Patent Publication Number: US-2003227998-A1

Title: X-ray image sensory system

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] The present invention relates to an X-ray image sensory system, and, more particularly, to an X-ray image sensory system placing its components which are more susceptible to the X-ray on the other side of the substrate board to avoid damages.  
       [0003] 2. Description of Prior Arts  
       [0004] Prior art X-ray sensory systems employ films to display the X-ray images, and as this result, about tens of minutes have to be taken to obtain a picture. In the process of exposure, transportation, processing and printing, the picture on film is susceptible to damages. If that happens, the whole process has to be repeated again from the beginning.  
       [0005] The contemporary X-ray image sensory system is digital-based. The image can be displayed on a screen in a matter of a few seconds. If any mistake occurs during the process, the new image can be taken immediately. Digital X-ray image sensory systems frequently adopt Charge Coupled Device (CCD), or Complementary Metal Oxygen Semiconductor (CMOS) for their image sensory components. In comparison, CCD is more sensitive to the X-ray, but has a lower tolerance to the X-ray damage. On the other hand, CMOS has a higher tolerance to the X-ray, and is easy for mass production as it is the mainstream in semiconductor fabrication. Furthermore, because the CMOS components are usually small in terms of area size, it is possible to manufacture the entire X-ray sensory system on a single chip, namely, the so-called System On Chip (SOC).  
       [0006] However, because the components of X-ray image sensory system are with different tolerances to the X-ray, it is possible that some components are more susceptible to the X-ray damage if they are all exposed to the same amount of X-ray. Furthermore, when the X-ray image sensory system is used in the dental checkup, the entire system needs to be placed inside the patient&#39;s mouth. This has imposed a strong limitation of the size of the system, which, in turn, limits the possible shields for the components less tolerant to the X-ray. One possible solution is to increase the distance between the less tolerant components and the sensory components to avoid the direct exposure while taking the image. However, this solution has the disadvantage of signal decay due to the longer transmission distance, and greater distortion due to the signal interference.  
       SUMMARY OF THE INVENTION  
       [0007] It is therefore a primary objective of the present invention to provide an X-ray image sensory system, and wherein the components with less tolerance to the x-ray damage are placed on the side of the substrate board to avoid the direct exposure to the X-ray. Hence, the system could prolong the life span.  
       [0008] For the aforementioned purpose, the present invention provides an X-ray image sensory system. The X-ray image sensory system includes an X-ray conversion module for converting the input X-ray, a sensory component for detecting the converted signals, a substrate board, a buffer and an analog-to-digital converter. The X-ray conversion module and the image sensory component are on the side of the substrate board facing the input X-ray, and the buffer and the analog-to-digital converter are on the other side of the substrate board.  
       [0009] These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment which is illustrated in the various figures and drawings. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0010]FIG. 1 is a schematic diagram of an embodiment according to the present invention.  
     [0011]FIG. 2 is a schematic diagram of another embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0012]FIG. 1 shows a schematic diagram of a preferred embodiment  10  of the present invention. The X-ray image sensory system  10  includes an X-ray conversion module  12 , a CMOS image sensory component  14 , a substrate board  16 , a buffer  17 , an analog-to-digital converter (ADC)  18 , and a sequencing control circuit  19 . The X-ray conversion module  12  could be either the direct or indirect type. An indirect conversion means that the X-ray  21  is first converted to visible light signals, then to electrical signals, while in direct conversion the X-ray  21  is directly converted to electrical signals. The X-ray conversion module  12  is connected to the CMOS image sensory component  14 , so that the CMOS image sensory component  14  can detect the electrical signals converted from the input X-ray  21 . The electrical signals are amplified by the buffer  17 , transmitted to ADC  18 , and then output by the sequencing control circuits  19 . The buffer  17 , ADC  18  and the sequencing control circuit  19  are all electrically connected by a printed circuit board (not shown) on the substrate board  16 . The connection allows the electrical signals converted from the X-ray  21  to be amplified, analogically-to-digitally converted, and read out sequentially. The buffer  17 , ADC  18 , and the sequencing control circuit  19  can also be electrically connected by the conductive wires, wire bonds, conductive bumps, Ball Gate Array (BGA), or conductive tape, all of which are not shown in the figures.  
