JP2005189549A - Imaging unit and imaging equipment having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging unit that has free curved face prisms and focusing mechanism which can be constructed compactly. <P>SOLUTION: The imaging unit 10 includes a prism unit 30, an imaging device 32, and a piezoelectric actuator 80. The piezoelectric actuator 80 functioning as a driving part has: a piezoelectric device 81 in which a plurality of piezoelectric bodies are stacked in a direction parallel to the light receiving face of the imaging device 32; refracting members 84 and 85 for increasing the expansion/contraction displacement of the piezoelectric device 81 and for changing the direction of the expansion/contraction displacement to a direction orthogonal to the light receiving face of the imaging device 32; and a communicating member 86. The piezoelectric actuator 80 transmits the displacement to the prism unit 30 in order to move the prism unit 30 in the direction orthogonal to the light receiving face of the imaging device 32. The imaging unit 10 includes a focusing control means for controlling the focused state of the prism unit 30 by applying a voltage of a specific level to the piezoelectric device 81. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an imaging device used for a digital camera, a camera-equipped mobile phone, and the like, and more particularly, to an imaging device using a prism using a free curved surface as a reflecting surface and an imaging device using the imaging device.

  In recent years, a large number of imaging apparatuses using a coaxial optical system have been filed as imaging apparatuses used for digital cameras and camera-equipped mobile phones. The coaxial system is an optical system in which optical elements such as lenses are provided in a rotationally symmetrical manner with respect to the optical axis of the optical system (the axis connecting the aperture of the imaging system and the center of the imaging screen). A coaxial imaging device is disclosed in, for example, the following Patent Documents 1 to 3.

  Recent digital cameras and camera-equipped mobile phones are required to be smaller, thinner, and higher in performance. In an imaging apparatus using a coaxial optical system for these devices, the size of the imaging apparatus is required. To make the lens compact, it is necessary to reduce the number of lenses. However, if the number of lenses is reduced, it becomes difficult to reduce the aberration generated in the optical system, and the image quality deteriorates. Further, when trying to improve the image quality, it is necessary to increase the number of lenses, and as a result, there arises a problem that the image pickup apparatus becomes large.

  As one means for solving these problems, an imaging apparatus using a decentered optical system has been proposed. For example, Patent Documents 4 to 6 below describe an imaging apparatus using an imaging optical system using a prism using a free-form surface or the like.

  The aim of the techniques described in Patent Documents 4 to 6 is to form an imaging optical system using a prism, and use a free-form surface for the light incident surface, light exit surface, or reflecting surface of the prism. Thus, a compact and high-quality image can be obtained. In particular, in Patent Document 5 (Japanese Patent Laid-Open No. 2002-196243) and Patent Document 6 (Japanese Patent Laid-Open No. 2003-84200), two light prisms are combined, and the light incident surface of the first prism closer to the object, It is described that free curved surfaces are used for all seven surfaces in total, that is, the light incident surface, the two reflective surfaces, and the light exit surface of the second prism closer to the reflective surface, the light exit surface, and the imaging surface.

As a feature of such an optical system,
(1) The three reflecting surfaces use free-form surfaces having power (refractive power), but these reflecting surfaces can obtain a large power with respect to a refractive optical system such as a lens, and at the same time, chromatic aberration. Not affected.

(2) It can have seven optical surfaces in a compact space. Accordingly, the optical elements can be condensed and set in a limited space.

(3) Although it is desirable to increase the optical path length of the entire optical system to some extent in order to improve the optical performance, by using such a prism optical system, the optical path is bent, but the entire optical path length is long. The size of can be made compact.
For the above reasons, it is possible to improve image quality while being compact.

