Abstract:
An image pickup device is provided with an optical system for taking the image of an object. A photoelectric converting element photoelectrically converts the object image taken by the optical system and an electric signal outputting board outputs an electrical signal from the photoelectric converting element. A position defining member defines the position of the optical system relative to the photoelectric converting element. The electric signal outputting board is positioned between the photoelectric converting element and the position defining member.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an image pickup element or a mounting device therefor, for use in an image pickup apparatus such as a video camera or a digital camera. 
     2. Related Background Art 
     FIG. 1 is a vertical cross-sectional view schematically showing the configuration of an image pickup device, employing a solid-state image pickup element contained in a conventional discrete package. 
     In FIG. 1 there are shown a package  1  for the solid-state image pickup element; an image pickup optical lens system  2 ; and a position defining member  3  for defining the position of the package  1  for the solid-state image pickup element relative to the image pickup optical system  2 . 
     The relative position of the package  1  of the solid-state image pickup element and the position defining member  3  along a plane perpendicular to the optical axis is defined by an unrepresented positioning jig. Also the relative position of the package  1  and the position defining member  3  along the optical axis is fixed by adhesion, with the impingement of the position defining member  3  on the rear face, constituting a reference plane, of the package  1 . Electrode portions  4  of the package  1  pass through apertures  5  provided in the position defining member  3  and are inserted into holes  7  formed on a printed circuit board  6  positioned at the rear side of the position defining member  3 , and are fixed at the rear face of the printed circuit board  6  by soldering  8  to rands formed on the rear face thereof. Also the position defining member  3 , on which the solid-state image pickup package  1  is fixed, impinges on the image pickup optical system  2  for defining the position of the solid-state image pickup element  9  in the axial direction relative to the image pickup optical system  2 , and positioning holes  10  provided on the position defining member  3  engage with positioning projections  11  correspondingly provided on the image pickup optical system  2  for defining the position of the solid-state image pickup element  9  relative to the image pickup optical system  2  along the plane perpendicular to the optical axis. In this configuration, a shield case  12  is mounted on the printed circuit board  6 , so as to cover the electrode portions  4  of the solid-state image pickup package  1  fixed by solderings  8  to the rear face of the printed circuit board  6 . 
     FIG. 2 is a vertical cross-sectional view, schematically showing another configuration of an image pickup device, in which the package containing the above-mentioned solid-state image pickup element is so modified that the electrode portions  4  are bent. In FIG. 2, the same portions as those in FIG. 1 are represented by the same numbers as in FIG.  1 . 
     Referring to FIG. 2, the relative position between the solid-state image pickup package  1  and the position defining member  3  along the plane perpendicular to the optical axis is defined by an unrepresented positioning jig, while the relative position in the axial direction is fixed by adhesion, upon impingement of the position defining member  3  on the reference rear face of the solid-state image pickup package  1 . The electrode portions  4  of the package  1  pass through the apertures  5  provided in the position defining member  3  and are fixed at the rear face of the printed circuit board  6 , positioned at the rear side of the position defining member  3 , by soldering  8  to rands formed on the front surface of the printed circuit board  6 . Also the position defining member  3 , on which the solid-state image pickup package  1  is fixed, impinges on the image pickup optical system  2  for defining the position of the solid-state image pickup element  9  in the axial direction relative to the image pickup optical system  2 , and positioning holes  10  provided on the position defining member  3  engage with positioning projections  11  correspondingly provided on the image pickup optical system  2  for defining the position of the solid-state image pickup element  9  relative to the image pickup optical system  2  along the plane perpendicular to the optical axis. 
     In the conventional configuration shown in FIG. 1, however, since the electrode portions  4  are fixed by solderings  8  to the rear surface of the printed circuit board  6 , such soldered portions  8  protrude on the rear side thereof and constitute a dead space against the compactization of the equipment. Also the solid-state image pickup element  9  is very susceptible to the influence of noises, but a shield case  12 , if provided for avoiding such influence, increases the total thickness, hindering also the compactization of the equipment. 
