Abstract:
A focus detecting device having a focus detecting sensor, a first holding member which holds the focus detecting sensor and a second holding member which holds at least an optical element is arranged to permit adjustment of a joint angle between the first holding member and the second holding member in the directions of a plurality of axes by forming, into a curved surface shape, at least one of a joint surface formed on the first holding member for joining with the second holding member and a joint surface formed on the second holding member for joining with the first holding member.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a focus detecting device having a plurality of focus detecting areas and, more particularly, to an arrangement for joining together a focus detection sensor and a holding member which holds an optical member. 
     2. Description of Related Art 
     In Japanese Laid-Open Patent Application No. HEI 8-29652, there is disclosed, as shown in FIG. 7, an arrangement in which the positioning of a focus detecting sensor  1100  with respect to a body block  1000  is effected by pushing a pair of shafts  1210  provided on a sensor holder  1200  against a pair of bearings provided on the body block  1000 . 
     According to the arrangement disclosed in the above Japanese Laid-Open Patent Application No. HEI 8-29652, however, the inclination of a focus detecting device with respect to an optical axis is adjustable only in the direction of rotation around the pair of shafts  1210 . Depending on the allocation of a field of focus detection, therefore, any slanting state of the focus detecting sensor  1100  might be left unadjusted. Under such a condition, there is a possibility that it is impossible to have any adequate performance of the focus detecting device. 
     BRIEF SUMMARY OF THE INVENTION 
     In accordance with one aspect of the invention, there is provided a focus detecting device having a first holding member which holds a focus detecting sensor and a second holding member which holds at least an optical element, wherein at least one of a joint surface formed on the first holding member for joining with the second holding member and a joint surface formed on the second holding member for joining with the first holding member is in a curved surface shape, so that an angle at which the first holding member and the second holding member are mounted relative to each other is adjustable in directions of a plurality of axes. 
     The above and other aspects and features of the invention will become apparent from the following detailed description of a preferred embodiment thereof taken in connection with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
     FIG. 1 is a sectional view showing a sensor adjustment part of a focus detecting device according to an embodiment of the invention. 
     FIG. 2 is a sectional view showing the sensor adjustment part shown in FIG. 1 as viewed from a direction which differs from the viewing direction in FIG.  1 . 
     FIG. 3 is a sectional view showing the sensor adjustment part shown in FIG. 2 in a state where the angle of a sensor is in process of being adjusted. 
     FIG. 4 is an exploded perspective view showing the focus detecting device including the sensor adjustment part shown in FIG.  1 . 
     FIG. 5 shows a focus detecting unit including the sensor adjustment part shown in FIG. 1 in a state where an infrared-cut filter is mounted on the focus detecting unit. 
     FIG. 6 is a perspective view showing exaggeratedly the shape of a sensor-support-member abutting surface provided on a body block in the sensor adjustment part shown in FIG.  1 . 
     FIG. 7 is a sectional view showing the arrangement of a conventional sensor holding mechanism. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinafter, preferred embodiments of the invention will be described in detail with reference to the drawings. 
     FIG. 1 is a sectional view showing a sensor adjustment part of a focus detecting device adapted, for example, for a camera. FIG. 2 is a sectional view of the sensor adjustment part shown in FIG. 1 as viewed from a direction which differs from the viewing direction in FIG.  1 . FIG. 3 is a sectional view showing the sensor adjustment part shown in FIG. 2 in a state where the angle of a sensor is in process of being adjusted. FIG. 4 is an exploded perspective view showing the focus detecting device including the sensor adjustment part shown in FIG.  1 . FIG. 5 shows a focus detecting unit including the sensor adjustment part shown in FIG. 1 in a state where an infrared-cut filter is mounted on the focus detecting unit. FIG. 6 is a perspective view showing exaggeratedly the shape of a sensor-support-member abutting surface provided on a body block in the sensor adjustment part shown in FIG.  1 . 
     Referring to FIG. 1, a field mask  10  is arranged to eliminate unnecessary light flux parts by dividing a focus detection light flux. A split field lens  20  is arranged to lead to a sensor  90  an image to be formed on a primary image forming plane. A light-blocking plate  30  is arranged to separate the light flux of a central focus detecting field and the light flux of a peripheral focus detecting field from each other and to prevent light fluxes other than an effective light flux corresponding to each focus detecting field from entering the sensor  90 . A surface mirror  40  is arranged to bend the focus detection light flux incident on the focus detecting unit toward the sensor  90 . An infrared-cut filter  50  is arranged to remove infrared light. 
