KR101475043B1 - Detector for X-ray image detection - Google Patents

Abstract

The present invention relates to a detector for X-ray image detection. The detector comprises a detector body having a closed space filled with gas, an electrode formed on the detector body, and a pixel formed inside the detector body, And a photoconductive layer formed on the lower portion of the lead-out electrode, the barrier rib having at least one or more barrier ribs and a plurality of lead-out electrodes defined by the barrier ribs to form pixels.

According to the present invention, an electrode layer to which an electric field is applied to each pixel, a lead-out electrode for reading information, and a photoconductive layer are formed below the structure of the X-ray detector using conventional thin film transistors , The amount of the detection signal is maximized, the electrons formed inside the detector can be efficiently read, and the signal noise can be reduced to realize a highly sensitive image.

An X-ray, a lead-out electrode, a barrier rib, a dielectric, a photoconductor,

Description

Detector For Detecting X-Ray Image Within Photoconductor [0002]

In the present invention, an electrode layer to which an electric field is applied to a pixel and a lead-out electrode for reading information are formed on the pixel, and a photoconductive layer is formed thereunder, thereby maximizing a detection signal amount, Ray detector that can efficiently read and reduce signal noise, thereby realizing a high-sensitivity image.

Currently, X-ray inspection methods widely used for medical, engineering, etc. are taken by using an X-ray detection film and subjected to a predetermined film printing step in order to know the result. However, there is a problem in that it takes a long time for the usability because the photograph can be recognized after a certain time after a certain time. Especially, when the film itself is damaged due to difficulty in storing and preserving the film after photographing, It has been difficult to confirm such a problem.

In order to solve the above problems, a detector for X-ray image detection using a TFT (Thin Film Transistor) has been researched / developed. The detector using the TFT can realize the advantage of using the TFT as a switching element and diagnosing the result in real time immediately after photographing the X-ray. The X-ray signal detecting method that is currently being commercialized is an indirect method and a direct method Can be divided.

1 is a cross-sectional view schematically showing a detector for detecting an X-ray image, which is implemented by a conventional indirect method.

1, a conventional indirect method includes a photodiode 120 formed on a TFT 110 and a scintillator 120 for converting an X-ray signal into a visible light on the photodiode 120 Ray signal converted into visible light by the scintillator 130 is converted into an electric signal through the photodiode 120 and stored in the capacitor of the TFT 110. The TFT 110 is then turned on, A readout signal is applied to the gate electrode of the X-ray source to read the X-ray signal charged in the capacitor.

However, in the conventional indirect method, since the photodiode 120 must be formed on the TFT 110 and the scintillator 130 must be deposited thereon, the structure is complicated and the fabrication process is complicated, There was a problem.

In addition, when the X-ray signal is converted into a visible light by the scintillator, the efficiency is low and the original signal becomes small, and visible light is lost through the photodiode 120, There is a problem that the quality of the detected image is lowered because the signal becomes smaller.

2 is a cross-sectional view schematically showing a detector for X-ray image detection, which is implemented in a conventional direct method.

Referring to FIG. 2, a conventional direct method uses a TFT similar to the indirect method, and a photoconductor (a-Se, Csl, PbO, 140) sensitive to X-rays is formed on the TFT 110 Ray signal to an electrical signal, storing electrons generated by the X-ray in the capacitor of the TFT 110, applying a read signal to the gate to read the X-ray signal charged in the capacitor, to be.

However, the conventional direct method requires applying a high voltage of several thousand volts to the photoconductor 140 in order to activate the photoconductor 140 deposited and applied on the TFT 110 to the X-ray signal. Therefore, not only the power consumption is large but also the stability of the device is deteriorated due to the high voltage of several thousands of volts, and a lot of heat is generated, which makes it impossible to continuously use the device. In addition, since the photoconductor 140 must be uniformly deposited and coated on the TFT 110, there is a problem that it is impossible to manufacture a large flat plate.

As described above, the conventional detector using a TFT requires a single thin film transistor for each pixel in the panel in addition to the difficulty in manufacturing, which makes it difficult to increase the size, increase the cost, and lower the sensitivity.