     On the other hand, in the above-described configuration shown in FIG. 2, in which the electrode portions  4  of the package  1  containing the solid-state image pickup element  9  are bent in L-shape, the soldered portions  8  of the electrode portions  4  are present on the front surface of the printed circuit board  6  and do not protrude to the rear surface thereof, thus eliminating the dead space on the rear surface of the printed circuit board  6  as in the configuration shown in FIG.  1 . Also on a surface of the printed circuit board  6 , opposite to the surface electrically connected to the solid-state image pickup package  1 , there is provided a ground pattern substantially covering the printed circuit board  6  to obtain the shield effect, thereby dispensing with the shield case which is a factor increasing the total thickness in the configuration shown in FIG.  2 . 
     In the configuration shown in FIG. 2, however, in forming the electrode portions  4  into L shape, such portions have to be chucked and a chucking area for this operation has to be secured, so that the gap from the mounting face of the position defining member  3  for the solid-state image pickup package  1  to the bent position of the electrode portions  4  cannot be made small. For this reason, the distance L from the solid-state image pickup package  1  to the printed circuit board  6  has a certain lower limit, thus hindering the reduction in the total thickness. Furthermore, the length from the rear face of the solid-state image pickup package  1  to the bent position of the electrode portions  4  tends to fluctuate considerably. Also, cracking tends to appear in the forming operation if the electrode portions are chucked incompletely. Furthermore, the image pickup element may be damaged by the electromotive force generated at the forming operation. 
     SUMMARY OF THE INVENTION 
     The present invention is to resolve the drawbacks mentioned in the foregoing, and a first object thereof is to provide a surface mountable image pickup device of a thin structure for mounting. 
     A second object of the present invention is to provide an image pickup device and a leadless electric component mounting device, capable of reducing the total thickness of the image pickup device. 
     A third object of the present invention is to provide an image pickup device and a leadless electric component mounting device, capable of providing a shield effect without utilizing the shield case which is a factor for increasing the total thickness. 
     The above-mentioned first object can be attained, according to a preferred embodiment of the present invention, by a surface mountable leadless image pickup element in which a light receiving face is formed on the upper face in a flat package, the lower face of the package is used as a position defining face in the axial direction, and plural electrodes for soldering are formed in at least mutually opposed pair of lateral faces, among the four lateral faces, of the flat package. 
     Also the above-mentioned second object can be attained, according to a preferred embodiment of the present invention, by an image pickup device comprising an optical system for picking up the image of an object, photoelectric conversion means for photoelectric conversion of the object image picked up by the optical system, electric signal output means for outputting electric signals from the photoelectric conversion means, and position defining means for defining the relative position of the optical system and the photoelectric conversion means, wherein the electric signal output means is positioned between the photoelectric conversion means and the position defining means. 
     Also the above-mentioned third object can be attained, according to a preferred embodiment of the present invention, by a leadless electric component mounting device for mounting a leadless electric component in a mounting position in the device, comprising a position defining member for mounting the leadless electric component in a part with a predetermined gap and positioning the leadless electric component in the mounting position, and a printed circuit board electrically connected to the electrodes of the leadless electric component and derived through the above-mentioned gap. 
     Still other objects of the present invention, and the features thereof, will become fully apparent from the following description, which is to be taken in conjunction with the attached drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a longitudinal cross-sectional view showing the configuration of a conventional image pickup device; 
     FIG. 2 is a longitudinal cross-sectional view showing the configuration of another conventional image pickup device; 
     FIG. 3 is an exploded perspective view showing the configuration of a first embodiment of the present invention; 
     FIG. 4 is a longitudinal cross-sectional view showing the configuration, in an assembled state, of an image pickup device constituting the first embodiment of the present invention; 
     FIG. 5 is a plan view, with the package of the solid-state image pickup element being removed, showing the configuration of the image pickup device of the first embodiment; 
     FIGS. 6A,  6 B and  6 C are views showing the configuration of a package for the solid-state image pickup element employed in the image pickup device of the first embodiment; 
     FIG. 7 is a plan view showing the configuration of a printed circuit board employed in the image pickup device constituting a second embodiment of the present invention; 
     FIG. 8 is a schematic view showing the mounting method for the solid-state image pickup element in a third embodiment of the present invention; 
     FIG. 9 is a plan view showing the relationship between the package for the solid-state image pickup element and the position defining member in the third embodiment; 
     FIG. 10 is a cross-sectional view of the package for the solid-state image pickup element in the third embodiment; 
     FIG. 11 is a view showing an example of the position defining method for the solid-state image pickup element relative to the position defining member in the third embodiment; 
     FIGS. 12 and 13 are views showing examples of the position defining method for the solid-state image pickup element relative to the position defining member in the embodiments of the present invention; 
     FIG. 14 is a view showing an example of the ground pattern in the embodiments of the present invention; 
     FIG. 15 is a view showing the shape of the board folded in a box shape in the embodiments of the present invention; and 
     FIG. 16 is a view showing an example of the ground pattern in the embodiments of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     At first there will be explained a first embodiment of the present invention with reference to FIGS. 3 to  5  and  6 A to  6 C, wherein FIG. 3 is an exploded perspective view showing the configuration of an image pickup device (leadless electric component mounting device) constituting a first embodiment of the present invention; FIG. 4 is a longitudinal cross-sectional view showing the configuration, in an assembled state, of an image pickup device constituting the first embodiment of the present invention; FIG. 5 is a plan view showing the configuration of the image pickup device of the first embodiment in the assembled state, wherein the image pickup optical system and the package of the solid-state image pickup element are removed; and FIGS. 6A to  6 C are respectively a plan view, a lateral view and a bottom view showing the configuration of the package for the solid-state image pickup element employed in the image pickup device of the first embodiment. 
