Abstract:
An image forming apparatus is provided, which enables various kinds of drive in accordance with purposes. The image forming apparatus includes photoelectric conversion elements and TFT units which are arranged in a matrix shape, a signal processing circuit unit (for processing a signal from each photoelectric conversion element, and a gate driver circuit unit for controlling connections among the photoelectric conversion elements. The gate driver circuit unit is connected to the TFT units through gate lines. The gate lines include one that is connected to the TFT units in each row, and the gate lines include one that is connected to the TFT units in plural rows.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to an image forming apparatus and a radiation detection system, and particularly to an image forming apparatus including a liquid crystal panel and a photoelectric conversion apparatus, and a radiation detection apparatus and a radiation detection system for detecting radiation containing X-ray, α-ray, β-ray, and Y-ray.  
           [0003]    2. Related Background Art  
           [0004]    In recent years, rapid progresses are being made in increasing the size of a panel using a TFT and increasing the drive speed. Those circumstances have been affected by the development in techniques for manufacturing a liquid crystal panel using a TFT and by the application of an X-ray image pickup apparatus having a photoelectric conversion element and the like to each field of area sensors.  
           [0005]    Also, concurrently with the increase in panel size, progresses in finer pixel pitches and finer wiring widths have caused a tendency to increase the wiring resistance of each unit. In a liquid crystal panel, the finer pixel pitches cause reduction in the pixel aperture ratio, thereby reducing the amount of light from a backlight. Thus, it is difficult to provide a liquid crystal panel having a high brightness.  
           [0006]    Also, the increases in panel size have caused increases in wiring pattern length, and the finer wiring patterns have caused increases in wiring resistance, thereby increasing the time constant and reducing the drive speed for a TFT.  
           [0007]    Similarly, in the X-ray image pickup apparatus, the reduction in the pixel aperture ratio causes reduction in the area of a sensor light receiving unit, thereby reducing the sensitivity of a sensor. Also, if the drive speed of a TFT is reduced, there is a case where the sensor cannot be used as a dynamic image sensor, thereby limiting the application of the sensor.  
           [0008]    [0008]FIG. 8 shows an equivalent circuit for a matrix panel using a conventional TFT. Here, an example will be described of the matrix panel applied to a photoelectric conversion apparatus or a radiation detection apparatus.  
           [0009]    Each pixel shown in FIG. 8 is composed of a pair of a thin film transistor unit (TFT unit)  12  and a photoelectric conversion element unit  11 .  
           [0010]    The photoelectric conversion element unit  11  generates electrons and holes when absorbing light, and accumulates the electrons or the holes in a capacitor that is provided to the inside thereof.  
           [0011]    Then, by driving a gate driver circuit unit  17 , an on voltage for turning on the TFT unit  12  is applied to gate lines  13  to drive the TFT units  12 . Thus, the electrons or the holes accumulated in the capacitor are transferred directly or indirectly through the TFT units  12  from data lines  14  to a signal processing circuit unit  15  to display an image.  
           [0012]    At this time, in the case of the photoelectric conversion element unit  11  of a metal-insulator-semiconductor (MIS) type, an operation is necessary of applying a forward bias from a common electrode driver circuit unit  16  to a common electrode wiring  10  to remove the electrons or the holes accumulated in an insulating film interface.  
           [0013]    Alternatively, if a phosphor layer for converting radiation into visible light is arranged on an upper portion of the matrix panel, or if amorphous selenium, lead iodide, or mercury iodide which generates electrons and holes directly from radiation is used as a photoelectric conversion element, a radiation detection apparatus can be obtained.  
           [0014]    For a liquid crystal panel, the photoelectric conversion element unit  11  is replaced by a liquid crystal capacitor unit  18 .  
           [0015]    The example described above presents the following problem.  
           [0016]    That is, a demand on the photoelectric conversion apparatus or the like when the TFT unit  12  is driven at a high speed is different from a demand thereon when the TFT unit  12  is driven at a slow speed, and it is difficult to meet the two demands simultaneously.  
