Array substrate for X-ray detector, method of manufacturing the same, X-ray detector having the same installed therein, and method of manufacturing X-ray detector

An x-ray detector including an array substrate including blocks extending along the array substrate in a first direction. Each of the blocks includes cells that are each associated with a data line extending in parallel with the first direction and a gate line extending perpendicularly to the first direction such that the data line crosses the gate line, a thin film transistor respectively connected to the gate and data lines, and a photodiode connected to the thin film transistor to receive light. The cells store charges corresponding to an amount of the light. Gate drivers are connected to ends of the gate lines to select rows of the cells associated with each of the gate lines. Read-out circuits are connected to ends of the data lines to read out charges stored in the cells, of each of the selected rows, that are respectively associated with each of the data lines.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Korean Patent Application No. 2007-99814, filed on Oct. 4, 2007, and all the benefits accruing therefrom under 35 U.S.C. §119, the contents of which in its entirety are herein incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Aspects of the present invention relate to an array substrate for an x-ray detector and an x-ray detector having the array substrate installed therein and, more particularly, aspects of the present invention relate to an array substrate for an x-ray detector that is capable of reducing a manufacturing cost thereof and of improving an image display quality thereof, a method of manufacturing the array substrate, an x-ray detector having the array substrate installed therein, and a method of manufacturing the x-ray detector.

2. Description of the Related Art

Recently, in order to process medical image information for medical appliances, a digital radiograph (DR) has been widely accepted. The DR may be classified into a charge-coupled device (CCD) DR, a complementary metal-oxide semiconductor (CMOS) DR, and/or a flat panel (FP) DR in accordance with a kind of sensor, which is installed therein, that converts green light emitted from a scintillator.

The CCD DR and CMOS DR operate by scaling up medical image information when displaying the medical image information. This scaling up of medical image information accounts for the fact that, in general, sizes of the sensors installed therein are relatively small. As a result, a projection DR, such as the above-mentioned CCD and CMOS DRs, may have defects that affect its image processing processes. These defects may result in relatively low quality images in terms of resolution, brightness, and contrast ratio, etc.

In detail, the FP DR displays superior x-ray images by using a photoelectric sensor. That is, the flat panel x-ray detecting (FPXD) device is one of the most advanced x-ray detecting device of all of the various DRs.FIG. 1is a plan view showing a conventional flat panel x-ray detector30. As shown inFIG. 1, the x-ray detector30may produce photographic images of objects having various vertical and horizontal sizes. The x-ray detector30includes an array substrate having a tile-like structure. Here, four array substrates20are combined with each other.

Referring toFIG. 1, the array substrates20of the x-ray detector30each include thin film transistor (TFT) arrays that are each arranged in rows and columns, read out circuits26that are connected to the TFT arrays, gate drivers28, and analog-to-digital converters27. Each TFT array includes cells22, and each cell22includes a thin film transistor23and a p-i-n (PIN) photodiode24. The PIN photodiode24includes a conductive layer and two electrodes that each respectively applies a voltage to both sides of the conductive layer. The conductive layer includes a p-type photoconductive layer into which p-type impurities are doped, a photoconductive layer into which impurities are not doped, and an n-type photoconductive layer into which n-type impurities are doped. A scintillator is formed on the PIN photodiode24.

In conventional appliances, however, image quality of the image information obtained through the x-ray detector30may be decreased by various factors, such as a uniformity, or lack thereof, of lines21aand21barranged on the array substrates20, uniformity, or lack thereof, and defects of the photodiode24, and leakage current levels, etc. Accordingly, in order to prevent a decrease in the image quality, an image correction operation is performed so as to adjust an offset voltage level of the gate and data lines21aand21b.

Where the x-ray detector30, including the array substrate of which four array substrates20are combined with each other (i.e., in a tile-like structure), is applied to take the photograph of the image, however, the offset correction may be imprecisely performed since the gate and data lines21aand21bmay be separated from each other in accordance with the arrangements of the array substrates20. Further, defects of the array substrates20may actually increase since external integrated circuits may be respectively bonded to every array substrate20.

BRIEF SUMMARY OF THE INVENTION

An aspect of the present invention provides an array substrate for an x-ray detector capable of improving yield and reducing a manufacturing cost thereof.

An aspect of the present invention also provides an x-ray detector having the array substrate installed therein.

An aspect of the present invention also provides a method of manufacturing the array substrate for the x-ray detector.

An aspect of the present invention also provides a method of manufacturing the x-ray detector.

