KR20200060815A - Ultrasonic sensor and display device - Google Patents

Abstract

Embodiments of the present invention relate to an ultrasonic sensor and a display device. In a pixel of a thin film transistor array of the ultrasonic sensor, by forming a plurality of contact holes disposed for the electrical connection between a pixel electrode and a thin film transistor and a piezoelectric material disposed therein, the intensity of ultrasonic waves generated by vibration of the piezoelectric material and the sensing sensitivity of the reflected ultrasonic waves can be improved. In addition, by configuring the size of the plurality of contact holes in a heterogeneous manner, high-frequency and low-frequency ultrasonic waves can be generated to perform sensing (e.g., fingerprint sensing) requiring high resolution and sensing (e.g., gesture sensing) performed through the air layer.

Description

Ultrasonic sensor and display device {ULTRASONIC SENSOR AND DISPLAY DEVICE}

Embodiments of the present invention relate to an ultrasonic sensor and a display device.

As the information society develops, the demand for a display device displaying an image is increasing, and various types of display devices such as a liquid crystal display device and an organic light emitting display device are being used.

Such a display device recognizes a user's touch on the display panel, provides biometric information (eg, fingerprint) or gestures that are in contact with or close to the display panel, and based on the recognized information in order to provide a variety of functions to the user. It provides a function to perform input processing.

For recognition of such biometric information, for example, an optical sensor or the like may be used, but when the optical sensor is disposed in the bezel area of the display panel, there is a problem that the active area is narrowed. In addition, when the optical sensor is disposed in the active area, there is a problem that may affect display driving or lower the accuracy of sensing.

Accordingly, there is a need for a method capable of improving the accuracy of sensing biometric information for the display panel while preventing the reduction of the active area of the display panel.

An object of the embodiments of the present invention is to provide an ultrasonic sensor, a display panel, and a device that can recognize biometric information in contact with the display panel in an active area of the display panel.

An object of the embodiments of the present invention is to provide an ultrasonic sensor capable of increasing the intensity of ultrasonic waves generated from pixels arranged in the ultrasonic sensor and improving the sensing sensitivity of the corresponding pixel.

An object of embodiments of the present invention is to provide an ultrasonic sensor, a display panel, and a device capable of recognizing both biometric information contacting a display panel and a gesture performed at a position close to the display panel.

In one aspect, embodiments of the present invention include a substrate on which a plurality of pixels are disposed, a plurality of thin film transistors disposed on a substrate and disposed on each of the plurality of pixels, and a plurality of contact holes disposed on the thin film transistors. It provides an ultrasonic sensor comprising a planarization layer, a pixel electrode disposed on each of the plurality of pixels on the planarization layer, a piezoelectric material disposed on the pixel electrode, and a common electrode disposed on the piezoelectric material.

In such an ultrasonic sensor, the pixel electrode may be electrically connected through at least two or more contact holes among a source electrode or a drain electrode of the first thin film transistor and a plurality of contact holes included in the planarization layer.

Further, the pixel electrode may be electrically connected through a gate hole of a second thin film transistor other than the first thin film transistor among the plurality of thin film transistors and a contact hole included in an insulating layer disposed under the planarization layer.

In another aspect, embodiments of the present invention include a thin film transistor array in which a plurality of scan lines, a plurality of sensing lines, and a plurality of pixels are disposed, a piezoelectric material disposed on the thin film transistor array, and a common disposed on the piezoelectric material. An electrode, each of the plurality of pixels, a pixel electrode, a first transistor for controlling the application of voltage to the pixel electrode, a second transistor controlled by the voltage level of the pixel electrode, and between the second transistor and the sensing line It provides an ultrasonic sensor including a third transistor connected to.

In such an ultrasonic sensor, the pixel electrode is electrically connected to a source electrode or a drain electrode of the first transistor through a plurality of first contact holes and electrically to a gate electrode of the second transistor through at least one second contact hole. Provide an ultrasonic sensor.

In another aspect, embodiments of the present invention provide a display panel and a display device in which the above-described ultrasonic sensor is disposed on at least one surface of the display panel.

According to embodiments of the present invention, by arranging a plurality of contact holes connecting a pixel electrode and a thin film transistor in a pixel of an ultrasonic sensor, it is possible to improve the intensity of ultrasonic waves generated in the pixel and the sensing sensitivity of the pixel. .

In addition, the piezoelectric material disposed on the thin film transistor array is patterned and arranged to correspond to a pixel or pixel electrode, thereby reducing signal interference between adjacent pixels to further improve sensing sensitivity.

In addition, by configuring the diameters of the plurality of contact holes arranged in the pixels to be heterogeneous, ultrasonic waves in a frequency band including a frequency band in which high-resolution sensing is required and a frequency band that can be transmitted through air are generated to generate an ultrasonic sensor or display. It is possible to recognize both the biometric information contacting the panel and the gesture performed at a close position.