JP-A-11-264927 describes a mechanism for amplifying the displacement of a piezoelectric element as a method for adjusting the focus of a coaxial optical system.
JP 2001-272587 A Japanese Patent Laid-Open No. 2002-267928 JP 2002-320122 A Japanese Patent Laid-Open No. 11-326766 JP 2002-196243 A JP 2003-84200 A JP 11-264927 A

  In an imaging device using an optical system of an optical axis system, a mechanism using a DC motor, a stepping motor, or the like is known as a focusing mechanism. However, when these motors are used, the size of the motor is small. There is a problem of being big. In addition, since the speed reduction mechanism for reducing the driving force of the motor is further required, the entire imaging apparatus is further increased. For this reason, it is disadvantageous when applied to, for example, a thin digital camera or a camera-equipped mobile phone.

  Further, a focusing mechanism using an ultrasonic motor has been proposed as a drive source that does not use a speed reduction mechanism. However, the focusing mechanism using an ultrasonic motor has a complicated structure and a high cost.

  Accordingly, an object of the present invention is to provide an imaging device having a free-form surface prism and a focusing mechanism that can be configured compactly, and an imaging device using the imaging device.

  An image pickup apparatus according to a first aspect of the present invention is a prism unit that forms an object image on an image formation surface by entering a light beam from an object, and has at least two free-form surfaces. The incident optical axis for entering the light beam from the object and the exit optical axis for emitting the light beam from the imaging optical system to the imaging surface are substantially parallel and spaced apart from each other. A prism unit including a prism optical system, an imaging element disposed on the imaging plane and converting an object image formed by the prism unit into an electrical signal, and the prism unit parallel to a light receiving surface of the imaging element. A restricting means for restricting to a predetermined position in a plane, a piezoelectric element formed by laminating a plurality of piezoelectric bodies in a direction parallel to the light receiving surface of the imaging element, and an expansion / contraction displacement of the piezoelectric element A displacement enlargement mechanism of A displacement direction converting means for converting the direction of expansion / contraction displacement of the piezoelectric element into a direction orthogonal to the light receiving surface of the imaging element, and the displacement expanded and direction-converted by the displacement enlarging mechanism and the displacement direction converting means. A displacement transmitting member that transmits to the prism unit and moves the prism unit in a direction orthogonal to the light receiving surface of the image sensor, and controls a focus state of the prism unit by applying a predetermined voltage to the piezoelectric element. And a focus control means.

  The imaging apparatus of the present invention based on the second aspect applies processing means for obtaining image data by applying predetermined electrical processing to an electrical signal obtained by the imaging device, and the image data from the processing means. Recording means for recording on the recorded information recording medium. An example of the imaging device is a digital camera or a mobile phone with a camera.

  In a preferred embodiment of the present invention, the piezoelectric element is formed by laminating the plurality of piezoelectric bodies in a direction in which the incident optical axis and the emission optical axis are aligned. According to this configuration, since a large number of piezoelectric bodies can be stacked in the longitudinal direction of the imaging optical system (prism unit), the total length in the stacking direction of the piezoelectric bodies can be increased, and the focus adjustment range can be increased. It can be expanded.

  An example of the prism unit includes two prisms, and each prism has at least one free-form reflecting surface, a light incident surface having refractive power, and a light emitting surface having refractive power. And a diaphragm member disposed between the prisms.

  In a preferred embodiment of the present invention, the displacement magnifying mechanism and the displacement direction converting means are constituted by members common to each other (for example, a plate member). According to this configuration, since the displacement enlarging mechanism and the displacement direction converting means are used as a common member, it is possible to reduce the number of parts and reduce the cost and the installation space of the piezoelectric element.

  In a preferred embodiment of the present invention, the displacement enlarging mechanism and the displacement direction converting means are respectively arranged so as to extend in the stacking direction of the piezoelectric elements with the piezoelectric elements interposed therebetween, and the substantially central portion is refracted and the end portions are at the ends. A pair of refracting members that connect both end surfaces of the piezoelectric elements in the stacking direction, and a connecting member that is refracted at a substantially central portion and communicates with the substantially central portions of the pair of refracting members at both ends. .

  An example of the focus control unit selectively selects a first position in a direction orthogonal to the light receiving surface of the image sensor and a second position farther from the light receiving surface than the first position. Switching is performed to control the positioning of the prism unit.