     A multiple-aperture diaphragm  60  is arranged to split the focus detection light flux. A reimaging lens  70  is an optical member having a plurality of pairs of lens elements for forming an image on the sensor  90 . The reimaging lens  70  has a pair of positioning dowels. 
     A sensor holder  80  is arranged to hold the sensor  90 . A sensor support member  100  is provided for adjusting the inclination of the sensor  90 . The sensor  90  is composed of a plurality of pairs of line sensors. A circuit board  300  has the sensor  90  mounted thereon. A light-blocking sheet  110  is arranged to cover any gap or clearance between the focus detecting unit and the focus-detecting-unit mounting part of the camera. A body block  120  is arranged to hold the various component parts of the focus detecting unit and to shield these parts from external light. 
     In the structural arrangement of the focus detecting device described above, the field mask  10 , the split field lens  20 , the light-blocking plate  30 , the mirror  40 , the infrared-cut filter  50 , the multiple-aperture diaphragm  60 , the reimaging lens  70 , the sensor holder  80 , the sensor support member  100 , the sensor  90  and the light-blocking sheet  110  are mounted on the body block  120 . The field mask  10  is positioned by fitting shafts and fitting holes and is fixed to the body block  120 . The split field lens  20  is secured by bonding to the body block  120 . The light-blocking plate  30 , the mirror  40  and the infrared-cut filter  50  are secured by bonding to the body block  120  after they are positioned. 
     The multiple-aperture diaphragm  60  is positioned and secured to the reimaging lens  70  by using holes and slots provided in the multiple-aperture diaphragm  60  in conjunction with a plurality of dowels provided on the reimaging lens  70 . The reimaging lens  70  is positioned and secured to the body block  120  by using positioning holes provided in the body block  120  and dowels provided on the reimaging lens  70  for positioning the reimaging lens  70 . The reimaging lens  70  and the body block  120  are fixed in their positions to have the multiple-aperture diaphragm  60  sandwiched in between them in such a way as to prevent the position of the multiple-aperture diaphragm  60  from deviating with respect to the body bock  120  and the reimaging lens  70 . 
     The sensor  90  is bonded and secured to the sensor holder  80  beforehand in a state of being mounted on the circuit board  300 . The inclination, with respect to the body block  120 , of the sensor  90  and the sensor holder  80  is thus adjusted as one sensor unit  200 . 
     The sensor unit  200  is held in position with respect to the body block  120  through the sensor support member  100 . The inclination of the sensor  90  with respect to the focus detecting device is adjusted between the body block  120  and the sensor support member  100 . The sensor unit  200  is bonded and fixed after completion of various adjusting actions on the sensor support member  100 . 
     The sensor support member  100  is positioned with respect to the body block  120  by means of at least one spherical positioning adjustment part provided on the sensor support member  100 . The spherical positioning adjustment part of the sensor support member  100  is arranged to permit adjustment of the inclination of the sensor support member  100  with respect to the body block  120  in the directions of a plurality of axes. The light-blocking sheet  110  is interposed in between the field mask  10  and the body block  120  and is held by a light-blocking-sheet positioning part  14  provided on the field mask  10 . 
     The arrangement of the sensor adjustment part is next described with reference to FIGS. 1,  2  and  3 . In FIGS. 1,  2  and  3 , reference numeral  91  denotes a sensor chip of the sensor  90  held on the sensor holder  80 . The sensor holder  80  and the sensor  90  are bonded and fixed to each other. The position and inclination of the sensor  90  are thus adjusted with the sensor  90  and the sensor holder  80  in the unified state. The adjustment permits addition of such a shape of the sensor  90  that facilitates holding with a tool. 
     The sensor support member  100  is provided with body-block abutting surfaces  101  which are formed as shown in FIG.  2 . At the body-block abutting surfaces  101 , the sensor support member  100  abuts on the body block  120 . 
     The body block  120  is provided with sensor-support-member abutting surfaces  151  at parts corresponding to the body-block abutting surfaces  101  of the sensor support member  100 . 
