KR20200117554A - Ultrasonic sensor and display device - Google Patents

Abstract

Embodiments of the present invention relate to an ultrasonic sensor and a display device. According to the present invention, one or more holes can be disposed in a planarization layer included in a thin film transistor array of the ultrasonic sensor, and a lower electrode of a piezoelectric material can be disposed to be spaced apart from the bottom surface of the holes in an area in which the holes are disposed. Therefore, the performance of the ultrasonic sensor is improved by securing a space for smooth deformation of the piezoelectric material, and the performance of the ultrasonic sensor can be further improved and various sensing functions can be provided by controlling the number and size of the holes arranged in the planarization 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, demand for a display device that displays 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 used.

Such a display device recognizes a user's touch on the display panel, or biometric information (e.g., fingerprint) or gestures in contact with or close to the display panel, and based on the recognized information in order to provide more diverse functions to the user. It provides a function to perform input processing by using.

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

Accordingly, there is a need for a method of improving the accuracy of sensing biometric information on 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 a display device including an ultrasonic sensor and an ultrasonic sensor capable of recognizing biometric information contacting a 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 having a structure capable of increasing the intensity of ultrasonic waves generated from a pixel of the ultrasonic sensor and improving sensing sensitivity.

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

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

In such an 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 at least one thin film transistor among the plurality of thin film transistors and electrically A connection electrode connected to each other, 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 may be included.

Here, the planarization layer may include one or more holes, and in a region in which at least one of the one or more holes is disposed, the pixel electrode may be disposed to be spaced apart from the bottom surface of the hole.

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

Alternatively, at least one of the one or more holes included in the planarization layer may be located in a region corresponding to a region other than a region in which a plurality of thin film transistors are disposed.

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

In addition, when there are a plurality of one or more holes included in the planarization layer, the sizes of each of the plurality of holes may be constant or different.

In another aspect, embodiments of the present invention provide a display device including a display panel, embedded in the display panel, or 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, a hole is disposed in a planarization layer included in a thin film transistor array of an ultrasonic sensor and a pixel electrode is spaced apart from the bottom surface of the hole, so that the piezoelectric material disposed on the pixel electrode can be smoothly deformed. This makes it possible to improve the sensing performance of the ultrasonic sensor.

According to embodiments of the present invention, by disposing a hole in a region in which a thin film transistor or the like is not disposed in a pixel, the size of the hole is increased to further improve the sensing performance of the ultrasonic sensor.

In addition, by arranging a plurality of holes of different sizes in the pixel, both sensing using high frequency (eg, fingerprint sensing) and sensing using low frequency (eg, gesture sensing) can be performed.

1 is a diagram illustrating 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 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.
3 is a diagram illustrating an example of a planar structure of a thin film transistor array of an ultrasonic sensor according to embodiments of the present invention.
4A and 4B are views showing examples of a cross-sectional structure of a portion AA′ shown in FIG. 3.
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.
6 is a view showing an example of a cross-sectional structure of a portion BB' shown in FIG. 5.
7 is a diagram illustrating 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 illustrating an example of a cross-sectional structure of a portion CC′ shown in FIG. 7.
9 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.
10 is a diagram illustrating an example of a cross-sectional structure of a portion DD' shown in FIG. 9.
11 is a diagram illustrating an example of a method of manufacturing an ultrasonic sensor according to embodiments of the present invention.
12 is a diagram illustrating an example of sensing performed by a 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 elements of each drawing, the same elements may have the same numerals as possible even if they are indicated on different drawings. In addition, in describing the present invention, when it is determined that a detailed description of a related known configuration or function may obscure the subject matter of the present invention, a detailed description thereof may be omitted. When "include", "have", "consists of" and the like mentioned in the present specification are used, other parts may be added unless "only" is used. In the case of expressing the constituent elements in the singular, the case including plural may be included unless there is a specific explicit description.

In addition, in describing the constituent elements 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 nature, order, order, or number of the component is not limited by the term.