1 is a view showing an example of a structure in which an ultrasonic sensor is disposed in a display device according to embodiments of the present invention.
2 is a view showing an example of a structure in which a piezoelectric material is disposed in an ultrasonic sensor according to embodiments of the present invention.
3 is a diagram illustrating an example of a circuit structure and a driving method of a pixel array of an ultrasonic sensor according to embodiments of the present invention.
4 is a view showing an example of a planar structure of a thin film transistor array of an ultrasonic sensor according to embodiments of the present invention.
5 is a view showing an example of a cross-sectional structure of the AA' portion shown in FIG.
6 is a view showing another example of the planar structure of the thin film transistor array of the ultrasonic sensor according to embodiments of the present invention.
7 is a view showing an example of a cross-sectional structure of the BB' portion shown in FIG. 6.
8 is a view showing another example of a planar structure of a thin film transistor array of an ultrasonic sensor according to embodiments of the present invention.
9 is a view showing an example of a cross-sectional structure of the CC′ portion shown in FIG. 8.
10 is a view showing another example of the planar structure of the thin film transistor array of the ultrasonic sensor according to embodiments of the present invention.
FIG. 11 is a view showing an example of a cross-sectional structure of DD' and EE' portions shown in FIG. 10.
FIG. 12 is a diagram illustrating an example of sensing performed by an display device on which an ultrasonic sensor is disposed according to embodiments of the present invention using an ultrasonic sensor.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. In adding reference numerals to the components of each drawing, the same components may have the same reference numerals as possible even though they are displayed on different drawings. In addition, in describing the present invention, when it is determined that detailed descriptions of related well-known structures or functions may obscure the subject matter of the present invention, detailed descriptions thereof may be omitted.

In addition, in describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are only for distinguishing the component from other components, and the essence, order, order, or number of the component is not limited by the term. When a component is described as being "connected", "coupled" or "connected" to another component, the component may be directly connected to or connected to the other component, but different components between each component It should be understood that the "intervenes" may be, or each component may be "connected", "coupled" or "connected" through other components.

1 is a view showing an example of a structure in which an ultrasonic sensor 200 is disposed in a display device according to embodiments of the present invention.

Referring to FIG. 1, a display device according to embodiments of the present invention includes a display panel 110 in which a plurality of gate lines, a plurality of data lines, and a plurality of subpixels are disposed, and a display panel 110. Various driving circuits for driving signal lines or voltage lines may be included.

On at least one surface of the display device, an ultrasonic sensor 200 or an ultrasonic sensing device for sensing biometric information (eg, a fingerprint) or a gesture that is in contact with or close to the display panel 110 may be disposed.

For example, the ultrasonic sensor 200 may be disposed on the opposite side of the surface on which the image is displayed on the display panel 110. In addition, the cover glass 120 may be disposed on a surface on which the image is displayed on the display panel 110.

The ultrasonic sensor 200 may be bonded to the display panel 110 through the adhesive unit 300, and the adhesive unit 300 may be made of resin, for example.

Then, the ultrasonic sensor 200 generates ultrasonic waves and senses the ultrasonic waves reflected on the fingerprints contacting the cover glass 120 disposed on the display panel 110 to recognize the fingerprints contacting the cover glass 120. Can be.

Specifically, when the ultrasonic wave generated by the ultrasonic sensor 200 reaches the valley portion of the fingerprint, it contacts the air existing between the human skin and the cover glass 120. Here, due to the difference in the acoustic impedance value between the cover glass 120 and the air, most of the ultrasonic waves hitting the air are reflected.

Then, when the ultrasonic waves generated by the ultrasonic sensor 200 reach the ridge portion of the fingerprint, they come into contact with the skin of a person in contact with the cover glass 120. Here, a part of the ultrasound may be reflected, but most of the ultrasound is transmitted inside the skin and is reflected inside the skin.

Accordingly, the bone portion and the floor portion of the fingerprint can be distinguished and the fingerprint can be sensed based on the intensity and timing of ultrasonic waves that reach and reflect on the valley portion and the floor portion of the fingerprint.

As described above, since the ultrasonic sensor 200 senses the inside of the skin, it is not sensitive to contamination or condition of the skin surface and provides excellent security. In addition, the display device allows the display device to sense the fingerprint without reducing the area where the image is displayed on the display panel 110.

The ultrasonic sensor 200 may include a material for generating ultrasonic waves and various circuit elements for generating and sensing ultrasonic waves.

For example, the ultrasonic sensor 200 may include a substrate 210, a thin film transistor array 220 disposed on the substrate 210, a first pad portion 231, and a second pad portion 232. . In addition, the thin film transistor array 220 may include a pixel electrode PE disposed in each pixel, and the piezoelectric material 240 and the common electrode COM may be sequentially disposed in the thin film transistor array 220. have.

The common electrode COM may be adhered to the reflective layer 260 through the adhesive layer 250, and the cover layer 270 may be disposed on the reflective layer 260.

The controller 400 that supplies signals, voltages, and the like to the thin film transistor array 220 and the common electrode COM, is disposed on the substrate 210 through the flexible printed circuit 290 and the bonding unit 280. The pad unit 232 may be electrically connected to the pad unit 232.

In the thin film transistor array 220, a transistor for generating ultrasonic waves and sensing of ultrasonic waves reflected on a fingerprint, a pixel electrode PE, and the like may be disposed.

The pixel electrode PE and the common electrode COM disposed on the thin film transistor array 220 may form a capacitor C.

In addition, the piezoelectric material 240 may be vibrated by the voltage applied to the pixel electrode PE and the common electrode COM disposed on the thin film transistor array 220 to generate ultrasonic waves.

The thin film transistor array 220 including the pixel electrode PE, the piezoelectric material 240, and the common electrode COM may also be viewed as a circuit pixel array.

