Patent Publication Number: US-9405406-B2

Title: Image pickup device, display-and-image-pickup device, electronic apparatus and method of detecting an object

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     This is a Continuation of application Ser. No. 12/451,485, filed on Nov. 13, 2009, which is a National Stage of PCT/JP09/055328, filed on Mar. 18, 2009, which claims priority to Japanese Patent Application Number 2008-076281, filed in the Japanese Patent Office on Mar. 24, 2008, the entire contents of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to an image pickup device and a display-and-image-pickup device obtaining information such as the position of an object touching or in proximity to a panel, and an electronic apparatus including such a display-and-image-pickup device, and a method of detecting an object for obtaining such information. 
     BACKGROUND ART 
     Techniques of detecting the position or the like of an object touching or in proximity to a surface of a display have been heretofore known. Among them, as a typical and widespread technique, a display including a touch panel is cited. 
     There are various types of touch panels, but as a commonly used type, a touch panel of a type detecting capacitance is cited. When a finger touches the touch panel, the touch panel captures a change in a surface electric charge of the panel to detect the position or the like of an object. Therefore, when such a touch panel is used, users are allowed to intuitively operate the touch panel. 
     Moreover, the applicant of the invention has proposed displays having a display function of displaying an image and an image pickup function (a detection function) of picking up an image of an object (detecting an object) in Patent Document 1 and Patent Document 2. 
     [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2004-127272 
     [Patent Document 2] Japanese Unexamined Patent Application Publication No. 2006-276223 
     DISCLOSURE OF THE INVENTION 
     When a display described in the above-described Patent Document 1 is used, for example, in the case where an object such as a finger touches or comes in proximity to a display-and-image-pickup panel, the position or the like of the object is detectable based on an image picked up by using reflected light reflected by the object from illumination light from the display-and-image-pickup panel. Therefore, when this display is used, the position or the like of the object is detectable with a simple configuration without separately arranging a component such as a touch panel on a display-and-image-pickup panel. 
     However, in the case where the reflected light reflected by the object is used as described above, in some cases, outside light (environment light) or variations in characteristics of light-receiving elements cause an issue. More specifically, the luminance of received light depends on the brightness of outside light, so in some cases, it is difficult to detect the position or the like of the object based on a picked-up image. Moreover, variations in characteristics of the light-receiving elements cause stationary noises, thereby in some cases, it is difficult to detect the position or the like of the object based on the picked-up image. 
     Therefore, in the above-described Patent Document 2, a difference between an image obtained in a light-emitting state (an image obtained by using reflected light originating from illumination light) and an image obtained in a lighting-off state is detected to remove an influence by the above-described outside light or stationary noise. 
     More specifically, for example, as illustrated in a sectional view of  FIG. 55(A) , in the case where incident outside light (environment light) L 0  is strong, as illustrated in  FIG. 55(B) , a light reception output voltage Von 101  in a state in which a backlight  105  is on has a voltage value Va corresponding to the brightness of the environment light L 0  at a point other than a point touched by a finger f in a display area  101 , and at the point touched by the finger f in the display area  101 , the light reception output voltage Von 101  is reduced to a voltage value Vb corresponding to reflectivity at which illumination light Lon from the backlight  105  is reflected on the surface of an object (the finger F) touching the point at this time. On the other hand, as in the case of the light reception output voltage Von 101 , a light reception output voltage Voff 101  in a state in which the backlight  105  is off has the voltage value Va corresponding to the brightness of the environment light L 0  at a point other than the point touched by the finger f, but the point touched by the finger f is in a state in which the environment light L 0  is blocked, so the light reception output voltage Voff 101  has a very low-level voltage value Vc. 
     Moreover, as illustrated in a sectional view of  FIG. 56(A) , in a state in which the incident environment light L 0  is weak (very little), as illustrated in  FIG. 56(B) , a light reception output voltage Von 201  in a state in which the backlight  105  is on has the very low-level voltage value Vc at a point other than the point touched by the finger f in the display area  101 , because the environment light L 0  is not present, and at the point touched by the finger f in the display area  101 , the light reception output voltage Von 201  is increased to the voltage value Vb corresponding to reflectivity at which the illumination light Lon from the backlight  105  is reflected on the surface of the object (the finger f) touching the point at this time. On the other hand, a light reception output voltage Voff 2  in a state in which the backlight  105  is off remains unchanged at the very low-level voltage value Vc at the point touched by the finger f and any other point. 
     As described above, at a point not touched by the finger f in the display area  101 , the light reception output voltage is greatly different between the case where the environment light L 0  is present and the case where the environment light L 0  is not present. On the other hand, at the point touched by the finger f in the display area  101 , the voltage Vb when the backlight  105  is on and the voltage Vc when the backlight  105  is off are substantially in the same state irrespective of the presence or absence of the environment light L 0 . Therefore, it is considered that when a difference between a voltage when the backlight  105  is on and a voltage when the backlight  105  is off is detected, a point where there is a certain or larger difference such as a difference between the voltages Vb and Vc is allowed to be determined as a point where the object touches or comes in proximity, and, for example, like a difference image C illustrated in  FIG. 57 , the position or the like of the object is detectable without influence of outside light or stationary noises. 
     However, in a method of detecting an object using such a difference image C, for example, as illustrated in  FIG. 57 , frame memories or the like for two images, that is, an image when a backlight is off (an image A) and an image when the backlight is on (an image B) are necessary, thereby to cause an increase in component costs. 
     As described above, in related art, it is difficult to stably detect an object touching or in proximity to a panel irrespective of use conditions at the time while reducing manufacturing costs, and there is room for improvement. 
     The present invention is made to solve the above-described issues, and it is an object of the invention to provide an image pickup device, a display-and-image-pickup device and a method of detecting an object which are capable of stably detecting an object irrespective of use conditions while reducing manufacturing costs, and an electronic apparatus including such a display-and-image-pickup device. 
     An image pickup device of the invention includes: an image pickup panel including a plurality of image pickup pixels, and having an illumination light source for a proximity object; an image pickup drive means for obtaining an image pickup signal from each of the image pickup pixels by performing an image pickup drive on each of the image pickup pixels; and an image processing means for obtaining object information including one or more of position, shape and size of the proximity object through utilizing a picked-up image based on the image pickup signal obtained from each of the image pickup pixels. Moreover, the above-described image pickup drive means performs an image pickup drive so that when illumination light is emitted from the illumination light source, an electric charge for charging is accumulated in each of the image pickup pixels in accordance with total light amount as a summation of reflected light originating from the illumination light and environment light, and when the illumination light is not emitted from the illumination light source, an electric charge for discharging is released from each of the image pickup pixels in accordance with light amount of the environment light, thereby to obtain the image pickup signal from each of the image pickup pixels. In addition, “a proximity object” means not only a literally proximity object but also an object in a touch state. 
     A display-and-image-pickup device of the invention includes: a display-and-image-pickup panel including a plurality of display pixels and a plurality of image pickup pixels; a display drive means for displaying an image by performing a display drive on each of the display pixels; an image pickup drive means for obtaining an image pickup signal from each of the image pickup pixels by performing an image pickup drive on each of the image pickup pixels; and an image processing means for obtaining object information including one or more of position, shape and size of a proximity object through utilizing a picked-up image based on the image pickup signal obtained from each of the image pickup pixels. Moreover, the above-described image pickup drive means performs an image pickup drive so that when illumination light is emitted from the display-and-image-pickup panel to the proximity object, an electric charge for charging is accumulated in each of the image pickup pixels in accordance with total light amount as a summation of reflected light originating from the illumination light and environment light, and when the illumination light is not emitted from the display-and-image-pickup panel, an electric charge for discharging is released from each of the image pickup pixels in accordance with light amount of the environment light, thereby to obtain the image pickup signal from each of the image pickup pixels. In addition, “illumination light” means not only display light applied from the display-and-image-pickup panel but also light applied from another light source (for example, an infrared light source or the like) on the display-and-image-pickup panel. 
     An electronic apparatus of the invention includes the above-described display-and-image-pickup device having an image display function and an image pickup function. 
     A method of detecting an object of the invention includes steps of: performing an image pickup drive on each of a plurality of image pickup pixels so that when illumination light is emitted to a proximity object from an image pickup panel including the plurality of image pickup pixels, an electric charge for charging is accumulated in each of the image pickup pixels in accordance with total light amount as a summation of reflected light originating from the illumination light and environment light, and when the illumination light is not emitted, an electric charge for discharging is released from each of the image pickup pixels in accordance with light amount of the environment light, thereby obtaining an image pickup signal from each of the image pickup pixels; and obtaining object information including one or more of position, shape and size of the proximity object through utilizing a picked-up image based on the image pickup signal obtained from each of the image pickup pixels. 
     In the image pickup device, the display-and-image-pickup device, the electronic apparatus and the method of detecting an object of the invention, when illumination light is emitted to the proximity object from the image pickup panel or the display-and-image-pickup panel, an electric charge for charging is accumulated in each of the image pickup pixels in accordance with total light amount as a summation of reflected light originating from the illumination light and environment light. Moreover, when the above-described illumination light is not emitted, an electric charge for discharging is released from each of the image pickup pixels in accordance with light amount of the environment light. Thereby, an image pickup signal is obtained from each of the image pickup pixels. Then, object information including one or more of position, shape and size of the proximity object is obtained through utilizing a picked-up image based on the image pickup signal obtained from each of the image pickup pixels. Thereby, a component by the environment light is subtracted in the image pickup signal from each of the image pickup pixels, so object information about the proximity object is obtainable without influence of such environment light. Moreover, the image pickup signal is obtained from each of the image pickup pixels based on an operation of accumulating the electric charge for charging and an operation of releasing the electric charge for discharging, so a smaller number of necessary frame memories or the like for producing a picked-up image from the image pickup signal than that in related art are necessary. 