In the description of the positional relationship of the 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" "It may be, but it should be understood that two or more components and other components may be further "interposed" to be "connected", "coupled" or "connected". Here, the other components may be included in one or more of two or more components "connected", "coupled" or "connected" to each other.

In the description of the temporal relationship or the flow relationship of the components, for example, a temporal predecessor relationship or a flow predecessor relationship such as “after”, “following”, “after”, “before”, etc. When described, it may also include non-continuous cases unless "directly" or "directly" is used.

On the other hand, when a numerical value for a component or its corresponding information (e.g., level, etc.) is mentioned, the numerical value or its corresponding information is related to various factors (e.g., process factors, internal or external impact, It can be interpreted as including an error range that may be caused by noise, etc.

1 is a diagram illustrating an example of a structure in which an ultrasonic sensor 200 is disposed in a display device according to example embodiments.

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 is disposed on the 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, fingerprint) or gestures in contact with or close to the display panel 110 may be disposed.

Alternatively, in some cases, such an ultrasonic sensor 200 may be disposed inside the display device.

When the ultrasonic sensor 200 is disposed on one surface of the display device, for example, the cover glass 120 may be disposed on the surface on which an image is displayed on the display panel 110. In addition, 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. That is, the ultrasonic sensor 200 may be disposed on a surface opposite to the surface on which the cover glass 120 is disposed on the display panel 110.

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

The ultrasonic sensor 200 may generate ultrasonic waves and sense ultrasonic waves reflected from a fingerprint contacting the cover glass 120 disposed on the display panel 110 to recognize a fingerprint contacted with the cover glass 120. . The ultrasonic sensor 200 is disposed on the opposite surface of the surface on which the image is displayed on the display panel 110 to perform sensing, thereby enabling fingerprint recognition without reducing an image display area.

Specifically, when the ultrasonic wave generated by the ultrasonic sensor 200 reaches the valley of the fingerprint, it touches 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 the acoustic impedance value of the cover glass 120 and the air.

In addition, when the ultrasonic wave generated by the ultrasonic sensor 200 reaches the ridge of the fingerprint, it touches the skin of the person in contact with the cover glass 120. Here, some of the ultrasound waves may be reflected, but most of the ultrasound waves are transmitted into the skin and reflected from the inside of the skin.

Accordingly, based on the intensity and timing of ultrasonic waves reflected by reaching the valley and the ridge of the fingerprint, the valley and the ridge of the fingerprint can be distinguished and the fingerprint can be sensed.

As described above, since the ultrasonic sensor 200 senses the inside of the skin, it is not sensitive to contamination or conditions of the skin surface, and provides an advantage of excellent security. In addition, a fingerprint can be sensed on the display panel 110 without reducing an area in which an image is displayed, so that the display device can perform input processing using the sensed fingerprint.

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 PXL disposed on each pixel, and the piezoelectric material 240 and the common electrode COM are sequentially disposed on the thin film transistor array 220. I 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 for supplying signals, voltages, etc. to the thin film transistor array 220 and the common electrode COM, etc., is provided with a second device disposed on the substrate 210 through the flexible printed circuit 290 and the bonding It may be electrically connected to the pad part 232.

In the thin film transistor array 220, a transistor for driving generating ultrasonic waves and sensing ultrasonic waves reflected by a fingerprint, a pixel electrode PXL, and the like 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.

Further, 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 circuitly viewed as a pixel array.

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 and returned to the thin film transistor array 220.

The cover layer 270 may be formed of, for example, polyimide, 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, a signal or the like that does not require a high voltage may be supplied from a driving circuit arranged to drive the display panel 110.

2 is a diagram illustrating an example of a circuit structure and driving method of a pixel array of an 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 disposed to cross each other, and a plurality of pixels may be disposed in an area defined by the intersection of the scan line SCL and the sensing line SSL.