           [0017]    When driven at a high speed, the speed of response is given a higher priority. That is, it is a higher priority to remove artifacts with respect to a display/take-in image due to an after-image in both the liquid crystal display panel and the photoelectric conversion element panel which is generated when the speed of response is reduced.  
           [0018]    On the other hand, when the TFT unit  12  is driven at a slow speed, a higher priority is given to displaying or taking in of an image having a high definition and a high contrast than the speed of response.  
           [0019]    Up to now, in order to execute individual photography, it is publicly known to use films having various resolutions, for example, a combination of films/sheets or storage sheets. An example using them is an X-ray image amplifier having a low lateral resolution and a magnification power that can be switched over for the purpose of transmission irradiation. Also, an X-ray diagnostic apparatus for performing a selection operation between a high-frame mode and a high-definition mode is publicly known.  
         SUMMARY OF THE INVENTION  
         [0020]    In view of the above, an object of the present invention is to make it possible, with a simple structure of a matrix panel, to realize high-speed drive and to obtain a high-definition image according to objects.  
           [0021]    In order to solve the above problem, according to the present invention, there is provided an image forming apparatus, including:  
           [0022]    pixels that are arranged in a matrix shape;  
           [0023]    a signal processing circuit unit for processing a signal from each of the pixels and sending a signal to each of the pixels; and  
           [0024]    a driver circuit unit for controlling connections among the pixels, in which:  
           [0025]    the driver circuit unit is connected to the pixels through at least two control wirings; and  
           [0026]    the control wirings include a control wiring in which the pixels in one of each row and each column are connected to each other, and a control wiring in which the pixels in ones of plural rows or plural columns are connected to each other in common.  
           [0027]    Further, there is provided a radiation detection apparatus, including:  
           [0028]    plural pixels that are arranged in a matrix shape and each include a conversion element for converting radiation into an electric signal and a switching element;  
           [0029]    a signal processing circuit unit for processing a signal from each of the conversion elements; and  
           [0030]    a driver circuit unit for controlling continuity of the switching element, in which:  
           [0031]    each of the pixels includes at least two signal transfer switching elements;  
           [0032]    a gate electrode of a first switching element is connected to a first gate line group in which only pixels arranged in the same row are connected to each other in common; and  
           [0033]    a gate electrode of a second switching element is connected to a second gate line group in which pixels arranged in plural rows are connected to each other in common. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0034]    [0034]FIG. 1 shows an equivalent circuit for a TFT matrix panel provided to a radiation detection apparatus according to Embodiment 1 of the present invention;  
         [0035]    [0035]FIG. 2 is a plan view schematically showing a part of a photoelectric conversion element unit  11  shown in FIG. 1;  
         [0036]    [0036]FIG. 3 is a sectional view taken along the line  3 - 3  in FIG. 2;  
         [0037]    [0037]FIG. 4 is a sectional view showing the vicinity of the photoelectric conversion element unit  11  provided to the radiation detection apparatus that uses amorphous selenium  35  for directly converting radiation into an electric signal;  
         [0038]    [0038]FIG. 5 shows an equivalent circuit for a TFT matrix panel provided to a liquid crystal display device according to Embodiment 2 of the present invention;  
         [0039]    [0039]FIG. 6 is a plan view showing a part of the liquid crystal display device including the TFT matrix panel shown in FIG. 5;  
         [0040]    [0040]FIG. 7 is a sectional view taken along the line  7 - 7  in FIG. 6;  
         [0041]    [0041]FIG. 8 shows an equivalent circuit for a matrix panel using a conventional TFT; and  
         [0042]    [0042]FIG. 9 shows a sectional view of an apparatus according to Embodiment 3. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0043]    Hereinafter, a description will be made of embodiments of the present invention based on the drawings.  
         [0044]    (Embodiment 1)  
         [0045]    [0045]FIG. 1 shows an equivalent circuit for a TFT matrix panel provided to a radiation detection apparatus according to Embodiment 1 of the present invention.  