  The first position is a standard imaging position for performing imaging corresponding to a case where the position of an object to be imaged is between a predetermined position and approximately infinity, and the second position is an imaging This is a macro imaging position for performing imaging corresponding to a case where the position of the object to be processed is closer than the predetermined position. According to this configuration, the standard imaging position and the macro imaging position can be switched, and a wide imaging area can be handled.

  The standard imaging position in this specification means a pan-focus imaging state in which the focus is almost in focus from a close range to infinity. The macro imaging position means an imaging state suitable for shooting in a very close range where the distance to the subject is further shorter than the close range.

  In a preferred embodiment of the present invention, there is further provided a distance measuring means for measuring the distance to the object, and the focus control means inputs the distance detection signal from the distance measuring means for performing the focus control. This constitutes a so-called autofocus mechanism.

  In another preferred embodiment of the present invention, the camera further includes a focus detection unit for detecting a focus state, and the focus control unit performs the focus control by inputting a focus detection signal from the focus detection unit. Yes, so-called hill-climbing control is applied.

  In another preferred embodiment of the present invention, the camera further comprises adjustment value recording means for recording fc adjustment data for fc adjustment, wherein the focus control means takes into account the fc adjustment data from the adjustment value recording means. Thus, a voltage to be applied to the piezoelectric element is determined.

  According to this configuration, even if the positions of the imaging surface of the prism unit and the light receiving surface of the image sensor are shifted due to dimensional variations of components inevitably occurring in manufacturing the imaging device, variations in assembly, etc. Then, focus control is performed so as to correct the deterioration of the imaging state due to this by using the fc adjustment data or the like. For this reason, good quality image data can always be obtained in the best imaging state.

  According to the present invention, a plurality of piezoelectric bodies constituting a multilayer piezoelectric element are stacked in a direction parallel to the light receiving surface of the image sensor, and the expansion and contraction displacement of the piezoelectric element is further expanded and the direction of the displacement is received. Since the direction parallel to the surface is changed to the direction orthogonal to the light receiving surface, the length of the piezoelectric element in the stacking direction is longer than the case where the piezoelectric material is stacked in the direction orthogonal to the light receiving surface. It becomes possible to enlarge.

  For this reason, the movable range of the prism unit, that is, the movable range in the direction orthogonal to the light receiving surface of the image sensor can be increased. A thin imaging device can be obtained.

A first embodiment of the present invention will be described below with reference to FIGS.
FIG. 1 shows a digital camera 1 as an example of an imaging device. As shown in FIG. 2, an imaging device 10, an image processing circuit 11 as a processing unit, a recording unit 12, and the like are accommodated in a housing 2 of the digital camera 1. The image processing circuit 11 has a function of obtaining image data by performing predetermined electrical processing on the electrical signal obtained by the imaging device 10. The recording unit 12 functions as a recording unit for recording the image data from the image processing circuit 11 on the applied recording medium. Here, the “applied recording medium” refers to a flash memory built in the digital camera 1, a memory card that can be inserted and removed externally, and the like.

  The housing 2 is provided with a release button 20, a flash 21, a finder optical system 22, a cover glass 23, and the like. An image monitor 24 is provided on the back surface of the housing 2.

  The imaging device 10 includes a prism unit 30 that constitutes a decentered optical system, and a fixed frame 31. An imaging element 32 such as a CCD mounted on the substrate is positioned and held at a predetermined position of the fixed frame 31.

  An example of the prism unit 30 is shown in FIGS. The prism unit 30 includes a first prism 41, a diaphragm member 43 having an aperture diaphragm, and a second prism 42. The diaphragm member 43 also functions as a holding member for holding the first and second prisms 41 and 42 at predetermined positions.

  An optical member 44 such as a filter is disposed on the exit side of the second prism 42. The light emitted from the second prism 42 forms an image on the image plane 45. A light receiving surface of an image sensor 32 for converting an object image formed by the prism unit 30 into an electric signal is disposed on the image plane 45.