Further, in the pixel array, a voltage line for supplying a driving voltage DV, a sensing voltage SV, etc. for generating and sensing ultrasonic waves of the pixel may be disposed.

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

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

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

Here, a case in which the first transistor T1, the second transistor T2, and the third transistor T3 are all N-type is shown as an example, but in some cases, all of the P-type may be implemented. Alternatively, only the first transistor T1 and the second transistor T2 may be implemented in the same type, and the third transistor T3 may be implemented in 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 generating ultrasonic waves to the pixel. The first driving voltage DV1 may be an AC voltage in the form of a pulse having a high voltage level. For example, the first driving voltage DV1 may be an AC 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.

In this case, the second transistor T2 may be driven by the same scan line SCL as the scan line SCL for driving the first transistor T1 disposed in an adjacent pixel.

That is, as illustrated in FIG. 2, the first transistor T1 disposed in the pixel in column A and the second transistor T2 disposed in the pixel in column B are connected to the same n-th scan line SCL(n). As a result, it may be simultaneously driven by the n-th scan signal SCO(n) applied to the n-th 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.

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 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 in the above-described thin film transistor array 220 and for forming a capacitance. In addition, an electrode of the capacitor C connected to the second driving voltage line DVL2 may be a common electrode COM.

The 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 generating ultrasonic waves to the pixel, and the second driving voltage DV2 is a constant voltage lower than the maximum voltage of the first driving voltage DV1. I can.

The scan signals SCO are sequentially applied to the scan lines SCL arranged in the pixel array, and ultrasonic waves may be generated and sensed.

For example, when an n-th scan signal SCO(n) of a level that turns on the first transistor T1 through the n-th scan line SCL(n) is applied, a first transistor disposed in a pixel in column A (T1) is turned 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 both electrodes of the capacitor C may vibrate and generate ultrasonic waves.

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

At this time, since the n-th scan signal SCO(n) of the level for turning on the first transistor T1 is applied to the n-th scan line SCL(n), the second transistor disposed in the pixel in column B ( T2) is also turned on.

In addition, when the first transistor T1 disposed in the pixel in column B is turned off and the ultrasound reflected by the fingerprint reaches column B, the voltage level of the sensing node Ns of the pixel disposed in column B may be changed. .

That is, the polarization state of the piezoelectric material 240 disposed between the pixel electrode PXL and the common electrode COM disposed in the pixel of column B is changed by the reflected ultrasonic wave, and thus, the pixel electrode PXL, that is, , The voltage level of the sensing node Ns may vary.

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

That is, ultrasonic waves reflected from the fingerprint and returned from the pixels in column B in which the second transistor T2 is turned on can be sensed.

As described above, by driving the first transistor T1 and the second transistor T2 disposed in the adjacent pixel column by the same scan line SCL, ultrasonic generation and sensing may be performed in the adjacent pixel column.

Further, embodiments of the present invention provide a structure in which the piezoelectric material 240 disposed on the thin film transistor array 220 can be smoothly deformed, thereby improving the sensing performance of the ultrasonic sensor 200 Provides.

3 is a diagram illustrating an example of a planar structure of a thin film transistor array 220 of an ultrasonic sensor 200 according to embodiments of the present invention. 4A and 4B are views showing examples of a cross-sectional structure of a portion AA′ shown in FIG. 3, including a piezoelectric material 240 and a common electrode COM disposed on the thin film transistor array 220. It is a figure shown.

3 and 4A, a plurality of scan lines SCL may be disposed in one direction in the thin film transistor array 220 of the ultrasonic sensor 200. In addition, a first driving voltage line DVL1, a sensing line SSL, a sensing voltage line SVL, and the like may be disposed along a direction crossing the scan line SCL.

Here, a region between the first driving voltage line DVL1 and the sensing voltage line SVL among the regions between adjacent scan lines SCL may 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 a 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. Also, 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 the first driving voltage ( DV1) can be applied and ultrasonic waves can be generated.