         [0046]    A TFT matrix panel  1  shown in FIG. 1 uses a bias applied from a gate driver circuit unit  17  to a first gate line group  13 A and/or a second gate line group  13  to drive TFT units  12  arranged in a matrix shape. Then, a signal from each of photoelectric conversion element units  11  is transferred through the corresponding TFT unit  12  from a first data line group  14 A and/or a second data line group  14 B to a signal processing circuit unit  15 , so that image information is read out. As the structure of a photoelectric conversion element, a metal-insulator-semiconductor (MIS) structure including a capacitance in the inside thereof can be used.  
         [0047]    Here, the photoelectric conversion element unit  11  includes a capacitor and generates carriers of electrons and holes from light taken in from the outside. Then, the carriers can be read out by the TFT unit  12 .  
         [0048]    Alternatively, by arranging a phosphor layer for converting radiation into visible light on the matrix panel  1 , or by using amorphous selenium, PbI 2 , HgI 2 , or the like, as a material of the photoelectric conversion element, which directly absorbs radiation and generates electrons and holes, a radiation detection flat panel sensor can be obtained.  
         [0049]    In the TFT matrix panel  1 , the gate driver circuit unit  17  has a system A corresponding to the first gate line group and a system B corresponding to the second gate line group which are separately provided therein such that the respective systems can be independently driven. Similarly, the signal processing circuit unit  15  has a system A corresponding to the first data line group and a system B corresponding to the second data line group which are separately provided therein so that signals can be outputted from the respective systems independently.  
         [0050]    The system A and the system B of the gate driver circuit unit  17  corresponds to the system A and the system B of the signal processing circuit unit  15 , respectively. In the case where the system A of the gate driver circuit unit  17  is driven to apply an on voltage for the TFT unit  12  to the gate lines  13 A of the system A, accumulated carriers are transferred to the signal processing circuit unit  15  through the data lines  14 A controlled by the system A.  
         [0051]    In contrast, in the case where the system B of the gate driver circuit unit  17  is driven to apply the on voltage for the TFT unit  12  to the gate lines  13 B of the system B, carriers accumulated in the capacitors are transferred to the signal processing circuit unit  15  through the data lines  14 B controlled by the system B.  
         [0052]    The system A of the gate driver circuit unit  17  applies the on voltage for the TFT unit  12  to the gate lines  13 A to drive the TFT units  12  in each row. Thus, the carriers are read out through the data lines  14 A.  
         [0053]    In contrast, the system B applies the on voltage for the TFT unit  12  to the gate lines  13 B to drive the TFT units  12 , for example, in two adjacent rows. Thus, the carriers are read out through the data lines  14 B.  
         [0054]    In the case where drive is performed by the system A in a panel having m×n photoelectric conversion element units  11  within the TFT matrix panel  1  having the gate lines  13 A arranged in the row direction and the data lines  14 A arranged in the column direction, in order to obtain one image, m gate lines  13 A are driven and the carriers are transferred to n data lines  14 A. That is, in the system A, only the pixels belonging to the same row are connected to each gate line.  
         [0055]    On the contrary, in the case where the drive is performed by the system B in the same panel as above, in order to obtain one image, m/2 gate lines are driven and the carriers are transferred to n/2 data lines  14 B. That is, in the system B, the pixels arranged in plural rows are connected in common to each gate line.  
         [0056]    Therefore, compared with the system A, the system B uses only half of the gate lines to drive, thereby making it possible to read out the carriers in approximately half the time.  
         [0057]    In other words, according to the structure of this embodiment, one pixel includes one photoelectric conversion element and two switching elements. One of the switching elements is connected to the gate line that connects in common only the pixels belonging to the same row (system A). The other switching element is connected to the gate line that connects in common the pixels arranged in plural rows (system B).  