In order to overcome these problems, there has been an effort to overcome by the structural changes. However, digital equipments have also suffered from low X-ray conversion efficiency, deterioration of image characteristics (resolution, luminance), image distortion, excessive patient dose, In recent years, there has been a great demand for the development of an innovative digital image device that can overcome these problems. Recently, as a substitute device, a PDP A method to utilize it was proposed. In PDP, a discharge voltage is applied to two substrates coated with a plurality of electrodes, such as Xe or Ne, and then a discharge voltage is applied. A phosphor formed in a predetermined pattern is excited by ultraviolet rays generated by the discharge voltage, , A video device that obtains text or graphics.

3 is a cross-sectional view schematically showing a detector for X-ray image detection using a conventional plasma display (PDP).

Referring to FIG. 3, a detector 200 using a plasma display (PDP) includes two substrates 210 disposed adjacent to and opposite to each other with a discharge gap, a dielectric layer 220 formed on an opposite surface side of the substrate, A barrier rib 240 formed between the dielectric layer and the dielectric layer to form a closed cell structure on the inner surface of the substrate and a barrier rib 240 formed on one side of the inner surface of the barrier rib and the substrate, And a gas layer 260 filled in the closed cell formed by the barrier ribs and the substrate and excited by the radiation to generate electrons.

In this configuration, in the digital X-ray image detector using the PDP structure, when the X-ray transmitted through the human body reaches the gas layer 260, the gas layer 260 is irradiated with X- And the PDP structure is used as a radiation detector substrate by utilizing the electron emission effect of the radiation by the gas layer 260. In addition, the X-ray which has not interacted with the gas layer 260 interacts with the fluorescent layer 250 located below the gas layer 260, and as a result, visible light is generated. (Not shown) is emitted to be used as a radiation detector substrate. The emitted electrons are accelerated by an electrode located on the substrate to ionize the gas in the gas layer 260 or directly reach the electrode.

As the gas is ionized, electrons and holes are generated. The electrons are also accelerated by the electric field to ionize the other gas or to be attracted to the collecting electrode. The electrons thus collected are converted into image data, which are output to the lead-out device, and output as an image, thereby generating a radiation image.

However, the PDP-based detector has a low sensitivity due to a high x-ray absorption rate on the upper substrate, and it is difficult to form a barrier which is an essential element in the internal structure. Particularly, it is necessary to provide a space for the gas layer by using the barrier ribs. In this case, the barrier ribs are often collapsed, resulting in a low production yield and difficulty in finely forming the barrier ribs. Particularly, there is a problem in quality due to complicated design and low sensitivity, and it is extremely difficult to uniformly apply the fluorescent layer, resulting in a problem that the sensitivity of the X-ray is remarkably decreased and that it is difficult to secure a wider gas filling space.

In addition, the boundaries between upper, lower, left, and right pixels are unclear and interferences are generated between the respective pixels, so that there is a limit to implement a high quality image.

In particular, it is difficult to inject a gas at a pressure higher than 1 atm due to the formation of a substrate, and thus the amount of gas reacting with the X-ray is relatively small. A structure capable of maximizing the amount of the supplied gas is required.

SUMMARY OF THE INVENTION The present invention has been conceived in order to solve the above-mentioned problems, and it is an object of the present invention to provide a liquid crystal display device in which an electrode layer to which an electric field is applied to a pixel and a leadout electrode for reading information are formed, Ray detector capable of maximizing the amount of detected signals, efficiently collecting electrons formed inside the detector, and simultaneously reducing signal noise, thereby realizing a high-resolution image.

According to an aspect of the present invention, there is provided a structure for solving the above problems, comprising: a detector body having a closed space filled with gas therein; At least one barrier rib formed inside the detector body to implement a pixel; A plurality of lead-out electrodes partitioned by the barrier ribs to form pixels; A photoconductor layer formed under the lead-out electrode; And a detector for detecting the X-ray image. It is possible to realize an increase in the amount of detected signals by adding electrons generated by colliding with the photoconductor in addition to the electrons generated by the incident X-rays colliding with the gas, thereby providing a large-area digital radiographic image of high resolution and high illuminance .

