CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of Chinese Patent Application No. 200810074226.0 filed Feb. 13, 2008, which is hereby incorporated by reference in its entirety. 
       BACKGROUND OF THE INVENTION 
       [0002]    The embodiments described herein relate to a detector panel and an X-ray imaging apparatus, and more particularly to a portable detector panel having an X-ray detector assembly housed in a case, and an X-ray imaging apparatus using such detector panel. 
         [0003]    As a type of X-ray imaging apparatuses, there are mobile imaging apparatuses. The X-ray imaging apparatus of this type is composed of a movable system console and a portable detector panel. The system console includes an X-ray irradiator and a control circuit, while the detector panel is composed of an X-ray detector assembly and an X-ray transmissive flat case. 
         [0004]    The X-ray imaging apparatus is carried to a hospital room of a patient for carrying out radiography. The radiography is carried out in the hospital room in such a manner that the detector panel is put on a part of the patient to be imaged, and an X-ray is irradiated from the opposite side. The X-ray signal detected by the detector panel is transmitted to the system console with wire or wirelessly (see, for example, Japanese Unexamined Patent Publication No. 2002-336227 (paragraph numbers 0017 to 0020,  FIG. 1 )). 
         [0005]    The X-ray detector assembly includes an X-ray detector including a two-dimensional array of X-ray detecting elements that convert the incident X-ray into an electrical signal, a support substrate, an interface circuit, and a flexible circuit board that connects the X-ray detector and the interface circuit. 
         [0006]    The two-dimensional array of the X-ray detecting elements is mounted to the surface of the support substrate, the interface circuit is mounted to the back surface of the support substrate, and the flexible circuit is mounted from the surface of the support substrate to the back surface. 
         [0007]    The X-ray detector described above is rigidly fixed to the inner bottom wall of the case via a spacer made of an appropriate hard material, or fixed through a cushion that is made of a soft material and arranged below the spacer for absorbing impact (see, for example, U.S. Pat. No. 6,700,126 (columns 3 to 5,  FIG. 4 )). 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0008]    When the X-ray detector assembly is fixed in the case through the spacer made of a hard material, a shock produced when the detector panel is dropped on the floor and hit against something is directly transmitted, so that the X-ray detector assembly is susceptible to breakdown. When the cushion is arranged below the spacer, the shock to the X-ray detector assembly is eased, but there is a problem in the reliability of the cushion material. 
         [0009]    Since the cushion is interposed, the precise positioning of the X-ray detector assembly becomes difficult, which brings poor productivity. Further, the stability of the X-ray detector assembly to the external environment is poor due to the temperature characteristic of the cushion or the affect by the external vibration. 
         [0010]    In view of this, a detector panel is provided having shock resistance and excellent stability to the external environment, and an X-ray imaging apparatus that uses the detector panel. 
         [0011]    In a first aspect, a portable detector panel includes an X-ray detector assembly having an X-ray detecting surface on its surface; a box-like case that houses the X-ray detector assembly therein and whose at least upper part that is opposite to the X-ray detecting surface is X-ray transmissive; and a buffer member that is arranged between the inner side wall of the case and the X-ray detector assembly, is made of a hard material, and has a flexible shape with respect to the movement of the X-ray detector assembly in the direction generally parallel to the X-ray detecting surface. 
         [0012]    In a second aspect, the X-ray detector assembly includes: a support substrate; an X-ray detector supported on the upper surface of the support substrate; an electric circuit board supported on the lower surface of the support substrate; and a flexible circuit board that electrically connects the X-ray detector with the electric circuit. 
         [0013]    In a third aspect, the detector panel also includes a spacer that supports the X-ray detector assembly housed in the case so as to be apart from the inner bottom wall of the case. 
         [0014]    In a fourth aspect, the spacer is movable with respect to the movement of the X-ray detector assembly in the direction generally parallel to the X-ray detecting surface. 
         [0015]    In a fifth aspect, the buffer member includes a beam arranged on the inner side wall of the case the X-ray detector assembly and is flexible with respect to the pressing force to the X-ray detector assembly in the direction generally parallel to the X-ray detecting surface. 
         [0016]    In a sixth aspect, the beam are provided at four corners of the inner side wall of the case or the X-ray detector. 
         [0017]    In a seventh aspect, the beam is a cantilever beam one end of which is supported on the inner side wall of the case or the X-ray detector assembly. 
