KR102690617B1 - Ultrasonic sensor and display device - Google Patents

Abstract

Embodiments of the present invention relate to an ultrasonic sensor and a display device, wherein one or more holes are disposed in a planarization layer included in a thin film transistor array of the ultrasonic sensor, and in the area where the holes are disposed, the lower electrode of the piezoelectric material is connected to the bottom surface of the hole. Can be placed spaced apart. Therefore, the performance of the ultrasonic sensor is improved by securing a space that allows smooth deformation of the piezoelectric material, and the performance of the ultrasonic sensor is further improved by adjusting the number and size of holes placed in the planarization layer or various sensing functions. Be able to provide it.

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 display devices that display images is increasing, and various types of display devices such as liquid crystal display devices and organic light emitting display devices are being utilized.

In order to provide more diverse functions to users, these display devices recognize the user's touch on the display panel, biometric information (e.g. fingerprint) or gestures in contact with or close to the display panel, and based on the recognized information. It provides a function to perform input processing.

To recognize biometric information, for example, an optical sensor can be used. However, when the optical sensor is placed in the bezel area of the display panel, there is a problem in that the active area is narrowed. Additionally, when an optical sensor is placed in an active area, there is a problem that it may affect display operation or reduce sensing accuracy.

Therefore, there is a need for a method that can improve the accuracy of sensing biometric information on a display panel while preventing a decrease in the active area of the display panel.

The purpose of embodiments of the present invention is to provide an ultrasonic sensor capable of recognizing biometric information touched on the display panel in an active area of the display panel and a display device including the ultrasonic sensor.

The purpose of embodiments of the present invention is to provide an ultrasonic sensor having a structure that can increase the intensity of ultrasonic waves generated from a pixel of the ultrasonic sensor and improve sensing sensitivity.

The purpose of embodiments of the present invention is to provide an ultrasonic sensor that can recognize both biometric information touched on a display panel and a gesture performed at a location close to the display panel and a display device including the ultrasonic sensor.

In one aspect, embodiments of the present invention provide an ultrasonic sensor including multiple scan lines, multiple sensing lines, and multiple pixels.

In this ultrasonic sensor, each of the plurality of pixels includes a plurality of thin film transistors, a planarization layer disposed on the plurality of thin film transistors, and an electrical connection disposed in at least a portion of the planarization layer and at least one thin film transistor among the plurality of thin film transistors. It may include a connected connection electrode, a pixel electrode disposed on the connection electrode, a piezoelectric material disposed on the pixel electrode, and a common electrode disposed on the piezoelectric material.

Here, the planarization layer includes one or more holes, and the pixel electrode may be disposed to be spaced apart from the bottom surface of the hole in an area where at least one of the one or more holes is disposed.

At this time, the connection electrode may be electrically connected to the thin film transistor in at least one hole among the one or more holes included in the planarization layer.

Alternatively, at least one hole among one or more holes included in the planarization layer may be located in an area corresponding to an area excluding an area where a plurality of thin film transistors are disposed.

Alternatively, at least one hole among one or more holes included in the planarization layer may be disposed in a plurality of adjacent pixels along the direction in which the scan line is disposed.

Additionally, when there are more than one hole included in the planarization layer, the size of each of the plurality of holes may be constant or different.

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

According to embodiments of the present invention, a hole is disposed in the planarization layer included in the thin film transistor array of an ultrasonic sensor and the pixel electrode is spaced apart from the bottom surface of the hole, so that the deformation of the piezoelectric material disposed on the pixel electrode is smooth. This allows the sensing performance of the ultrasonic sensor to be improved.

According to embodiments of the present invention, by placing a hole in an area in a pixel where a thin film transistor, etc. are not placed, the size of the hole can be increased to further improve the sensing performance of the ultrasonic sensor.

In addition, by arranging a plurality of holes of different sizes within a pixel, it is possible to perform both sensing using high frequencies (eg, fingerprint sensing) and sensing using low frequencies (eg, gesture sensing).

Figure 1 is a diagram showing an example of a structure in which an ultrasonic sensor is disposed in a display device according to embodiments of the present invention.
Figure 2 is a diagram showing an example of a circuit structure and driving method of a pixel array of an ultrasonic sensor according to embodiments of the present invention.
Figure 3 is a diagram showing an example of a planar structure of a thin film transistor array of an ultrasonic sensor according to embodiments of the present invention.
Figures 4a and 4b are diagrams showing examples of the cross-sectional structure of portion AA' shown in Figure 3.
Figure 5 is a diagram showing another example of a planar structure of a thin film transistor array of an ultrasonic sensor according to embodiments of the present invention.
FIG. 6 is a diagram showing an example of the cross-sectional structure of portion BB′ shown in FIG. 5.
Figure 7 is a diagram showing another example of a planar structure of a thin film transistor array of an ultrasonic sensor according to embodiments of the present invention.
FIG. 8 is a diagram showing an example of the cross-sectional structure of the CC' portion shown in FIG. 7.
Figure 9 is a diagram showing another example of a planar structure of a thin film transistor array of an ultrasonic sensor according to embodiments of the present invention.
FIG. 10 is a diagram showing an example of the cross-sectional structure of portion DD' shown in FIG. 9.
Figure 11 is a diagram showing an example of a method of manufacturing an ultrasonic sensor according to embodiments of the present invention.
FIG. 12 is a diagram illustrating an example of sensing performed by a display device equipped with an ultrasonic sensor 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 the exemplary drawings. In adding reference numerals to components in each drawing, identical components may have the same reference numerals as much as possible even if they are shown in different drawings. Additionally, when describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description may be omitted. When “comprises,” “has,” “consists of,” etc. mentioned in the specification are used, other parts may be added unless “only” is used. When a component is expressed in the singular, it can also include the plural, unless specifically stated otherwise.