The common electrode COM may be disposed, for example, through a method of coating silver ink, and in some cases, may be disposed in a form that covers the entire piezoelectric material 240 or may be disposed in a constant pattern.

The reflective layer 260 may be made of copper, for example, and may function to reflect ultrasonic waves reflected from the fingerprint and return to the thin film transistor array 220.

The cover layer 270 may be formed of, for example, polyimide, and may function to cap the pixel array and the reflective layer 260 of the ultrasonic sensor 200.

Signals and voltages for driving the pixel array are supplied from the controller 400, but in some cases, signals that do not require high voltage may be supplied from a driving circuit arranged for driving the display panel 110.

2 is a diagram illustrating an example of a structure in which a piezoelectric material 240 is disposed in an ultrasonic sensor 200 according to embodiments of the present invention.

Referring to FIG. 2, a thin film transistor array 220, a piezoelectric material 240, and a common electrode COM may be sequentially disposed on a substrate of the ultrasonic sensor 200. The pixel electrode PE for ultrasonic generation and sensing may be disposed in the thin film transistor array 220.

The pixel electrode PE may be disposed to correspond to each of a plurality of pixels arranged in the thin film transistor array 220.

That is, the pixel electrodes PE are separately arranged for each pixel, so that the first driving voltage DV1 applied for generating ultrasonic waves is supplied for each pixel, and voltage fluctuations due to reflected ultrasonic waves can occur for each pixel. .

Here, the piezoelectric material 240 disposed on the thin film transistor array 220 may be disposed separately to correspond to a pixel, or may be disposed separately to correspond to a pixel electrode PE disposed in a pixel. For example, a plurality of piezoelectric materials 240 may be disposed separately, and each separated piezoelectric material 240 may be disposed in a structure surrounding the pixel electrode PE disposed in each pixel.

In addition, the common electrode COM disposed on the piezoelectric material 240 may be disposed between the upper surface of the piezoelectric material 240 and the piezoelectric material 240 disposed separately. That is, as illustrated in FIG. 2, the common electrode COM may be disposed in a structure surrounding the piezoelectric material 240.

As the piezoelectric material 240 disposed on the thin film transistor array 220 is disposed separately for each pixel or pixel electrode PE, the piezoelectric material 240 vibrates in units of pixels, and thus, when generating and sensing ultrasonic waves, Signal interference between pixels can be prevented.

In addition, since the common electrode COM is disposed to surround the side surface of the piezoelectric material 240 separated and disposed, so that there is no portion where the electrode is not in contact with the outer surface of the piezoelectric material 240, unless the efficiency of ultrasonic generation is lowered Therefore, it is possible to prevent interference between ultrasonic waves transmitted or received from adjacent pixels.

3 is a diagram illustrating an example of a circuit structure and a driving method of a pixel array of an ultrasonic sensor 200 according to embodiments of the present invention.

Referring to FIG. 3, a plurality of scan lines SSL and a plurality of sensing lines SSL may be disposed in the pixel array of the ultrasonic sensor 200. The scan line SSL and the sensing line SSL may be disposed to cross each other, and a plurality of pixels may be disposed in an area defined by the intersection of the scan line SSL and the sensing line SSL.

In addition, a voltage line for supplying a driving voltage (DV), a sensing voltage (SV), etc. for ultrasonic generation and sensing of pixels may be arranged.

In addition, the ultrasonic sensor 200 may include a circuit for driving a plurality of scan lines arranged in the pixel array, a circuit for detecting a sensing signal through the plurality of sensing lines, and the like.

In each pixel, various circuit elements for ultrasonic generation and sensing may be arranged.

For example, each pixel is controlled by voltages of the first transistor T1, the third transistor T3, and the first node N1 controlled by the scan signal SCO applied to the scan line SCL. The second transistor T2 and one capacitor C may be disposed.

Here, the first transistor T1, the second transistor T2, and the third transistor T3 are all illustrated as an N type, but may be implemented as a P type in some cases. Alternatively, only the first transistor T1 and the third transistor T3 may be implemented with the same type, and the second transistor T2 may be implemented with different types.

The first transistor T1 is controlled by the scan signal SCO applied to the scan line SCL and may be electrically connected between the first driving voltage line DVL1 and the first node N1.

Here, the first driving voltage line DVL1 may supply the first driving voltage DV1 for ultrasonic generation to a pixel. The first driving voltage DV1 may be a pulsed AC voltage having a high voltage level, for example, an AC voltage swinging from +100V to -100V.

The third transistor T3 is controlled by the scan signal SCO applied to the scan line SCL, and may be electrically connected between the sensing line SSL and the second transistor T2.

Here, the first transistor T1 and the third transistor T3 disposed in adjacent pixels may be driven by the same scan line SCL.

That is, as illustrated in FIG. 3, the first transistor T1 arranged in column A and the third transistor T3 arranged in column B are connected to the same n-th scan line SCL(n) to perform n-th scan. The n-th scan signal SCO(n) applied to the line SCL(n) may be simultaneously driven.

The second transistor T2 is controlled according to the voltage level of the first node N1 and may be electrically connected between the sensing voltage line SVL and the third transistor T3.

In addition, the sensing voltage SV applied to the sensing voltage line SVL may be a constant voltage.

The capacitor C may be electrically connected between the first node N1 and the second driving voltage line DVL2.