     According to the image pickup device, the display-and-image-pickup device, the electronic apparatus or the method of detecting an object of the invention, when illumination light is emitted to the proximity object from the image pickup panel or the display-and-image-pickup panel, an electric charge for charging is accumulated in each of the image pickup pixels in accordance with total light amount as a summation of reflected light originating from the illumination light and environment light, and when the above-described illumination light is not emitted, an electric charge for discharging is released from each of the image pickup pixels in accordance with light amount of the environment light, thereby the image pickup signal is obtained from each of the image pickup pixels, so object information about the proximity object is obtainable without influence of the environment light, and a smaller number of necessary frame memories or the like for producing a picked-up image from the image pickup signal than that in related art are necessary. Therefore, the object is stably obtainable irrespective of use conditions while reducing manufacturing costs. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram illustrating a configuration of a display-and-image-pickup device according to an embodiment of the invention. 
         FIG. 2  is a block diagram illustrating a configuration example of an I/O display panel illustrated in  FIG. 1 . 
         FIG. 3  is a plan view illustrating a pixel arrangement example in a display area (a sensor area) illustrated in  FIG. 2 . 
         FIG. 4  is a schematic plan view illustrating an example of a connection relationship between light-receiving sections and signal lines in a pixel arrangement illustrated in  FIG. 3 . 
         FIG. 5  is a circuit diagram illustrating a configuration example of a light-receiving section according to the embodiment of the invention. 
         FIG. 6  is a schematic view illustrating details of the connection relationship between the light-receiving sections and the signal lines in the pixel arrangement illustrated in  FIG. 3 . 
         FIG. 7  is a timing waveform chart illustrating an example of an image pickup operation in the display-and-image-pickup device according to the embodiment. 
         FIG. 8  is a timing waveform chart for describing details of the image pickup operation illustrated in  FIG. 7 . 
         FIG. 9  is a circuit diagram for describing a charge operation and a discharge operation during the image pickup operation illustrated in  FIGS. 7 and 8 . 
         FIG. 10  is a timing waveform chart for describing details of SW control signals illustrated in  FIG. 8  and a backlight state. 
         FIG. 11  is a plot for describing an image pickup operation according to a comparative example. 
         FIG. 12  is a schematic view for describing the image pickup operation illustrated in  FIG. 11 . 
         FIG. 13  is another plot for describing the image pickup operation according to the comparative example. 
         FIG. 14  is another plot for describing the image pickup operation according to the comparative example. 
         FIG. 15  is a circuit diagram illustrating a configuration example of a light-receiving section according to Modification Example 1 of the invention. 
         FIG. 16  is a schematic view illustrating details of a connection relationship between light-receiving sections and signal lines in a display area (a sensor area) according to Modification Example 1. 
         FIG. 17  is a circuit diagram for describing a charge operation and a discharge operation during an image pickup operation according to Modification Example 1. 
         FIG. 18  is a timing waveform chart for describing SW control signals and a backlight state during the image pickup operation according to Modification Example 1. 
         FIG. 19  is a circuit diagram illustrating a configuration example of another light-receiving section according to Modification Example 1 of the invention. 
         FIG. 20  is a circuit diagram illustrating a configuration example of a light-receiving section according to Modification Example 2 of the invention. 
         FIG. 21  is a timing waveform chart for describing an image pickup operation according to Modification Example 2. 
         FIG. 22  is a circuit diagram for describing a charge operation and a discharge operation during the image pickup operation according to Modification Example 2. 
         FIG. 23  is a timing waveform chart for describing SW control signals and a backlight state during the image pickup operation according to Modification Example 2. 
         FIG. 24  is a circuit diagram illustrating a configuration example of a light-receiving section in a display area (a sensor area) according to Modification Example 3 of the invention. 
         FIG. 25  is an illustration for describing an on-operation region and an off-operation region in a photoelectric transducer. 
         FIG. 26  is an illustration for describing an on-operation region and an off-operation region in a photoelectric transducer according to Modification Example 3. 
         FIG. 27  is a timing waveform chart for describing an image pickup operation according to Modification Example 3. 
         FIG. 28  is a timing waveform chart for specifically describing an on operation and an off operation in the photoelectric transducer according to Modification Example 3. 
         FIG. 29  is a circuit diagram for describing a charge operation and a discharge operation during the image pickup operation according to Modification Example 3. 
         FIG. 30  is a circuit diagram illustrating a configuration example of a light-receiving section in a display are (a sensor area) according to Modification Example 4 of the invention. 
         FIG. 31  is an illustration for describing an on-operation region and an off-operation region in a photoelectric transducer according to Modification Example 4. 
         FIG. 32  is an illustration for describing the on-operation region and the off-operation region in the photoelectric transducer according to Modification Example 4. 
         FIG. 33  is a timing waveform chart for describing an image pickup operation according to Modification Example 4. 
         FIG. 34  is a timing waveform chart for specifically describing an on operation and an off operation in the photoelectric transducer according to Modification Example 4. 
         FIG. 35  is a circuit diagram for describing a charge operation and a discharge operation during the image pickup operation according to Modification Example 4. 
         FIG. 36  is a circuit diagram illustrating a configuration example of a light-receiving section in a display area (a sensor area) in Modification Example 5 of the invention. 
         FIG. 37  is an illustration for describing an on-operation region and an off-operation region in a photoelectric transducer according to Modification Example 5. 
         FIG. 38  is an illustration for describing the on-operation region and the off-operation region in the photoelectric transducer according to Modification Example 5. 
         FIG. 39  is an illustration for describing the on-operation region and the off-operation region in the photoelectric transducer according to Modification Example 5. 
         FIG. 40  is an illustration for describing the on-operation region and the off-operation region in the photoelectric transducer according to Modification Example 5. 
         FIG. 41  is a timing waveform chart for describing an image pickup operation according to Modification Example 5. 
         FIG. 42  is a timing waveform chart for specifically describing an on operation and an off operation in the photoelectric transducer according to Modification Example 5. 
         FIG. 43  is a circuit diagram for describing a charge operation and a discharge operation during the image pickup operation according to Modification Example 5. 
         FIG. 44  is a circuit diagram illustrating a configuration example of a light-receiving section in a display area (a sensor area) in Modification Example 6 of the invention. 
         FIG. 45  is a plan view illustrating a pixel arrangement example in the display area (the sensor area) illustrated in  FIG. 44 . 
         FIG. 46  is an illustration for describing an example of an application using an image pickup result (a result of a fingertip extraction process) in the invention. 
         FIG. 47  is an illustration for describing an example of the application using the image pickup result (the result of the fingertip extraction process) in the invention. 
         FIG. 48  is an illustration for describing an example of the application using the image pickup result (the result of the fingertip extraction process) in the invention. 
         FIG. 49  is an illustration for describing an example of the application using the image pickup result (the result of the fingertip extraction process) in the invention. 
         FIG. 50  is a perspective view illustrating an appearance of Application Example 1 of a display-and-image-pickup device of the invention. 
         FIG. 51(A)  is a perspective view illustrating an appearance viewed from a front side of Application Example 2, and  FIG. 51(B)  is a perspective view illustrating an appearance viewed from a back side of Application Example 2. 
         FIG. 52  is a perspective view illustrating an appearance of Application Example 3. 
         FIG. 53  is a perspective view illustrating an appearance of Application Example 4. 
         FIGS. 54(A) and 54(B)  are a front view and a side view in a state in which Application Example 5 is opened, respectively, and  FIGS. 54(C), 54(D), 54(E), 54(F) and 54(G)  are a front view, a left side view, a right side view, a top view and a bottom view in a state in which Application Example 5 is closed, respectively. 
         FIG. 55  is a plot illustrating an example of an image pickup operation (a difference image fingertip extraction process) by a display-and-image-pickup device in related art. 
         FIG. 56  is a plot illustrating another example of the image pickup operation (the difference image fingertip extraction process) by the display-and-image-pickup device in related art. 
         FIG. 57  is photographs for describing the image pickup operation (the difference image fingertip extraction process) by the display-and-image-pickup device in related art. 
     
    
    
     BEST MODE(S) FOR CARRYING OUT THE INVENTION 
     A best mode for carrying out the invention (hereinafter simply referred to as embodiment) will be described in detail below referring to the accompanying drawings. 
       FIG. 1  illustrates the whole configuration of a display-and-image-pickup device according to an embodiment of the invention. The display-and-image-pickup device includes an I/O display panel  20 , a backlight  15 , a display drive circuit  12 , a light reception drive circuit  13 , an image processing section  14  and an application program execution section  11 . 
     The I/O display panel  20  configured of a liquid crystal panel (LCD (Liquid Crystal Display)) in which a plurality of pixels are arranged in a matrix form on the whole surface thereof, and has a function (display function) of displaying an image such as a predetermined symbol or character based on display data while performing a line-sequential operation, and a function (image pickup function) of picking up an image of an object (a proximity object) touching or in proximity to the I/O display panel  20 , as will be described later. Moreover, the backlight  15  is a light source for display and detection of the I/O display panel  20 , and is formed, for example, by arranging a plurality of light-emitting diodes, and as will be described later, the backlight  15  performs an on-off operation at high speed at a predetermined timing in synchronization with an operation timing of the I/O display panel  20 . 
     The display drive circuit  12  is a circuit driving the I/O display panel  20  (driving a line-sequential display operation) so as to display an image based on display data on the I/O display panel  20  (to perform a display operation). 
     The light reception drive circuit  13  is a circuit driving the I/O display panel  20  (driving a line-sequential image pickup operation) so as to obtain a light reception signal (an image pickup signal) from each pixel of the I/O display panel  20  (to pick up an image of an object). In addition, the light reception signal from each pixel is accumulated in a frame memory  13 A, for example, on a frame-by-frame basis to be outputted to the image processing section  14  as a picked-up image. 
     The image processing section  14  performs predetermined image processing (arithmetic processing) based on the picked-up image outputted from the light reception drive circuit  13 , and detects and obtains object information about the object touching or in proximity to the I/O display panel  20  (position coordinate data, data about the shape or size of the object, or the like). A process of detecting the object information will be described in detail later. 
     The application program execution section  11  executes a process according to predetermined application software based on a detection result by the image processing section  14 , and as the application program execution section  11 , for example, a section in which the position coordinates of a detected object are included in display data, and are displayed on the I/O display panel  20 , or the like is cited. In addition, display data produced in the application program execution section  11  is supplied to the display drive circuit  12 . 