In one aspect of the present invention, an array substrate for an x-ray detector is provided and includes a plurality of cells to store charges respectively corresponding to an amount of received light, and a light blocking layer to cover dummy pixels of the cells, the light blocking layer being arranged in a peripheral area of the x-ray detector so as to be positioned to block light advancing toward the dummy pixels, wherein each cell includes a gate line extending along the array substrate in a predetermined direction, a data line crossing the gate line to define a pixel area, a thin film transistor respectively connected to the gate and the data lines, and a photodiode connected to the thin film transistor to receive the light as having been converted from an x-ray.

The light blocking layer may include a carbon-containing organic material that is configured to be patterned by exposure to a light.

In another aspect of the present invention, an x-ray detector is provided and includes an array substrate including a plurality of blocks extending along the array substrate in a first direction, each of the blocks including a plurality of cells that are each associated with a data line extending substantially in parallel with the first direction and a gate line extending substantially perpendicularly with respect to the first direction such that the data line crosses the gate line at a location of the cell, a thin film transistor respectively connected to the gate and data lines, and a photodiode connected to the thin film transistor to receive light converted from x-rays, the cells storing charges corresponding to an amount of the light, a plurality of gate drivers arranged adjacent to a first side of the array substrate and connected to ends of the gate lines to select rows of the cells associated with each of the gate lines through a scanning operation, and a plurality of read-out circuits arranged adjacent to a second side of the array substrate and connected to ends of the data lines to read out charges stored in the cells, of each of the selected rows, that are respectively associated with each of the data lines to which each of the read-out circuits are respectively connected.

The x-ray detector may further include a plurality of analog-to-digital converters that each convert analog signals substantially simultaneously applied from the each of the read-out circuits into digital signals, the analog-to-digital converters being arranged adjacent to the read-out circuits along the second side of the array substrate in numbers that correspond to a number of the blocks in one-to-one fashion.

In another aspect of the present invention, a method of manufacturing an array substrate for an x-ray detector is provided and includes forming a plurality of cells to each receive light converted from x-rays and to each store charges corresponding to an amount of the light, and forming a light blocking layer covering dummy pixels of the cells in a peripheral area to block light advancing toward the dummy pixels, wherein the forming of each of the cells includes forming a gate line extending in a predetermined direction, a data line crossing the gate line to define a pixel area, and a thin film transistor connected to the gate and data lines; and forming a photodiode connected to the thin film transistor to receive the light.

In another aspect of the present invention, a method of manufacturing an x-ray detector is provided and includes forming an array substrate including a plurality of blocks extending along the array substrate in a first direction, each of the blocks including a plurality of cells that are each associated with a data line extending substantially in parallel with the first direction and a gate line extending substantially perpendicularly with respect to the first direction such that the data line crosses the gate line at a location of the cell, a thin film transistor respectively connected to the gate and data lines, and a photodiode connected to the thin film transistor to receive light converted from x-rays, the cells storing charges corresponding to an amount of the light, forming a plurality of gate drivers at respective positions adjacent to a first side of the array substrate, each of the gate drivers being connected to ends of the gate lines to select rows of the cells associated with each of the gate lines through a scanning operation, and forming a plurality of read-out circuits at respective positions adjacent to a second side of the array substrate, each of the read-out circuits being connected to ends of the data lines to read out charges stored in the cells of each of the selected rows that are respectively associated with each of the data lines to which each of the read-out circuits are respectively connected.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 2is a view showing an exemplary x-ray system100having a flat panel x-ray detector300according to the present invention.

As shown inFIG. 2, the exemplary x-ray system100includes an x-ray generator140to irradiate x-rays160onto a predetermined area180of a patient's body190, the x-ray detector300to detect the x-rays160, an image capture/process controller400to capture an x-ray image and to process the captured x-ray image, and a display device500to display the x-ray image captured by the image capture/process controller400.

In the x-ray system100, the x-rays160are transmitted through the predetermined area180of the patient's body190. The x-ray detector300provides the x-ray image with a light intensity that corresponds to an amount of the x-rays160irradiated onto and through the patient's body190, and the image capture/process controller400captures and processes the x-ray image provided by the x-ray detector300. Then, the display device500displays the x-ray image in real time. In the present exemplary embodiment, the display device500may include a flat panel (“FP”) display that may display the x-ray image data in a digital format, such as a liquid crystal display (“LCD”).

As shown inFIG. 2, the x-ray detector300includes an array substrate200having a plurality of arrays220defined therein. Gate drivers280are arranged alongside a first side of the array substrate200. Read-out circuits260are arranged alongside a second side of the array substrate200. The x-ray detector300further includes a scintillator layer350that is disposed on the array substrate200. The scintillator layer350converts the x-rays160, which are transmitted through the patient's body190, into visible light and provides the visible light to the array substrate200.