         [0018]    In an eighth aspect, the beam is in a shape corresponding to the shape of a corner of the X-ray detector assembly. 
         [0019]    In a ninth aspect, the buffer member includes a beam that is arranged between the inner side wall of the case and the X-ray detector assembly and is flexible with respect to the pressing force to the X-ray detector assembly in the direction generally parallel to the X-ray detecting surface. 
         [0020]    In a tenth aspect, the buffer member includes a straddle mounted beam that is arranged on a side face of the supporting substrate and is flexible with respect to the pressing force by a projecting portion arranged on an inner side wall of the case in the direction generally parallel to the X-ray detecting surface. 
         [0021]    In an eleventh aspect, an X-ray imaging apparatus includes a system console having an X-ray irradiator and a control circuit; and a portable detector panel that detects an X-ray generated from the X-ray irradiator, the detector panel including: an X-ray detector assembly having an X-ray detecting surface on its surface; a box-like case that houses the X-ray detector assembly therein and whose at least upper part that is opposite to the X-ray detecting surface is X-ray transmissive; and a buffer member that is arranged between the inner side wall of the case and the X-ray detector assembly, is made of a hard material, and has a flexible shape with respect to the movement of the X-ray detector assembly in the direction generally parallel to the X-ray detecting surface. 
         [0022]    In a twelfth aspect, the X-ray detector assembly includes: a support substrate; an X-ray detector supported on the upper surface of the support substrate; an electric circuit board supported on the lower surface of the support substrate; and a flexible circuit board that electrically connects the X-ray detector with the electric circuit. 
         [0023]    In a thirteenth aspect, the detector panel further includes a spacer that supports the X-ray detector assembly housed in the case so as to be apart from the inner bottom wall of the case. 
         [0024]    In a fourteenth aspect, the spacer is movable with respect to the movement of the X-ray detector assembly in the direction generally parallel to the X-ray detecting surface. 
         [0025]    In a fifteenth aspect, the buffer member includes a beam arranged on the inner side wall of the case the X-ray detector assembly and is flexible with respect to the pressing force to the X-ray detector assembly in the direction generally parallel to the X-ray detecting surface. 
         [0026]    In a sixteenth aspect, the beam are provided at four corners of the inner side wall of the case or the X-ray detector assembly. 
         [0027]    In a seventeenth aspect, the beam is a cantilever beam one end of which is supported on the inner side wall of the case or the X-ray detector assembly. 
         [0028]    In an eighteenth aspect, the beam is in a shape corresponding to the shape of a corner of the X-ray detector assembly. 
         [0029]    In a nineteenth aspect, the buffer member includes a beam that is arranged between the inner side wall of the case and the X-ray detector assembly and is flexible with respect to the pressing force to the X-ray detector assembly in the direction generally parallel to the X-ray detecting surface. 
         [0030]    In a twentieth aspect, the buffer member includes a straddle mounted beam that is arranged on a side face of the supporting substrate and is flexible with respect to the pressing force by a projecting portion arranged on an inner wall of the case in the direction generally parallel to the X-ray detecting surface. 
         [0031]    In some embodiments, the detector panel includes a buffer member that is arranged between the inner side wall of the case and the X-ray detector assembly, is made of a hard material, and has a flexible shape with respect to the movement of the X-ray detector assembly in the direction generally parallel to the X-ray detecting surface. Therefore, the detector panel facilitates shock resistance and excellent stability with respect to the external environment. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0032]      FIG. 1  is a view showing an appearance of an exemplary X-ray imaging apparatus. 
           [0033]      FIG. 2  is a view showing the state in which the X-ray imaging apparatus shown in  FIG. 1  is being moved. 
           [0034]      FIG. 3  is a view showing the state in which a patient is imaged by the X-ray imaging apparatus shown in  FIG. 1 . 
           [0035]      FIG. 4  is a view showing a basic configuration of a detector panel that may be used with the X-ray imaging apparatus shown in  FIG. 1 . 
           [0036]      FIG. 5  is a view showing a basic internal configuration of the detector panel shown in  FIG. 4 . 
           [0037]      FIG. 6  is a horizontal sectional view showing a basic configuration of the detector panel shown in  FIG. 4 . 
           [0038]      FIG. 7  is a horizontal sectional view showing another basic configuration of the detector panel shown in  FIG. 4 . 