         [0058]    Therefore, if the drive is performed in the system A, an image composed of the normal number of pixels is outputted, and if performed in the system B, an image in which four pixels are processed as one pixel is outputted. Accordingly, it becomes possible to perform the drive depending on the cases to obtain an image  1  having a long readout time and a high definition or an image  2  having a shorter readout time and a lower definition than the image  1 .  
         [0059]    In the case of using the photoelectric conversion element unit  11  of the MIS type, after reading out the carriers as described above, a bias is applied from a common electrode driver circuit unit  16  to a common electrode wiring  10  to perform a refresh drive for removing the electrons or the holes accumulated in an insulating film interface.  
         [0060]    [0060]FIG. 2 is a plan view schematically showing a part of the photoelectric conversion element unit  11  shown in FIG. 1. Here, each pixel composed of the photoelectric conversion element unit  11  and the TFT unit  12  is formed into a square so as to have a pixel pitch of approximately 100 to 200 μm both vertically and horizontally.  
         [0061]    In the system A, signals can be read out from the respective pixels in each row. In the system B, signals can be simultaneously read out from four pixels in two rows.  
         [0062]    In other words, by reading out the signals in the system A, it is possible to take in a high-definition image having a resolution of 100 to 200 μm being the pixel pitch.  
         [0063]    Also, by reading out the signals in the system B, a high-sensitivity sensor having a resolution of 200 to 400 μm which is double the pixel pitch can be realized. At the same time, both a processing time by the gate driver circuit unit  17  to drive and a processing time by the signal processing circuit unit  15  are approximately half of those in the system A, thereby enabling high-speed drive compared with the system A.  
         [0064]    [0064]FIG. 3 is a sectional view taken along the line  3 - 3  in FIG. 2. Here, a phosphor for converting radiation into visible light is also shown therein.  
         [0065]    The TFT unit  12  includes a gate electrode  22 , a gate insulating film  23 , a semiconductor layer  24 , an n-type semiconductor layer  25 , and a source/drain electrode  26 .  
         [0066]    The photoelectric conversion element unit  11  has the same structure as the TFT unit  12 . Each film of the photoelectric conversion element unit  11  is formed at the same time of the film forming process when forming the TFT unit  12 .  
         [0067]    The gate electrode  22  and a lower electrode  21  composes a two-layer structure of an Al—Nd film and a Mo film. The Al—Nd film is first formed by sputtering to have a thickness of approximately 30 to 400 nm. Then, while maintaining vacuum, the Mo film is formed thereon by sputtering as well to have a thickness of approximately 15 to 70 nm.  
         [0068]    The gate insulating film  23 , the semiconductor layer  24 , and the n-type semiconductor layer  25  are formed by CVD. A silicon nitride film as the gate insulating film  23 , the semiconductor layer  24 , and the n-type semiconductor layer  25  are continuously formed without breaking vacuum to have film thicknesses of approximately 150 to 400 nm, approximately 300 to 1000 nm, and approximately 10 to 100 nm, respectively.  
         [0069]    The source/drain electrode  26  and the common electrode wiring  10  are each formed of aluminum by sputtering to have a film thickness of approximately 200 to 2000 nm.  
         [0070]    After forming the TFT unit  12  and the photoelectric conversion element unit  11 , a silicon nitride protective film serving as an insulating protective film is formed thereon by CVD to have a thickness of approximately 200 to 1500 nm. In addition, a polyimide film  28  is formed thereon by spin coating to have a thickness of approximately 1 to 10 μm.  
         [0071]    Arranged in the further upper portion is a phosphor layer for converting radiation into visible light, in particular, a gadolinium oxysulphide phosphor (GOS) film in this embodiment. Lastly, a reflective film  30  is formed of aluminum serving both as a reflective layer and to protect the panel.  
         [0072]    Alternatively, instead of the structure as shown in FIG. 3, a layer structure as shown in FIG. 4 may be adopted as follows.  
         [0073]    [0073]FIG. 4 is a sectional view showing the vicinity of the photoelectric conversion element unit  11  and the TFT unit  12  provided to the radiation detection apparatus that uses amorphous selenium  35  for converting radiation into an electric signal.  