     Next, a specific configuration example of the I/O display panel  20  will be described below referring to  FIG. 2 . The I/O display panel  20  includes a display area (a sensor area)  21 , a display H driver  22 , a display V driver  23 , a sensor readout H driver  25  and a sensor V driver  24 . 
     The display area (the sensor area)  21  is an area where light from the backlight  15  is modulated to emit illumination light (including display light and illumination light for detection from, for example, an infrared light source or the like (not illustrated), hereinafter the same meaning shall apply), and an image of an object touching or in proximity to the area is picked up, and in the display area  21 , liquid crystal elements which are light-emitting elements (display elements) and light-receiving elements (image pickup elements) which will be described later are arranged in a matrix form. 
     The display H driver  22 , together with the display V driver  23 , line-sequentially drives a liquid crystal element of each pixel in the display area  21  in response to a display signal for display drive and a control clock which are supplied from the display drive circuit  12 . 
     The sensor readout H driver  25 , together with the sensor V driver  24 , line-sequentially drives a light-receiving element of each pixel in the display area  21  to obtain a light reception signal. Moreover, although details will be described later, the sensor readout H driver  25  and the sensor V driver  24  perform an image pickup drive so that when illumination light is emitted from the I/O display panel  20  to a proximity object, an electric charge for charging is accumulated in each pixel in accordance with total light amount as a summation of reflected light originating from the illumination light and environment light, and when the illumination light is not emitted from the I/O display panel  20 , an electric charge for discharging is released from each pixel in accordance with the light amount of the environment light, thereby to obtain an image pickup signal (a light reception signal) for each pixel. 
     Next, referring to  FIGS. 3 to 6 , a specific configuration example of each pixel in the display area  21  will be described below. 
     First, for example, as illustrated in  FIG. 3 , the pixels  31  include display pixels (display sections)  31 RGB, image pickup pixels (light-receiving sections)  33 , and wiring sections  32  in which wiring for the image pickup pixels  33  is formed. Moreover, the display pixels  31 RGB include red (R) display pixels  31 R, green (G) display pixels  31 G and blue (B) display pixels  31 B. The display pixels  31 RGB, the image pickup pixels  33  and the wiring sections  32  are arranged on the display area  21  (the sensor area) in a matrix form. Moreover, the image pickup pixels  33  and the wiring sections  32  for performing an image pickup drive on the image pickup pixels  33  are arranged separately from each other at regular intervals. Such an arrangement allows the sensor area including the image pickup pixels  32  and the wiring sections  33  to be extremely inconspicuous among the display pixels  31 RGB, and allows a decline in aperture ratio in the display pixels  31 RGB to be minimized. Moreover, when the wiring sections  32  are arranged in a region not contributing the apertures of the display pixels  31 RGB (for example, a region where light is shielded by a black matrix, a reflection region, or the like), a light-receiving circuit is allowed to be arranged without degradation in display quality. In addition, as will be described in detail later, for example, as illustrated in  FIG. 4 , reset signal lines Reset_ 1  to Reset_n and read signal lines Read_ 1  to Read_n are connected to each of the image pickup pixels (light-receiving sections)  33  along a horizontal line direction. 
     Moreover, for example, as illustrated in  FIG. 5 , each of the light-receiving sections  33  includes a photoelectric transducer PD 1  as a light-receiving element generating an electric charge corresponding to the light amount of received light, a capacitor C 1  as a capacitor, four switching element SW 11  to SW 14  and three transistors Tr 1  to Tr 3 . The photoelectric transducer PD 1  generates both of an electric charge for charging and a discharge electric charge for the capacitor C 1 , and is configured of, for example, a photodiode, a phototransistor or the like. Herein, the photoelectric transducer PD 1  is configured of a PIN photodiode including an anode (formed in a p-type semiconductor region), a cathode (formed in an n-type semiconductor region) and a gate (for example, formed in an intrinsic semiconductor region), and the same hold true for photoelectric transducers according to modification examples which will be described later. Further, the transistors Tr 1  to Tr 3  each are configured of a thin film transistor (TFT) or the like. In the light-receiving section  33 , one end of the switching element SW 1  is connected to a power source VDD, and the other end of the switching element SW 1  is connected to one end of the switching element SW 13  and the cathode and the gate of the photoelectric transducer PD 1 . Moreover, one end of the switching element SW 12  is connected to a ground VSS, and the other end of the switching element SW 12  is connected to one end of the switching element SW 14  and the anode of the photoelectric transducer PD 1 . Further, the other end of the switching element SW 13  and the other end of the switching element SW 14  are connected to one end of the capacitor C 1 , a drain of the transistor Tr 1  and a gate of the transistor Tr 2  through a connection point P 1 . The other end of the capacitor C 1  is connected to the ground VSS. Moreover, a gate of the transistor Tr 1  is connected to a reset signal line Reset, and a source of the transistor Tr 1  is connected to a reset power source Vrst. Further, a source of the transistor Tr 2  is connected to the power source VDD, and a drain of the transistor Tr 2  is connected to a drain of the transistor Tr 3 . Moreover, a gate of the transistor Tr 3  is connected to a read signal line Read, and a source of the transistor Tr 3  is connected to a readout line  41 . Moreover, a charge circuit allowing an electric charge for charging to be accumulated (charged) in the capacitor C 1  is configured of the switching elements SW 11  and SW 14  functioning as switching elements for charging. Further, a discharge circuit allowing an electric charge for discharging to be released (discharged) from the capacitor C 1  is configured of the switching elements SW 12  and SW 13  functioning as switching elements for discharging. By such a configuration, as will be described in detail later, the switching elements SW 11  to SW 14  in the above-described charge circuit and the above-described discharge circuit are driven to pick up an image so that the electric charge for charging generated in the photoelectric transducer PD 1  is accumulated in the capacitor C 1  through the switching elements SW 11  and SW 14  for charging, and the electric charge for discharging generated in the photoelectric transducer PD 1  is released from the capacitor C 1  through the switching elements SW 12  and SW 13  for discharging, thereby an image pickup signal is obtained from each of the light-receiving sections (the image pickup pixels)  33 . In addition, the voltage of the above-described reset power source Vrst (a reset voltage allowing whole of the electric charge accumulated in the capacitor C 1  in each of the light-receiving sections  33  to be released) is settable to an arbitrary voltage between a power source voltage VDD and a ground voltage VSS. 
     In addition, a circuit part in each of the light-receiving sections (the image pickup pixels)  33  described in  FIG. 5 , the display pixels  31 RGB, the reset signal line Reset, the read signal line Read, the readout line  41 , a power source line VDD, a ground line VSS and a reset voltage line Vrst, an SW control line Sa to which an SW control signal for controlling switching of the switching signals SW 11  and S 14  is supplied, and an SW control line Sb to which an SW control signal for controlling switching of the switching signals SW 12  and S 13  is supplied are arranged in the display area (the sensor area)  21 , for example, as illustrated in  FIG. 6 . 
     Next, operation of the display-and-image-pickup device of the embodiment will be described in detail below. 
     First, an operation of displaying an image and an operation of picking up an image of an object by the display-and-image-pickup device will be briefly described below. 
     In the display-and-image-pickup device, a drive signal for display is produced in the display drive circuit  12  based on display data supplied from the application program execution section  11 , and a line-sequential display drive is performed on the I/O display panel  20  in response to the drive signal to display an image. Moreover, at this time, the backlight  15  is also driven by the display drive circuit  12  to perform a lighting-on/off operation in synchronization with the I/O display panel  20 . 
     Here, in the case where there is an object (for example, a fingertip or the like) which touches or comes in proximity to the I/O display panel  20 , an image of the object is picked up in each of the image pickup pixels  33  in the I/O display panel  20  by a line-sequential light reception drive by the light reception drive circuit  13 , and an image pickup signal from each of the image pickup pixels  32  is supplied to the light reception drive circuit  13 . In the light reception drive circuit  13 , the image pickup signals from the image pickup pixels  33  for one frame are accumulated, and are outputted to the image processing section  14  as a picked-up image. 
     Then, in the image processing section  14 , predetermined image processing (arithmetic processing) which will be described later is performed based on the picked-up image so as to obtain object information about the object touching or in proximity to the I/O display panel  20  (position coordinate data, data about the shape or size of the object, or the like). 
     Next, details of an image pickup operation of the embodiment, and a process (a fingertip extraction process) of extracting an object (a proximity object such as a fingertip) which touches or comes in proximity to the I/O display panel  20  by the image processing section  14  will be described below referring to  FIGS. 7 to 14 . Here,  FIG. 7  illustrates an example of the image pickup operation of the embodiment with a timing waveform chart, and (A) to (D) indicate reset signal voltages V(Reset_ 1 ), V(Reset_ 2 ), V(Reset_ 3 ) and V(Reset_n), respectively, and (E) to (H) indicate read signal voltages V(Read_ 1 ), V(Read_ 2 ), V(Read_ 3 ) and V(Read_n), respectively, and (I) indicates a control signal (the SW control signal Sa) for the switching elements SW 11  and SW 14 , and (J) indicates a control signal (the SW control signal Sb) for the switching elements SW 12  and SW 13 . Moreover,  FIG. 8  illustrates details (an image pickup operation in one light-receiving element  31 ) of the image pickup operation illustrated in  FIG. 7  with a timing waveform chart, and (A) indicates a reset signal voltage V(Reset), and (B) indicates a read signal voltage V(Read), and (C) and (D) indicate the SW control signals Sa and Sb, respectively, and (E) indicates a potential (accumulation potential) VP 1  at the connection point P 1 , and (F) indicates a potential (readout voltage) V 41  of the readout line  41 . Further,  FIGS. 11 to 14  are plots and a schematic view for describing an image pickup operation in related art according to a comparative example. 