     [0013] The X-ray conversion module  12  and the CMOS image sensory component  14  are on the side of the substrate board  16  facing the input X-ray  21 . The buffer  17 , ADC  18  and the sequencing control circuit  19  are on the other side of the substrate board  16 . Because the buffer  17 , ADC  18  and the sequencing control circuit  19  are less tolerant to the X-ray damage than the CMOS image sensory component  14 , they are placed on the other side of the substrate board  16  to avoid the direct exposure to the X-ray  21 . This is to ensure the normal operation of the image sensory system  10 . For better protection of the buffer  17 , ADC  18  and the sequencing control circuit  19 , the substrate board  16  is made of the material highly tolerant to the X-ray  21 . Furthermore, the components of the image sensory system  10 , including the X-ray conversion module  12 , CMOS image sensory component  14 , buffer  17 , ADC  18  and sequencing control circuit  19 , are all manufactured separately, then connected to the substrate board  16  later. Separately manufacturing each component respectively is to avoid the low yield problem that is usually associated with the SOC technology. Also, all the components are replaceable, therefore increasing the flexibility of the present invention image sensory system  10 .  
     [0014]FIG. 2 shows a schematic diagram of another image sensory system  30  of the present invention. The second embodiment  30  includes an X-ray conversion module  32 , a CMOS image sensory component  34 , an X-ray shield layer  35 , a substrate board  36 , a buffer  37 , an analog-to-digital converter (ADC)  38 , and a sequencing control circuit  39 . The X-ray conversion module  32  could be either direct or indirect type. An indirect conversion means that the X-ray  41  is first converted to the visible light, then to electrical signals, while direct conversion converts the X-ray  41  directly to electrical signals. The X-ray conversion module  32  is connected to the CMOS image sensory component  34 , so that the CMOS image sensory component  34  can detect the electrical signals converted from the input X-ray  41 . The electrical signals are amplified by the buffer  37 , transmitted to ADC  38 , then outputted by the sequencing control circuit  39 . The buffer  37 , ADC  38  and the sequencing control circuit  39  are all electrically connected by a printed circuit board (not shown) on the substrate board  36 . The connection allows the electrical signals converted from the X-ray  41  to be amplified, analogically-to-digitally converted, and read out sequentially. The buffer  37 , ADC  38 , and the sequencing control circuit  39  can also be electrically connected by the conductive wires, wire bonds, conductive bumps, Ball Gate Array (BGA), or conductive tape (not shown).  
     [0015] The X-ray conversion module  32  and the CMOS image sensory component  34  are on the side of the substrate board  36  facing the input X-ray  41 . The buffer  37 , ADC  38  and the sequencing control circuit  39  are on the other side of the substrate board  36 . Because the buffer  37 , ADC  38  and the sequencing control circuit  39  are less tolerant to the X-ray than the CMOS image sensory component  34 , which therefore are placed on the other side of the substrate board  36  to avoid the direct exposure to the X-ray  41 . This is to ensure the normal operation of the image sensory system  30 . For better protection of the buffer  37 , ADC  38  and the sequencing control circuit  39 , the substrate board  36  is made of the material that is highly tolerant to the X-ray  41 . To rid off the impact of the X-ray  41  on the buffer  37 , ADC  38  and the sequencing control circuit  39 , the image sensory system  30  further includes an X-ray shield layer  35  between the CMOS image sensory component  34  and the substrate board  36 . This provides an enhanced protection to the buffer  37 , ADC  38  ad the sequencing control circuit  39  on the other side of the substrate board  36 .  
     [0016] Furthermore, the components of the image sensory system  30 , including the X-ray conversion module  32 , CMOS image sensory component  34 , the buffer  37 , ADC  38  and the sequencing control circuit  39 , are all manufactured separately, then connected to the substrate board  36  later. Separately manufacturing above components is to avoid the low yield problem that is usually associated with the SOC technology. Also, all the components are replaceable, thereby increasing the flexibility of this preferred embodiment  30 .  
     [0017] Compared to the prior arts, the present invention places the components more susceptible to the X-ray damage on the back side of the substrate board to avoid the direct exposure to the X-ray. These less-tolerant components include a buffer, an analog-to-digital converter, and a sequencing control circuit. This design allows a better protection to the components as well as reducing the size of the entire system. In addition, because the buffer and the image sensory component are on the opposite sides of the substrate board, the converted signals (electrical signals) can be directly transmitted and amplified. The shortened transmission distance can reduce the signal decay or interference distortion. Furthermore, the components of the system are all manufactured separately, then assembled together on the substrate board later, thus avoiding the low yield problem that is usually associated with the SOC technology. Also, all the components are replaceable for the purpose of increasing the flexibility of the system.  
     [0018] Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teachings of the invention.  
     [0019] Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.