Further, 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 is changed by reflected ultrasonic waves, the third transistor T3 is turned on and off. And sensing can be done.

In this case, the planarization layer 226 disposed under the pixel electrode PXL may include one or more holes, and the pixel electrode PXL may be disposed to be spaced apart from the bottom surface of the hole in the region where the hole is disposed.

In addition, the pixel electrode PXL may be electrically connected to the first transistor T1, the third transistor T3, and the like by a connection electrode CE disposed in at least a partial region on the planarization layer 226. That is, the connection electrode CE is electrically connected to the first source electrode SE1 of the first transistor T1, is electrically connected to the gate electrode of the third transistor T3, and the pixel electrode PXL is connected. The first transistor T1 and the third transistor T3 may be electrically connected through the electrode CE.

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

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 an example, and only one insulating layer or two or more insulating layers may be disposed on the first gate electrode GE1.

The first passivation layer 225 may be disposed on the first source electrode SE1 and the first drain electrode DE1, and the planarization layer 226 may be disposed on the first passivation layer 225.

Here, the planarization layer 226 may include one or more holes, and at least one of the one or more holes is on the first transistor T1 and the planarization layer 226 located under the planarization layer 226. It may be a contact hole CH for electrically connecting the pixel electrodes PXL positioned in the. In the present specification, such a contact hole CH is also referred to as a "first hole H1".

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

The connection electrode CE may be separated and disposed in pixel units. In addition, the connection electrode CE may be entirely disposed in a region other than a region in which a hole is disposed on the planarization layer 226. In addition, 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 portion of the inside of the contact hole CH and is disposed on the upper surface of the planarization layer 226, and thus is disposed under the planarization layer 226 through the connection electrode CE. The first transistor T1 and the pixel electrode PXL may be electrically connected. In addition, 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 a partial area of the planarization layer 226 except for the area in which the hole is disposed, as illustrated in FIG. 4A, the hole is disposed on the planarization layer 226. The contact area with the pixel electrode PXL may be increased by being entirely disposed in the area excluding the formed 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 formed of the contact hole CH in the region where the contact hole CH is disposed. It may be disposed to be spaced apart from the first bottom surface H_Bot1. Here, the first bottom surface H_Bot1 may mean an upper surface of the connection electrode CE disposed inside the contact hole CH.

Since the pixel electrode PXL disposed under 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 the piezoelectric material 240 is formed, a space for smooth vibration of the piezoelectric material 240 may be secured. Accordingly, the ultrasonic generation performance due to vibration of the piezoelectric material 240 may be improved. That is, since the intensity of vibration of the piezoelectric material 240 may be increased by the secured space, the performance of generating ultrasonic waves may be improved. Alternatively, in some cases, even if the driving voltage is supplied slightly lower, the performance of generating ultrasonic waves can be maintained, and thus the efficiency of the ultrasonic sensor 200 may be increased.

In addition, even when the reflected ultrasonic wave is received, a space in which the piezoelectric material 240 can be smoothly deformed is secured, thereby improving sensing performance.

In addition, by increasing the first size S1, which is the size of the contact hole CH, the ultrasonic generation performance due to vibration of the piezoelectric material 240 and the sensing performance of reflected ultrasonic waves may be further improved. Here, the first size S1 may mean a diameter or an area of the contact hole CH.

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

By arranging the auxiliary electrode AE on the connection electrode CE disposed inside the contact hole CH, voltage fluctuations according to the change of the polarization state of the piezoelectric material 240 due to reflected ultrasonic waves are reduced to the contact hole CH ), so that it can be concentrated with the electrodes placed on it.

Further, 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 may be improved.

That is, the auxiliary electrode AE is disposed inside the contact hole CH, so that the electrode disposed inside the contact hole CH has a lower resistance than other parts of the connection electrode CE, so that sensing when receiving ultrasonic waves The voltage fluctuation of the node Ns may be increased. In this case, the first bottom surface H_Bot1 of the contact hole CH may mean a top surface of the second protective layer 227 disposed inside the contact hole CH. That is, in the present specification, the bottom surface of the hole may mean the top surface of the topmost configuration among the configurations arranged inside the hole.