Additionally, when describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are only used to distinguish the component from other components, and the nature, sequence, order, or number of the components are not limited by the term.

In the description of the positional relationship of components, when two or more components are described as being “connected,” “coupled,” or “connected,” the two or more components are directly “connected,” “coupled,” or “connected.” ", but it should be understood that two or more components and other components may be further "interposed" and "connected," "combined," or "connected." Here, other components may be included in one or more of two or more components that are “connected,” “coupled,” or “connected” to each other.

In the description of the time relationship or flow relationship of components, for example, the temporal relationship or flow relationship is expressed as "after", "after", "after", "before", etc. Where described, non-contiguous cases may be included unless “immediately” or “directly” is used.

Meanwhile, when a numerical value or corresponding information (e.g., level, etc.) for a component is mentioned, even if there is no separate explicit description, the numerical value or corresponding information is related to various factors (e.g., process factors, internal or external shocks, It can be interpreted as including the error range that may occur due to noise, etc.).

Figure 1 is a diagram 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 on which a plurality of gate lines, a plurality of data lines, and a plurality of subpixels are arranged, and a display panel 110 arranged on the display panel 110. It may include various driving circuits for driving signal lines or voltage lines.

An ultrasonic sensor 200 or an ultrasonic sensing device for sensing biometric information (eg, fingerprints) or gestures that are in contact with or close to the display panel 110 may be disposed on at least one surface of such a display device.

Alternatively, in some cases, the ultrasonic sensor 200 may be placed inside the display device.

When the ultrasonic sensor 200 is disposed on one side of the display device, for example, the cover glass 120 may be disposed on the side of the display panel 110 where an image is displayed. Additionally, the ultrasonic sensor 200 may be placed on the opposite side of the display panel 110 where the image is displayed. That is, the ultrasonic sensor 200 may be disposed on a side of the display panel 110 opposite to the side where the cover glass 120 is disposed.

This ultrasonic sensor 200 can be bonded to the display panel 110 through the adhesive portion 300. And, the adhesive portion 300 may be made of resin, for example.

The ultrasonic sensor 200 generates ultrasonic waves and senses the ultrasonic waves reflected by the fingerprint in contact with the cover glass 120 disposed on the display panel 110, thereby recognizing the fingerprint in contact with the cover glass 120. . The ultrasonic sensor 200 is disposed on the opposite side of the display panel 110 to the side where the image is displayed to perform sensing, thereby enabling fingerprint recognition without reducing the area where the image is displayed.

Specifically, when the ultrasonic waves generated from the ultrasonic sensor 200 reach the valley portion of the fingerprint, they reach the air existing between the human skin and the cover glass 120. Here, most of the ultrasonic waves hitting the air are reflected due to the difference in acoustic impedance values between the cover glass 120 and the air.

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

Therefore, based on the intensity and timing of ultrasonic waves that reach and reflect the valleys and ridges of the fingerprint, the valleys and ridges of the fingerprint can be distinguished and the fingerprint can be sensed.

In this way, since the ultrasonic sensor 200 senses even the inside of the skin, it is not sensitive to contamination or condition of the skin surface and provides the advantage of excellent security. In addition, it is possible to sense a fingerprint without reducing the area where the image is displayed on the display panel 110, so that the display device can perform input processing using the sensed fingerprint.

This ultrasonic sensor 200 may include a material for generating ultrasonic waves and several circuit elements for generating and sensing ultrasonic waves.

As an example, the ultrasonic sensor 200 may include a substrate 210, a thin film transistor array 220, a first pad portion 231, and a second pad portion 232 disposed on the substrate 210. . In addition, the thin film transistor array 220 may include a pixel electrode (PXL) 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. You can.

The piezoelectric material 240 may be, for example, a material such as PZT, ZnO, or perovskite, but is not limited thereto.

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, which supplies signals, voltage, etc. to the thin film transistor array 220 and the common electrode (COM), is a second circuit disposed on the substrate 210 through the flexible printed circuit 290 and the bonding portion 280. It may be electrically connected to the pad portion 232.

In the thin film transistor array 220, a transistor for driving to generate ultrasonic waves and sensing ultrasonic waves reflected by a fingerprint, a pixel electrode (PXL), etc. may be disposed.

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

Additionally, the piezoelectric material 240 may be vibrated by a voltage applied to the pixel electrode (PXL) 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 (PXL), the piezoelectric material 240, and the common electrode (COM) may be viewed as a pixel array in a circuit manner.

The common electrode COM may be disposed, for example, by coating silver ink, and in some cases, may be disposed to cover the entire piezoelectric material 240 or may be disposed in a certain pattern.