  As shown in FIG. 3, the first prism 41 is an eccentric prism having an entrance surface 51, a rotationally asymmetric reflection surface 52, and an exit surface 53. As shown in FIG. 5, the exit surface 53 of the first prism 41 has a flat surface portion 53b formed in a flat surface outside the effective diameter portion 53a. The flat surface portion 53b has two positioning portions 53c and 53d formed in a columnar shape, three projecting portions 53e, 53f, and 53g formed in a hemispherical shape. The positioning portions 53c and 53d are provided at positions outside the effective diameter portion 53a. In FIG. 4, the positioning portions 53c and 53d are provided to face each other with the effective diameter portion 53a interposed therebetween.

  The protrusions 53e and 53g are provided at positions outside the positioning portions 53c and 53d that sandwich the effective diameter portion 53a. Therefore, when compared with the distance from the center position of the effective diameter portion 53a, the distance to the projecting portions 53e and 53g is longer than the distance to the positioning portions 53c and 53d. The protruding portion 53f is provided outside the effective diameter portion 53a and inside the positioning portions 53c and 53d. As described above, at least two of the three protrusions are provided at positions that are longer (distant) than the distance to the positioning portion as compared with the distance from the center position of the effective diameter portion 53a. .

  As shown in FIG. 3, the second prism 42 is composed of an eccentric prism having an incident surface 61, a reflecting surface 62, a reflecting surface 63, and an exit surface 64. At least one of the reflecting surface 62 and the reflecting surface 63 is a rotationally asymmetric surface.

  As shown in FIG. 6, the incident surface 61 of the second prism 42 has a flat surface portion 61 b that is formed in a flat surface outside the effective diameter portion 61 a. The flat portion 61b has two positioning portions 61c and 61d formed in a columnar shape and three protrusions 61e, 61f and 61g formed in a hemispherical shape. The positioning portions 61c and 61d are provided at outer positions sandwiching the effective diameter portion 61a. The protrusions 61e and 61g are provided at positions outside the positioning portions 61c and 61d that sandwich the effective diameter portion 61a. The protrusion 61f is provided outside the effective diameter portion 61a and inside the positioning portions 61c and 61d. Further, the protrusions 61e, 61f, 61g are arranged asymmetrically on the incident surface 61.

  As shown in FIGS. 7 to 9, the diaphragm member 43 that also functions as a holding member includes an opening 62 a configured to match the effective diameter of the optical action surfaces of the two prisms 41 and 42. The diaphragm member 43 has planar portions 62b and 62c formed on the both sides on the outside of the opening 62a.

  Positioning and holding portions 62d, 62e, 62f, and 62g are formed on the flat portions 62b and 62c. These positioning holding portions 62d to 62g are formed at positions corresponding to the positioning portions 53c, 53d, 61c, 61d of the first and second prisms 41, 42, and are matched to the shapes of the positioning portions 53c, 53d, 61c, 61d. Thus, it is formed as a through-hole that can be fitted.

  An example of the thickness H of the diaphragm member 43 is designed to be H = 1.12 mm, and examples of the lengths t of the positioning portions of the first and second prisms 41 and 42 are each set to t = 0.55 mm. In this case, t / H = 0.49.

  In the prism unit 30 configured in this way, the first prism 41 is fitted from the flat portion 62b side of the diaphragm member 43 with the positioning portion 53c fitted into the positioning holding portion 62d and the positioning portion 53d fitted into the positioning holding portion 62e. Combine. Thereby, the position of the first prism 41 is determined.

  At this time, the protrusions 53e, 53f, 53g of the first prism 41 abut on the flat surface portion 62b of the diaphragm member 43, whereby the inclination of the first prism 41 with respect to the diaphragm member 43 is determined. Similarly, the positioning part 61c is fitted to the positioning holding part 62f, and the positioning part 61d is fitted to the positioning holding part 62g from the flat part 62c side of the diaphragm member 43. Thereby, the position of the second prism 42 is determined. At this time, the protrusions 61e, 61f, 61g of the second prism 42 abut on the flat surface portion 62c of the diaphragm member 43, whereby the inclination of the second prism 42 with respect to the diaphragm member 43 is determined.

