KR20230072148A - Intraoral X-ray sensor and manufacturing method thereof - Google Patents

Abstract

An intraoral X-ray sensor for detecting an X-ray image in the oral cavity includes a sensor substrate having a sensing region in which a plurality of light-sensing pixels are formed. Each light-sensing pixel includes a photodiode and a thin film transistor electrically connected to the photodiode, and the thin film transistor is formed on the photodiode.

Description

Intraoral X-ray sensor and manufacturing method thereof

The present invention relates to an X-ray sensor for X-ray imaging, and more particularly, to an intraoral X-ray sensor capable of X-ray imaging by being inserted into the oral cavity.

An X-ray sensor is a device that generates an electrical signal for detecting an image of a subject using X-rays. The X-ray sensor is used in various image detection devices such as medical diagnostic equipment, and is also used as an intraoral X-ray sensor inserted into the oral cavity to obtain an X-ray image of teeth or tissues surrounding teeth in the oral cavity.

Intraoral X-ray imaging methods can be divided into methods using analog film, digital methods using CR, and methods using digital intraoral X-ray sensors. It is inconvenient that it takes a lot of time for the post-development process and it is difficult to store the film, and in the case of the CR method, there are cumbersome lights such as having to fetch data and erase stored data. It is being used. A digital type intraoral X-ray sensor includes a plurality of light-sensing pixels each configured to sense transmitted X-rays and generate an electrical signal according to an amount of X-ray transmission. A plurality of light-sensing pixels are arranged in a matrix form forming a plurality of rows and columns, and each light-sensing pixel includes a photodiode that outputs an electrical signal by X-rays and a switching element that transmits the electrical signal output from the photodiode. do. A CMOS transistor is mainly used as a switching element of an intraoral X-ray sensor, and a thin film transistor (TFT) may also be used.

An intraoral X-ray sensor using a thin film transistor (TFT) as a switching element is manufactured by first forming a thin film transistor switching element on a substrate and then forming a photodiode. At this time, since the photodiode and the thin film transistor are formed in areas divided on the same plane, that is, since the photodiode is formed on an area excluding the area of the thin film transistor switching element, the area of the thin film transistor switching element causes the individual photodiodes to area is reduced. For example, the thin film transistor switching element is formed to have a square-shaped area, and the photodiode is formed in an area excluding the area of the thin film transistor switching element and an area of a certain separation distance from the square, thereby forming a thin film transistor switching element. As a result, the area of the photodiode is reduced. The fill factor of the TFT intraoral X-ray sensor is determined according to the size of the photodiode, and the fill factor is one of the important criteria for determining the performance of the X-ray sensor. In particular, as the pixel size is smaller, the size of the fill factor becomes a more important factor in determining product characteristics. As described above, the existing intraoral X-ray sensor has a problem in that the area of the photodiode is reduced because the thin film transistor switching element and the photodiode are formed on the same plane, thereby lowering the filling factor.

Publication No. 10-2009-0028884 (published date: 2009.03.20) Publication No. 10-2009-0102185 (published date: 2009.09.30) Publication No. 10-2017-0018881 (published date: 2017.02.20)

An object to be solved by the present invention is to provide an intraoral X-ray sensor having improved performance by increasing the photodiode area ratio.

An intraoral X-ray sensor for detecting an X-ray image in an oral cavity according to an embodiment of the present invention includes a sensor substrate having a sensing region in which a plurality of light-sensing pixels are formed. Each light-sensing pixel includes a photodiode and a thin film transistor electrically connected to the photodiode, and the thin film transistor is formed on the photodiode.

The sensor substrate may be formed to be bendable. The sensor substrate may include a connection area formed with a pair of connection pads to which a lead-out circuit and an interface board are respectively connected and spaced apart from the sensing area, and a middle area connecting the connection area and the sensing area. The intermediate region may be bent so that the readout circuit and the interface board are positioned behind the sensing region.

The intraoral X-ray sensor according to another embodiment of the present invention may further include a scintillator layer that receives X-rays and outputs visible light, and the scintillator layer includes the photodiode and the thin film among both sides of the sensor substrate. It may be disposed on a side opposite to the side on which the transistor is formed.

The intraoral X-ray sensor according to another embodiment of the present invention may further include a protective layer formed on the sensor substrate to cover the photodiode and the thin film transistor.