That is, the electrode of the capacitor C connected to the first node N1 may mean the pixel electrode PE for forming the capacitance disposed in the thin film transistor array 220 described above, and the second driving voltage. The electrode of the capacitor C connected to the line DVL2 may mean a common electrode COM.

Further, the common electrode COM may be an electrode commonly connected to at least two pixels.

The second driving voltage line DVL2 may supply the second driving voltage DV2 for ultrasonic generation to the pixel, and the second driving voltage DV2 may be a constant voltage lower than the maximum voltage of the first driving voltage DV1. You can.

The scan signal SCO is sequentially applied to the scan lines SCL arranged in the pixel array, and ultrasonic generation and sensing may be performed.

For example, when the n-th scan signal SCO(n) having a level that turns on the first transistor T1 by the n-th scan line SCL(n) is applied, the first transistor T1 disposed in the A column ) Is turned on.

Since the first transistor T1 is turned on, the first driving voltage DV1 is applied to the first node N1.

Since high voltage and low constant voltage in the form of pulses are applied to both electrodes of the capacitor C, the piezoelectric material 240 disposed between the electrodes of the capacitor C may vibrate to generate ultrasonic waves.

That is, ultrasonic waves are generated in column A where the first transistor T1 is turned on.

At this time, since the n-th scan signal SCO(n) having a level that turns on the first transistor T1 is applied to the n-th scan line SCL(n), the third transistor T3 arranged in the B column is applied. It will also turn on.

In a state in which the first transistor T1 disposed in the B column is turned off, the voltage level of the first node N1 of the pixel disposed in the B column may fluctuate when the ultrasound reflected on the fingerprint reaches the B column.

That is, the polarization state of the piezoelectric material 240 disposed between the pixel electrode PE and the second electrode COM disposed in column B is changed by the reflected ultrasound, thereby causing the pixel electrode PE, that is, the agent The voltage level of one node N1 may vary.

And, as the voltage level of the first node N1 of column B changes, the second transistor T2 is turned on and off, and the sensing voltage SV is sensed because the third transistor T3 is turned on. It can be detected through (SSL).

That is, it is possible to sense ultrasonic waves reflected from the fingerprint and returned from the column B where the third transistor T3 is turned on.

As described above, by driving the first transistor T1 and the third transistor T3 disposed in adjacent pixel columns by the same scan line SCL, ultrasonic generation and sensing can be performed in adjacent pixel columns.

4 is a diagram illustrating an example of a planar structure of the thin film transistor array 220 of the ultrasonic sensor 200 according to embodiments of the present invention.

Referring to FIG. 4, in the thin film transistor array 220 of the ultrasonic sensor 200, a plurality of scan lines SCL are disposed in one direction, and a first driving voltage line (in a direction crossing the scan line SCL) ( DVL1), a sensing line SSL, and a sensing voltage line SVL may be disposed.

In addition, each pixel includes a first transistor T1 and a third transistor T3 controlled by a signal applied to the scan line SCL, and a second transistor controlled by a voltage level of the pixel electrode PE. (T2) may be disposed.

Here, the pixel electrode PE may be electrically connected to the first source electrode S1 or the first drain electrode D1 of the first transistor T1. Also, the pixel electrode PE may be electrically connected to the second gate electrode G2 of the second transistor T2.

That is, the pixel electrode PE is electrically connected to the first source electrode S1 or the first drain electrode D1 of the first transistor T1, and thus the first driving voltage (1) through the first transistor T1. DV1) may be applied and ultrasonic waves may be generated.

Then, the pixel electrode PE is electrically connected to the second gate electrode G2 of the second transistor T2, and when the voltage level of the pixel electrode PE changes due to reflected ultrasonic waves, the second transistor T2 ) Is turned on and off and sensing can be performed.

5 is a view showing an example of a cross-sectional structure of portion A-A' shown in FIG. 4.

Referring to FIG. 5, a buffer layer 221 may be disposed on the substrate 210, and a thin film transistor may be disposed on the buffer layer 221.

The first transistor T1 may include a first gate electrode G1, a first active layer ACT1, a first source electrode S1, and a first drain electrode D1.

In addition, the second transistor T2 and the third transistor T3 include the second gate electrode G2, the third gate electrode G3, the second active layer ACT2, the second drain electrode D2, and It may be composed of two source electrodes (S2).

That is, the second transistor T2 and the third transistor T3 may have a structure sharing the second active layer ACT2.

A gate insulating layer 222 may be disposed between the active layer constituting the thin film transistor and the gate electrode. Further, at least one insulating layer, for example, the first insulating layer 223 and the second insulating layer 224 may be disposed between the gate electrode and the source/drain electrode.

The first passivation layer 225 and the planarization layer 226 may be disposed on the source/drain electrode, and the pixel electrode PE may be disposed on the planarization layer 226. In addition, the sensing auxiliary electrode SE may be disposed in a portion of the pixel electrode PE, and the second protective layer 227 may be disposed on the pixel electrode PE and the sensing auxiliary electrode SE.

The pixel electrode PE is the first source electrode S1 or the first drain electrode of the first transistor T1 through the first contact hole CH1 formed in the first protective layer 225 and the planarization layer 226. It may be electrically connected to (D1), and FIG. 5 shows a case where the pixel electrode PE is connected to the first source electrode S1 of the first transistor T1.