  In this way, the first prism 41 and the second prism 42 are held on both sides of the aperture member 43 as shown in FIG. In the state of FIG. 10, when it is necessary to adjust the inclination of the first and second prisms 41 and 42 with respect to the diaphragm member 43, the protrusions 53 e, 53 f, 53 f, 53 f, 53 f, 53 f, The inclinations of the prisms 41 and 42 can be easily adjusted by cutting the protrusions 61e, 61f, and 61g of the second prism 42 by a predetermined amount.

  As described above, the prism unit 30 according to the present embodiment is used to form an object image on the imaging surface 45 by entering a light beam from an object, and includes at least two free-form reflecting surfaces 52. , 62, 63. In addition, the incident optical axis for entering the light beam from the object and the exit optical axis for emitting the light beam from the prism unit 30 to the imaging surface 45 are substantially parallel, and the prism optical system has a predetermined interval. It is configured.

  The prism unit 30 is accommodated in a case 70 as shown in FIGS. An incident window 71 is formed in the case 70 at a position facing the incident surface 51 of the first prism 41. The prism unit 30 is fixed at a predetermined position inside the case 70. For example, the receiving member 72 formed of a convex portion formed on the side portion of the diaphragm member 43 is fitted into the concave portion (notch portion) 73 of the case 70, and both are bonded to each other.

  As shown in FIGS. 12 and 13, a pair of guide members 75 and 76 are formed on the fixed frame 31. These guide members 75 and 76 are fitted into engaging portions 77 and 78 formed in the case 70. The guide members 75 and 76 restrict the case 70 from moving in a direction parallel to the light receiving surface of the image sensor 32 (directions indicated by arrows X and Z in FIG. 11), and the case 70 receives the light receiving surface of the image sensor 32. It is allowed to move in a direction orthogonal to the direction (direction indicated by arrow Y). The guide members 75 and 76 and the engaging portions 77 and 78 constitute restriction means for restricting the prism unit 30 to a predetermined position in a plane parallel to the light receiving surface of the image sensor 32.

  The imaging apparatus 10 includes a piezoelectric actuator 80 that functions as a driving unit for driving the prism unit 30 in a direction orthogonal to the light receiving surface of the imaging element 32. The piezoelectric actuator 80 has a function of driving the prism unit 30 so as to be movable in the Y direction while maintaining the posture of the prism unit 30 along the guide members 75 and 76.

Hereinafter, the piezoelectric actuator 80 will be described.
As shown in FIG. 14, the piezoelectric actuator 80 includes a laminated piezoelectric element 81 that uses a piezoelectric effect (piezo effect), holding members 82 and 83 that hold the piezoelectric element 81, a displacement enlarging mechanism, and a displacement direction converting means. And a pair of thin plate spring-like refracting members 84 and 85, and connecting members 86 and 87 that communicate with the substantially central portions of the refracting members 84 and 85 and also serve as a displacement enlarging mechanism.

  The piezoelectric element 81 is formed by laminating a plurality of piezoelectric bodies 90 each having a plate shape in a direction parallel to the light receiving surface of the imaging element 32. Although the displacement amount of each piezoelectric body 90 is small, Thus, a large displacement can be obtained as a whole of the piezoelectric element 81 by laminating a large number of piezoelectric bodies 90 in the thickness direction.

  The refracting members 84 and 85 functioning as expansion spring members are arranged so as to extend in the stacking direction of the piezoelectric elements 81 with the piezoelectric element 81 interposed therebetween. Both end portions 84a and 85a of the refracting members 84 and 85 are fixed to the holding members 82 and 83 provided on both end surfaces of the piezoelectric element 81 in the stacking direction by adhesion or the like.

  The substantially central portions 84b and 85b of the refracting members 84 and 85 are refracted in a mountain shape at a predetermined angle (obtuse angle) so that each of them protrudes outward. Arm portions 84c and 84d are formed on both sides of the central portion 84b of one refractive member 84. Arms 85c and 85d are also formed on both sides of the central portion 85b of the other refractive member 85.