In order to realize such a structure, the photoconductive layer described above may be formed of any one selected from MgO, HgI ₂ , CdS, CdTe, and a-Se.

In addition, in the above-described structure, the detector body includes an upper substrate and a lower substrate, and the electrode may be formed in a two-electrode structure formed on the upper substrate.

In addition to the above two-electrode structure, the detector body includes an upper substrate and a lower substrate, and the electrode may have a three-electrode structure including a first electrode formed on the upper substrate and a second electrode formed on the lower substrate It is possible.

In particular, in the case of a detector having a three-electrode structure, it is preferable that a dielectric layer is further formed on the second electrode.

In addition, in the present invention, the barrier ribs for implementing pixels may be formed to have a height higher than that of the lead-out electrodes and at least a part of the barrier ribs may not come into contact with the upper substrate. The material may be any one selected from ceramic, plastic, And the like.

In the present invention, it is preferable to further include a circuit unit for reading a signal amount due to electrons and holes formed by the voltage applied to the electrode from the lead-out electrode.

In addition, the electrode or the lead-out electrode may be a sliver electrode.

The gas to be filled may be pure Penning gas obtained by mixing any one selected from Xe, Kr, Ar, Ne, and He, or a mixture of two or more gases selected therefrom.

According to the present invention, an electrode layer to which an electric field is applied to each pixel, a lead-out electrode for reading information, and a photoconductive layer are formed below the structure of the X-ray detector using conventional thin film transistors , The amount of the detected signal is maximized, electrons formed in the detector can be efficiently read, and signal noise can be reduced to realize a high-resolution image.

Particularly, in the structure according to the present invention, a gas filling space formed as a closed space is ensured and at the same time, each pixel or lead-out electrode is divided through barrier ribs to prevent crosstalk phenomenon which affects electrons neighboring pixels .

In the case of a three-phase structure in which electrodes are formed on the upper and lower substrates, the speed of detec- tion is improved by applying an electric field through the lower electrode, a dielectric layer is formed between the electrodes, In addition, a function of protecting the lead-out electrode can be realized.

Compared with detectors for X-ray image detection using commercially available TFTs, TFTs, photodiodes, scintillators, and photoconductors are not used, resulting in an excellent effect of simplifying the fabrication process and making large-sized flat plates.

In addition, it is possible to easily manufacture fine pixels with a plurality of electrode lines and remarkably shorten the convenience of information detection, thereby achieving an excellent effect of detecting x-ray detection capable of efficiently collecting image information even on a large area substrate do.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

4 is a conceptual diagram showing a configuration of a detector for detecting an X-ray image (hereinafter referred to as a detector) according to the present invention.

The detector according to the present invention includes a detector body 310 and 320, a gas layer 360 filled with gas therein, an electrode 330a formed on the detector body, and a plurality of pixels 330 formed inside the detector body Of the barrier ribs 350. In addition, a plurality of lead-out electrodes 330b are formed in the pixel space defined by the barrier ribs, and a photoconductive layer 340 is formed under the lead-out electrodes.

The structure of the detector body is basically such that the upper substrate 310 and the lower substrate 320 are spaced apart from each other by a predetermined distance and the electrode 330a is formed on the lower surface of the upper substrate. It is preferable that the upper electrode uses a sliver electrode, and it is basically formed as a whole surface electrode. In the present invention, the upper electrode is basically formed on the lower surface of the upper substrate. Alternatively, the upper electrode may be formed inside or outside the substrate with a separate structure.

In particular, the upper substrate 310 and the lower substrate 320 can be used as various materials for forming a PDP structure. For example, a soda glass, a PD 200, or the like can be used. Of course, it is preferable that the upper substrate is made as thin as possible (soda glass 2T, 3T) by using a material having a high X-ray transmittance. Further, the lower substrate generally uses the same material as that of the upper substrate, and preferably the degree of thermal expansion matches the upper substrate.