In this case, the pixel electrode PE may be electrically connected to the first source electrode S1 of the first transistor T1 through the first contact pattern CP1 disposed under the first contact hole CH1. .

Also, the pixel electrode PE may be electrically connected to the second gate electrode G2 of the second transistor T2 through the first contact pattern CP1.

As an example, the first contact pattern CP1 is connected to the second gate electrode G2 through the second contact hole CH2 formed in the first insulating layer 223 and the second insulating layer 224, so that the pixel electrode The PE and the second gate electrode G2 of the second transistor T2 may be electrically connected.

Therefore, the pixel electrode PE receives the first driving voltage DV1 through the first transistor T1 and turns on and off the second transistor T2 according to the voltage fluctuation of the pixel electrode PE. Can be.

The sensing auxiliary electrode SE may be disposed in a portion of the pixel electrode PE, and at least a portion may be disposed inside the first contact hole CH1.

The sensing auxiliary electrode SE may be disposed of the same material (eg, Mo/Al) as the source/drain electrode, and has superior ability to absorb radio waves than the pixel electrode PE, thereby increasing sensing sensitivity. .

The piezoelectric material 240 and the common electrode COM may be sequentially disposed on the second protective layer 227 disposed on the pixel electrode PE and the sensing auxiliary electrode SE.

Here, a portion of the piezoelectric material 240 disposed on the second protective layer 227 may be disposed inside the first contact hole CH1.

In addition, the first contact hole CH1 may serve as a ringing plate when the piezoelectric material 240 vibrates. That is, the frequency and intensity of the piezoelectric material 240 vibrating by the first contact hole CH1 may be determined.

Embodiments of the present invention, by arranging a plurality of first contact holes CH1 in which a piezoelectric material 240 is disposed inside a pixel, it is possible to improve the intensity and sensing sensitivity of the generated ultrasonic waves.

6 is a view showing another example of the planar structure of the thin film transistor array 220 of the ultrasonic sensor 200 according to embodiments of the present invention.

Referring to FIG. 6, the thin film transistor array 220 of the ultrasonic sensor 200 includes a signal for driving a pixel, a scan line (SCL) to which a voltage is applied, a first driving voltage line (DVL1), and a sensing voltage line ( SVL) and a sensing line (SSL) for sensing may be arranged.

In addition, the first transistor T1, the second transistor T2, and the third transistor T3 for controlling ultrasonic generation and sensing may be disposed in each pixel.

Here, each pixel may include a plurality of first contact holes CH1a and CH1b for electrical connection of the pixel electrode PE and the first source electrode S1 of the first transistor T1.

That is, the pixel electrode PE disposed in each pixel may be electrically connected to the first source electrode S1 of the first transistor T1 through a plurality of first contact holes CH1a and CH1b. A piezoelectric material 240 may be disposed inside the first contact holes CH1a and CH1b.

In addition, at least one second contact hole CH2 for electrical connection between the pixel electrode PE and the second gate electrode G2 of the second transistor T2 may be disposed in each pixel.

That is, as illustrated in FIG. 6, the pixel electrode PE and the second gate electrode G2 of the second transistor T2 may be electrically connected through one second contact hole CH2. Accordingly, the pixel electrode PE and the second gate electrode G2 of the second transistor T2 may be electrically connected through the plurality of second contact holes CH2.

7 is a view showing an example of a cross-sectional structure of the B-B' portion shown in FIG.

Referring to FIG. 7, the buffer layer 221 is disposed on the substrate 210, and the first transistor T1, the second transistor T2, and the third transistor T3 are disposed on the buffer layer 221. have.

The planarization layer 226 disposed on the thin film transistor may include a plurality of first contact holes CH1a and CH1b.

Here, the diameters R1 and R2 of the plurality of first contact holes CH1a and CH1b may be the same.

In addition, the pixel electrode PE may be disposed on the planarization layer 226, and the sensing auxiliary electrode SE or the like may be disposed on the pixel electrode PE.

Accordingly, the pixel electrode PE may be electrically connected to the first source electrode S1 of the first transistor T1 through the plurality of first contact holes CH1a and CH1b, for example, the first contact hole. The first source electrode S1 of the first transistor T1 may be electrically connected to the first contact pattern CP1 disposed under the (CH1a, CH1b).

Then, the second gate electrode G2 of the second transistor T2 through the second contact hole CH2 in which the first contact pattern CP1 is formed in the first insulating layer 223 and the second insulating layer 224. By being connected to, the pixel electrode PE can be electrically connected to the second gate electrode G2 of the second transistor T2.

Accordingly, the planarization layer 226 includes a plurality of first contact holes CH1a and CH1b, and the pixel electrode PE has a first source electrode S1 and a second transistor T2 of the first transistor T1. It can be electrically connected to the second gate electrode (G2).

The piezoelectric material 240 may be disposed on the pixel electrode PE, and a part of the piezoelectric material 240 may be disposed inside the plurality of first contact holes CH1a and CH1b formed in the planarization layer 226. .

As described above, by arranging a plurality of first contact holes CH1a and CH1b functioning as a ringing plate when the piezoelectric material 240 vibrates, the intensity of ultrasonic waves generated by the vibration of the piezoelectric material 240 may be increased. .

In addition, by arranging the plurality of first contact holes CH1a and CH1b on the planarization layer 226, the area where the first contact pattern CP1, the pixel electrode PE, and the sensing auxiliary electrode SE is stacked is enlarged. , Sensitivity for sensing reflected ultrasonic waves may be improved.