The intraoral X-ray sensor according to another embodiment of the present invention may further include an X-ray blocking layer formed on the passivation layer to be positioned in front of the read-out circuit.

A manufacturing method for manufacturing an intraoral X-ray sensor for detecting an X-ray image in the oral cavity according to an embodiment of the present invention includes a sensing region in which a plurality of light-sensing pixels are formed, a connection region separated from the sensing region, and preparing a sensor substrate having an intermediate region connecting the sensing region and the connection region; forming a readout circuit on the connection region to receive an output signal of the light-sensing pixel; forming an interface board for input/output of an output signal of the lead-out circuit and a driving signal for driving the light-sensing pixel on the connection area, and bending the middle area to connect the lead-out to the connection area. and positioning the circuit and the interface board behind the sensing area.

The thin film transistor may be formed on the photodiode.

The manufacturing method according to another embodiment of the present invention may further include forming a protective film on the sensor substrate to cover the photodiode and the thin film transistor.

The manufacturing method according to another embodiment of the present invention may further include forming an X-ray blocking layer positioned in front of the readout circuit on the passivation layer.

According to the present invention, since the thin film transistor of the light-sensing pixel is formed on the photodiode, the ratio of the area of the photodiode to the total area of the pixel can be increased, so that light-sensing performance can be improved.

1 is a schematic plan view of a sensor substrate on which light sensing pixels and interfaces of an intraoral X-ray sensor according to an embodiment of the present invention are formed.
2 is a diagram showing an electrical circuit diagram of a photo-sensing pixel of an intraoral X-ray sensor according to an embodiment of the present invention.
3 is a cross-sectional view of an intraoral X-ray sensor according to an embodiment of the present invention.
4 is a cross-sectional view showing a scintillator of an intraoral X-ray sensor according to an embodiment of the present invention, a substrate, and a photodiode and a switching element sequentially formed on the substrate.
5 is a plan view of a photodiode of an intraoral X-ray sensor according to an embodiment of the present invention and a switching element formed thereon.
6 schematically illustrates a manufacturing process of an intraoral X-ray sensor according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

An intraoral X-ray sensor according to an embodiment of the present invention is inserted into the oral cavity and is configured to generate an electrical signal for acquiring an X-ray image of teeth or surrounding tissues. An intraoral X-ray sensor according to an embodiment of the present invention is configured to detect X-rays generated by an X-ray generator and passing through teeth or surrounding tissues and generate electrical signals accordingly. The intraoral X-ray sensor of the present invention is configured to receive an electrical signal for operation from the outside and outputs an output electrical signal generated by X-ray detection. The output electrical signal may be transmitted to an image display device and used to display a corresponding X-ray image.

1 is a schematic plan view of a sensor substrate 10 on which a plurality of light-sensing pixels arranged in a matrix form and an interface circuit of the intraoral X-ray sensor of the present invention are formed. city is omitted. The sensor substrate 10 may have a shape that can be inserted into an oral cavity and may be accommodated in an external housing. Although a sensor substrate is illustrated in FIG. 1 as an example, the shape of the sensor substrate is not limited thereto and may be variously changed.

The sensor substrate 10 may include a plurality of light sensing pixels 11 that detect X-rays and output electrical signals according to the detected X-rays. The photo-sensing pixels 11 may be arranged in a matrix form to form a plurality of rows and columns. FIG. 1 illustratively illustrates a case in which 30 light-sensing pixels 11 are arranged to form 6 rows and 5 columns, but the number of light-sensing pixels and the number of rows and columns are not limited thereto. The sensor substrate 10 may be configured by forming a plurality of photo-sensing pixels 11 on a substrate configured to be flexible in order to secure bendable characteristics of the intraoral X-ray sensor.

Each photo-sensing pixel 11 includes a thin film transistor 111 and a photodiode 112 . The thin film transistor 111 and the photodiode 112 may be electrically connected to each other as known in the related art X-ray sensor. The thin film transistor 111 may be a thin film transistor based on low temperature polycrystalline silicon (LTPS) material. As shown in FIGS. 1 and 2 , each thin film transistor 111 may include a gate electrode G, a source electrode S, and a drain electrode D, and the cathode of the photodiode 112 ) may be electrically connected to the drain electrode D.