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

The cover layer 270 may be made of polyimide, for example, and may provide a function of capping the pixel array and the reflective layer 260 of the ultrasonic sensor 200.

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

FIG. 2 is a diagram illustrating an example of the circuit structure and driving method of the pixel array of the ultrasonic sensor 200 according to embodiments of the present invention.

Referring to FIG. 2, a plurality of scan lines (SCL) and a plurality of sensing lines (SSL) may be disposed in the pixel array of the ultrasonic sensor 200. The scan line (SCL) and the sensing line (SSL) may be arranged to intersect each other, and a plurality of pixels may be arranged in an area defined by the intersection of the scan line (SCL) and the sensing line (SSL).

Additionally, a voltage line may be disposed in the pixel array to supply a driving voltage (DV), a sensing voltage (SV), etc. for generating and sensing ultrasonic waves of the pixel.

Additionally, the ultrasonic sensor 200 may include a circuit that drives a plurality of scan lines (SCL) arranged in a pixel array and a circuit that detects a sensing signal through a plurality of sensing lines (SSL).

In each pixel, several circuit elements for generating and sensing ultrasonic waves may be disposed.

As an example, each pixel has a first transistor (T1) and a second transistor (T2) controlled by the scan signal (SCO) applied to the scan line (SCL), and a voltage of the sensing node (Ns). A third transistor (T3) and one capacitor (C) may be disposed.

Here, the first transistor (T1), the second transistor (T2), and the third transistor (T3) are all N-type as an example, but in some cases, they may all be implemented as P-type. Alternatively, only the first transistor T1 and the second transistor T2 may be implemented as the same type, and the third transistor T3 may be implemented as a different type.

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 sensing node Ns.

Here, the first driving voltage line DVL1 may supply the first driving voltage DV1 for ultrasonic generation to the pixel. This first driving voltage DV1 may be an alternating current voltage in the form of a pulse having a high voltage level. For example, it may be an alternating voltage swinging from +100V to -100V.

The second transistor T2 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 third transistor T3.

At this time, the second transistor T2 may be driven by the same scan line SCL as the scan line SCL that drives the first transistor T1 disposed in an adjacent pixel.

That is, as an example shown in FIG. 2, the first transistor T1 disposed in a pixel in column A and the second transistor T2 disposed in a pixel in column B are connected to the same nth scan line (SCL(n)). and can be simultaneously driven by the nth scan signal (SCO(n)) applied to the nth scan line (SCL(n)).

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

And, 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 sensing node Ns and the second driving voltage line DVL2.

That is, the electrode of the capacitor C connected to the sensing node Ns may be a pixel electrode PXL disposed on the thin film transistor array 220 and used to form capacitance. And, the electrode of the capacitor C connected to the second driving voltage line DVL2 may be the common electrode COM.

This common electrode COM may be an electrode commonly connected to at least two or more pixels.

The second driving voltage line DVL2 may supply a 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.

A scan signal (SCO) is sequentially applied to the scan line (SCL) arranged in this pixel array, and ultrasonic waves can be generated and sensed.

For example, when the nth scan signal (SCO(n)) at a level that turns on the first transistor (T1) is applied to the nth scan line (SCL(n)), the first transistor disposed in the pixel in column A (T1) turns on.

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

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

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

At this time, since the nth scan signal (SCO(n)) at a level that turns on the first transistor (T1) is applied to the nth scan line (SCL(n)), the second transistor ( T2) is also turned on.

In addition, when the first transistor T1 disposed in the pixel in column B is turned off, the voltage level of the sensing node Ns of the pixel disposed in column B may change when ultrasonic waves reflected by the fingerprint reach column B. .

That is, the polarization state of the piezoelectric material 240 disposed between the pixel electrode (PXL) disposed in the pixel of column B and the common electrode (COM) is changed by the reflected ultrasonic waves, and this causes the pixel electrode (PXL), i.e. , the voltage level of the sensing node (Ns) may change.

As the voltage level of the sensing node (Ns) of the pixel arranged in column B changes, the third transistor (T3) can be turned on or off, and the second transistor (T2) is turned on. The sensing voltage (SV) can be detected through the sensing line (SSL).

That is, it is possible to sense the ultrasonic waves reflected by the fingerprint and returned from the pixel in column B where the second transistor T2 is turned on.

In this way, by driving the first transistor T1 and the second transistor T2 arranged in adjacent pixel columns by the same scan line SCL, ultrasonic waves can be generated and sensed in adjacent pixel columns.

In addition, embodiments of the present invention provide a structure that allows smooth deformation of the piezoelectric material 240 disposed on the thin film transistor array 220, thereby improving the sensing performance of the ultrasonic sensor 200. provides.

FIG. 3 is a diagram showing 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. 4A and 4B are diagrams showing examples of the cross-sectional structure of portion A-A' shown in FIG. 3, including the piezoelectric material 240 and the common electrode (COM) disposed on the thin film transistor array 220. This is the drawing shown.

Referring to FIGS. 3 and 4A , a plurality of scan lines SCL may be arranged in one direction on the thin film transistor array 220 of the ultrasonic sensor 200. Additionally, a first driving voltage line (DVL1), a sensing line (SSL), and a sensing voltage line (SVL) may be disposed along a direction intersecting the scan line (SCL).