           [0039]      FIG. 8  is a horizontal sectional view showing another basic configuration of the detector panel shown in  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0040]    Various embodiments of the present invention will be explained in detail with reference to the drawings. The present invention is not limited to the embodiments described herein.  FIG. 1  schematically shows the appearance of an X-ray imaging apparatus. The configuration of this apparatus represents only one example of the X-ray imaging apparatus. 
         [0041]    As shown in  FIG. 1 , the present apparatus has a system console  100 . The system console  100  has a box-like structure of substantially a rectangular solid, and has an electric circuit for imaging control in its inside. The system console  100  has a caster  102  for movement at its lower part and a grip handle  104  at its upper part. Thus, the present apparatus becomes a movable X-ray imaging apparatus that can be freely moved as shown in  FIG. 2 . 
         [0042]    An operation panel  106  is provided to the upper surface of the system console  100 . The operation panel  106  includes a man-machine communication device such as, for example, a graphic display or a keyboard. 
         [0043]    A vertical column  110  is provided to the back of the system console  100 . An X-ray irradiator  130  is mounted to a leading end of an arm  120  that extends horizontally from the column  110 . The X-ray irradiator  130  generates X-ray by a high voltage supplied from the system console  100  through a cable  132 . 
         [0044]    The direction of the X-ray irradiator  130  is changeable at the leading end of the arm  120 . The arm  120  can be moved up and down along the column  110 . The column  110  is spinnable about the longitudinal shaft. 
         [0045]    The present apparatus has a detector panel  200 . The detector panel  200  has a plate-like structure of substantially a rectangular shape. It is provided separate from the system console  100 , and is portable. The detector panel  200  is stored in a bin  108  at the front of the system console  100  when radiography is not carried out. When the radiography is carried out, the detector panel  200  is take out of the bin  108  for use. The detector panel  200  is one example of a best mode for carrying out the present invention. The configuration of the detector panel  200  illustrates one example of the best mode for carrying out the present invention relating to a detector panel. 
         [0046]      FIG. 3  shows the scene when the present apparatus is used. As shown in  FIG. 3 , the present apparatus is used in a hospital room. Radiography is carried out in such a manner that the detector panel  200  is put on the back of a patient, and X-ray is irradiated from the front side by the X-ray irradiator  130  of the system console  100 . The X-ray signal detected by the detector panel  200  is transmitted wirelessly or by a cable (not shown) to the system console  100 . 
         [0047]      FIG. 4  shows a basic configuration of the detector panel  200 . As shown in  FIG. 4 , the detector panel  200  has a box-like case  55  and a rectangular plate-like X-ray detector assembly  51  housed in the case  55 . The upper part of the case  55  that is opposite to an X-ray detecting surface  52   a ′ of the X-ray detector assembly  51  is made of an X-ray transmissive material. The case  55  has a grip  552  at its one end. 
         [0048]      FIG. 5  shows one example of an internal configuration of the detector panel  200 .  FIG. 5  is a vertical sectional view of the detector panel  200 . As shown in  FIG. 5 , the X-ray detector assembly  51  is composed of an X-ray detector  52 , a support substrate  53 , and an electronic circuit board  54 . The X-ray detector  52  is mounted to the surface of the support substrate  53 , and the electronic circuit board  54  is mounted to the back surface of the support substrate  53 , wherein both are electrically connected by a flexible circuit board  56 . 
         [0049]    The X-ray detector  52  is constructed by laminating a scintillator layer  52   a  and a photoelectric conversion layer  52   b  over a glass substrate  52   c.  The scintillator layer  52   a  converts X-rays into light, and the photoelectric conversion layer  52   b  converts this light into an electrical signal. The photoelectric conversion layer  52   b  is constructed of a two-dimensional array of such photoelectric conversion elements as photodiodes. The electrical signal obtained as the result of conversion is inputted to the electric circuit board  54  through the flexible circuit board  56 . 
         [0050]    An electric circuit is mounted to the electric circuit board  54 . The electric circuit is an interface to the system console  100 . It converts the inputted signal into digital data and transmits the resultant to the system console  100  wirelessly or by a cable (not shown). 