As described above, 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 contact hole CH. It can be arranged in a structure spaced apart from the bottom 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.

Further, embodiments of the present invention may further improve sensing performance and perform gesture sensing by increasing the size of the lower space of the pixel electrode PXL.

5 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. And, FIG. 6 is a view showing an example of a cross-sectional structure of a portion B-B' shown in FIG. 5. Descriptions of the same parts as the above-described examples are omitted, and the omitted parts may be understood based on the description of the above-described examples. And, 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 is described as an example, but as in the example described above with reference to FIG. 200 may have a structure in which only the connection electrode CE is disposed inside the contact hole CH. In addition, in some cases, only the connection electrode CE and the auxiliary electrode AE may be disposed inside the contact hole CH, or only the connection electrode CE and the second protective layer 227 may be disposed.

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

The connection electrode CE may be disposed in at least a partial region of the inside of the contact hole CH and the top surface of the planarization layer 226 so that the first transistor T1 and the pixel electrode PXL are electrically connected to each other. have.

In addition, 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 the reflected ultrasonic wave is 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 positioned under the pixel electrode PXL, it is possible to improve ultrasonic generation performance and sensing performance of reflected ultrasonic waves.

In addition, by increasing the size of the contact hole CH, ultrasonic waves in a low frequency band may be generated according to the vibration of the piezoelectric material 240 so that a gesture performed without contacting the display device may 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 from each other in the region where the contact hole CH is disposed, and the size of the contact hole CH Sensing performance may be further improved or gesture sensing may be performed through adjustment.

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

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

Hereinafter, in a structure in which a hole is additionally disposed in addition to the contact hole CH, a case in which both the contact hole CH and the additionally disposed hole have a structure for improving sensing performance will be described as an example, but is not limited thereto. No.

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

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 are two holes in one pixel. The case where 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 electrically connecting the first transistor T1 and the pixel electrode PXL. In addition, the second hole H2 may be disposed in a region where the thin film transistor is not disposed, for example, may be disposed in a region between the sensing line SSL and the sensing voltage line SVL. Here, the region in which the thin film transistor is disposed may mean a region in which a gate electrode, a source/drain electrode, and an active layer constituting the thin film transistor are disposed. In addition, a region in which a metal is disposed for connection between thin film transistors or connection between the thin film transistor and the connection electrode CE may be included. That is, as illustrated in FIG. 7, a region indicated by 700 may be viewed as a region in which a thin film transistor is disposed, and a region in which the thin film transistor is not disposed may mean a region excluding a region indicated by 700. In addition, the region in which the thin film transistor is disposed may be implemented in various ways according to 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 portion of the inside of the first hole H1. . In addition, the auxiliary electrode AE and the second protective layer 227 may be disposed on the connection electrode CE.

In the region where the first hole H1 is disposed, the pixel electrode PXL is disposed in a structure spaced apart from the first bottom surface H_Bot1 of the first hole H1, and is a piezoelectric electrode disposed on the pixel electrode PXL. The material 240 may be smoothly deformed.

In addition, the pixel electrode PXL in the region where the second hole H2 is disposed may be disposed in a structure 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, so that the piezoelectric material 240 disposed on the pixel electrode PXL can be smoothly deformed, the area is increased. I can do it.

Here, since the second hole H2 is provided to secure a space under 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, since the connection electrode CE needs to be entirely disposed on the pixel, the connection electrode CE is also inside the second hole H2. ) May be placed. In addition, the arrangement structure of the connection electrode CE may provide convenience of a process.

Further, the auxiliary electrode AE or the like may not be disposed inside the second hole H2, but in some cases, the auxiliary electrode AE or the like 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 provides a function of the contact hole CH, and the pixel electrode 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 under the pixel electrode PXL can be increased. Accordingly, ultrasonic generation and sensing performance due to vibration of the piezoelectric material 240 disposed on the pixel electrode PXL may be improved.