Here, among the areas between adjacent scan lines (SCL), the area between the first driving voltage line (DVL1) and the sensing voltage line (SVL) can be viewed as one pixel.

Each pixel includes a first transistor (T1) and a second transistor (T2) controlled by a signal applied to the scan line (SCL), and a third transistor (T3) controlled by the voltage level of the pixel electrode (PXL). ) can be placed.

Here, the pixel electrode PXL may be electrically connected to the first source electrode SE1 or the first drain electrode DE1 of the first transistor T1. Additionally, the pixel electrode PXL may be electrically connected to the gate electrode of the third transistor T3.

That is, the pixel electrode PXL is electrically connected to the first source electrode SE1 or the first drain electrode DE1 of the first transistor T1, and generates a first driving voltage ( DV1) can be approved and ultrasonic waves can be generated.

Additionally, the pixel electrode PXL is electrically connected to the gate electrode of the third transistor T3, and when the voltage level of the pixel electrode PXL changes due to reflected ultrasonic waves, the third transistor T3 is turned on or off. and sensing can be achieved.

At this time, the planarization layer 226 disposed below the pixel electrode PXL may include one or more holes, and in the area where the hole is disposed, the pixel electrode PXL may be disposed to be spaced apart from the bottom surface of the hole.

In addition, the pixel electrode PXL may be electrically connected to the first transistor T1, the third transistor T3, etc. through the connection electrode CE disposed in at least a portion of the planarization layer 226. That is, the connection electrode (CE) is electrically connected to the first source electrode (SE1) of the first transistor (T1), the gate electrode of the third transistor (T3), and the pixel electrode (PXL) is connected to the first source electrode (SE1) of the first transistor (T1). It may be electrically connected to the first transistor T1 and the third transistor T3 through the electrode CE.

Specifically, referring to the example shown in FIG. 4A, the buffer layer 221 is disposed on the substrate 210. Additionally, a thin film transistor may be disposed on the buffer layer 221, and FIG. 4A shows an example of a portion where the first transistor T1 is disposed.

The first transistor T1 may include a first gate electrode GE1, a first active layer ACT1, a first drain electrode DE1, and a first source electrode SE1.

The gate insulating layer 222 is disposed between the first gate electrode GE1 and the first active layer ACT1.

The first insulating layer 223 and the second insulating layer 224 may be disposed on the first gate electrode GE1. Here, the first insulating layer 223 and the second insulating layer 224 are examples, and only one insulating layer or two or more insulating layers may be disposed on the first gate electrode GE1.

A first protective layer 225 may be disposed on the first source electrode SE1 and the first drain electrode DE1, and a planarization layer 226 may be disposed on the first protective layer 225.

Here, the planarization layer 226 may include one or more holes, and at least one of the one or more holes is located on the first transistor T1 located below the planarization layer 226 and on the planarization layer 226. It may be a contact hole (CH) for electrically connecting the pixel electrodes (PXL) located in to each other. In this specification, this contact hole (CH) is also referred to as “first hole (H1).”

The contact hole (CH) may be formed by etching the planarization layer 226. Additionally, a connection electrode (CE) may be disposed inside the contact hole (CH) and on the upper surface of the planarization layer (226).

These connection electrodes CE may be arranged separately on a pixel basis. Additionally, the connection electrode CE may be disposed entirely on the planarization layer 226 except for the area where the hole is disposed. Additionally, the connection electrode CE may be disposed in at least a partial area inside the contact hole CH.

In this way, the connection electrode (CE) is disposed in at least a partial area inside the contact hole (CH) and on the upper surface of the planarization layer 226, and is disposed on the lower part of the planarization layer 226 through the connection electrode (CE). The first transistor T1 and the pixel electrode PXL can be electrically connected. Additionally, the third transistor T3 and the pixel electrode PXL may be electrically connected through the connection electrode CE.

In addition, the connection electrode CE may be disposed only in some areas of the planarization layer 226 excluding the area where the hole is disposed, but as an example shown in FIG. 4A, the hole is disposed on the planarization layer 226. The contact area with the pixel electrode (PXL) can be increased by being entirely disposed in the area excluding the exposed area.

By increasing the contact area between the connection electrode CE and the pixel electrode PXL, the first driving voltage DV1 supplied through the first transistor T1 can be evenly transmitted to the pixel electrode PXL.

Here, as the pixel electrode (PXL) is electrically connected to the first transistor (T1) through the connection electrode (CE), the pixel electrode (PXL) is connected to the contact hole (CH) in the area where the contact hole (CH) is disposed. It may be arranged to be spaced apart from the first bottom surface (H_Bot1). Here, the first bottom surface (H_Bot1) may refer to the upper surface of the connection electrode (CE) disposed inside the contact hole (CH).

Since the pixel electrode (PXL) disposed below the piezoelectric material 240 is disposed to be spaced apart from the first bottom surface (H_Bot1) of the contact hole (CH), the first driving voltage (DV1) is applied to the pixel electrode (PXL) When this happens, a space that allows smooth vibration of the piezoelectric material 240 can be secured. Accordingly, ultrasonic generation performance by vibration of the piezoelectric material 240 can be improved. That is, the intensity of vibration of the piezoelectric material 240 can be increased by the secured space, and thus the performance of ultrasonic generation can be improved. Alternatively, in some cases, ultrasonic generation performance can be maintained even if the driving voltage is supplied at a slightly low level, thereby increasing the efficiency of the ultrasonic sensor 200.