     First, for example, as illustrated in  FIG. 7 , the reset signal voltages V(Reset_ 1 ), V(Reset_ 2 ), V(Reset_ 3 ) and V(Reset_n) and the read signal voltages V(Read_ 1 ), V(Read_ 2 ), V(Read_ 3 ) and V(Read_n) are brought into an H (high) state by a line-sequential operation. In the light-receiving sections  33  on each horizontal line, as will be described in detail later, a period from when the read signal voltage V(Read) is brought into the H state to when the read signal voltage V(Read) is brought into the H state is an exposure period. Moreover, the backlight  15  alternately changes between an ON state and an OFF state in synchronization with the line-sequential operations of such a reset signal voltage V(Reset) and such a read signal voltage V(Read), and the SW control signals Sa and Sb are brought into the H (high) state in synchronization with the switching operation between ON/OFF states of the backlight  15 , and the switching SW 11  to SW 14  are brought into an on-state. Further, the SW control signal Sa and the SW control signal Sb are alternately brought into the H state. More specifically, when the backlight  15  is in the ON state, the SW control signal Sa is brought into the H state, and the SW control signal Sb is brought into an L (low) state, and when the backlight  15  is in the OFF state, the SW control signal Sa is brought into the L state, and the SW control signal Sb is brought into the H state. 
     At this time, the image pickup operation in one light-receiving element  31  is, for example, as illustrated in  FIG. 8 . That is, first, when the reset signal voltage V(Reset) is brought into the H state at a timing t 10 , the transistor Tr 1  is brought into the on-state, thereby the potential VP 1  (the accumulation potential) at the connection point P 1  is reset to the reset voltage Vrst (in this case, Vrst=VSS) which is arbitrarily set. 
     Next, in a period from a timing t 11  to a timing t 12 , the backlight  15  is brought into the ON state, and the SW control signal Sa and the SW control signal Sb are brought into the H state and the L state, respectively, thereby an operation of accumulating an electric charge for charging in the capacitor C 1  (a charge operation) is performed in synchronization with a horizontal period (an ON switching period and an OFF switching period of the backlight  15 ) during a display drive. More specifically, for example, as illustrated in  FIG. 9(A) , the switching elements SW 11  and SW 14  for charging are brought into the on-state, and the switching elements SW 12  and SW 13  for discharging are brought into the off-state. Thereby, the electric charge for charging is accumulated in the capacitor C 1  along a path of a charging current I 11  illustrated in the drawing in accordance with the total light amount as a summation of reflected light Lon reflected by the proximity object of illumination light from the backlight  15  and outside light (environment light) L 0  so as to cause a rise in the accumulation potential VP 1 . 
     Next, in a period from the timing t 12  to a timing t 13 , the backlight  15  is brought into the OFF state, and the SW control signal Sa and the SW control signal Sb are brought into the L state, and the H state, respectively, thereby an operation of releasing the electric charge for discharging from the capacitor C 1  (a discharge operation) is performed in synchronization with a horizontal period (the ON/OFF switching operation of the backlight  15 ) during the display drive. More specifically, for example, as illustrated in  FIG. 9(B) , the switching elements SW 11  and SW 14  for charging are brought into the off-state, and the switching elements SW 12  and SW 13  for discharging are brought into the on-state. Thereby, the electric charge for discharging is released from the capacitor C 1  through a path of a discharging current I 12  illustrated in the drawing in accordance with the light amount of the outside light (the environment light) L 0  to cause a decline in the accumulation potential VP 1 . 
     Then, multiple times of switching between such an operation of accumulating the electric charge for charging and such an operation of releasing the electric charge for discharging are performed until a timing t 14  (during the exposure period), and after that, an electric charge accumulated in the capacitor C 1  during the switching is read out as an image pickup signal. More specifically, when the read signal voltage V(Read) is brought into the H state at the timing t 14 , the transistor Tr 3  is brought into the on-state, and in a period from a timing t 15  to a timing t 16 , the voltage of the accumulation potential VP 1  is read out from the readout line  41 . Thus, when the image pickup signal is read out after multiple times of switching between the operation of accumulating the electric charge for charging and the operation of releasing the electric charge for discharging, the exposure period becomes longer, so as illustrated in  FIG. 8(E) , a signal component (the accumulation potential VP 1 ) of the image pickup signal increases. Moreover, the image pickup signal obtained herein is an analog value, so A/D (analog/digital) conversion is performed on the image pickup signal in the light reception drive circuit  13 . In addition, after that, the reset signal voltage V(Reset) is brought into the H state at a timing t 16 , thereby the same operation from the timing t 10  to the timing t 16  is repeated. 
     In addition, more specifically, for example, as illustrated in  FIG. 10 , a period in which the SW control signal Sa is in the H state and a period in which the SW control signal Sb is in the H state are set so as not to overlap one another (a non-overlap period is set), thereby the generation of a leakage current in the light-receiving section  33  is prevented. 
     Next, in the image processing section  14 , arithmetic processing of determining the centroid of an picked-up image for one frame produced in the light reception drive circuit  13  is performed to determine the touch (proximity) center. Then, a result of the detection of the proximity object is outputted from the image processing section  14  to the application program execution section  11 , thereby the fingertip extraction process by the image processing section  14  is completed. 
     Thus, in the fingertip extraction process of the embodiment, when illumination light is emitted from the backlight  15  to the proximity object by the I/O display panel  20 , the electric charge for charging is accumulated in each of the image pickup pixels  33  in accordance with the total light amount as a summation of the reflected light Lon originating from the illumination light and the environment light (the outside light) L 0 . Moreover, when the above-described illumination light is not emitted, the electric charge for discharging is released from each of the image pickup pixels  33  in accordance with the light amount of the environment light L 0 . Therefore, the image pickup signal is obtained from each of the image pickup pixels  33 . Then, in the image processing section  14 , object information including one or more of position, shape and size of the proximity object is obtained through utilizing a picked-up image based on the image pickup signal obtained from each of the image pickup pixels  33 . Thereby, a component by the environment light L 0  is subtracted in the image pickup signal obtained from each of the image pickup pixels  33 , so the object information about the proximity object is obtainable without influence of such environment light L 0 . 
     Moreover, the image pickup signal is obtained from each of the image pickup pixels  33  based on the operation of accumulating the electric charge for charging and the operation of releasing the electric charge for discharging, so in the light reception drive circuit  13 , a smaller number of necessary frame memories  13 A for producing the picked-up image from the image pickup signal than that in related art (for example, as illustrated in  FIG. 58 , frame memories for two images, that is, an image (an image A) when a backlight is off and an image (an image B) when the backlight is on are necessary) are necessary. 
     In addition, in the fingertip extraction process, information about a plurality of touching or proximity objects which are placed on the display area  21  of the I/O display panel  20  at one time such as the positions, shapes, sizes or the like of the objects is obtainable. 
     Moreover, in a comparative example illustrated in  FIGS. 11 and 12  (for example, a fingertip extraction process in related art illustrated in  FIGS. 57 and 58 ), as indicated by an arrow in  FIG. 11 , in the case where the proximity object is moving on the display area  21  of the I/O display panel  20 , the following issue occurs. That is, under actual use conditions, for example, as illustrated in  FIG. 12 , there is a time difference between an image A 101  obtained when the backlight is in the off-state and an image B 101  obtained when the backlight is in the on-state. Therefore, for example, as illustrated in  FIG. 11 , in the case where the proximity object is moving at high speed on the I/O display panel  20 , or the like, the time difference causes a difference in the position of a part corresponding to the proximity object between a light reception output signal Voff(A 101 ) in the image A 101  and a light reception output signal Von(B 101 ) in the image B 101 . Then, due to such a position, in a difference image C 101  (=B 101 −A 101 ) between these two images A 101  and B 101  and a light reception detection signal V(C 101 ) (=Von(B 101 −Voff(A 101 )), as illustrated in  FIGS. 11 and 12 , in addition to an original signal corresponding to the position of the proximity object, a spurious signal F 101  is generated at another position. Therefore, in the fingertip extraction process according to the comparative example, in some cases, it is difficult to stably detect the proximity object due to the presence of such a spurious signal F 101 . In addition, when the proximity object moves quickly, an area where the spurious signal is generated tends to increase, and the stronger the outside light, the stronger the spurious signal tends to be. 
     On the other hand, in the embodiment, as described above, in the case where, for example, at least the proximity object is moving on the I/O display panel  20 , or the like, the image pickup drive is performed on each of the image pickup pixels  33  so that the electric charge for charging is accumulated, and the electric charge for discharging is released, thereby the image pickup signal is obtained from each of the image pickup pixels  33 , and object information about the proximity object is obtained through utilizing the picked-up image based on such an image pickup signal. Therefore, for example, when the period of switching between the ON/OFF states of the backlight  15  is set to be extremely short, even if the proximity object is moving on the display area  21  of the I/O display panel  20  during such a period of switching, the moving distance of the proximity object is extremely short, so the generation of the spurious signal is minimized (or prevented). 
     Moreover, in a comparative example illustrated in  FIGS. 13 and 14  (for example, the fingertip extraction process in related art illustrated in  FIGS. 57 and 58 ), the following issue may occur. That is, in each image pickup pixel in the actual I/O display panel  20 , the accumulation capacity for light is limited. Here, for example, as illustrated in  FIGS. 13(A)  and (B), when the light amount of the outside light L 0  is large, and an electric charge larger than the accumulation capacity flows, in the case where the proximity object is a finger f or the like, as indicated by light reception output signals Von 301  and Voff 301  in the drawings, the light reception output signals Von 301  and Voff 301  do not exceed the accumulation capacity in a part shadowed by the finger f, or the like, so the detection of the proximity object is allowed. On the other hand, as illustrated in  FIGS. 14(A)  and (B), in the case where the proximity object is a very thin object such as a pen ob 1 , the case where the proximity object has a distance from the I/O display panel  20 , or the like, as indicated by light reception output signals Von 401  and Voff 401  and a reference numeral P 401 , in some cases, in a part shadowed by the pen ob 1  or the like, the light reception output signals Von 401  and Voff 401  exceed the accumulation capacity and reach a high level. In such a case, a difference signal between the light reception output signals Von 401  and Voff 401  exceeds the accumulation capacity of the image pickup pixel, thereby the proximity object is not allowed to be detected by using a difference result. 
