reference voltage lines and detecting a signal using at least one reference voltage line among the plurality of reference voltage lines,
At least one sub-pixel of the plurality of sub-
Organic light emitting diodes;
A driving transistor connected to the first electrode of the organic light emitting diode;
A first transistor electrically connected between the gate node of the driving transistor and the data line;
A second transistor electrically connected to the reference voltage line;
A third transistor electrically connected between the second transistor and a second node of the driving transistor;
An optical sensor electrically connected between a first node and a second node of the second transistor; And
A storage capacitor electrically connected between the gate node and the second node of the driving transistor;
.
The method according to claim 1,
Among the plurality of gate lines,
The first gate line is connected to the gate node of the first transistor,
The second gate line is connected to the gate node of the second transistor,
And the third gate line is connected to the gate node of the third transistor.
The method according to claim 1,
Wherein the driving circuit comprises:
A sensing driving voltage is output as the reference voltage line in a first period of a fingerprint sensing period, a sensing reference voltage is output as a reference voltage line in a second period of the fingerprint sensing period, and in a third period of the fingerprint sensing period, And a voltage is sensed through the reference voltage line.
The method of claim 3,
Wherein the driving circuit comprises:
And outputs the sensing reset voltage as the reference voltage line during at least a part of the period between the second period and the third period of the fingerprint sensing period.
5. The method of claim 4,
Wherein the second transistor comprises:
The fingerprint sensing period is turned on during the first period and the third period during the fingerprint sensing period and is turned off during the period except for the first period and the third period in the fingerprint sensing period.
The method of claim 3,
Wherein the third transistor comprises:
Wherein the display device is turned off during the fingerprint sensing period and is turned on during a display period that is temporally distinguished from the fingerprint sensing period.
The method according to claim 1,
Further comprising a light source for emitting light during the second period of the fingerprint sensing period,
Wherein a current flows between the first node and the second node of the second transistor when the sub-pixel in which the optical sensor is disposed is exposed to light emitted from the light source.
A reference voltage output unit for outputting a reference voltage as a reference voltage line arranged in a subpixel in a display driving period;
A sensing voltage is outputted as a reference voltage line in a first period of a fingerprint sensing period which is temporally distinguished from the display driving period and a sensing voltage is outputted as a sensing voltage in the second period of the fingerprint sensing period, An output section; And
Sensing a voltage through the reference voltage line in a third period of the fingerprint sensing period and sensing a fingerprint based on the sensed voltage,
.
9. The method of claim 8,
Wherein the sensing voltage output unit comprises:
And outputs a sensing reset voltage as the reference voltage line during at least a part of the period between the second period and the third period of the fingerprint sensing period.
9. The method of claim 8,
Wherein the level of the sensing driving voltage is different from the level of the sensing reference voltage.
A data line and a reference voltage line;
A first gate line, a second gate line and a third gate line crossing the data line;
Organic light emitting diodes;
A driving transistor connected to the first electrode of the organic light emitting diode;
A first transistor electrically connected between the gate node of the driving transistor and the data line;
A second transistor electrically connected to the reference voltage line;
A third transistor electrically connected between the second transistor and a second node of the driving transistor;
An optical sensor electrically connected between a first node and a second node of the second transistor; And
A storage capacitor electrically connected between the gate node and the second node of the driving transistor;
/ RTI >
12. The method of claim 11,
The first gate line is connected to the gate node of the first transistor,
The second gate line is connected to the gate node of the second transistor,
And the third gate line is connected to the gate node of the third transistor.
12. The method of claim 11,
Wherein the second transistor comprises:
The third transistor is turned on for a part of the period during which the third transistor is turned off, and is turned off for another part of the period.
12. The method of claim 11,
The reference voltage line may include:
A subpixel that is supplied with a sensing driving voltage in a first period of a fingerprint sensing period, receives a sensing reference voltage during a second period of the fingerprint sensing period, and is electrically connected to a sensing circuit during a third period of the fingerprint sensing period.
15. The method of claim 14,
The reference voltage line may include:
And a sensing reset voltage is supplied to at least a part of the period between the second period and the third period of the fingerprint sensing period.

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