In the intraoral X-ray sensor according to an embodiment of the present invention, a photodetection electric signal induced by the photodiode is generated by X-rays in a state in which a bias voltage is applied to the photodiode 112 (FIG. 1 and FIG. 2 in the horizontal direction) can be configured to be read sequentially in units. To this end, a plurality of bias lines 12 for applying a bias voltage, a plurality of bias lines 12 for applying a gate signal for turning on the thin film transistor 111 in a row unit to a plurality of photo-sensing pixel arrays A gate line 13 and a plurality of data lines 14 for outputting light detection electrical signals of each pixel may be provided.

For example, the bias line 12 is provided for each column (in the vertical direction in FIGS. 1 and 2) and is connected to the anode of the photodiode 112 of the light sensing pixel 11 of each column to form a photodiode ( 112) is configured to apply a bias voltage. The bias line 12 may be electrically connected to the connection pad 105 to which the interface board 30 for electrical connection with an external circuit is fastened through the bias connection line 17 .

The gate line 13 is provided for each row and is connected to the gate electrode G of the thin film transistor 111 of the photo-sensing pixel 11 of each row to apply a gate signal (turn-on voltage). . In this case, the plurality of gate lines 13 may be connected to gate drivers 15 for turn-on operation for each row. The gate driver 15 may be electrically connected to the connection pad 105 to which the interface board 30 for electrical connection with the external circuit is fastened through the gate connection line 16, and transmits the received gate signal to each row. It works so that it can be applied sequentially.

The data line 14 may be provided for each column and is electrically connected to the source electrode S of the thin film transistor 111 of the photo-sensing pixel 11 of each column. The plurality of data lines 14 extend to the connection pad 104 to which the readout circuit 20 is connected. The output electrical signal of each photo-sensing pixel 11 is transmitted to the readout circuit 20 through the data line 14 . The read-out circuit 20 may include a plurality of amplifiers and multiplexers for amplifying electric signals, and the output signal output from the read-out circuit 20 is passed through an interface board 30 to an external connection line. Through this, it can be transmitted to the main controller of the X-ray imaging device and used to create an X-ray image.

In a state in which the sensor substrate 10 of the intraoral X-ray sensor is irradiated with X-rays that have passed through the tooth or surrounding tissue, a bias voltage is applied to the photodiode 112 through the bias line 12 and the gate line 13 When the thin film transistors 111 are sequentially turned on row by row, the electrical signal output from the photodiode 112 is applied to the data line 14 through the turned on thin film transistor 111 . The output electrical signal is input to the readout circuit 20 connected to the data line 14, amplified, and then output through the interface board 30 through an external connection line. At this time, since the photo-sensing pixels 11 are sequentially turned on by the row unit by the gate signal, the output electrical signal may also be transmitted to the readout circuit 20 by the row unit. Accordingly, the X-ray imaging apparatus may display an X-ray image using the electrical signal output from the intraoral X-ray sensor.

The sensor substrate 10 includes a sensing area R1 in which a plurality of photo-sensing pixels 11 are arranged, a connection area R3 separated from the sensing area R1, and a sensing area R1 and connection area R3. A connecting intermediate region R2 may be included. The lead-out circuit 20 may be mounted on the connection pad 104 formed in the connection region R3, and the interface board 30 may also be mounted on the connection pad 105 formed in the connection region R3. . The connection pads 104 and 105 may include conductive patterns for transmitting electrical signals, and the lead-out circuit 20 and the interface board 30 are connected to the connection pads 104 and 105 through corresponding conductive patterns, respectively. can be electrically connected.