     Each of the body-block abutting surfaces  101  is in a convex spherical shape formed by cutting out a part of a sphere having a radius R 1 , as shown in FIG.  2 . The center of the spherical shape of radius R 1  of the body-block abutting surface  101  is arranged to be located approximately at the sensor chip  91  of the sensor  90 . 
     Each of the sensor-support-member abutting surfaces  151  of the body block  120  is in a concave shape formed by turning the body-block abutting surface  101  (a convex spherical shape of radius R 1 ) with a radius R 2 , which is larger than the radius R 1 . Thus, as shown in FIG. 6, each of the sensor-support-member abutting surfaces  151  of the body block  120  is in such a concave shape that an arc of radius R 2  is drawn with a groove of radius R 1  in the depth direction thereof. 
     As a result, the amount of movement of the sensor support member  100  with respect to the body block  120  at the time of adjustment becomes larger in the direction parallel with the plane of a circle of the radius R 2  than in the direction parallel with the plane of a circle of the radius R 1 . Therefore, an aperture part  103  provided in the sensor support member  100  for passing an effective light flux is arranged to have a larger aperture width in the direction for the radius R 2  than in the direction for the radius R 1 . 
     Reference numeral  102  denotes a sensor-support-member rotation restricting part of the sensor support member  100 . Reference numeral  152  denotes a sensor-support-member rotation restricting part of the body block  120 . 
     As shown in FIG. 3, the sensor-support-member rotation restricting part  102  and the sensor-support-member rotation restricting part  152  are arranged to prevent the sensor support member  100  from rotating to any degree more than necessary, by coming into contact with each other. 
     By virtue of the above arrangement, the sensor support member  100  can be arranged not to come into contact with the reimaging lens  70  with the reimaging lens  70  interposed in between the body block  120  and the sensor support member  100 . 
     The position and inclination of the sensor  90  are adjusted, with the sensor  90  in the state of adhering to the sensor holder  80 , by applying a driving force from a driving member (not shown) to each of the driving parts  81  and  82  provided on the sensor holder  80 . The shape of each of the sensor-support-member abutting surfaces  151  varies with the directions of adjustment. 
     To assist driving in the direction parallel with the plane of a circle of the radius R 2  of the sensor-support-member abutting surface  151 , the sensor support member  100  is provided with sensor-support-member driving assisting parts  104  so as to allow the sensor support member  100  to be directly driven. The provision of the sensor-support-member driving assisting parts  104  facilitates the adjustment work on the sensor  90 . 
     FIG. 4 is an exploded perspective view showing a focus detecting device which includes the arrangement described above. FIG. 5 shows a focus detecting unit as having an infrared-cut filter mounted thereon. The component members of the focus detecting device having the above-stated arrangement are described in detail below. 
     Referring to FIG. 4, the body block  120  is formed to have various positioning and fixing shapes for fixing the focus detecting unit after positioning the focus detecting unit. The infrared-cut filter  50  shown in FIG. 5 is positioned with respect to the body block  120  by mounting the infrared-cut filter  50  on an infrared-cut-filter positioning-and-fixing part  121  of the body block  120 . After positioning, the infrared-cut filter  50  is bonded and fixed to the body block  120  by a plurality of infrared-cut-filter bonding parts  122  which are arranged around the infrared-cut-filter positioning-and-fixing part  121 . 
     The light-blocking plate  30  is positioned with respect to the body block  120  by a light-blocking-plate positioning-and-fixing part  31  provided on the light blocking plate  30  and a light-blocking-plate positioning-and-fixing part  123  provided on the body block  120 , and is mounted into an inner part of the body block  120 . The light-blocking plate  30  is provided with walls  32  and  33  which are arranged to prevent unnecessary light fluxes other than an effective light flux of each of focus detecting fields passing through the split field lens  20  from entering other focus detecting fields. An aperture part  34  is formed between the walls  32  and  33  of the light-blocking plate  30  to pass a focus detection light flux therethrough. After completion of various adjusting actions thereon, the split field lens  20  is secured by bonding to the body block  120  through a split-field-lens securing part provided on the body block  120 . 