         [0051]    The rear face of the support member  53  is provided with a plurality of spacers  57 . The support member  53  is kept at a distance from the inner bottom wall of the case  55  by the spacers  57 . The end faces  58  of the spacers  57  are not fixed on the inner bottom wall of the case  55 . That is, the end faces  58  of the spacers  57  are moving ends. The spacers  57  may be provided on the case  55  side. In this case, the end faces on the support member  53  side are moving ends. 
         [0052]      FIG. 6  illustrates an example of the internal configuration of the detector panel  200  in the form of horizontal sectional view. As illustrated in  FIG. 6 , the case  55  has a buffer member  59  at each of the four corners of its inner circumferential surface. The buffer members  59  are each constructed of a pair of cantilever beams having a flexible structure in the direction of bending. Each pair of cantilever beams has an opening angle of 90 degrees at a cantilever portion. 
         [0053]    The flexible shape here means the shape that functions as a rigid body with respect to a shock or vibration produced upon a normal use, and that functions as an elastic body so as to absorb energy with respect to an extreme shock or vibration applied when dropped on a floor or hit against something. The buffer members described above can be realized by appropriately designing the material, shape and size. The buffer members  59  are constructed integrally with the case  55 . These buffer members  59  are constructed, for example, by molding the case  55  integrally with the buffer members  59 . 
         [0054]    The support member  53  has a projecting portion  53   a  at each of its four corners in correspondence with these buffer members  59 . The four projecting portions  53   a  are respectively abutted against the four buffer members  59 . Each portion constructed of a buffer member  59  and a protruded portion  53   a  is an example of a supporting mechanism of the invention. 
         [0055]    When excessive impact or vibration is horizontally applied, the buffer members  59  perform buffering action by flexing their beams. Impact or vibration is horizontally applied when a corner or an edge of the detector panel  200  hits the floor or a foreign object or on any other like occasion. Impact and like on the X-ray detector assembly  51  is lessened by the buffer members, and the X-ray detector assembly  51  becomes less prone to fail. In addition, a cushion material or the like is not used for buffering, and high reliability is obtained. 
         [0056]      FIG. 7  illustrates another example of the internal configuration of the detector panel  200  in the form of horizontal sectional view. As illustrated in  FIG. 7 , the case  55  has four projecting portions  60  on its inner circumferential surface on four sides. The support member  53  has a buffer member  61  on its four side in correspondence with these protruded portions  60 . The four buffer members  61  are abutted against the four respective protruded portions  60 . The buffer members  61  are each constructed of a straddle mounted beam flexible when horizontally pressed by the X-ray detector assembly  51 . The buffer members  61  are constructed integrally with the support member  53 . These buffer members  61  are constructed, for example, by molding the support member  53  integrally with the buffer members  61 . 
         [0057]    When excessive impact or vibration is horizontally applied, the buffer members  59  perform buffering action by flexing their beams. This lessens impact or the like on the X-ray detector assembly  51 , and the X-ray detector assembly  51  becomes less prone to fail. In addition, a cushion material or the like is not used for buffering, and high reliability is obtained. 
         [0058]      FIG. 8  illustrates another example of the internal configuration of the detector panel  200  in the form of horizontal sectional view. As illustrated in  FIG. 8 , the support member  53  has buffer members  62  respectively formed at its four corners. The buffer members  62  are diagonally extended from the four corners. Their ends are each constructed of a beam abutted against the corresponding one of the four corners on the inner circumference of the case  55 . The beams are in such a shape that they are flexible under pressing force horizontally applied to the X-ray assembly  51 . 
         [0059]    The buffer members  62  are constructed integrally with the support member  53 . These buffer members  62  are constructed, for example, by molding the support member  53  integrally with the buffer members  62 . When excessive impact or vibration is horizontally applied, the buffer members  62  perform buffering action by flexing their beams. This lessens impact or the like on the X-ray detector assembly  51 , and the X-ray detector assembly  51  becomes less prone to fail. In addition, a cushion material or the like is not used for buffering, and high reliability is obtained.
A portable detector panel includes an X-ray detector assembly having an X-ray detecting surface on its surface, a box-like case that houses the X-ray detector assembly therein and whose upper part that is opposite to the X-ray detecting surface is X-ray transmissive, and a buffer member that is arranged between the inner side wall of the case and the X-ray detector assembly, is made of a hard material, and has a flexible shape with respect to the movement of the X-ray detector assembly in the direction generally parallel to the X-ray detecting surface.