In addition, even when receiving reflected ultrasonic waves, sensing performance can be improved by securing a space where the piezoelectric material 240 can be smoothly deformed.

Also, by increasing the first size S1, which is the size of the contact hole CH, the ultrasonic generation performance by vibration of the piezoelectric material 240 and the sensing performance of reflected ultrasonic waves can be further improved. Here, the first size (S1) may mean the diameter or area of the contact hole (CH).

Meanwhile, in some cases, as in the example shown in FIG. 4B, an auxiliary electrode (AE) is disposed on the connection electrode (CE) inside the contact hole (CH), and a second protection electrode is placed on the auxiliary electrode (AE). Layer 227 may be disposed. This auxiliary electrode (AE) may be made of the same material as the first source electrode (SE1) of the first transistor (T1).

By disposing the auxiliary electrode (AE) on the connection electrode (CE) disposed inside the contact hole (CH), the voltage change due to the change in the polarization state of the piezoelectric material 240 due to reflected ultrasonic waves is caused by the contact hole (CH). ) so that it can be concentrated with electrodes placed in the area.

Additionally, since the electrode disposed in the contact hole CH is electrically connected to the gate electrode of the third transistor T3 as well as the first transistor T1, sensing sensitivity can be improved.

In other words, the auxiliary electrode (AE) is placed inside the contact hole (CH) so that the electrode placed inside the contact hole (CH) has a lower resistance than other parts of the connection electrode (CE), thereby enabling sensing when receiving ultrasonic waves. It can increase the voltage fluctuation of the node (Ns). In this case, the first bottom surface (H_Bot1) of the contact hole (CH) may mean the top surface of the second protective layer 227 disposed inside the contact hole (CH). That is, in this specification, the bottom surface of the hole may mean the top surface of the topmost component among the components arranged inside the hole.

As such, embodiments of the present invention allow the pixel electrode PXL to be electrically connected to the first transistor T1 through the connection electrode CE, so that the pixel electrode PXL is connected to the first transistor T1 of the contact hole CH. Ensure that it can be placed in a structure spaced apart from the floor surface (H_Bot1). Accordingly, the piezoelectric material 240 disposed on the pixel electrode PXL can be smoothly deformed by the lower space of the pixel electrode PXL, thereby improving ultrasonic generation performance and sensing performance.

Additionally, embodiments of the present invention can further improve sensing performance and perform gesture sensing by increasing the size of the space below the pixel electrode (PXL).

FIG. 5 is a diagram 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. And, FIG. 6 is a diagram showing an example of the cross-sectional structure of portion B-B' shown in FIG. 5. Descriptions of parts that are the same as the above-described examples are omitted, and the omitted parts can be understood based on the description of the above-described examples. For convenience of explanation, a structure in which the auxiliary electrode (AE) and the second protective layer 227 are disposed inside the contact hole (CH) will be described as an example. However, as in the example described above with reference to FIG. 4A, the ultrasonic sensor ( 200) may have a structure in which only the connection electrode (CE) is disposed inside the contact hole (CH). Additionally, in some cases, only the connection electrode (CE) and the auxiliary electrode (AE) or only the connection electrode (CE) and the second protective layer 227 may be disposed inside the contact hole (CH).

Referring to FIGS. 5 and 6 , the planarization layer 226 of the thin film transistor array 220 may include one or more holes. And, as in the above-described example, this hole may be a contact hole (CH) for electrically connecting the first transistor (T1) and the pixel electrode (PXL).

The connection electrode CE may be disposed in at least a portion of the inside of the contact hole CH and the upper surface of the planarization layer 226 to electrically connect the first transistor T1 and the pixel electrode PXL to each other. there is.

Additionally, the pixel electrode (PXL) may be disposed to be spaced apart from the first bottom surface (H_Bot1) of the contact hole (CH). Accordingly, when the first driving voltage DV1 is applied or reflected ultrasonic waves are received, the piezoelectric material 240 disposed on the pixel electrode PXL can be smoothly deformed.

Here, the contact hole (CH) may have a second size (S2) that is larger than the first size (S1) in the above-described example. This second size (S2) may mean the diameter or area of the contact hole (CH).

In this way, by increasing the size of the contact hole (CH) located below the pixel electrode (PXL), ultrasonic generation performance and sensing performance of reflected ultrasonic waves can be improved.

In addition, by increasing the size of the contact hole (CH), ultrasonic waves in a low-frequency band can be generated according to the vibration of the piezoelectric material 240, allowing gestures performed without contact with the display device to be sensed.

That is, sensing performance is improved by a structure in which the pixel electrode (PXL) and the first bottom surface (H_Bot1) of the contact hole (CH) are spaced apart in the area where the contact hole (CH) is placed, and the size of the contact hole (CH) is improved. Through adjustment, sensing performance can be further improved or gesture sensing can be enabled.

Additionally, in embodiments of the present invention, one or more holes may be further disposed in areas other than the area where the contact hole CH is disposed. For example, a hole may be located in an area of the pixel other than the area where the thin film transistor is disposed.