In addition, the barrier ribs 350 may be formed on the lower substrate, and may be formed as a structure vertically extending between the lead-out electrodes 330b. The barrier ribs partition the lead-out electrodes and form pixels, which are basic units of a video image. The barrier ribs 350 partitioning the respective lead-out electrodes to form one pixel are formed vertically on the lower substrate, but are preferably formed so as not to touch the upper substrate. The barrier ribs 350 may be formed of materials such as ceramics, plastics, and polymers, and use materials that are stable to X-rays.

The height of the barrier rib 350 should be higher than that of the lead-out electrode in order to divide each pixel. However, when the height of the barrier rib contacts the upper substrate, each pixel is completely cut off to block the flow of gas, It may cause image problems. Therefore, the height of the barrier rib is preferably set to be higher than that of the lead-out electrode but not to be in contact with the upper substrate. The barrier ribs may be formed by etching, screen printing, vapor deposition, or the like. In order to seal the space separated to the upper and lower substrates, it is preferable to include a support portion (a portion sealing the edges of the upper substrate and the lower substrate) for sealing the entire outside of the panel.

A lead-out electrode 330b is formed in the unit space defined by the barrier rib 350 and a photoconductive layer 340 is formed under the lead-out electrode. The lead-out electrode may also be formed of a silver electrode.

The photoconductive layer 340 may be formed on the top of the lead-out electrode, more preferably on the bottom of the lead-out electrode. This is because, when a photoconductor is formed on the lead-out electrode, it hinders the detection of electrons generated by the gas. As a material for forming the photoconductive layer, any one selected from MgO, HgI ₂ , CdS, CdTe, and a-Se can be used. Thereby, in addition to the electrons generated by the incident X-ray and the gas layer, electrons generated by the X-ray colliding with the photoconductive layer exist, so that the amount of detected signal is increased and the efficiency of the signal can be increased .

In addition, after the structure is completed, the vacuum is evacuated at a high temperature, and the gas layer is finally injected to complete the detector. The gas layer 360 may be a pure penning gas, or a mixed gas of any one selected from Xe, Kr, Ar, Ne, and He, or two or more gases selected therefrom. That is, when the mixed gas is for example, Xe + Ne, Kr + Ne , Ar + Ne, Xe + CO 2, Kr + CO 2, Ar + CO 2, Xe + CH 4, Kr + CH 4, Ar + CH 4 Or the like.

In the detection method using the detector for detecting an X-ray image according to the present invention, for example, X-rays collide with the gas layer and the photoconductive layer, in which case the gas layer is ionized and electrons are generated in the photoconductive layer. The holes in the ionized gas layer are collected in the upper electrode, and the ionized electrons are collected in the lead-out electrode. In this case, between the lead-out electrodes, electrons ionized in the gas layer due to the presence of the barrier ribs are linearly accumulated to the lead-out electrodes, and the charge signals are read to realize each pixel.

Therefore, the barrier rib can realize a high-quality image without interfering with upper, lower, left, and right pixels, and further, the amount of electrons collected by the presence of the photoconductive layer is maximized. As described above, the present invention preferably further includes a circuit unit 370 for ionizing the gas due to electric field formation, and sequentially reading the amount of the ionized electrons and holes accumulated in each pixel portion through the lead-out electrode Do.

Another embodiment according to the present invention will be described with reference to FIG. Signs of the same configuration are the same as those in Fig. Embodiments will now be described, focusing on additional configurations.

5 illustrates a three-phase electrode structure in which one electrode is formed on a lower substrate to implement the detector according to the present invention. That is, the electrode formed on the upper substrate is used as the first electrode 330a, the electrode formed on the lower substrate is used as the electrode structure of the second electrode 330c, and the lead-out electrode 330b formed on each unit pixel .

4, a second electrode 330c is provided on the upper surface of the lower substrate 320, and a dielectric layer 380 is formed between the photoconductor and the lower electrode. have. The first and second electrodes may be formed by first printing the electrodes on the upper substrate and the lower substrate, forming a pattern through the exposure and development processes, or by patterning the pattern formed by another method And then an electrode may be formed by printing. The patterned first and second electrodes may be arranged to cross the lead-out electrode. The first electrode and the second electrode apply an electric field, and the lead-out electrode collects electrons. By adding the second electrode, the detector of the present invention can realize the effect of reducing the noise of the signal.