         [0074]    In that case, the phosphor layer for converting radiation into a visible light as shown in FIG. 3 is not used, thereby enabling simplification of the manufacturing process. More specifically, after forming the TFT unit  12 , the amorphous selenium  35  is deposited by vacuum evaporation. After that, ITO  31  is formed into a film serving as a common electrode, and the silicon nitride protective film and the polyimide film are formed thereon in order.  
         [0075]    An amorphous capacitor unit sandwiched between the ITO  31  and the lower electrode  21  functions as the photoelectric conversion element unit  11  to directly generate electrons and holes. Note that instead of the amorphous selenium  35 , lead iodide or mercury iodide may be used. Also, instead of the ITO  31 , a metal thin film having a low specific resistance, for example, an aluminum film having a thickness of approximately 100 to 1000 nm may be employed.  
         [0076]    Photolithography is used for patterning of each film and wet etching is used for etching of the metal films such as the Al—Nd film, the Mo film, and the aluminum film. However, dry etching may be used particularly for the Mo film and the aluminum film.  
         [0077]    Dry etching is used for etching of the silicon-based gate insulating film  23 , the semiconductor layer  24 , the n-type semiconductor layer  25 , and the silicon nitride protective film  27 .  
         [0078]    (Embodiment 2)  
         [0079]    [0079]FIG. 5 shows an equivalent circuit for a TFT matrix panel provided to a liquid crystal display device according to Embodiment 2 of the present invention.  
         [0080]    By using a bias applied from the gate driver circuit unit  17  to the plural gate lines  13 A,  13 B, TFT units  12  arranged in a matrix shape are driven.  
         [0081]    Thus, signals sent from the signal processing circuit unit  15  are transferred through the plural data lines  14 A,  14 B, and a voltage is applied to a liquid crystal capacitor unit  18  corresponding to each TFT unit  12 , so that an orientation direction of liquid crystal is changed to control liquid crystal display.  
         [0082]    Note that the adjacent data lines  14 A,  14 B may be made common so as to apply a voltage to each liquid crystal capacitor unit  18 .  
         [0083]    In the TFT matrix panel  1 , the gate driver circuit unit  17  has the system A and the system B which are separately provided therein, so that the respective systems can be independently driven. Similarly, the signal processing circuit unit  15  has the system A and the system B which are separately provided therein, so that signals can be outputted from the respective systems independently.  
         [0084]    The system A and the system B of the gate driver circuit unit  17  corresponds to the system A and the system B of the signal processing circuit unit  15 , respectively. In the case where the system A of the gate driver circuit unit  17  is driven to apply an on voltage for the TFT unit  12  to the gate lines  13 A of the system A, signals from the system A in the signal processing circuit unit  15  can be transferred to the liquid crystal capacitor unit  18  through the data lines  14 A.  
         [0085]    In contrast, in the case where the system B of the gate driver circuit unit  17  is driven to apply the on voltage for the TFT unit  12  to the gate lines  13 B of the system B, signals from the system B in the signal processing circuit unit  15  can be transferred to the liquid crystal capacitor unit  18  through the data lines  14 B.  
         [0086]    When the system A of the gate driver circuit unit  17  applies the on voltage for the TFT unit  12  to one gate line  13 A, the TFT unit  12  is driven for connecting one source electrode connected to the capacitor and one drain electrode connected to one data line  14 A for transferring a signal from the system A of the signal processing circuit unit  15 .  
         [0087]    In contrast, when the system B of the gate driver circuit unit  17  applies the on voltage for the TFT unit  12  to one gate line  13 B, the TFT unit  12  is driven for connecting two source electrodes connected to the capacitor and two drain electrodes connected to one data line  14 B for transferring a signal from the system B of the signal processing circuit unit  15 . That is, a common voltage can be applied to the pixels arranged in plural rows.  