FIG. 3is a plan view showing an exemplary embodiment of the x-ray detector300ofFIG. 2, andFIG. 4is a sectional view showing an exemplary PIN junction diode240ofFIG. 3.

Referring toFIG. 3, the array substrate200of the x-ray detector300may comprise a single array substrate. In other words, the array substrate200of the present invention does not have a tile-like structure and may have a single array structure to which one original glass substrate is applied.

The array substrate200includes a plurality of cells220that are defined therein in a pattern. In an exemplary embodiment of the invention, the pattern may comprise a matrix of cells. The array substrate200may also be divided into four blocks with each block extending in a direction that is substantially parallel to a longitudinal direction of data lines202. Of course, it is understood that, even where the array substrate200is divided into blocks, the array substrate200remains a singular feature. Moreover, it is further understood that the array substrate200may be arranged in other formats in accordance with other embodiments of the invention.

The read-out circuits260are arranged at positions alongside and/or adjacent to a second side of the array substrate200and are electrically connected to the cells220. The gate drivers280are arranged at positions such that the gate drivers280are alongside and/or adjacent to a first side of the array substrate200. Here, the gate drivers280are also electrically connected to the cells220. The x-ray detector300includes analog-to-digital converters270each of which is electrically connected to a corresponding individual read-out circuit260of the read-out circuits260. In an embodiment of the present embodiment, the gate drivers280and the read-out circuits260may each include a plurality of integrated circuits (IC) or chips. That is, the analog-to-digital converters270may include four chips that each correspond to a single one of the four blocks of the array substrate200, and each chip may be electrically connected to one or more other chips that together constitute the read-out circuits260.

Each of the cells220includes a thin film transistor230, a PIN junction diode240, a corresponding individual gate line201from among a group of gate lines201, and a corresponding data line202from among a group of data lines202. The PIN junction diode240receives visible light (e.g., green light) that is obtained as a result of the conversion of the x-rays160via the scintillator350after the x-rays160are emitted from the x-ray generator140and, subsequently, transmitted through the patient's body190.

As shown inFIG. 4, the PIN junction diode240includes an intrinsic silicon layer241, a p-type silicon layer242, and an n-type silicon layer243. The n-type silicon layer243faces the p-type silicon layer242with the intrinsic silicon layer241interposed between the p-type silicon layer242and the n-type silicon layer243. When visible light is incident onto the intrinsic silicon layer241, silicon (Si) in the intrinsic silicon layer241is dissociated and converted into electrical charges (e.g., electron-hole pairs). While the intrinsic silicon layer241is in the Si dissociated state, a negative voltage of about 5 to 7 volts is applied to the p-type silicon layer242, so that electrons (negative charges) move to the n-type silicon layer243. The electrons that are moved to the n-type silicon layer243are stored in a source layer of the thin film transistor230, which is formed on the array substrate200. When the thin film transistor230is turned on in response to a gate signal that is applied through the corresponding individual gate line201from among the group of the gate lines201, the stored charges are read out to the data lines202and stored in the read-out circuits260.

Referring toFIG. 3, signals that are read out from the pixels are stored in analog form in accordance with a photocurrent thereof. The read-out analog signals are different from each other in accordance with an amount of light that is applied to each pixel. The analog signals, which are different from each other in quantity, are then converted into digital signals by the analog-to-digital converters270. The digital signals are then displayed as digital images on the display500. In general, when reading out photoelectric signals that are converted via the read-out circuits260, the photoelectric signals corresponding to one gate line201are substantially simultaneously read out by the read-out circuits260, and the photoelectric signals corresponding to the number of channels of each of the read-out circuits260are sequentially applied to the analog-to-digital converters270through a multiplexer (MUX). As a result, the read-out time of the read-out circuits260is relatively lengthened.

Accordingly, as shown inFIG. 3, in an embodiment of the present invention, the data lines202are divided into groups of data lines202with the groups of data lines202corresponding to the four blocks of the array substrate200. The photoelectric signals of the cells220connected to the corresponding gate line201are substantially simultaneously read out by all of the read-out circuits260that are arranged alongside and/or adjacent to the array substrate200. The read-out photoelectric signals are then simultaneously applied to the analog-to-digital converters270, which are connected to the corresponding read-out circuits260. Thus, since the number of the analog-to-digital converters270corresponds to the number of the groups of the data lines202, the number of the gate drivers280and the number of the read-out circuits260of the x-ray detector300may be reduced. As a result, the read-out time may be prevented from being relatively lengthened, thereby reducing a manufacturing cost of the x-ray detector300.