     On the other hand, in the embodiment, irrespective of an exposure time, the component of the outside light L 0  is invariably removed, so under any outside light condition, the limited accumulation capacity is allowed to be prevented from being filled with only the component of the outside light L 0  (depending on the period of switching between the ON/OFF states of the backlight  15 , a capacity accumulated by one charge operation and one discharge operation is determined). 
     As described above, in the embodiment, when illumination light from the backlight  15  is emitted to the proximity object from the I/O display panel  20 , the electric charge for charging is accumulated in each image pickup pixel  33  in accordance with the total light amount as a summation of the reflected light Lon originating from the illumination light and the environment light (outside light) L 0 , and when the above-described illumination light is not emitted, the electric charge for discharging is released from each image pickup pixel  33  in accordance with the light amount of the environment light L 0 , thereby the image pickup signal is obtained from each image pickup pixel  33 , so in the image pickup signal obtained from each image pickup pixel  33 , the component by the environment light L 0  is subtracted, so the object information about the proximity object is obtainable without influence of such environment light L 0 . Moreover, the image pickup signal is obtained from each image pickup pixel  33  based on the operation of accumulating the electric charge for charging and the operation of releasing the electric charge for discharging, so in the light reception drive circuit  13 , a smaller number of necessary frame memories  13 A for producing a picked-up image from the image pickup signal than that in related art are necessary (a frame memory for difference detection is not necessary). Therefore, the object is stably detectable irrespective of use conditions while reducing manufacturing costs. 
     More specifically, in each image pickup pixel (each light-receiving section)  33 , the photoelectric transducer PD 1  generates both of the electric charge for charging and the electric charge for discharging, and the electric charge for charging generated in the photoelectric transducer PD 1  is accumulated in the capacitor C 1  through the switching elements SW 11  and SW 14  for charging, and the electric charge for discharging generated in the photoelectric transducer PD 1  is released from the capacitor C 1  through the switching elements SW 12  and SW 13  for discharging, so the above-described effects are obtainable. 
     Moreover, the operation of accumulating the electric charge for charging (charge operation) and the operation of releasing the discharge electric charge (discharge operation) each are in synchronization with the horizontal period during the display drive, so coupling noises are allowed to be reduced. 
     Further, the object information is obtained based on the image pickup signals obtained after multiple times of switching between the operation of accumulating the electric charge for charging and the operation of releasing the electric charge for discharging, so the exposure period is allowed to be longer, and an improvement in the detection sensitivity is allowed by increasing the signal component (the accumulation potential VP 1 ) of the image pickup signal, and the exposure time is freely settable, so an increase in an S/N ratio is allowed. 
     Moreover, for example, when the period of switching between the ON/OFF states of the backlight  15  is set to be extremely short, even in the case where the proximity object is moving on the display area  21  of the I/O display panel  20 , the generation of the spurious signal is allowed to be minimized (or prevented), thereby a further improvement in the detection sensitivity is allowed. Further, difference processing is performed in synchronization with a rapid period of switching between the ON/OFF states of the backlight  15 , so the moving object is easily detectable. 
     Further, in the capacitor C 1  in each image pickup pixel  33 , only the electric charge by the reflected light Lon is accumulated, so at the time of A/D conversion on the image pickup signal, it is not necessary to set an unnecessary range for the outside light L 0  or the like (the bit length (word length) of an A/D converter is effectively utilizable), and an improvement in use efficiency is allowed (an improvement in the S/N ratio is allowed). 
     In addition, a dark current component resulting from a temperature change is removable by the image pickup drive by the embodiment. 
     Moreover, at the time of reading out the image pickup signal, in related art, the moving object is followed more precisely by reading out the image pickup signal at high speed, but on the other hand, in the embodiment, the readout speed and the following capability for the moving object may be completely independent of each other. Therefore, the exposure time is freely settable, so a demand for light reception sensitivity is allowed to be more moderate than that in related art, and the readout speed is allowed to be set slower. 
     Further, in the light-receiving section  33  of the embodiment, when the backlight  15  is brought into the OFF state, and only the operation of accumulating the electric charge for charging is performed, shadow detection using the outside light L 0  is allowed to be performed. 
     Some modification examples of the invention will be described below. In addition, like components are denoted by like numerals as of the above-described embodiment and will not be further described. 
     Modification Example 1 
       FIG. 15  illustrates a circuit configuration of a light-receiving section (a light-receiving section  33 A) according to Modification Example 1. The light-receiving section (image pickup pixel)  33 A is distinguished from the light-receiving section  33  described in the above-described embodiment by the fact that the light-receiving section  33 A includes two photoelectric transducers PD 21  and PD 22  and two switching elements SW 21  and SW 22 . More specifically, a cathode and a gate of the photoelectric transducer PD 21  are connected to the power source VDD, and an anode of the photoelectric transducer PD 21  is connected to one end of the switching element SW 21 . Moreover, an anode of the photoelectric transducer PD 22  is connected to the ground VSS, and a cathode and a gate of the photoelectric transducer PD 22  are connected to one end of the switching element SW 22 . Further, the other end of the switching element SW 21  and the other end of the switching element SW 22  are connected to the connection point P 1 . Moreover, as in the case of the above-described embodiment, for example, as illustrated in  FIG. 16 , the light-receiving section  33 A is arranged so that the image pickup pixel  33 A and the wiring section  32  for driving the image pickup pixel  33 A to pick up an image are separated from each other in a display area (a sensor area)  21 A. In addition, any other circuit configuration is the same as that of the light-receiving section  33 , and will not be further described. 
     Moreover, in the light-receiving section  33 A, the photoelectric transducer PD 21  functions as a photoelectric transducer for generating an electric charge for charging, and the photoelectric transducer PD 22  functions as a photoelectric transducer for generating an electric charge for discharging. Further, the switching element SW 21  functions as a switching element for charging, and the switching element SW 22  functions as a switching element for discharging. Thereby, an image pickup drive is performed so that, for example, as illustrated in  FIG. 17(A) , the electric charge for charging (in accordance with the total light amount as a summation of the reflected light Lon and the outside light L 0 ) generated in the photoelectric transducer PD 21  is accumulated in the capacitor C 1  through the switching element SW 21  for charging, and, for example, as illustrated in  FIG. 17(B) , the electric charge for discharging (in accordance with the light amount of the outside light L 0 ) generated in the photoelectric transducer PD 22  is released from the capacitor C 1  through the switching element SW 22  for discharging. 
     Thus, also in the modification example, the same fingertip extraction process is performed by the same image pickup operation as that in the above-described embodiment. Thereby, also in the modification example, the object is stably detectable irrespective of use conditions while reducing manufacturing costs. 
     Moreover, one of the cathode of the photoelectric transducer PD 21  and the anode of the photoelectric transducer PD 22  is constantly connected to the power source VDD or the ground VSS, so coupling noises which occur during on/off operations of the switching elements SW 21  and SW 22  is allowed to be reduced. 
     Further, only two switching elements are necessary in the light-receiving section  33 A (in the light-receiving section  33  of the above-described embodiment, four switching elements SW 11  to SW 14  are necessary), so wiring capacities in signal lines of the SW control signals Sa and Sb are reduced to allow a reduction in power consumption. 
     Moreover, in the light-receiving section  33 A of the modification example, unlike the light-receiving section  33  of the above-described embodiment, a path for the generation of a leakage current is not present, so, for example, as illustrated in  FIG. 18 , a period in which the SW control signal Sa is in the H state and a period in which the SW control signal Sb is in the H state may overlap one another (a non-overlap period is not set). 
     In addition, in the modification example, for example, like a light-receiving section (an image pickup pixel)  33 B, switching elements SW 23  and SW 24  for removing an electric charge accumulated in a parasitic capacity during the off-states of the switching elements SW 21  and SW 22  are preferably arranged. More specifically, the switching element SW 23  is arranged between the anode of the photoelectric transducer PD 21  and the one end of the switching element SW 21 , and the ground VSS. Moreover, the switching element SW 24  is arranged between the cathode of the photoelectric transducer PD 22  and the one end of the switching element SW 22 , and the power source VDD. 
     Modification Example 2 
       FIG. 20  illustrates a circuit configuration of a light-receiving section (a light-receiving section  33 C) according to Modification Example 2. The light-receiving section (image pickup pixel)  33 C includes two photoelectric transducers PD 31  and PD 32  and four switching elements SW 31  to SW 34 . More specifically, one end of the switching element SW 31  and one end of the switching element SW 33  are connected to the power source VDD, and the other end of the switching element SW 31  is connected to a cathode and a gate of the photoelectric transducer PD 31 , and the other end of the switching element SW 33  is connected to one end of the capacitor C 1  and one end of the switching element SW 34 . Moreover, an anode of the photoelectric transducer PD 31  is connected to the other end of the capacitor C 1 , a cathode and a gate of the photoelectric transducer PD 32  and the connection point P 1 . Further, an anode of the photoelectric transducer PD 32  is connected to one end of the switching element SW 32 . Moreover, the other end of the switching element SW 32  and the other end of the switching element SW 34  are connected to the ground VSS. In addition, any other circuit configuration is the same as those in the light-receiving sections  33  and  33 A, and will not be further described. 
     In the light-receiving section  33 C, for example, as illustrated in  FIG. 21 , an image pickup operation is performed at timings t 20  to t 26  in the drawing by SW control signals S 1  to S 4  for the switching elements SW 31  to SW 34 , the read signal voltage V(Read) and the reset signal voltage V(Reset). More specifically, an image pickup drive is performed so that, for example, as illustrated in  FIG. 22(A) , an electric charge for charging (in accordance with the total light amount as a summation of the reflected light Lon and the outside light L 0 ) generated in the photoelectric transducer PD 31  is accumulated in the capacitor C 1  through the switching elements SW 31  and SW 34  for charging, and, for example, as illustrated in  FIG. 22(B) , an electric charge for discharging (in accordance with the light amount of the outside light L 0 ) generated in the photoelectric transducer PD 32  is released from the capacitor C 1  through the switching elements SW 32  and SW 33  for discharging. Moreover, at this time, one end of the capacitor C 1  is alternately switched to be connected to the power source VDD through the switching element SW 33  and the ground VSS through the switching element SW 34  between a period of accumulating the electric charge for charging and a period of releasing the electric charge for discharging. 