At this time, as illustrated in FIG. 7, although the diameters R1 and R2 of the plurality of first contact holes CH1a and CH1b may be constant, the intensity of ultrasonic waves may be increased in a certain frequency band, but the plurality of first contact holes By configuring the diameters R1 and R2 of (CH1a, CH1b) differently, the frequency band of ultrasonic waves generated by vibration of the piezoelectric material 240 may be adjusted.

8 is a view showing another example of the planar structure of the thin film transistor array 220 of the ultrasonic sensor 200 according to embodiments of the present invention.

Referring to FIG. 8, a scan line (SCL), a first driving voltage line (DVL1), a sensing line (SSL), and a sensing voltage line (SVL) are disposed on the thin film transistor array 220 of the ultrasonic sensor 200. Can be.

In addition, the first transistor T1, the second transistor T2, and the third transistor T3 may be disposed in each pixel.

Here, a plurality of first contact holes CH1a and CH1b for electrical connection between the pixel electrode PE and the thin film transistor may be disposed in each pixel, and the pixel electrode PE may include a plurality of first contact holes. The first source electrode S1 of the first transistor T1 may be electrically connected through (CH1a, CH1b).

Also, the pixel electrode PE may be electrically connected to the second gate electrode G2 of the second transistor T2 through at least one second contact hole CH2.

At this time, the plurality of first contact holes CH1a and CH1b may have different diameters from each other.

That is, a plurality of first contact holes CH1a and CH1b for electrical connection between the pixel electrode PE and the thin film transistor is disposed in each pixel, and at least one of the plurality of first contact holes CH1a and CH1b is provided. Can have different diameters.

FIG. 9 is a view showing an example of a cross-sectional structure of a portion C-C' shown in FIG. 8.

Referring to FIG. 9, the buffer layer 221 is disposed on the substrate 210, and the first transistor T1, the second transistor T2, and the third transistor T3 are disposed on the buffer layer 221. have.

A plurality of first contact holes CH1a and CH1b may be disposed on the planarization layer 226 disposed on the thin film transistor, and the pixel electrode PE and the sensing auxiliary electrode SE may be formed on the planarization layer 226. Etc. can be arranged.

Here, the diameters R1 and R2 of the plurality of first contact holes CH1a and CH1b disposed on the planarization layer 226 may be different, for example, R2 may be larger than R1.

In addition, a portion of the piezoelectric material 240 disposed on the second protective layer 227 is disposed inside the first contact holes CH1a and CH1b, and the diameters of the first contact holes CH1a and CH1b are different. Therefore, the frequency of ultrasonic waves generated by vibration of the piezoelectric material 240 may be different.

For example, the piezoelectric material 240 disposed in the first contact hole CH1a having a relatively small diameter R1 has a relatively high frequency ultrasound (eg, 1 MHz) because the diameter R1 of the first contact hole CH1a is small. ~50MHz).

In addition, the piezoelectric material 240 disposed in the first contact hole CH1b having a relatively large diameter R2 has a relatively large diameter R2 of the first contact hole CH1b (eg, 50 kHz~ 400 kHz).

That is, when the diameter of the first contact holes CH1a and CH1b serving as a ringing plate when the piezoelectric material 240 vibrates is small, the wavelength of the generated ultrasonic waves is shortened, and thus high-frequency ultrasonic waves may be generated. In addition, when the diameters of the first contact holes CH1a and CH1b are large, the wavelength of the generated ultrasonic waves is increased, so low-frequency ultrasonic waves may be generated.

Accordingly, high-frequency ultrasound and low-frequency ultrasound may be generated in each of the first contact holes CH1a and CH1b by a plurality of first contact holes CH1a and CH1b having different diameters R1 and R2.

Alternatively, ultrasonic waves in a band including both a high-frequency band and a low-frequency band may be generated in one pixel, or ultrasonic waves in a middle band between high-frequency and low-frequency may be generated.

Since high-frequency ultrasonic waves generated by vibration of the piezoelectric material 240 can be sensed at a high resolution, it can be used for fingerprint sensing or the like that requires high resolution.

In addition, since low-frequency ultrasound generated by vibration of the piezoelectric material 240 has a higher property of passing air than high-frequency ultrasound, the ultrasonic sensor 200 or the display device on which the ultrasonic sensor 200 is disposed is not contacted. It can be used for gesture sensing, etc. performed in a proximate location.

That is, by configuring the diameters R1 and R2 of the plurality of first contact holes CH1a and CH1b differently, fingerprint sensing requiring high resolution and gesture sensing performed at a position close to the ultrasonic sensor 200 are performed. Can be.

Two or more first contact holes CH1a and CH1b disposed in the pixel may be disposed in each pixel, and may be arranged in various structures according to the arrangement structure of the pixels.

10 is a view showing another example of the planar structure of the thin film transistor array 220 of the ultrasonic sensor 200 according to embodiments of the present invention.

Referring to FIG. 10, various signal wires and voltage lines are disposed on the thin film transistor array 220 of the ultrasonic sensor 200, and thin film transistors for generating and sensing ultrasonic waves may be disposed.

In addition, a plurality of first contact holes CH1a and CH1b for electrical connection between the pixel electrode PE and the thin film transistor may be disposed in each pixel.