  The connecting members 86 and 87 connecting the central portions 84b and 85b of the refracting members 84 and 85 each have a predetermined angle (obtuse angle) such that the substantially central portion 86b (only one is shown in FIG. 14) is convex outward. It is refracted into a mountain shape.

  Arm portions 86 c and 86 d are formed on both sides of the central portion 86 b of one connecting member 86. Each of the arm portions 86c and 86d of the connecting member 86 has a tapered shape such that the width becomes wider toward the central portion 86b. The reason why the arm portions 86c and 86d have such a tapered shape is to make the bending moment uniform when the arm portions 86c and 86d are deformed. Similar arm portions are formed on both sides of the central portion of the other connecting member 87.

  By applying a predetermined voltage to the multilayer piezoelectric element 81 configured as described above, the piezoelectric element 81 expands and contracts in the stacking direction. The central portion 86b of one connecting member 86 functions as an output portion, and the abutting surface 72a of the receiving member 72 on the prism unit 30 side comes into contact with the central portion 86b.

  In the piezoelectric actuator 80 configured as described above, when a voltage is applied to the piezoelectric element 81, the piezoelectric element 81 is displaced in the primary displacement direction indicated by the arrow X1 in FIG. This primary displacement X1 is transmitted to the refracting members 84 and 85 through the holding members 82 and 83, and the arm portions 84c, 84d, 85c and 85d of the refracting members 84 and 85 according to the polarity of the applied voltage. While being amplified in the direction in which the bent state increases or extends, the central portions 84b, 85b of the refractive members 84, 85 are displaced in the direction of the secondary displacement indicated by the arrow X2.

  By transmitting this secondary displacement X2 to the connecting members 86 and 87, the bending state of the arm portions 86c and 86d (only one connecting member 86 is shown in FIG. 14) is amplified in the direction of increasing or extending, The central portion 86b is displaced in the direction of the tertiary displacement indicated by the arrow Y1. For example, the secondary displacement X2 is expanded from several times to several tens of times of the primary displacement X1, and further, the tertiary displacement Y1 is expanded to several tens of times or more of the primary displacement X1. A similar amplifying action occurs in the other connecting member 87.

  By these refracting members 84 and 85 and connecting members 86 and 87, a displacement enlarging mechanism (mechanism for enlarging expansion / contraction displacement of the piezoelectric element 81) referred to in the present invention and a displacement direction converting means (direction of expansion / contraction displacement of the piezoelectric element 81). The amplifying unit 91 is also configured to serve as a means for converting the signal into a direction orthogonal to the light receiving surface of the image sensor 32.

  As a result, the displacement of the piezoelectric element 81 is enlarged several tens of times or more by the amplifying unit 91 and transmitted to the prism unit 30 through the receiving member 72 from the central portion 86b of the connecting member 86 functioning as the output unit. . The central portion 86b of the connecting member 86 transmits the displacement of the piezoelectric element 81 expanded and direction-converted by the displacement magnifying mechanism and the displacement direction converting means to the prism unit 30, and the prism unit 30 is received by the image sensor 32. It also functions as a displacement transmission member for moving in a direction orthogonal to the surface.

  The amplifying portion 91 of the piezoelectric actuator 80 according to the present embodiment configured as described above expands the displacement by utilizing the buckling deformation of the refracting members 84 and 85 and the connecting members 86 and 87 that function as expanding spring members. Yes, it can be formed integrally by a plate member having springiness. For this reason, the displacement of the multilayer piezoelectric element 81 can be efficiently expanded and transmitted to the output unit, and the piezoelectric actuator 80 itself as the drive unit can be configured in a small size.

  In addition, a plurality of piezoelectric bodies 90 constituting the piezoelectric element 81 are stacked in the direction parallel to the light receiving surface of the imaging element 32, that is, the direction in which the incident optical axis and the outgoing optical axis are aligned, and the piezoelectric element 81 expands and contracts. In order to expand the displacement and change the direction of displacement from a direction parallel to the light receiving surface (a direction indicated by an arrow X) to a direction orthogonal to the light receiving surface (a direction indicated by an arrow Y), Compared with the case where the piezoelectric elements 81 are stacked in the direction orthogonal to the light receiving surface, the length of the piezoelectric elements 81 in the stacking direction can be increased.