In this case, the contact hole CH may be disposed only for electrical connection between the first transistor T1 and the pixel electrode PXL, or may be provided as a structure to improve ultrasonic sensing performance.

Below, in a structure in which holes are additionally arranged in addition to the contact hole (CH), a case where both the contact hole (CH) and the additionally arranged holes have a structure for improving sensing performance will be described as an example, but is not limited to this. No.

FIG. 7 is a diagram 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. And, Figure 8 is a diagram showing an example of the cross-sectional structure of the C-C' portion shown in Figure 7.

Referring to FIGS. 7 and 8, the planarization layer 226 included in the thin film transistor array 220 may include one or more holes, and the examples shown in FIGS. 7 and 8 include two holes in one pixel. A case where this is included is shown as an example.

Among the two holes included in the planarization layer 226, the first hole H1 may be a contact hole CH for electrical connection between the first transistor T1 and the pixel electrode PXL. Additionally, the second hole H2 may be disposed in an area where the thin film transistor is not disposed. For example, the second hole H2 may be disposed in an area between the sensing line SSL and the sensing voltage line SVL. Here, the area where the thin film transistor is disposed may mean the area where the gate electrode, source/drain electrodes, and active layer constituting the thin film transistor are disposed. Additionally, it may include a region where metal is disposed for connection between thin film transistors or between thin film transistors and the connection electrode (CE). That is, as shown in the example shown in FIG. 7, the area indicated by 700 can be viewed as the area where the thin film transistor is disposed, and the area where the thin film transistor is not disposed can refer to the area excluding the area indicated by 700. Additionally, the area where these thin film transistors are placed may be implemented in various ways depending on the structure of the pixel.

Since the first transistor T1 and the pixel electrode PXL must be electrically connected through the first hole H1, the connection electrode CE may be disposed in at least a partial area inside the first hole H1. . Additionally, an auxiliary electrode (AE) and a second protective layer 227 may be disposed on the connection electrode (CE).

In the area where the first hole H1 is disposed, the pixel electrode PXL is arranged in a structure spaced apart from the first bottom surface H_Bot1 of the first hole H1, and the piezoelectric electrode disposed on the pixel electrode PXL It is possible to enable smooth deformation of the material 240.

Additionally, in the area where the second hole H2 is disposed, the pixel electrode PXL may be arranged to be spaced apart from the second bottom surface H_Bot2 of the second hole H2. That is, the second hole H2 is additionally disposed in an area other than the area where the first hole H1 is disposed, thereby increasing the area to enable smooth deformation of the piezoelectric material 240 disposed on the pixel electrode PXL. I can do it for you.

Here, since the second hole H2 is a hole provided to secure space below the pixel electrode PXL, the connection electrode CE may not be disposed therein.

However, in order to increase the contact area between the connection electrode (CE) and the pixel electrode (PXL), the connection electrode (CE) needs to be disposed entirely on the pixel, so the connection electrode (CE) is also placed inside the second hole (H2). ) may be placed. Additionally, the arrangement structure of the connection electrode (CE) may provide convenience in the process.

Additionally, the auxiliary electrode (AE) may not be disposed inside the second hole (H2), but in some cases, the auxiliary electrode (AE) may be disposed in the same manner as the first hole (H1).

In this way, the second hole (H2) is disposed in addition to the first hole (H1) that functions as a contact hole (CH), and the pixel electrode is located in the area where the first hole (H1) and the second hole (H2) are disposed. By arranging the PXL in a structure spaced apart from the bottom surface of the hole, the space secured below the pixel electrode PXL can be increased. Accordingly, ultrasonic generation and sensing performance by vibration of the piezoelectric material 240 disposed on the pixel electrode PXL can be improved.

Here, the sizes of the first hole H1 and the second hole H2 may be the same. Alternatively, the sizes of the first hole H1 and the second hole H2 may be different.

For example, the size of the first hole (H1) may be the first size (S1), and the size (H2) of the second hole (H2) may be the second size (S2). And, the second size (S2) may be larger than the first size (S1). That is, the size of the hole placed in an area where it is easy to place a hole, such as an area where a thin film transistor or signal line is not placed, may be larger, but is not limited to this.

By arranging a plurality of holes in one pixel and keeping the pixel electrode (PXL) spaced apart from the bottom surface of the hole in the area where each hole is disposed, ultrasonic generation and sensing performance can be improved.

Additionally, by varying the sizes of the first hole (H1) and the second hole (H2), ultrasonic waves in the high-frequency band and low-frequency band can be generated, enabling both fingerprint sensing and gesture sensing.

For example, relatively high frequency ultrasonic waves (eg, 1 MHz to 50 MHz) can be generated by the first hole H1 having a small size. In addition, relatively low frequency ultrasonic waves (eg, 50 kHz to 400 kHz) can be generated by the second hole H2 having a large size.

Therefore, high-frequency ultrasound and low-frequency ultrasound can be generated from one pixel. Additionally, by performing sensing through frequency component analysis of reflected ultrasonic waves, fingerprint sensing and gesture sensing can be performed through the ultrasonic sensor 200.

As in the above-described example, one or more holes may be disposed in the planarization layer 226 of the thin film transistor array 220 to secure space below the pixel electrode PXL, and these holes may be contact holes ( CH) or a hole other than a contact hole (CH).