     In FIGS. 3 to  5  and  6 A to  6 C, the same components as those in FIGS. 1 and 2 are represented by the same numbers as therein. 
     Referring to FIGS. 3 and 4, there are shown a package  1  for the solid-state image pickup element; an image pickup optical system  2 ; a position defining member  3 ; electrode portions  4 ; and a printed circuit board  6 . 
     The package  1  for the solid-state image pickup element is of a leadless chip carrier type having the electrode portions  4  at the end faces of the package as shown in FIGS. 6A to  6 C. The printed circuit board  6  is a flexible printed circuit board, provided with a pattern for outputting the signal from the solid-state image pickup element (leadless electric component)  9  and soldering rands for electrical connection therewith. 
     Referring to FIG. 3, after the electrode portions  4  of the solid-state image pickup package  1  are soldered to the rands formed on the printed circuit board  6 , the relative position of the package  1  and the position defining member  3  along the plane perpendicular to the optical axis is defined by an unrepresented positioning jig. Also the relative position of the package  1  and the position defining member  3  along the optical axis is defined by the impingement of the package  1  on plural projections  13   a  to  13   d  provided on the position defining member  3 , and the package  1  and the position defining member  3  are fixed by adhesion by introducing an adhesive material  15  into the gap therebetween through apertures  14   a,    14   b  provided in the vicinity of the projections  13   a  to  13   d.    
     Then the position defining member  3 , supporting the solid-state image pickup package  1  thereon, is made to impinge on the image pickup optical system  2 , thereby defining the axial position of the solid-state image pickup element  9  relative to the image pickup optical system  2 . In this state the positioning holes  10  provided on the position defining member  3  engage with the positioning projections  11  provided correspondingly on the image pickup optical system  2  to define the position of the solid-state image pickup element  9  relative to the optical system  2  along the plane perpendicular to the optical axis. 
     Since the projections  13   a  to  13   d  provided on the position defining member  3  have a height h satisfying a condition h≧t wherein t is the thickness of the printed circuit board  6 , the printed circuit board  6  can be positioned between the solid-state image pickup package  1  and the position defining member  3 . 
     Also as the apertures  14   a,    14   b  formed on the position defining member  3  for introducing the adhesive material are positioned in the vicinity of the projections  13   a  to  13   d  of the position defining member  3 , the package  1  and the position defining member  3  are adhered in mutually contacting areas thereof and in the surrounding areas to attain a high adhesion strength. If the apertures  14   a,    14   b  of the position defining member  3  are separated from the projections  13   a  to  13   d,  the adhesion between the package  1  and the position defining member  3  is to be made across the gap therebetween, so that there cannot be obtained a sufficient strength. 
     The printed circuit board  6  is so shaped as to substantially cover the rear face of the solid-state image pickup package  1  but so as to be absent in the portions where the projections  13   a  to  13   d  formed on the position defining member  3  are in contact with the package  1  and in the portions of the apertures  14   a,    14   b  for introducing the adhesive material  15 , whereby the rear face of the solid-state image pickup package  1  is exposed in portions corresponding to the projections  13   a  to  13   d  and the apertures  14   a,    14   b  and such exposed portions constitute adhering areas for the package  1  and the position defining member  3 . 