Here, the first hole H1 and the second hole H2 may have the same size. 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 a first size S1, and the size H2 of the second hole H2 may be a second size S2. In addition, the second size S2 may be larger than the first size S1. That is, the size of a hole disposed in a region where the hole is easily disposed may be larger, such as a region in which the thin film transistor or the signal line is not disposed, but is not limited thereto.

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

In addition, by making the sizes of the first hole H1 and the second hole H2 different, ultrasonic waves in a high frequency band and a low frequency band may be generated, so that both fingerprint sensing and gesture sensing are possible.

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

Accordingly, high-frequency ultrasonic waves and low-frequency ultrasonic waves may be generated in one pixel. In addition, by performing sensing through frequency component analysis of reflected ultrasonic waves, fingerprint sensing and gesture sensing may be performed through the ultrasonic sensor 200.

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

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

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

In addition, as for the holes included in the planarization layer 226, in some cases, one hole may be disposed in a region corresponding to two or more pixels.

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

9 and 10, in the planarization layer 226 of the thin film transistor array 220, electrical connection between the first transistor T1 and the pixel electrode PXL and securing a space under the pixel electrode PXL are provided. A first hole H1 for may be disposed.

In addition, the second hole H2 may be disposed in a region other than the region in which 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 disposed 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 pixels adjacent along the direction in which the scan line SCL is disposed. As an example, the structure may be disposed on two adjacent pixels, and may be disposed between two adjacent sensing lines SSL. Accordingly, the sensing voltage line SVL may be disposed under the second hole H2, and the depth of the second hole H2 may be determined in consideration of the placement of the sensing voltage line SVL.

That is, in the embodiments of the present invention, ultrasonic generation and sensing may be performed along a column direction, which is a direction in which the scan line SCL is arranged. Therefore, since pixels arranged in the same column generate or sense ultrasonic waves in the same period, the second hole H2 is arranged in two pixels arranged in the same column, and ultrasonic generation and sensing performance may be improved.

In particular, as illustrated 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 two adjacent pixels. It can be placed in the area to be.

Further, since the second hole H2 is disposed in the two pixels, the size of the hole may 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 size of the hole for securing a space under the pixel electrode PXL, ultrasonic generation and sensing performance may be further improved. In addition, by increasing the difference in size between the first hole H1 and the second hole H2, it is possible to improve the performance of sensing using ultrasonic waves in a high frequency band and ultrasonic waves in a low frequency band, respectively.

In addition, although the structure in which the second hole H2 is arranged in two adjacent pixels in the column direction is described as an example, the embodiments of the present invention provide a second hole for 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 including a hole capable of securing a space under the pixel electrode PXL, by bonding a structure in which electrodes are disposed on both sides of the piezoelectric material 240 on the thin film transistor array 220 Can be implemented.

11 is a diagram illustrating 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 or the like is disposed on a 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 the first hole H1 in the planarization layer 226, and the connection electrode CE is disposed on the top surface of the planarization layer 226 and inside the first hole H1. . In addition, the auxiliary electrode AE and the second protective layer 227 are disposed on the connection electrode CE inside the first hole H1 to complete the thin film transistor array 220 excluding the pixel electrode PXL. I 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.

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

That is, the pixel electrode PXL is not directly disposed on the planarization layer 226 like the connection electrode CE, but is attached to the lower surface of the piezoelectric material 240 and bonded on the connection electrode CE. The pixel electrode PXL and the first bottom surface H_Bot1 of the first hole H1 are spaced apart from each other in the region where the one hole H1 is disposed.

12 is a diagram illustrating 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.

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

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

In addition, since the ultrasonic sensor 200 generates ultrasonic waves in a low frequency band, it is possible to sense a gesture performed at a position close to the cover glass 120 without contacting the cover glass 120.