Additionally, the sizes of the plurality of holes may be the same or different.

In this way, the performance of the ultrasonic sensor 200 is improved through the holes disposed in the planarization layer 226, and the performance can be further improved or various functions can be provided by adjusting the number and size of the holes.

In addition, in some cases, the holes included in the planarization layer 226 may be disposed in an area where one hole corresponds to two or more pixels.

FIG. 9 is a diagram 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. And, FIG. 10 is a diagram showing an example of the cross-sectional structure of portion D-D' shown in FIG. 9.

9 and 10, the planarization layer 226 of the thin film transistor array 220 is provided to electrically connect the first transistor T1 and the pixel electrode PXL and secure the space below the pixel electrode PXL. A first hole H1 may be disposed for.

Additionally, the second hole H2 may be disposed in an area other than the area where the thin film transistor is disposed. The pixel electrode PXL is disposed to be spaced apart from the first bottom surface H_Bot1 of the first hole H1 and to be spaced apart from the second bottom surface H_Bot2 of the second hole H2.

Here, the second hole H2 may be disposed in a plurality of adjacent pixels along the direction in which the scan line SCL is disposed. For example, it may be a structure disposed in two adjacent pixels, or it may be a structure disposed between two adjacent sensing lines (SSL). Accordingly, the sensing voltage line (SVL) may be placed below the second hole (H2), and the depth of the second hole (H2) may be determined considering the arrangement of the sensing voltage line (SVL).

That is, embodiments of the present invention can perform ultrasonic generation and sensing along the column direction, which is the direction in which the scan line (SCL) is arranged. Therefore, since pixels arranged in the same row generate or sense ultrasonic waves in the same period, the second hole H2 is placed in two pixels arranged in the same row and can improve ultrasonic generation and sensing performance.

In particular, as shown in the example shown in FIG. 9, in a structure in which two pixels adjacent in the column direction are symmetrically arranged with respect to the sensing voltage line SVL, the second hole H2 easily corresponds to the two adjacent pixels. It can be placed in an area where

Additionally, since the second hole H2 is disposed in two pixels, the size of the hole can be further increased compared to the case where the hole is disposed in each pixel, as in the above-described example.

For example, the second hole H2 disposed in two pixels may have a third size S3 that is larger than the first size S1 or the second size S2.

In this way, by arranging a larger hole to secure space at the bottom of the pixel electrode (PXL), ultrasonic generation and sensing performance can be further improved. Additionally, by increasing the size difference between the first hole (H1) and the second hole (H2), the performance of sensing using ultrasonic waves in a high frequency band and sensing using ultrasonic waves in a low frequency band can be improved, respectively.

In addition, although the structure in which the second hole H2 is disposed in two adjacent pixels in the column direction is described as an example, embodiments of the present invention provide a second hole H2 in a plurality of pixels that perform ultrasonic generation and sensing in the same period. A structure in which the hole H2 is disposed may be provided.

The ultrasonic sensor 200, which includes a hole that secures space at the bottom of the pixel electrode (PXL), is created by bonding a structure in which electrodes are placed on both sides of the piezoelectric material 240 onto the thin film transistor array 220. It can be implemented.

Figure 11 is a diagram showing an example of a manufacturing method of the ultrasonic sensor 200 according to embodiments of the present invention.

Referring to FIG. 11, a thin film transistor including a first transistor T1 is disposed on the substrate 210, and a first protective layer 225 and a planarization layer 226 are disposed on the thin film transistor.

The planarization layer 226 is etched to form a first hole H1 in the planarization layer 226, and a connection electrode CE is placed on the upper surface of the planarization layer 226 and inside the first hole H1. . Then, the auxiliary electrode (AE) and the second protective layer 227 are placed on the connection electrode (CE) inside the first hole (H1) to complete the thin film transistor array 220 excluding the pixel electrode (PXL). You can. Here, in some cases, the auxiliary electrode AE and the second protective layer 227 may not be disposed inside the first hole H1, or only one of them may be disposed.

Additionally, the ultrasonic sensor 200 can be manufactured by bonding a structure in which a common electrode (COM) and a pixel electrode (PXL) are disposed on the upper and lower surfaces of the piezoelectric material 240, respectively, onto the connection electrode (CE).

That is, the pixel electrode (PXL) is not directly placed on the planarization layer 226 like the connection electrode (CE), but is bonded to the connection electrode (CE) while attached to the lower surface of the piezoelectric material 240. In the area where the first hole H1 is placed, the pixel electrode PXL and the first bottom surface H_Bot1 of the first hole H1 are spaced apart from each other.

FIG. 12 is a diagram illustrating an example of sensing performed by a display device equipped with an ultrasonic sensor 200 according to embodiments of the present invention using an ultrasonic sensor.

Referring to FIG. 12, since the first hole H1 and the second hole H2 of different sizes are disposed in the planarization layer 226 included in the pixel of the ultrasonic sensor 200, ultrasonic waves in the high frequency band and ultrasonic waves in the low frequency band are Ultrasound waves can be generated simultaneously.

The ultrasonic sensor 200 generates ultrasonic waves in a high frequency band, making it possible to easily perform fingerprint sensing that requires high resolution.