         [0088]    In the case where drive is performed by the system in a panel composed of m×n liquid crystal capacitor units  18  within the TFT matrix panel  1  having the gate lines  13 A arranged in the row direction and the data lines  14 A arranged in the column direction, in order to display one image, m gate lines  13 A and n data lines  14 A are driven.  
         [0089]    In contrast, in the case where the drive is performed by the system B in the same panel as above, m/2 gate lines  13 B and the n/2 data lines  14 B are driven.  
         [0090]    Accordingly, in the system B, the gate driver circuit unit  17  can be driven in approximately half the time of the case in the system A. Similarly, a process by the signal processing circuit unit  15  can be performed in approximately half the time.  
         [0091]    [0091]FIG. 6 is a plan view showing a part of the liquid crystal display device including the TFT matrix panel shown in FIG. 5. Each pixel including the liquid crystal capacitor unit  18  is formed into a rectangle so as to have a pixel pitch of approximately 100 to 500 μm vertically and ⅓ thereof, that is, approximately 30 to 170 μm, horizontally.  
         [0092]    Each liquid crystal capacitor unit  18  is composed of a liquid crystal capacitor and a memory storage capacitor. Also, liquid crystal and color filters are arranged on each capacitor, and red (R), green (G), and blue (B) filters are arranged in order in the horizontal direction.  
         [0093]    By driving the system A, the signals from the signal processing circuit unit  15  can be independently transferred to the respective liquid crystal capacitor units  18 . By driving the system B, the signals can be simultaneously transferred to two liquid crystal capacitor units  18  arranged in vertical positions and having the same color filter thereon.  
         [0094]    Thus, in the liquid crystal display panel, by transferring the signals in the system A, it is possible to taken in a high-definition image having a resolution of 100 to 500 μm which is the pixel pitch.  
         [0095]    Also, in the liquid crystal display panel, by reading out the signals in the system B, while maintaining the horizontal resolution, the vertical resolution becomes 200 to 1000 μm which is double the pixel pitch. Therefore, the processing time by the gate driver circuit unit  17  becomes approximately half, thereby enabling high-speed drive.  
         [0096]    As a result, the liquid crystal display device of this embodiment includes a resolution priority mode, in particular, a mode for a personal computer display or high-quality still image display device, and a high-speed priority mode, in particular, a mode for a moving picture image display used for a household television set.  
         [0097]    Also, regarding the above pixel pitch, it is described that the horizontal pixel pitch is approximately ⅓ of the vertical pixel pitch. However, to the contrary, the vertical pixel pitch may be approximately ⅓ of the horizontal pixel pitch. Alternatively, the ratio of the vertical pixel pitch to the horizontal pixel pitch may be 3:2 or 2:3, and may also be 1:1 when driving two adjacent pixels having the same color simultaneously by the system B.  
         [0098]    [0098]FIG. 7 is a sectional view taken along the line  7 - 7  in FIG. 6. The TFT unit  12  is formed of the gate electrode  22 , the gate insulating film  23 , the semiconductor layer  24 , the n-type semiconductor layer  25 , and the source/drain electrode  26 .  
         [0099]    Also, the upper portion and the lower portion of the capacitor unit  18  are formed of ITO. As the insulating film therebetween, the gate insulating film formed when forming the TFT unit  12  is used.  
         [0100]    The gate electrode  22  is formed of chromium by sputtering to have a film thickness of approximately 30 to 250 nm.  
         [0101]    The gate insulating film  23 , the semiconductor layer  24 , and the n-type semiconductor layer  25  are formed by CVD. A silicon nitride film as the gate insulating film  23 , the semiconductor layer  24 , and the n-type semiconductor layer  25  are continuously formed without breaking vacuum to have film thicknesses of approximately 150 to 400 nm, approximately 50 to 200 nm, and approximately 10 to 100 nm, respectively.  
         [0102]    The source/drain electrode  26  is formed of aluminum by sputtering to have a film thickness of approximately 200 to 2000 nm.  