3 to 5, one side surface of the sensing region R1 of the sensor substrate 10 on which a plurality of photo-sensing pixels 11 each including a photodiode 112 and a thin film transistor 111 are formed, FIG. 3 is formed on the upper surface. Meanwhile, in the case of an indirect type X-ray sensor, a scintillator layer 50 may be provided, and the scintillator layer 50 may be disposed on the opposite side of the surface on which the light sensing pixels 11 are formed. That is, referring to FIG. 4 , the photodiode 112 and the thin film transistor 111 are disposed on one side of the sensor substrate 10, and the scintillator layer 50 is disposed on the other side of the sensor substrate 10. The X-rays emitted by the X-ray generator pass through the irradiation target and are incident on the scintillator layer 50, and the scintillator layer 50 is excited by the incident X-rays and emits visible light. That is, X-rays travel from the bottom to the top of the scintillator layer 50 in FIG. 3 and are incident into the scintillator layer 50 . A flash of light emitted from the scintillator layer 50 flows into the photodiode 112, and the photodiode 112 applies an electrical signal according to the incident flash to the thin film transistor 111 as described above. In FIG. 3, the light sensing pixel 11 is omitted for convenience of illustration, and the thicknesses of the scintillator layer 50, sensor substrate 10, photodiode 112, and thin film transistor 111 in FIG. randomly appearing for The sensor substrate 10 may be formed of a flexible polyamide (PI) material, and more specifically, may be formed of a transparent fluorine-based polyamide material. At this time, the sensor substrate 10 made of polyamide may be formed to have a small thickness, for example, 30 to 40 μm in order to reduce the problem of light spreading.

According to an embodiment of the present invention, referring to FIGS. 4 and 5 , the photodiode 112 and the thin film transistor 111 are not formed to occupy a certain portion of the pixel area on the surface of the sensor substrate 10, respectively. , the photodiode 112 is first formed on the surface of the sensor substrate 10, and the thin film transistor 111 is formed on the photodiode 112. Accordingly, it is possible to maximize the ratio of the area of the photodiode 112 to the area of the pixel in the determined pixel size, thereby maximizing the filling factor of the photodiode 112 and efficiently using the characteristics of the photodiode 112. there is.

On the other hand, according to the embodiment of the present invention, the protective film 40 fixed to one side of the sensor substrate 10, that is, the surface on which the photodiode 112 and the thin film transistor 111 are formed may be provided. The protective film 40 may be formed to cover the sensing region R1 of the sensor substrate 10, and the protective film 40 may be bent, for example, to implement the bendable characteristics of the intraoral X-ray sensor. It can be formed of a synthetic resin material that can be worn.

In addition, as described above, the middle region R2 of the sensor substrate 10 is bent and the lead-out circuit 20 and the interface board 30 connected to the connection pads 104 and 105, respectively, are opposite to the scintillator layer 50. It is configured to be located in A connector connected to the main body of the X-ray imaging apparatus is connected to the interface board 30 so that signals input/output with the sensor substrate 10 can be performed.

1 shows a state before the sensor substrate 10 is bent in a state where the lead-out circuit 20 and the interface board 30 are not installed, and FIG. 3 shows the connection area in the completed intraoral X-ray sensor ( R3) is shown in a state where the sensor substrate 10 is bent so that it is located behind the protective film 40. As shown in FIG. 3 , since the sensor substrate 10 is installed in a bent state, the lead-out circuit 20 and the interface board 30 connected to the connection region R3 of the sensor substrate 10 also have a protective film 40 ) is located behind the Accordingly, the readout circuit 20 and the interface board 30 may be disposed in the region of the photo-sensing pixel 11 and behind the protective film 40 due to the curved structure of the sensor substrate 10, unlike the conventional COF. Electrical connection can be implemented without a separate connection member such as.

Meanwhile, according to an embodiment of the present invention, the protective film 40 may include an X-ray blocking layer 41 covering the read-out circuit 20 . For example, the X-ray blocking layer 41 may be formed of a coated copper film. Since the read-out circuit 20 is covered by the X-ray blocking layer 41, the read-out circuit 20 can be prevented from being damaged by X-rays.

Hereinafter, a method of manufacturing an intraoral X-ray sensor according to an embodiment of the present invention will be described with reference to FIG. 6 . 6 sequentially shows each process for manufacturing an intraoral X-ray sensor according to an embodiment of the present invention. The order of each process of the manufacturing method is not limited to that shown in FIG. 6 and may be changed according to needs and process efficiency.

Referring to (a) of FIG. 6 , a photodiode 112 and a thin film transistor 111 are formed on the sensor substrate 10 . The photodiode 112 and the thin film transistor 111 are indicated by dotted lines in FIG. 6 (a), and are omitted from drawings of subsequent steps. As described above, the photodiode 112 is first formed in a portion corresponding to each light-sensing pixel of the sensing region R1 of the sensor substrate 10, and the thin film transistor 111 is formed on the photodiode 112. Also, although not shown in the drawings, connection pads 104 and 105 may be formed in the connection region R3 of the sensor substrate 10 .