     Thus, also in the modification example, the same fingertip extraction process is performed by the same image pickup operation as in the case of the above-described embodiment. Thereby, also in the modification example, the object is stably detectable irrespective of use conditions while reducing manufacturing costs. 
     Moreover, one end of the capacitor C 1  is alternately switched to be connected to the power source VDD through the switching element SW 33  and the ground VSS through the switching element SW 34  between a period accumulating the electric charge for charging and a period of releasing the electric charge for discharging, so a voltage applied to both ends of the photoelectric transducers PD 31  and PD 32  is allowed to be substantially equal to (VDD−VSS) without arbitrarily inputting a reset voltage, and the reset signal lines are allowed to be reduced. 
     In addition, also in the light-receiving section  33 C of the modification example, to prevent the generation of a leakage current as in the case of the light-receiving section  33  of the above-described embodiment, for example, as illustrated in  FIG. 23 , a period in which the SW control signal Sa is in the H state and a period in which the SW control signal Sb is in the H state are preferably prevented from overlapping one another (a non-overlap period is preferably set). 
     Modification Example 3 
       FIG. 24  illustrates a circuit configuration of a light-receiving section (a light-receiving section  33 D) according to Modification Example 3. The light-receiving section (an image pickup pixel)  33 D includes two photoelectric transducer PD 41  (a first photoelectric transducer) and PD 42  (a second photoelectric transducer). More specifically, in the photoelectric transducer PD 41 , a cathode is connected to the power source VDD, and an anode is connected to a cathode of the photoelectric transducer PD 42  and the connection point P 1 , and a gate is connected to a signal line φ 1 . Moreover, in the photoelectric transducer PD 42 , an anode is connected to the ground VSS, and a gate is connected to a signal line φ 2 . That is, in the light-receiving section  33 D, unlike the above-described light-receiving sections  33 ,  33 A,  33 B and  33 C, while the switching element is not arranged, gate potentials of the photoelectric transducers PD 41  and PD 42  are controlled by the signal lines φ 1  and φ 2 , respectively. In addition, any other circuit configuration is the same as that of the light-receiving section  33  or the like, and will not be further described. 
     In the modification example (and Modification Examples 4 and 5 which will be described later), an operation of switching a current path is performed by switching the photoelectric transducers between an on-operation region and an off-operation region instead of the above-described operation of switching a current path by using the switching element. More specifically, the photoelectric transducers PD 41  and PD 42  are separately set to the on-state or the off-state through separately changing a potential relationship between the cathode and the gate in the photoelectric transducer PD 41  and a potential relationship between the anode and the gate in the photoelectric transducer PD 42 . 
     Here, for example, as illustrated in  FIG. 25(A) , in the case where the anode potentials of the photoelectric transducers PD 41  and PD 42  are Vp, the cathode potentials of the photoelectric transducers PD 41  and PD 42  are Vn, the gate potentials of the photoelectric transducers PD 41  and PD 42  are Vg, and a photocurrent flowing from the cathode to the anode is Inp, I-V characteristics in the photoelectric transducers PD 41  and PD 42  are, for example, as illustrated in  FIG. 25(B) . That is, when the gate potential (a gate voltage) Vg is changed, a voltage region of Vp&lt;Vg&lt;Vn is an on-operation region α in which the photoelectric transducers PD 41  and PD 42  are in an on-state. On the other hand, a voltage region of Vn&lt;Vg is an off-operation region β 1  in which the photoelectric transducers PD 41  and PD 42  are in an off-state, and a voltage region of Vg&lt;Vp is an off-operation region β 2  in which the photoelectric transducers PD 41  and PD 42  are in the off-state. Thus, photoelectric conversion efficiency in these photoelectric transducers PD 41  and PD 42  is allowed to be changed through separately changing the potential relationship between the cathode and the gate in the photoelectric transducer PD 41  and the potential relationship between the anode and the gate in the photoelectric transducer PD 42 . Therefore, in the modification example (and Modification Examples 4 and 5 which will be described later), the photoelectric transducers PD 41  and PD 42  are separately set to the on-state or the off-state by actively using such a change in photoelectric conversion efficiency. 
     More specifically, in the modification example, first, as illustrated in  FIG. 24 , the cathode potential in the photoelectric transducer PD 41  is fixed to the power source VDD, and the anode potential in the photoelectric transducer PD 42  is fixed to the ground VSS. Moreover, as illustrated in  FIG. 24  and  FIGS. 26(A)  to (C), the gate voltages Vg in these photoelectric transducers PD 41  and PD 42  are changed by the signal lines φ 1  and φ 2 , respectively. More specifically, the gate voltage Vg of the photoelectric transducer PD 41  is changed alternately between Vg 11  and Vg 12  by the potential V(φ 1 ) of the signal line φ 1  (refer to an arrow P 41  in  FIG. 26(C) ; Vg 12 &lt;Vg 11 ). Moreover, the gate voltage Vg of the photoelectric transducer PD 42  is changed alternately between Vg 21  and Vg 22  by the potential V(φ 2 ) of the signal line φ 2  (refer to an arrow P 42  in  FIG. 26(C) ; Vg 22 &lt;Vg 21 ). Thereby, for example, as indicated by operation points P 41 on and P 41 off in  FIG. 26(C) , the on/off-states of the photoelectric transducer PD 41  are arbitrarily settable by the potential V(φ 1 ) of the signal line φ 1 . Moreover, for example, as indicated by operation points P 42 on and P 42 off in  FIG. 26(C) , the on/off-states of the photoelectric transducer PD 42  are arbitrarily settable by the potential V(φ 2 ) of the signal line φ 2 . 
     In the light-receiving section  33 D of the modification example, for example, as illustrated in  FIGS. 27(A)  to (F) and  FIGS. 28(A)  to (C), the image pickup operation is performed at timings in the drawings by the reset signal voltage V(Reset), the read signal voltage V(Read), the potentials V(φ 1 ) and V(φ 2 ) of the signal lines φ 1  and φ 2 , the reset power source Vrst and the like. Herein, β 10  and β 20  indicate transition regions from the on-operation region to the off-operation region in the photoelectric transducers PD 41  and PD 42 , respectively. 
     More specifically, for example, as illustrated in  FIG. 29(A) , the electric charge for charging (in accordance with the total light amount as a summation of the reflected light Lon and the outside light L 0 ) generated in the photoelectric transducer PD 41  is accumulated in the capacitor C 1  through a current path I 41  in the drawing through bringing the photoelectric transducers PD 41  and PD 42  into the on-state and the off-state, respectively. Moreover, for example, as illustrated in  FIG. 29(B) , the electric charge for discharging (in accordance with the light amount of the outside light L 0 ) generated in the photoelectric transducer PD 42  is released from the capacitor C 1  through a current path I 42  in the drawing through bringing the photoelectric transducers PD 41  and PD 42  into the off-state and the on-state, respectively. In addition, a current flowing when the photoelectric transducers PD 41  and PD 42  are in the off-state is not 0, so to be precise, charging or discharging is performed by a current difference between the photoelectric transducer which is in the on-state and the photoelectric transducer which is in the off-state. 
     Thus, also in the modification example, by the above-described image pickup operation, the object is stably detectable irrespective of use conditions while reducing manufacturing costs. 
     In addition, also in the modification example, to prevent the generation of a leakage current, as illustrated in  FIG. 27 , a period in which the potential V(φ 1 ) of the signal line φ 1  is in the H state and a period in which the potential V(φ 2 ) of the signal line φ 2  is in the H state are preferably prevented from overlapping one another (a non-overlap period is preferably set). Further, in the case where a PIN diode turns on or off, a through current hardly flows, so the non-overlap period may not be arranged, but arranging the non-overlap period does not cause an issue. 
     Modification Example 4 
       FIG. 30  illustrates a circuit configuration of a light-receiving section (a light-receiving section  33 E) according to Modification Example 4. The light-receiving section (image pickup pixel)  33 E includes two photoelectric transducer PD 51  (a first photoelectric transducer) and PD 52  (a second photoelectric transducer). More specifically, in the photoelectric transducer PD 51 , a cathode is connected to the signal line φ 1 , an anode is connected to a cathode of the photoelectric transducer PD 52  and the connection point P 1 , and a gate is connected to the power source VDD. Moreover, in the photoelectric transducer PD 52 , an anode is connected to the signal line φ 2 , and a gate is connected to the ground VSS. That is, in the light-receiving section  33 E, unlike the above-described light-receiving section  33 D of Modification Example 3, while the gate potentials of the photoelectric transducers PD 51  and PD 52  are fixed by the power source VDD or the ground VSS, the cathode potential of the photoelectric transducer PD 51  and the anode potential of the photoelectric transducer PD 52  are controlled by the signal lines φ 1  and φ 2 . In addition, any other circuit configuration is the same as that of the light-receiving section  33 D, and will not be further described. 
     In the modification example, first, as illustrated in  FIG. 30 , the gate potential in the photoelectric transducer PD 51  is fixed to the power source VDD, and the gate potential in the photoelectric transducer PD 52  is fixed to the ground VSS. Moreover, as illustrated in  FIG. 30  and  FIGS. 31(A)  to (C), the cathode voltage Vn in the photoelectric transducer PD 51  is changed by the signal line φ 1 . More specifically, the cathode voltage Vn of the photoelectric transducer PD 51  is changed alternately between Vn 1  and Vn 2  by the potential V(φ 1 ) of the signal line φ 1  (refer to an arrow P 51  in  FIG. 31(C) ; Vn 2 &lt;Vn 1 ). Thereby, for example, as illustrated in  FIG. 31(C) , the voltage ranges of the on-operation region α and the off-operation region β 1  are different from each other between in the case of Vn=Vn 1  and in the case of Vn=Vn 2  (refer to on-operation regions α 1  and α 2  and off-operation regions β 11  and β 21 ). Therefore, when such a change in photoelectric conversion efficiency is actively used, as illustrated by operation points P 51 on and P 51 off in the drawing, the on/off-state of the photoelectric transducer PD 51  is arbitrarily settable by the potential V(φ 1 ) of the signal line φ 1 . Moreover, as illustrated in  FIG. 30  and  FIG. 32(A)  to (C), the anode voltage Vp in the photoelectric transducer PD 52  is changed by the signal line φ 2 . More specifically, the anode voltage Vp of the photoelectric transducer PD 52  is changed alternately between Vp 1  and VP 2  by the potential V(φ 2 ) of the signal line φ 2  (refer to an arrow P 52  in  FIG. 32(C) ; Vp 2 &lt;Vp 1 ). Thereby, for example, as illustrated in  FIG. 32(C) , the voltage ranges of the on-operation region α and the off-operation region β 2  are different from each other between in the case of Vp=Vp 1  and in the case of Vp=Vp 2  (refer to the on-operation regions α 1  and α 2  and off-operation regions β 12  and (β 22 ). Therefore, when such a change in photoelectric conversion efficiency is actively used, as illustrated by operation points P 52 on and P 52 off in the drawing, the on/off-state of the photoelectric transducer PD 52  is arbitrarily settable by the potential V(φ 2 ) of the signal line φ 2 . 