         [0103]    The silicon nitride protective film  27  serving as an insulating protective film is formed on the TFT unit  12  by CVD to have a thickness of approximately 200 to 1000 nm. In addition, a polyimide film  28  is formed thereon by spin coating to have a thickness of approximately 1 to 10 μm.  
         [0104]    Liquid crystal  32  is arranged in the further upper portion and the ITO  31  serving as an electrode and upper glass  33  are arranged thereon.  
         [0105]    Photolithography is used for patterning of each film and wet etching is used for etching of metal films such as the chromium film and the aluminum film. However, dry etching may be used therefor.  
         [0106]    Dry etching is used for etching of the silicon-based gate insulating film  23 , the semiconductor layer  24 , the n-type semiconductor layer  25 , and the silicon nitride protective film  27 .  
         [0107]    Note that in each embodiment of the present invention, the case of arranging the pixels in a matrix shape is exemplified. However, the pixels may be arranged in a delta shape or a honeycomb shape. Also, the TFT units  12  may be replaced by other transistors.  
         [0108]    Further, in each embodiment, the case of providing the gate line  13 B for connecting the pixels in two adjacent rows is exemplified. However, in the case of performing readout of the electric signal or the like at a higher speed, the gate line  13 B may be provided for connecting the pixels arranged in three rows.  
         [0109]    Further, the structure as shown in FIG. 5 described in Embodiment 2 can be applied to the photoelectric conversion apparatus or the radiation detection apparatus. That is, while four pixels in the system A are read out as one pixel by the system B in Embodiment 1, two pixels in the system A may be read out as one pixel.  
         [0110]    (Embodiment 3)  
         [0111]    This embodiment is described in relation to forming a structure provided with a photoelectric conversion unit on a switching element in the photoelectric conversion apparatus or the radiation detection apparatus. In FIG. 3 of Embodiment 1, the photoelectric conversion element and the switching element are arranged within the same plane. On the other hand, in this embodiment, by providing the photoelectric conversion unit on the switching element, further an improved aperture ratio can be realized. FIG. 9 is a sectional view thereof. FIG. 1 or FIG. 5 can be used as the equivalent circuit diagram.  
         [0112]    In FIG. 9, reference numeral  41  denotes an insulating substrate such as glass,  12  a switching element A belonging to the system A described in the above embodiments, and  19  a switching element B belonging to the system B. Reference numeral  61  denotes a gate electrode of the switching element A,  62  a gate electrode of the switching element B,  45  a gate insulating film,  46  a first semiconductor layer,  47  a first ohmic contact layer,  63  a leveling film,  64  a first electrode layer of the photoelectric conversion element,  65  an insulating layer,  66  a second semiconductor layer,  67  a second ohmic contact layer,  68  a second electrode layer,  69  a main electrode connected to the photoelectric conversion element of the switching element A, and  70  a main electrode connected to the photoelectric conversion element of the switching element B. Although not shown in FIG. 9, the main electrode  70  is further connected to the photoelectric conversion element of the adjacent pixel.  
         [0113]    Wherein, the main electrode of the switching element A and the main electrode of the switching element B are connected to the same photoelectric conversion element. And, either one of the switching elements A and B is by itself capable of transferring a signal to a data line. The other of the switching elements is at a time of operation capable of transferring the signals from a plurality of pixels simultaneously to one data wiring.  
         [0114]    According to the above structure, the photoelectric conversion element is formed by being laminated on the switching element, so that the aperture ratio can be improved and it is possible to simplify a drive circuit unit composed of the switching elements such as TFTs. In particular, in the case of using an MIS-type photoelectric conversion element as the photoelectric conversion element, after forming the leveling film  63 , a contact hole is formed. Then, the first electrode layer contacts an electrode of the TFT. Accordingly, by using the leveling film, it is possible to make the insulating film of the MIS-type photoelectric conversion element thinner, so that the sensitivity of the element can be more preferably improved.  
         [0115]    The present invention can also be effected by appropriately combining the embodiments described above. Further, the terms “row” and “column” are defined for illustration and can be interchangeably used.