The pixel electrode PE may be electrically connected to the first source electrode S1 of the first transistor T1 through the plurality of first contact holes CH1a and CH1b.

Here, the plurality of first contact holes CH1a and CH1b may be disposed at various positions within the pixel. In the example illustrated in FIG. 10, the first contact hole CH1b having a large diameter may have a small diameter. 1 shows a case where the contact hole CH1a is disposed apart.

That is, as two or more first contact holes CH1a and CH1b are disposed in the pixel, positions in which the first contact holes CH1a and CH1b are disposed may vary.

And, as shown in the example shown in Figure 10, when the first contact hole (CH1b) having a large diameter is disposed, the signal wiring or voltage line between the first contact hole (CH1b) and the first transistor (T1), work For example, a sensing line SSL may be arranged.

In this case, an additional pattern for electrical connection between the pixel electrode PE and the first source electrode S1 of the first transistor T1 needs to be disposed.

11 is a view showing an example of a cross-sectional structure of the portion D-D' and E-E' shown in FIG.

Referring to FIG. 11, the DD′ portion shows a cross-sectional structure of a portion in which the first contact hole CH1a having a small diameter is disposed, and the pixel electrode PE is formed in a lower portion of the first contact hole CH1a. The first source electrode S1 of the first transistor T1 and the second gate electrode G2 of the second transistor T2 may be electrically connected through the first contact pattern CP1.

In addition, the E-E' portion represents a cross-sectional structure of a portion in which a first contact hole CH1b having a large diameter is disposed.

Since the sensing line SSL is disposed between the first contact hole CH1b and the first transistor T1, the connection between the first contact hole CH1b and the first source electrode S1 of the first transistor T1 is connected. A separate pattern may be required, for example, a second contact pattern CP2 may be disposed on a layer on which the gate electrode is disposed.

In addition, the second contact pattern CP2 may be located under the sensing line SSL.

That is, the second contact pattern CP2 is formed through the fourth contact hole CH4 in which the first source electrode S1 of the first transistor T1 is formed in the first insulating layer 223 and the second insulating layer 224. And is connected. In addition, the third contact pattern CP3 disposed under the first contact hole CH1b may be connected to the second contact pattern CP2 through the fourth contact hole CH4.

Therefore, the pixel electrode PE disposed in the first contact hole CH1b includes the first source electrode S1 of the first transistor T1 through the second contact pattern CP2 and the third contact pattern CP3. ).

Also, the pixel electrode PE may be electrically connected to the second gate electrode G2 of the second transistor T2 through the third contact pattern CP3.

Here, the second contact pattern CP2 and the third contact pattern CP3 are examples, and additional contact patterns may be arranged at various positions according to the pixel structure.

As described above, the pixel electrode PE disposed on the first contact hole CH1b having a large diameter through the contact pattern that is additionally disposed on the thin film transistor array 220 has the first source electrode ( S1) and the second gate electrode G2 of the second transistor T2 can be electrically connected.

Accordingly, a plurality of first contact holes CH1a and CH1b having the same diameter or a plurality of first contact holes CH1a and CH1b having different diameters may be variously disposed within the pixel, and the first contact hole ( CH1a, CH1b) can improve the performance and range of ultrasonic sensing.

12 is a view showing an example of sensing performed by the display device on which the ultrasonic sensor 200 is disposed according to embodiments of the present invention using the ultrasonic sensor 200.

Referring to FIG. 12, in the ultrasonic sensor 200 according to embodiments of the present invention, since a plurality of first contact holes CH1a and CH1b having different diameters are disposed in a pixel, high-frequency ultrasound and low-frequency ultrasound are simultaneously performed. Can occur. Alternatively, it may be considered that the frequency of the band including the high frequency band and the low frequency band is generated.

The ultrasonic sensor 200 generates high-frequency ultrasonic waves so that fingerprint sensing requiring high resolution can be easily performed.

In addition, the ultrasound sensor 200 generates low-frequency ultrasound, so that a gesture performed in a position close to the cover glass 120 in a state in which it is not in contact with the cover glass 120 can be sensed.

According to the above-described embodiments of the present invention, the piezoelectric material 240 disposed on the thin film transistor array 220 is disposed in a separate structure to correspond to the pixel or the pixel electrode PE, thereby preventing signal interference between adjacent pixels. And improve the performance of ultrasonic sensing.

In addition, a plurality of first contact holes CH1 functioning as a ringing plate when the piezoelectric material 240 vibrates is disposed in pixels of the thin film transistor array 220 of the ultrasonic sensor 200, thereby generating the intensity and reflection of ultrasonic waves. It can improve the sensing sensitivity of the ultrasonic.

In addition, by configuring the diameters of the first contact holes CH1 disposed in the pixels of the thin film transistor array 220 to be heterogeneous, ultrasonic sensors capable of generating both high-frequency and low-frequency ultrasound to perform both fingerprint sensing and gesture sensing ( 200) and a display device including the same.

In addition, the above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and variations 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 technical spirit of the present invention, but to explain the scope of the technical spirit of the present invention. The protection scope of the present invention should be interpreted by the following claims, and all technical spirits within the equivalent scope should be interpreted as being included in the scope of the present invention.