In addition, the ultrasonic sensor 200 generates ultrasonic waves in a low-frequency band, allowing gestures performed at a location close to the cover glass 120 without being in contact with the cover glass 120.

In the ultrasonic sensor 200 according to the above-described embodiments of the present invention, one or more holes are disposed in the planarization layer 226 of the thin film transistor array 220, and the pixel electrode PXL is located in the area where the holes are disposed. By being spaced apart from the bottom surface, smooth deformation of the piezoelectric material 240 disposed on the pixel electrode PXL is possible.

Therefore, ultrasonic generation and sensing performance can be improved by smooth deformation of the piezoelectric material 240.

In addition, by adjusting the number and size of holes arranged in the planarization layer 226, ultrasonic sensing performance can be further improved, or fingerprint sensing and gesture sensing can be enabled to provide various functions.

The above description is merely an illustrative explanation of the technical idea of the present invention, and various modifications and variations will be possible to 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 technical idea of the present invention, but rather to explain it, and therefore the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted in accordance with the claims below, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of rights 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 portion 290: Flexible printed circuit
300: Adhesive part 400: Controller

Claims (17)

Containing a plurality of scan lines, a plurality of sensing lines, and a plurality of pixels,
Each of the plurality of pixels is,
a plurality of thin film transistors;
a planarization layer disposed on the plurality of thin film transistors;
a connection electrode disposed in at least a portion of the planarization layer and electrically connected to at least one thin film transistor among the plurality of thin film transistors;
a pixel electrode disposed on the connection electrode;
a piezoelectric material disposed on the pixel electrode; and
comprising a common electrode disposed on the piezoelectric material,
The planarization layer includes one or more holes overlapping the piezoelectric material, and the pixel electrode is disposed to be spaced apart from a bottom surface of the hole in a region where at least one hole is disposed among the one or more holes,
An ultrasonic sensor wherein each of the plurality of pixels has a plurality of holes, and at least two of the plurality of holes have different sizes.
According to paragraph 1,
An ultrasonic sensor in which the connection electrode is electrically connected to the thin film transistor in at least one hole among the one or more holes included in the planarization layer.
According to paragraph 1,
An ultrasonic sensor, wherein at least one hole among the one or more holes included in the planarization layer is located in an area corresponding to an area excluding an area where the plurality of thin film transistors are disposed.
According to paragraph 1,
At least one hole among the one or more holes included in the planarization layer is disposed in a plurality of adjacent pixels along a direction in which the scan line is disposed.
delete delete According to paragraph 1,
The one or more holes included in the planarization layer are plural, and in a first hole among the plurality of holes, the connection electrode is electrically connected to the thin film transistor, and the second hole excludes the area where the plurality of thin film transistors are disposed. Ultrasonic sensor located in the area corresponding to the area.
In clause 7,
An ultrasonic sensor in which the size of the second hole is larger than the size of the first hole.
According to paragraph 1,
The connection electrode is,
An ultrasonic sensor that is disposed entirely on an area of the planarization layer excluding an area where the one or more holes are disposed, is disposed in at least a partial area inside at least one of the one or more holes, and is in contact with the pixel electrode.
According to paragraph 1,
The connection electrode is,
Electrically connected to the source electrode or drain electrode of any one of the plurality of thin film transistors,
An ultrasonic sensor electrically connected to the gate electrode of another thin film transistor among the plurality of thin film transistors.
display panel; and
Includes an ultrasonic sensor built into the display panel or disposed on at least one surface of the display panel,
The ultrasonic sensor is,
Containing a plurality of scan lines, a plurality of sensing lines, and a plurality of pixels,
Each of the plurality of pixels is,
a plurality of thin film transistors;
a planarization layer disposed on the plurality of thin film transistors;
a connection electrode disposed in at least a portion of the planarization layer and electrically connected to at least one thin film transistor among the plurality of thin film transistors;
a pixel electrode disposed on the connection electrode;
a piezoelectric material disposed on the pixel electrode; and
comprising a common electrode disposed on the piezoelectric material,
The planarization layer includes one or more holes overlapping the piezoelectric material, and the pixel electrode is disposed to be spaced apart from a bottom surface of the hole in a region where at least one hole is disposed among the one or more holes,
A display device wherein each of the plurality of pixels has a plurality of holes, and at least two of the plurality of holes have different sizes.
According to clause 11,
A display device wherein the connection electrode is electrically connected to the thin film transistor in at least one hole among the one or more holes included in the planarization layer.
According to clause 11,
A display device wherein at least one hole among the one or more holes included in the planarization layer is located in an area corresponding to an area excluding an area where the plurality of thin film transistors are disposed.
According to clause 11,
A display device wherein at least one of the one or more holes included in the planarization layer is disposed in a plurality of adjacent pixels along a direction in which the scan line is disposed.
According to clause 11,
The one or more holes included in the planarization layer are plural, and in a first hole among the plurality of holes, the connection electrode is electrically connected to the thin film transistor, and in a second hole excluding the area where the plurality of thin film transistors are disposed. A display device located in an area corresponding to the area.
According to clause 15,
A display device in which the size of the first hole and the size of the second hole are different.
According to clause 11,
Further comprising a cover glass disposed on the display panel,
The ultrasonic sensor is,
A display device disposed on a side of the display panel opposite to the side on which the cover glass is disposed.

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