     In the light-receiving section  33 E of the modification example, for example, as illustrated in  FIGS. 33(A)  to (F) and  FIGS. 34(A)  to (C), the image pickup operation is performed at timings in the drawings by the reset signal voltage V(Reset), the read signal voltage V(Read), the potentials V(φ 1 ) and V(φ 2 ) of the signal lines φ 1  and φ 2 , the reset power source Vrst and the like. Herein, β 120  and β 210  indicate transition regions from the on-operation region to the off-operation region in the photoelectric transducers PD 51  and PD 52 , respectively. 
     More specifically, for example, as illustrated in  FIG. 35(A) , the electric charge for charging (in accordance with the total light amount as a summation of the reflected light Lon and the outside light L 0 ) generated in the photoelectric transducer PD 51  is accumulated in the capacitor C 1  through a current path I 51  in the drawing through bringing the photoelectric transducers PD 51  and PD 52  into the on-state and the off-state, respectively. Moreover, for example, as illustrated in  FIG. 35(B) , the electric charge for discharging (in accordance with the light amount of the outside light L 0 ) generated in the photoelectric transducer PD 52  is released from the capacitor C 1  through a current path I 52  in the drawing through bringing the photoelectric transducers PD 51  and PD 52  into the off-state and the on-state, respectively. In addition, a current flowing when the photoelectric transducers PD 51  and PD 52  are in the off-state is not 0, so to be precise, charging or discharging is performed by a current difference between the photoelectric transducer which is in the on-state and the photoelectric transducer which is in the off-state. 
     Thus, in the modification example, by the above-described image pickup operation, the object is stably detectable irrespective of use conditions while reducing manufacturing costs. 
     Modification Example 5 
       FIG. 36  illustrates a circuit configuration of a light-receiving section (a light-receiving section  33 F) according to Modification Example 5. The light-receiving section (image pickup pixel)  33 F includes two photoelectric transducers PD 61  (a first photoelectric transducer) and PD 62  (a second photoelectric transducer), five transistors Tr 1 , Tr 2  and Tr 3 , and Tr 61  (an N-channel transistor) and Tr 62  (a P-channel transistor) and four capacitors C 61 A, C 61 B, C 62 A and C 62 B. More specifically, in the photoelectric transducer PD 61 , a cathode is connected to the signal line φ 1  and a source of the transistor Tr 61 , an anode is connected to a cathode of the photoelectric transducer PD 62  and the connection point P 1 , and a gate is connected to a drain of the transistor Tr 61 , one end of the capacitor C 61 A and one end of the capacitor C 61 B. Moreover, a gate of the transistor Tr 61  is connected to the other end of the capacitor C 61 A and a reset line Reset 1  (corresponding to the reset line Reset described above). On the other hand, in the photoelectric transducer PD 62 , an anode is connected to the signal line φ 2  and a source of the transistor Tr 62 , and a gate is connected to a drain of the transistor Tr 62  and one end of the capacitor C 62 A and one end of the capacitor C 62 B. Moreover, a gate of the transistor Tr 62  is connected to the other end of the capacitor C 61 A and an inversion signal of a reset line Reset 2 . In addition, the other end of the capacitor C 61 B and the other end of the capacitor C 62 B are connected to the power source VDD. That is, in the light-receiving section  33 F, unlike the above-described light-receiving section  33 E of Modification Example 4, the gate potentials of the photoelectric transducers PD 61  and PD 62  are not fixed, and the photoelectric transducers PD 61  and PD 62  are in a high impedance state from after a precharge period to a readout period (a period of accumulating the electric charge for charging and a period of releasing the electric charge for discharging). In addition, any other circuit configuration is the same as that of the light-receiving section  33 E, and will not be further described. 
     In the modification example, first, as schematically illustrated in  FIGS. 37(A)  and (B), the cathode potential Vn in the photoelectric transducer PD 61  is changed by the signal line φ 1 . Then, the gate voltage Vg 1  in the photoelectric transducer PD 61  is changed by connecting or disconnecting between the signal line φ 1  and a gate electrode through allowing a switching element SW 61  configured of the transistor Tr 61  to be turned on or off. More specifically, as illustrated in  FIG. 37  and  FIGS. 38(A)  and (B), the cathode potential Vn in the photoelectric transducer PD 61  is changed alternately between Vn 1  and Vn 2  by the potential V(φ 1 ) of the signal line φ 1  (refer to an arrow P 611  in  FIG. 38(A) ; Vn 2 &lt;Vn 1 ). At this time, after the gate voltage Vg 1  of the photoelectric transducer PD 61  is reset to Vn 1  through bringing the switching element SW 61  into the on-state, the switching element SW 61  is brought into the off-state. Then, after that, in the case where the cathode potential Vn is Vn=Vn 2 , as illustrated in a C-V characteristic in  FIG. 38(B) , the gate voltage Vg of the photoelectric transducer PD 61  is reduced due to a coupling capacity between the gate and the cathode, and stops at an operation point (Vg=Vg 12 ) where the coupling capacity is increased. That is, the gate voltage Vg 1  in the photoelectric transducer PD 61  is changed alternately between Vg 11  and Vg 12  (refer to an arrow P 612  in  FIG. 38(A) ; Vg 12 &lt;Vg 11 ). Thus, for example, as illustrated in  FIG. 38(A) , the voltage ranges of the on-operation region α and the off-operation region β 1  are different from each other between in the case of Vn=Vn 1  and in the case of Vn=Vn 2  (refer to the on-operation regions α 1  and α 2  and the off-operation regions β 11  and β 21 ). Therefore, when such a change in photoelectric conversion efficiency is actively used, as illustrated by operation points P 61 on and P 61 off in  FIGS. 38(A)  and (B), the on/off-state of the photoelectric transducer PD 61  is arbitrarily settable by the potential V(φ 1 ) of the signal line φ 1  and the operation by the switching element SW  61 . 
     On the other hand, also in the modification example, as schematically illustrated in  FIGS. 39(A)  and (B), the anode potential Vp in the photoelectric transducer PD 62  is changed by the signal line φ 2 . Then, the gate voltage Vg 2  in the photoelectric transducer PD 62  is changed by connecting or disconnecting between the signal line φ 2  and a gate electrode through allowing a switching element SW 62  configured of the transistor Tr 62  to be turned on or off. More specifically, as illustrated in  FIG. 39  and  FIGS. 40(A)  and (B), the anode potential Vp in the photoelectric transducer PD 62  is changed alternately between Vp 1  and Vp 2  by the potential V(φ 2 ) of the signal line φ 2  (refer to an arrow P 621  in  FIG. 40(A) ; Vp 2 &lt;Vp 1 ). At this time, after the gate voltage Vg 2  of the photoelectric transducer PD 62  is reset to Vp 2  through bringing the switching element SW 62  into the on-state, the switching element SW 62  is brought into the off-state. Then, after that, when the anode potential Vp is Vp=Vp 1 , as illustrated in a C-V characteristic in  FIG. 40(B) , the gate voltage Vg of the photoelectric transducer PD 62  is reduced due to a coupling capacity between the gate and the anode, and stops at an operation point (Vg=Vg 21 ) where the coupling capacity is increased. That is, the gate voltage Vg 1  in the photoelectric transducer PD 62  is changed alternately between Vg 21  and Vg 22  (refer to an arrow P 622  in  FIG. 40(A) ; Vg 22 &lt;Vg 21 ). Thus, for example, as illustrated in  FIG. 40(A) , the voltage ranges of the on-operation region α and the off-operation region β 2  are different from each other between in the case of Vp=Vp 1  and in the case of Vp=Vp 2  (refer to the on-operation regions α 1  and α 2  and the off-operation regions β 21  and β 22 ). Therefore, when such a change in photoelectric conversion efficiency is actively used, as illustrated by operation points P 62 on and P 62 off in  FIGS. 40(A)  and (B), the on/off-state of the photoelectric transducer PD 62  is arbitrarily settable by the potential V(φ 2 ) of the signal line φ 2  and the operation by the switching element SW 62 . 
     In the light-receiving section  33 F of the modification example, for example, as illustrated in  FIGS. 41(A)  to (G) and  FIGS. 42(A)  to (C), by the reset signal voltages V(Reset 1 ) and V(Reset 2 ), the read signal voltage V(Read), the potentials V(φ 1 ) and V(φ 2 ) of the signal lines φ 1  and φ 2 , the reset power source Vrst and the like, the image pickup operation is performed at timings in the drawings. 
     More specifically, for example, as illustrated in  FIG. 43(A) , the electric charge for charging (in accordance with the total light amount as a summation of the reflected light Lon and the outside light L 0 ) generated in the photoelectric transducer PD 61  is accumulated in the capacitor C 1  through a current path I 61  in the drawing through bringing the photoelectric transducers PD 61  and PD 62  into the on-state and the off-state, respectively. Moreover, for example, as illustrated in  FIG. 43(B) , the electric charge for discharging (in accordance with the light amount of the outside light L 0 ) generated in the photoelectric transducer PD 62  is released from the capacitor C 1  through a current path I 62  in the drawing through bringing the photoelectric transducers PD 61  and PD 62  into the off-state and the on-state, respectively. In addition, a current flowing when the photoelectric transducers PD 61  and PD 62  are in the off-state is not 0, so to be precise, charging or discharging is performed by a current difference between the photoelectric transducer which is in the on-state and the photoelectric transducer which is in the off-state. 