In addition, the dielectric layer 380 prevents the lead-out electrode and the lower electrode from conducting, and protects the lower electrode. The upper dielectric layer can be applied in various thicknesses, but it can be formed to 20 to 100 탆. As a method of forming such a dielectric layer, a screen printing method can be used.

Materials for forming the dielectric layer _{PbO- SiO 2 - B 2 O 3} - Al 2 O 3 based glass, P ₂ O ₅ -ZnO-based, Bi ₂ O ₃ -SiO _{2 type, ZnO-B 2 O 3 -SiO} 2 _{system, BaO-B 2 O 3 -Al} 2 O 3 system can consider a glass or the like, particularly preferably _{PbO- SiO 2 - B 2 O 3} - can be used for Al ₂ O ₃ based glass, this glass stabilized by And has excellent withstand voltage characteristics and can prevent crystallization. Further, CuO may be added to the PbO-SiO ₂ -B ₂ O ₃ -Al ₂ O ₃ glass material to suppress the electrode reactivity, or TiO ₂ may be further added to control the firing temperature and the dielectric constant. However, if an alkali metal oxide such as Na ₂ O, K ₂ O, or Li ₂ O is additionally contained as a component for lowering the softening point of the glass in order to lower the firing temperature of the dielectric layer, energization due to electrode discoloration and migration of alkali ions (For example, TiO ₂ , Al ₂ O ₃ , ZnO, ZrO 2 or the like) may be further added to the glass material forming the dielectric layer.

FIG. 6 is a graph comparing signal amounts of detectors according to presence or absence of a photoconductor.

As shown in the figure, in the case where there is no photoconductor, it can be confirmed that the amount of signal at the time of irradiation is increased in case (b) where the photoconductor is present as compared with (a). Therefore, in the present invention, electrons generated by the gas and electrons generated by the photoconductor are added to the PDP type detector, so that the effect of increasing the signal amount can be realized.

In the foregoing detailed description of the present invention, specific examples have been described. However, various modifications are possible within the scope of the present invention. The technical idea of the present invention should not be limited to the embodiments of the present invention but should be determined by the equivalents of the claims and the claims.

1 to 3 are conceptual diagrams of a driving method of an X-ray image tracer according to a conventional technique.

4 is a conceptual diagram showing a configuration of a detector for X-ray image detection according to the present invention.

5 is a conceptual diagram showing another embodiment of the detector for X-ray image detection according to the present invention.

Claims (10)

A detector body having a closed space filled with a gas and an electrode formed on the detector body; At least one barrier rib formed inside the detector body to implement a pixel; A plurality of lead-out electrodes partitioned by the barrier ribs to form pixels; And A photoconductor layer formed under the lead-out electrode; And a detector for detecting the X-ray image. The method according to claim 1, The photoconductive layer is MgO, HgI _2, X- ray image detector for detecting, characterized in that CdS, CdTe, is any one selected from a-Se. The method according to claim 1, Wherein the detector body includes an upper substrate and a lower substrate, and the electrode is formed on the upper substrate. The method according to claim 1, Wherein the detector body includes an upper substrate and a lower substrate, and the electrode is formed of a first electrode formed on the upper substrate and a second electrode formed on the lower substrate. The method of claim 4, And a dielectric layer is further formed on the second electrode. The method according to claim 3 or 4, Wherein the barrier rib is formed to be higher than the lead-out electrode, and at least a part of the barrier rib is not in contact with the upper substrate. The method of claim 6, Wherein the barrier rib is formed of any one material selected from the group consisting of ceramic, plastic, and polymer film. The method according to claim 4 or 5, Further comprising: a circuit unit for reading signal amounts of electrons and holes formed by the voltages applied to the first and second electrodes from the lead-out electrodes. The method according to claim 3 or 4, Wherein the electrode or the lead-out electrode is a sliver electrode. The method according to claim 1, Wherein the gas to be filled is a pure Penning gas which is a mixture of any one selected from Xe, Kr, Ar, Ne, and He, or two or more gases selected from these.

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