     The printed circuit board  6  is positioned between the solid-state image pickup package  1  and the position defining member  3  of the above-described configuration, and the package  1  is supported and fixed by the projections  13   a  to  13   d  formed on the position defining member  3 , so that the height h of the projections  13   a  to  13   d  can be extremely precisely determined at a value close to the thickness t of the printed circuit board  6 . It is therefore rendered possible to reduce the gaps of the package  1 , the position defining member  3  and the printed circuit board  6 , thereby reducing the entire thickness. 
     Also as the electrode portions  4  of the solid-state image pickup package  1  are electrically connected to a face, at the side of the package  1 , of the printed circuit board  6 , the electrode portions  4  of the package  1  and the soldered portions  8  do not protrude on the rear face of the printed circuit board  6 , whereby a dead space is not created on the rear face. 
     Furthermore, a shield effect can be obtained by forming a ground pattern substantially covering the printed circuit board  6 , on a face thereof opposite to the face where electrical connection is made with the electrode portions  4  of the package  1 . 
     In FIGS. 3 and 4 there are also shown bolt holes  16   a,    16   b,    16   c  formed on the position defining member  3 , and bolts  17   a,    17   b,    17   c  are inserted into these bolt holes  16   a  to  16   c  to fix the position defining member  3  to the image pickup optical system  2 . 
     In a second embodiment of the present invention shown in FIG. 7, a ground pattern is formed in an extended portion  6   a  of the printed circuit board  6 , and, after the solid-state image pickup package  1  and the position defining member  3  are fixed by adhesion, the extended portion  6   a  is folded back over the position defining member thereby completely covering the rear face of the package  1  and obtaining a higher shielding effect. 
     In the foregoing embodiments, the printed circuit board  6  is composed of a flexible printed circuit board, but it may also be composed of a hard board except in the second embodiment in which the extended portion  6   a  is to be folded. 
     As explained in the foregoing, there is obtained an effect of reducing the entire thickness as the gaps of the electric signal output means, the photoelectric conversion means and the position defining means can be reduced. 
     Also there is obtained an advantage of obtaining the shield effect without employing the shield case which has been a factor of increasing the entire thickness. 
     In the following there will be explained a third embodiment of the present invention, providing a package for the solid-state image pickup element having a position defining face on the rear face of the package. More specifically there is disclosed a package for a solid-state image pickup element for use in an image pickup device, comprising an image pickup optical system, a solid-state image pickup package of a chip carrier type containing a solid-state image pickup element, a position defining member for defining the position of the solid-state image pickup package relative to the optical system, and a printed circuit board having rands for electrical connection with the solid-state image pickup element, wherein a step difference is formed, on the rear face thereof, between a mounting face for the position defining member and a face for electrical connection with the printed circuit board. 
     In such configuration, the step difference between the mounting face of the solid-state image pickup package for mounting the position defining member and the electrical connecting face with the printed circuit board can be selected close to the thickness of the position defining member, whereby the dimension of the package can be uniquely and precisely determined to eliminate the dead space. 
     FIG. 8 is a schematic view showing the mounting method of the solid-state image pickup element in the present embodiment, and FIG. 9 is a plan view of the solid-state image pickup package and the position defining member. 
     There are shown a solid-state image pickup package  101 ; a position defining member  102 ; a printed circuit board  103 ; an image pickup optical system  104 ; holes/projections  105 / 106 ; electrode portions  107 ; soldering portions  108 ; and a solid-state image pickup element (CCD)  109 . 
     The solid-state image pickup package  101  is of chip carrier type, and is provided, on the rear face thereof, with a step  120  having a difference of height L′ between a mounting face for the position defining member  102  and a face to be soldered to the printed circuit board  103  so as to satisfy a condition t′≦L′ wherein t′ is the thickness of the position defining member  102 . 
     As the solid-state image pickup package  101  is composed, as shown in a cross section in FIG. 10, by laminating ceramic wafers, there can be uniquely and precisely determined a mounting face  110  for the solid-state image pickup element, a mounting face  111  for the position defining member and an electrical connection face  112  to be soldered to the printed circuit board  103 . 