As shown in (b) of FIG. 6 , a protective film 40 may be formed on the sensor substrate 10 . In this case, the passivation layer 40 may be formed to entirely cover the sensing region R1 and to cover the matrix of light sensing pixels. Although not shown, the protective film 40 may be formed to cover the photodiode 112 and the thin film transistor 111 formed in FIG. 6(a). The X-ray blocking layer 41 may be formed on a predetermined area on the protective film 40 after forming the protective film 40 .

Referring to (c) and (d) of FIG. 6 , the readout circuit 20 and the interface board 30 may be connected to the connection region R3 of the sensor substrate 10 .

Referring to (e) of FIG. 6 , the scintillator layer 50 may be formed on a surface opposite to the surface on which the photodiode 112 and the thin film transistor 111 are formed among both sides of the sensor substrate 10 .

Referring to FIG. 6(f), the middle region R2 of the sensor substrate 10 is bent to form a connection region R3 where the read-out circuit 20 and the interface board 30 are connected to the rear side of the protective film 40. move to Although not specified in the drawing, a separate process for fixing the positions of the readout circuit 20 and the interface board 30 may be performed or a process for installing a separate fixing means may be performed.

Although the embodiments of the present invention have been described above, the scope of the present invention is not limited thereto, and it is recognized that the embodiments of the present invention are easily changed by those skilled in the art to which the present invention belongs and are equivalent. including all changes and modifications within the scope of

10: sensor board
R1: sensing area
R3: connection area
R2: middle region
11: light detection pixel
111: thin film transistor
112: photodiode
12: bias line
13: gate line
14: data line
15: gate driver
16, 17: connection line
20: readout circuit
30: interface board
104, 105: connection pad
40: shield
41: X-ray blocking layer
50: scintillator layer

Claims (9)

As an intraoral X-ray sensor for detecting an X-ray image in the oral cavity,
A sensor substrate having a sensing region in which a plurality of light-sensing pixels are formed;
Each light-sensing pixel includes a photodiode and a thin film transistor electrically connected to the photodiode;
The thin film transistor is formed on the photodiode
Intraoral X-ray sensor. In paragraph 1,
The sensor substrate is formed to be bendable,
The sensor substrate includes a connection area in which a pair of connection pads to which a lead-out circuit and an interface board are respectively connected and spaced apart from the sensing area, and a middle area connecting the connection area and the sensing area,
The middle region is bent so that the readout circuit and the interface board are positioned behind the sensing region.
Intraoral X-ray sensor. In paragraph 2,
Further comprising a scintillator layer for receiving X-rays and outputting visible light;
The scintillator layer is disposed on a surface opposite to the surface on which the photodiode and the thin film transistor are formed among both sides of the sensor substrate
Intraoral X-ray sensor. In paragraph 3,
The intraoral X-ray sensor further comprises a protective film formed on the sensor substrate to cover the photodiode and the thin film transistor. In paragraph 4,
The intraoral X-ray sensor further comprises an X-ray blocking layer formed on the protective film to be positioned in front of the read-out circuit. As a manufacturing method for manufacturing an intraoral X-ray sensor for detecting an X-ray image in the oral cavity,
Preparing a sensor substrate having a sensing area in which a plurality of photo-sensing pixels are formed, a connection area separated from the sensing area, and an intermediate area connecting the sensing area and the connection area;
Forming a readout circuit formed to receive an output signal of the light-sensing pixel on the connection area;
Forming an interface board for inputting and outputting an output signal of the read-out circuit and a driving signal for driving the light-sensing pixel on the connection area on the connection area; and
bending the intermediate region so that the interface board and the lead-out circuit connected to the connection region are positioned behind the sensing region;
Intraoral X-ray sensor comprising a. In paragraph 6,
The thin film transistor is formed on the photodiode. In paragraph 6,
The manufacturing method further comprising forming a protective film covering the photodiode and the thin film transistor on the sensor substrate. In paragraph 6,
The manufacturing method further comprising the step of forming an X-ray blocking layer located in front of the read-out circuit on the protective film.

Images