Image quality of the x-ray image obtained through the x-ray detector300having the above-mentioned structure and function depends on various factors. These factors may include a relative uniformity of the manners in which the gate and data lines201and202, respectively, are arranged on the array substrate200, relative uniformities, type and quantity of defects of the PIN junction diode240, and leakage current levels, etc.

FIG. 5is an exemplary photographic diagram showing a conventional x-ray image of which an image offset correction with respect to gate and data lines are not performed, andFIG. 6is an exemplary photographic diagram showing an x-ray image of which an image offset correction with respect to gate and data lines201and202, respectively, are performed in accordance with an embodiment of the present invention.

As shown inFIG. 5, in a conventional x-ray image, horizontal and vertical lines appear on the x-ray image due to image offset voltage differences between gate lines201and due to image offset voltage differences between data lines202.

According to a conventional method of gain and offset correction, which may be employed in accordance with the manufacturing of a display panel, the image offset voltage levels of respective lines (e.g., gate and data lines201and202, respectively) are set. The setting of the image offset voltage levels may be accomplished as a result of a comparison of dark image data that is obtained when the x-rays are not applied to the display panel with image data that is obtained when the x-rays are applied to the display panel. However, since the method of gain and offset correction may be varied in accordance with varied characteristics of amorphous silicon thin film transistors (a-Si TFT) for the duration of the use of the display panel, an improper x-ray image may be captured, as shown inFIG. 5, where the method of gain and offset correction is not applied to the display panel.

As shown inFIG. 6, however, when the method of gain and offset correction is performed in real time, the horizontal and vertical lines, as shown inFIG. 5, may be reduced or substantially prevented from appearing on the display panel. Such prevention may thereby improve image quality of the x-ray image.

FIG. 7is a plan view showing another exemplary embodiment of an x-ray detector in accordance with the present invention. InFIG. 7, the same reference numerals denote the same elements inFIG. 3. Thus, detailed descriptions of the same elements will be omitted.

Referring toFIG. 7, an x-ray detector301may include a light blocking layer370in order to perform the method of gain and offset correction in real time. The light blocking layer370comprises a carbon-containing organic material that is configured to be patterned by exposure to light. Also, the x-ray detector301may further include dummy pixels (not shown) having substantially similar structures as those of the cells220with the dummy pixels being arranged under the light blocking layer370. The light blocking layer370has a closed-loop shape and is arranged along an outermost area of the x-ray detector301to surround the cells220. The light blocking layer370blocks light advancing toward the PIN junction diode240(seeFIG. 3) that is arranged in the dummy pixels. Thus, the x-ray image detected by the x-ray detector301is corrected with reference to the read-out signals through the dummy pixels. Particularly, offset voltage differences caused by electrical characteristics of the gate and data lines201and202, respectively, are measured based on differences between signals that are detected at both ends of the dummy pixels arranged under the light blocking layer370. Accordingly, the offset voltage levels may be corrected by the offset voltage differences, so that the image quality of the x-ray image may be relatively improved.

Also, since the thin film transistors230(see,FIG. 3) that are arranged on the array substrate200include a material made of a semiconductor, it is possible that characteristics of the transistors230may be varied in accordance with temperature variations. Thus, where signals are fed back whenever the temperature varies, the offset voltage levels are corrected by the variation in characteristics of the thin film transistor230due to the temperature variation.

In accordance with an embodiment of the present embodiment, the light blocking layer370may comprise a black resin that is non-transparent or another similar material that is similarly non-transparent.

Accordingly, the x-ray detectors300and301, as described above, include the data lines202that are divided into the groups of data lines202. Further, each of the x-ray detectors300and301includes analog-to-digital converters270that each correspond to each of the groups of data lines202in one-to-one fashion. Thus, the read-out signals from the data lines202are substantially simultaneously transmitted to the corresponding analog-to-digital converter270of the analog-to-digital converters270. As a result, a number of the read-out circuits260are substantially reduced along with associated manufacturing costs. Moreover, a read-out time is substantially prevented from being relatively lengthened.

In an embodiment of the invention, the x-ray detector301may further include the light blocking layer370formed on the outermost area of the array substrate200and the dummy pixels formed under the light blocking layer370, so that the method of gain and offset correction may be performed in real time, to thereby improve the image quality of the x-ray image detected by the x-ray detector300.