     Thus, also in the modification example, by the above-described image pickup operation, the object is stably detectable irrespective of use conditions while reducing manufacturing costs. 
     Modification Example 6 
       FIG. 44  illustrates a circuit configuration of a light-receiving section (light-receiving sections  33 A 1  and  33 A 2 ) in a display area (a display area (a sensor area)  21 C) according to Modification Example 6. In the display area  21 C, an image pickup pixel (the light-receiving section) includes an image pickup pixel (the light-receiving section)  33 A 1  including light-shielding sections  341  and  342  for shielding the photoelectric transducers PD 21  and PD 22  from the reflected light Lon and the environment light L 0 , and an image pickup pixel (the light-receiving section)  33 A 2  not including such a light-shielding section. In addition, any circuit configuration other than the light-shielding sections in the light-receiving sections  33 A 1  and  33 A 2  is the same as that of the above-described light-receiving section  33 A described in Modification Example 1, and will not be further described. 
     In addition, also in these light-receiving sections (the image pickup pixels)  33 A 1  and  33 A 2 , in the display area (the sensor area)  21 C, for example, as illustrated in  FIG. 45 , the image pickup pixels  33 A 1  and  33 A 2  and the wiring sections  32  for driving these image pickup pixels  33 A 1  and  33 A 2  to pick up an image are arranged separately from each other. 
     In the modification example, the object information is obtained based on a difference signal between an image pickup signal obtained from the image pickup pixel  33 A 1  (an image pickup signal read out from a readout line  411 ) and an image pickup signal obtained from the image pickup pixel  33 A 2  (an image pickup signal read out from a readout line  412 ). 
     Thus, also in the modification example, the same fingertip extraction process is performed by the same image pickup operation as in the case of the above-described embodiment. Thereby, also in the modification example, the object is stably detectable irrespective of use conditions while reducing manufacturing costs. 
     Moreover, the image pickup pixel (the light-receiving section) includes the image pickup pixel (the light-receiving section)  33 A 1  including the light-shielding sections  341  and  342  and the image pickup pixel (the light-receiving section)  33 A 2  not including such a light-shielding section, and the object information is obtained based on the difference signal between the image pickup signal obtained from the image pickup pixel  33 A 1  and the image pickup signal obtained from the image pickup pixel  33 A 2 , so an influence of a voltage gradient or the like generated in the I/O display panel  20 , a noise component generated in the drive of a display system, or the like is allowed to be removed, and an improvement in the S/N ratio is allowed. 
     In addition, in the modification example, the case where the light-receiving sections  33 A 1  and  33 A 2  of two kinds each are based on the circuit configuration of the light-receiving section  33 A according to Modification Example 1 is described, but such light-receiving sections of two kinds may be based on the circuit configuration of any one of the light-receiving section  33  according to the above-described embodiment and the light-receiving sections  33 B to  33 F according to Modification Examples 2 to 5. 
     Execution Example of Application Program 
     Next, referring to  FIGS. 46 to 49 , some execution examples of an application program by the application program execution section  11  using object position information or the like detected by the above-described fingertip extraction process will be described below. 
     First, an example shown in  FIG. 46(A)  is an example in which when a fingertip  61  touches a surface of the I/O display panel  20 , a trail of points where the fingertip  61  touches is displayed on a screen as a drawing line  611 . 
     Moreover, an example shown in  FIG. 46(B)  is gesture recognition using the shape of a hand. More specifically, the shape of a hand  62  touching (or in proximity to) the I/O display panel  20  is recognized, and the shape of the recognized hand is displayed as an image, and some process is performed on the image by a movement  621  of a displayed object. 
     Further, an example shown in  FIG. 47  is that by changing from a hand  63 A in a closed state to a hand  63 B in an opened state, the hands touching or coming in proximity in both states are image-recognized by the I/O display panel  20  to execute a process on the basis of these image recognitions. When the process is performed based on these recognitions, for example, an instruction such as zoom-in is performed. Moreover, as such an instruction is performed, for example, the I/O display panel  20  is connected to a personal computer, and an operation of switching a command on the computer or the like is inputted by these image recognitions in a more natural way. 
     Moreover, for example, as illustrated in  FIG. 48 , when a plurality of I/O display panels  20  are prepared, and the plurality of I/O display panels  20  are connected to one another by some transmission means, users operating the I/O display panels  20  may communicate with each other by transmitting and displaying an image obtained by detecting an object touching or coming in proximity to one I/O display panel  20  to and on another I/O display panel  20 . That is, as illustrated in  FIG. 48 , two I/O display panels  20  are prepared, thereby a process such as transmitting the shape of a hand  65  which is image-recognized in one panel to the other panel so that a hand shape  642  is displayed on the other panel, or transmitting and displaying a track  641  displayed by touching one panel by a hand  64  to and on the other panel is allowed to be performed. Thus, the I/O display panel  20  which transmits a drawing state as a moving image, and transmits a handwriting character, symbol or the like to other I/O display panel  20  may be a potential new communication tool. As such an example, it is expected that, for example, the I/O display panel  20  is applied to a display panel of a cellular phone or the like. 
     Moreover, for example, as illustrated in  FIG. 49 , a brush  66  is used, and touches a surface of the I/O display panel  20  so as to draw a character, and a point where the brush  66  touches is displayed on the I/O display panel  20  as an image  661 , thereby handwriting input by a brush is allowed. In this case, a fine touch by a brush is allowed to be recognized and displayed. In handwriting recognition in related art, for example, in some digitizers, the inclination of a special pen is reflected by detecting an electric field; however, in the example, a surface where a real brush touches is detected, thereby information input is performed with a more realistic sense. 
     Module and Application Examples 
     Next, application examples of the display-and-image-pickup device described in the above-described embodiment and modification examples will be described referring to  FIGS. 50 to 54 . The display-and-image-pickup device of the above-described embodiment or the like is applicable to electronic apparatuss displaying a picture signal inputted from outside or a picture signal produced inside as an image or a picture in any fields, such as televisions, digital cameras, notebook personal computers, portable terminal elements such as cellular phones, and video cameras. 
     Application Example 1 
       FIG. 50  illustrates an appearance of a television to which the display-and-image-pickup device of the above-described embodiment or the like is applied. The television has, for example, a picture display screen section  510  including a front panel  511  and a filter glass  512 , and the picture display screen section  510  is configured of the display-and-image-pickup device according to the above-described embodiment or the like. 
     Application Example 2 
       FIG. 51  illustrates appearances of a digital camera to which the display-and-image-pickup device of the above-described embodiment or the like is applied. The digital camera has, for example, a light-emitting section for a flash  521 , a display section  522 , a menu switch  523 , and a shutter button  524 , and the display section  522  is configured of the display-and-image-pickup device according to the embodiment or the like. 
     Application Example 3 
       FIG. 52  illustrates an appearance of a notebook personal computer to which the display-and-image-pickup device of the above-described embodiment or the like is applied. The notebook personal computer has, for example, a main body  531 , a keyboard  532  for operation of inputting characters and the like and a display section  533  for displaying an image, and the display section  533  is configured of the display-and-image-pickup device according to the above-described embodiment or the like. 
     Application Example 4 
       FIG. 53  illustrates an appearance of a video camera to which the display-and-image-pickup device of the above-described embodiment or the like is applied. The video camera has, for example, a main body  541 , a lens for shooting an object  542  arranged on a front surface of the main body  541 , a shooting start/stop switch  543  and a display section  544 , and the display section  544  is configured of the display-and-image-pickup device according to the above-described embodiment or the like. 
     Application Example 5 
       FIG. 54  illustrates appearances of a cellular phone to which the display-and-image-pickup device of the above-described embodiment or the like is applied. The cellular phone is formed by connecting, for example, a top-side enclosure  710  and a bottom-side enclosure  720  to each other by a connection section (hinge section)  730 , and the cellular phone has a display  740 , a sub-display  750 , a picture light  760 , and a camera  770 . The display  740  or the sub-display  750  is configured of the display-and-image-pickup device according to the above-described embodiment or the like. 
     Although the present invention is described referring to the embodiment, the invention is not limited thereto, and may be variously modified. 
     For example, in the above-described embodiment or the like, the case of the I/O display panel configured of a liquid crystal panel including the backlight  15  is described; however, the backlight for display may also serve as a lighting device for detection, or a lighting device for detection only may be arranged. Moreover, in the case where a lighting device for detection is arranged, light in a wavelength region other than a visible light region (for example, infrared light) is more preferably used. 
     Moreover, in the above-described embodiment or the like, for example, as illustrated in  FIG. 7 , the case where a reset operation or a readout operation is performed on the light-receiving sections (the image pickup pixels) in one line in one ON period or one OFF period of the backlight  15  (the case where a blinking operation of a high-frequency backlight is performed) is described; however, the invention is not limited to the case. That is, for example, the reset operation or the readout operation may be performed on the light-receiving sections (the image pickup pixels) in a plurality of lines in one ON period or one OFF period of the backlight  15  (a blinking operation of a low-frequency backlight may be performed). 
     Further, in the above-described embodiment or the like, the case where in the I/O display panel  20 , display elements are liquid crystal elements, and light-receiving elements are separately arranged is described; however, for example, like an organic EL (ElectroLuminescence) element, a light-emitting/receiving element (a display-and-image-pickup element) capable of performing a light-emitting operation and a light-receiving operation in a time-divisional manner may constitute an I/O display panel. In addition, a period in which display light is not emitted in this case is a period in which the light-emitting operation by the display-and-image-pickup element is not performed. 
     Moreover, in the above-described embodiment or the like, the display-and-image-pickup device including a display-and-image-pickup panel (the I/O display panel  20 ) which includes a plurality of display elements and a plurality of image pickup elements is described; however, the invention is applicable to an image pickup device including an image pickup panel including a plurality of image pickup elements and not including a display element.