     The position defining member  102  defines the position of the solid-state image pickup element  109  in the axial direction by impingement on the mounting face  111 , for the position defining member, of the package  101 . Also the position of the package  101  relative to the position defining member  102  in the plane perpendicular to the optical axis is defined by the adhesion of the package  101  to the position defining member  102 , utilizing a positioning jig therefor. 
     In such configuration, the position of the solid-state image pickup element  109  in the plane perpendicular to the optical axis may be defined either, for example as shown in FIG. 11, by the engagement of holes  113  formed on the package  101  and corresponding projections  114  formed on the position defining member  102 , or, as shown in FIG. 12, by defining the position of the position defining member  102  by stepped portions  115  and lateral end faces thereof, formed on the solid-state image pickup package  101 . 
     In addition, in order to prevent the mounting of the solid-state image pickup package  101  in an opposite direction to the position defining member  102 , the package  101  is preferably provided, as shown in FIG. 13, with a stepped portion  116  for preventing such mounting in the opposite direction and the position defining member  102  is likewise provided with an extended portion  117  for preventing such mounting in the opposite direction. 
     The electrode portions  107  of the package  101  of which position is defined by the position defining member  102  are soldered, as explained in the foregoing, to the rands formed on the printed circuit board  103  at the side of the solid-state image pickup package  101 . 
     The position of the solid-state image pickup element  109  relative to the image pickup optical system  104  in the axial direction is defined by the impingement of the position defining member  102  on the pick up optical system  104 . Also the position of the solid-state image pickup element  109  relative to the image pickup optical system  104  in the direction of the plane perpendicular to the optical axis is defined by the engagement of the holes  105  formed on the position defining member  102  with the corresponding projections  106  formed on the image pickup optical system  104 . 
     The above-described configuration ensures the dimensional precision between the mounting face  110  of the solid-state image pickup element  109  and the mounting face  111  of the position defining member  102 . Also the dead space can be eliminated since the step difference, between the mounting face  111 , for the position defining member, of the package  101  and the face thereof for electrical connection with the printed circuit board  103 , is close to the thickness of the position defining member  102 . Furthermore, as the electrode portions of the solid-state image pickup package are electrically connected to the front face of the printed circuit board, there can be eliminated the dead space on the rear face of the printed circuit board, which has been a drawback in the conventional configuration. 
     Furthermore, the above-described configuration allows obtaining a shield effect which is effective for the solid-state image pickup element susceptible to noises, by forming, as shown in FIG. 14, a ground pattern  118  so as to substantially cover the printed circuit board  103  on a face of the printed circuit board  103  opposite to the electrical connecting face thereof and preferably connecting such ground pattern to a predetermined potential (including ground potential). In such case, the printed circuit board  103  may be so folded in a box shape, as shown in FIG. 15, as to substantially cover the solid-state image pickup package  101  in order to attain further enhanced shield effect. 
     Furthermore, thus formed ground pattern  118  may be provided, as shown in FIG. 16, with slit portions  119  so as to surround rear face areas corresponding to the rands, thereby preventing the heat loss in soldering the solid-state image pickup package  101 . 
     The above-mentioned ground pattern may be provided at least in a size approximately the same as that of the rear face of the solid-state image pickup package and directly behind the package, in order to prevent the noises entering the package from the rear face side thereof. 
     As explained in the foregoing, in the package for the solid-state image pickup element for use in an image pickup device including an image pickup optical system, a package of the chip carrier type containing a solid-state image pickup element, a position defining member for defining the position of the package relative to the optical system, and a printed circuit board having rands for electrical connection with the solid-state image pickup element, the package comprises a step difference between a mounting face on the rear face of the package for mounting the position defining member and a face of the package for electrical connection with the printed circuit board whereby such step difference can be selected close to the thickness of the position defining member and the dimension of the package can be uniquely and precisely determined to eliminate the dead space. 
     Also the dead space at the rear face side of the printed circuit board, which has been a drawback in the conventional configuration, can be eliminated since the electrode portions of the solid-state image pickup package are electrically connected at the front face of the printed circuit board. 
     Furthermore, a shield effect against noises can be obtained without utilizing a shield case. 
     Many widely different embodiments of the present invention may be constructed without departing from the spirit and scope of the present invention. It should be understood that the present invention is not limited to the specific embodiments described in the specification, except as defined in the appended claims.