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

Therefore, it is possible to improve the ultrasonic generation and sensing performance by smooth deformation of the piezoelectric material 240.

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

The above description is merely illustrative of the technical idea of the present invention, and those of ordinary skill in the art to which the present invention pertains will be able to make various modifications and variations without departing from the essential characteristics of the present invention. In addition, since the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention, but are intended to describe the technical idea, 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 by the claims below, and all technical ideas within the scope equivalent thereto should be construed 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 part 400: controller

Claims (17)

Including a plurality of scan lines, a plurality of sensing lines and a plurality of pixels,
Each of the plurality of pixels,
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 partial region on the planarization layer and electrically connected to at least one of the plurality of thin film transistors;
A pixel electrode disposed on the connection electrode;
A piezoelectric material disposed on the pixel electrode; And
Including a common electrode disposed on the piezoelectric material,
The planarization layer includes one or more holes, and the pixel electrode is disposed to be spaced apart from a bottom surface of the hole in a region in which at least one of the one or more holes is disposed.
The method of claim 1,
An ultrasonic sensor in which the connection electrode is electrically connected to the thin film transistor in at least one of the one or more holes included in the planarization layer.
The method of claim 1,
At least one of the one or more holes included in the planarization layer is located in a region corresponding to a region excluding a region in which the plurality of thin film transistors are disposed.
The method of claim 1,
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.
The method of claim 1,
The at least one hole included in the planarization layer is a plurality, and each of the plurality of holes has a constant size.
The method of claim 1,
An ultrasonic sensor having a plurality of the one or more holes included in the planarization layer, and at least two of the plurality of holes have different sizes.
The method of claim 1,
The at least one hole included in the planarization layer is a plurality, the connection electrode is electrically connected to the thin film transistor in a first hole among the plurality of holes, and a second hole is except for a region in which the plurality of thin film transistors are disposed. An ultrasonic sensor located in an area corresponding to the area.
The method of claim 7,
The size of the second hole is larger than the size of the first hole ultrasonic sensor.
The method of claim 1,
The connection electrode,
An ultrasonic sensor that is entirely disposed on the planarization layer except for an area in which 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 contacts the pixel electrode.
The method of claim 1,
The connection electrode,
Electrically connected to a source electrode or a drain electrode of any one of the plurality of thin film transistors,
An ultrasonic sensor electrically connected to a 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,
Including a plurality of scan lines, a plurality of sensing lines and a plurality of pixels,
Each of the plurality of pixels,
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 partial region on the planarization layer and electrically connected to at least one of the plurality of thin film transistors;
A pixel electrode disposed on the connection electrode;
A piezoelectric material disposed on the pixel electrode; And
Including a common electrode disposed on the piezoelectric material,
The planarization layer includes one or more holes, and the pixel electrode is disposed to be spaced apart from a bottom surface of the hole in a region in which at least one of the one or more holes is disposed.
The method of claim 11,
A display device in which the connection electrode is electrically connected to the thin film transistor in at least one of the one or more holes included in the planarization layer.
The method of claim 11,
At least one of the one or more holes included in the planarization layer is located in a region corresponding to a region other than a region in which the plurality of thin film transistors are disposed.
The method of claim 11,
At least one of the one or more holes included in the planarization layer is disposed in a plurality of pixels adjacent to each other along a direction in which the scan line is disposed.
The method of claim 11,
The at least one hole included in the planarization layer is a plurality, the connection electrode is electrically connected to the thin film transistor in a first hole among the plurality of holes, and a second hole is except for a region in which the plurality of thin film transistors are disposed. A display device positioned in an area corresponding to the area.
The method of claim 15,
A display device having different sizes of the first hole and the second hole.
The method of claim 11,
Further comprising a cover glass disposed on the display panel,
The ultrasonic sensor,
A display device disposed on a surface of the display panel opposite to a surface on which the cover glass is disposed.

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