     The field mask  10  is positioned with respect to the body block  120  by using a pair of field-mask-positioning fitting shafts  11  provided on the field mask  10  and a pair of fitting holes including a field-mask-positioning fitting hole  125  which restricts the plain movement of the field mask  10  within a mounting plane thereof and a field-mask-positioning fitting slot  126 . After positioning, the field mask  10  is secured to the body block  120  by causing a pair of field-mask-fixing elastic claw parts  12  provided on the field mask  10  to engage a pair of field-mask-fixing holes  127  formed in the body block  120 . Further, to prevent the field mask  10  from buoying up from the body block  120  after the focus detecting unit is mounted on the camera even when the pair of field-mask-fixing elastic claw parts  12  happen to disengage from the pair of field-mask-fixing holes  127 , the field mask  10  is provided with a field-mask-buoying preventing part  13 . The field-mask-buoying preventing part  13  serves also to lessen a gap between a mirror box of the camera and the focus detecting device. 
     The light-blocking sheet  110  is positioned by using a pair of light-blocking-sheet positioning holes  111  provided in the light-blocking sheet  110  and a pair of light-blocking-sheet positioning parts  14  provided on the field mask  10 . After positioning, the light-blocking sheet  110  is secured to the body block  120  in a state of being interposed in between the field mask  10  and the body block  120 . 
     The mirror  40  is positioned by using a mirror-positioning-and-fixing part  134  which is provided on the body block  120 . After positioning, the mirror  40  is secured by bonding to the bock block  120 . The mirror  40  has light-blocking mask parts  41  added to its surface in a mask-like shape to block unnecessary light fluxes for each of focus detecting fields. The light-blocking mask parts  41  are thus arranged to block unnecessary light fluxes passing through a gap between the light-blocking plate  30  and the mirror  40  in deflecting a focus detection light flux for the sensor and are formed approximately in parallel with the sensor arrays of the line sensors of peripheral focus detecting fields. Therefore, since there is no light-blocking pattern in the direction of splitting the focus detection light flux, no ghost is generated by reflection at any pattern edge part. 
     The reimaging lens  70  is positioned by a pair of reimaging-lens fitting shafts  71  of the reimaging lens  70  in conjunction with a pair of fitting holes formed in the body block  120  including a reimaging-lens positioning square hole  131  and a reimaging-lens positioning slot  132 . After positioning, the reimaging lens  70  is secured by bonding to the body block  120 . 
     The multiple-aperture diaphragm  60  is positioned with respect to the reimaging lens  70  by a pair of positioning parts  61  which correspond to the fitting shafts  71  of the reimaging lens  70 . After positioning, the multiple-aperture diaphragm  60  is held in position with respect to the body block  120  in a state of being interposed in between the reimaging lens  70  and the body block  120 . 
     The sensor support member  100  is positioned with respect to the body block  120  by using the pair of body-block abutting surfaces  101  which are provided on the sensor support member  100  in a spherical shape having the radius R 1  for positioning adjustment and the pair of sensor-support-member abutting surfaces  151  which are formed on the side of the body block  120  in a spherical shape having a plurality of radii of curvature, i.e., the radii R 1  and R 2 . The sensor support member  100  is thus positioned for swinging adjustment with the radius of curvature R 2  of the sensor-support-member abutting surfaces  151  of the body block  120  and also with the radius of curvature R 1  of the body-block abutting surfaces  101  of the sensor support member  100 . Such a positioning arrangement permits the sensor support member  100  to have its inclination, etc., adjusted with respect to a plurality of axes perpendicular to the optical axis. After the positioning adjustment, the sensor support member  100  is secured by bonding to the body block  120 . 
     The sensor  90  is fixed by bonding to the sensor holder  80 , so that the sensor holder  80  and the sensor  90  are united into the sensor unit  200 . 
     The sensor unit  200  is held in position with respect to the body block  120  through the sensor support member  100 . After the inclination, position, etc., of the sensor  90  are adjusted, the sensor unit  200  is secured by bonding to the sensor support member  100 . The sensor holder  80  is provided with a groove for leading an adhesive to a bonding face of the sensor support member  100 . 
     In the case of the embodiment disclosed above, the invention is applied to the adjustment of the sensor in the focus detecting device. However, the invention is of course applicable also to the adjustment of mechanisms other than that of the sensor.