110: display panel 120: cover glass
200: ultrasonic sensor 210: substrate
220: thin film transistor array 221: buffer layer
222: gate insulating layer 223: first insulating layer
224: second insulating layer 225: first protective layer
226: planarization layer 227: second protective layer
231: first pad portion 232: second pad portion
240: piezoelectric material 250: adhesive layer
260: reflective layer 270: cover layer
280: bonding unit 290: flexible printed circuit
300: adhesive 400: controller

Claims (21)

A substrate on which a plurality of pixels are disposed;
A plurality of thin film transistors disposed on the substrate and disposed in each of the plurality of pixels;
A planarization layer disposed on the thin film transistor and including a plurality of contact holes;
A pixel electrode disposed on the planarization layer and disposed on each of the plurality of pixels;
A piezoelectric material disposed on the pixel electrode; And
A common electrode disposed on the piezoelectric material,
The pixel electrode,
An ultrasonic sensor electrically connected to a source electrode or a drain electrode of the first thin film transistor among the plurality of thin film transistors and at least two contact holes among the plurality of contact holes included in the planarization layer.
According to claim 1,
A part of the piezoelectric material is an ultrasonic sensor disposed inside the plurality of contact holes included in the planarization layer.
According to claim 1,
The pixel electrode,
An ultrasonic sensor electrically connected to a gate electrode of a second thin film transistor other than the first thin film transistor among the plurality of thin film transistors and a contact hole included in an insulating layer disposed under the planarization layer.
According to claim 1,
The ultrasonic sensors having the same diameter of the plurality of contact holes included in the planarization layer.
According to claim 1,
The plurality of contact holes included in the planarization layer includes at least one first diameter contact hole and at least one second diameter contact hole, wherein the first diameter and the second diameter are different ultrasonic sensors.
According to claim 1,
The ultrasonic sensor further includes a sensing auxiliary electrode disposed between the pixel electrode and the piezoelectric material, disposed in a portion of the pixel electrode, and at least partially disposed inside the plurality of contact holes included in the planarization layer.
According to claim 1,
The piezoelectric material,
The ultrasonic sensor is disposed separately for each region corresponding to the pixel or is disposed separately to correspond to the pixel electrode.
The method of claim 7,
The common electrode,
An ultrasonic sensor disposed between the upper surface of the piezoelectric material and the piezoelectric material separately disposed.
A thin film transistor array in which a plurality of scan lines, a plurality of sensing lines, and a plurality of pixels are disposed;
A piezoelectric material disposed on the thin film transistor array; And
A common electrode disposed on the piezoelectric material,
Each of the plurality of pixels,
Pixel electrode;
A first transistor for controlling the application of voltage to the pixel electrode;
A second transistor controlled by the voltage level of the pixel electrode; And
And a third transistor connected between the second transistor and the sensing line,
The pixel electrode,
An ultrasonic sensor electrically connected to a source electrode or a drain electrode of the first transistor through a plurality of first contact holes, and electrically connected to a gate electrode of the second transistor through at least one second contact hole.
The method of claim 9,
A part of the piezoelectric material is an ultrasonic sensor disposed inside the plurality of first contact holes.
The method of claim 9,
The diameters of the plurality of first contact holes are all the same.
The method of claim 9,
The plurality of first contact holes include a first contact hole having at least one first diameter and a first contact hole having at least one second diameter, wherein the first diameter and the second diameter are different.
The method of claim 9,
The diameter of the plurality of first contact holes is larger than the diameter of the at least one second contact hole.
The method of claim 9,
Each of the plurality of pixels,
The ultrasonic sensor further includes a sensing auxiliary electrode disposed in a portion of the pixel electrode, and at least a portion disposed inside the plurality of first contact holes.
The method of claim 9,
The piezoelectric material,
The ultrasonic sensor is disposed separately for each region corresponding to the pixel or is disposed separately to correspond to the pixel electrode.
Display panel; And
It includes an ultrasonic sensor disposed on at least one surface of the display panel,
The ultrasonic sensor,
A substrate on which a plurality of pixels are disposed;
A plurality of thin film transistors disposed on the substrate and disposed in each of the plurality of pixels;
A planarization layer disposed on the thin film transistor and including a plurality of contact holes;
A pixel electrode disposed on the planarization layer and disposed on each of the plurality of pixels;
A piezoelectric material disposed on the pixel electrode; And
A common electrode disposed on the piezoelectric material,
The pixel electrode,
A display device electrically connected to a source electrode or a drain electrode of a first thin film transistor among the plurality of thin film transistors and at least two contact holes among the plurality of contact holes included in the planarization layer.
The method of claim 16,
The pixel electrode,
A display device electrically connected to a gate electrode of a second thin film transistor other than the first thin film transistor among the plurality of thin film transistors and a contact hole included in an insulating layer disposed under the planarization layer.
The method of claim 16,
A display device having the same diameter of the plurality of contact holes included in the planarization layer.
The method of claim 16,
The plurality of contact holes included in the planarization layer includes at least one first diameter contact hole and at least one second diameter contact hole, wherein the first diameter and the second diameter are different.
The method of claim 16,
The ultrasonic sensor,
The display device further includes a sensing auxiliary electrode disposed between the pixel electrode and the piezoelectric material, disposed in a portion of the pixel electrode, and at least partially disposed inside the plurality of contact holes included in the planarization layer.
The method of claim 16,
The display panel further includes a cover glass disposed on a surface on which an image is displayed,
The ultrasonic sensor,
A display device disposed on a surface opposite to a surface on which the cover glass is disposed on the display panel.

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