  In other words, since a large number of piezoelectric bodies 90 can be stacked in the longitudinal direction of the imaging optical system (prism unit 30), the total length of the piezoelectric bodies 90 in the stacking direction can be increased, and the focus adjustment range can be increased. It can be expanded.

  The imaging apparatus 10 further includes a focus control unit 100 (shown in FIG. 15) for applying a predetermined voltage to the piezoelectric element 81 to control the focus state of the prism unit 30. The focus control means 100 will be described below.

  FIG. 15 is a block diagram illustrating a circuit configuration and the like of the digital camera 1 incorporating the focus control unit 100. The focus control means 100 has a function of controlling the piezoelectric actuator 80 to move the prism unit 30 along the guide members 75 and 76 in order to focus the prism unit 30, and the prism unit 30 is shown in FIG. This also serves as a function of selectively positioning and holding the standard imaging position P1 and the macro imaging position P2.

  The focus control means 100 of this embodiment includes a distance measuring device 101 that functions as a distance measuring means, and uses this distance measuring device 101 and the piezoelectric actuator 80 to focus the prism unit 30. is there.

  The distance measuring device 101, like the known distance measuring device, emits a light beam from the light emitting device 102 toward the object and receives the reflected light by the light receiving device 103, for example, based on the principle of triangulation. The distance circuit 104 calculates the distance. The distance to the object detected by the distance measuring circuit 104 is input to the sequence control circuit 110.

  The sequence control circuit 110 is connected to an operation member group 111, an adjustment value memory 112 for storing AF adjustment data and fc adjustment data used for adjusting distance measurement data, a frame memory 113, and the like. The operation member group 111 includes a release button 20 and a mode switching switch for switching between standard imaging and macro imaging.

  The electrical signal of the image obtained by the image pickup device 32 is input to the image processing circuit 11 as processing means via the CCD interface 114, and further passes through the compression / decompression circuit 115 and the recording unit 12, and then the image recording medium 116. To be recorded. The image can be displayed on the monitor 24 via the monitor interface 117.

  A piezoelectric element driving circuit 120 is connected to the piezoelectric element 81 constituting the piezoelectric actuator 80, and controls the voltage applied to the piezoelectric actuator 80 based on the distance detection signal output from the distance measuring device 101. It is like that.

  FIG. 16 shows the flow of processing at the time of shooting with the digital camera 1 using the distance measuring device 101. When it is detected in step S1 in FIG. 16 that the release button has been pressed, it is determined in step S2 whether or not the changeover switch of the operation member group 111 is in the macro mode.

  In the macro mode, the driving amount of the prism unit 30 corresponding to macro imaging is calculated in step S3 of FIG. 16, and a predetermined voltage is applied to the piezoelectric actuator 80, whereby the prism unit 30 is moved to the macro imaging position (FIG. 2). After that, the process proceeds to step S7 below. The prism unit 30 uses the term “lens” in FIGS. 16, 18 and 19 because the prisms 41 and 42 having refractive power also function as lenses.

  If not in the macro mode, the distance measuring data (AFD) up to the object is obtained using the distance measuring device 101 in step S4. FIG. 17 shows the relationship between the actual object distance and distance measurement data. As shown in this figure, the relationship between the object distance and the distance measurement data (corresponding relationship in design) is generally proportional as indicated by a line segment L1.

  However, depending on the product, as indicated by the line segment L2 or L3, a deviation (ΔAFD1 or ΔAFD2) may occur with respect to the design correspondence (L1). This deviation (for example, ΔAFD1 or ΔAFD2) is obtained by actual measurement or the like for each product and stored in advance in the adjustment value memory 112 (shown in FIG. 15) as AF adjustment data.

  Furthermore, it is best for an object at a predetermined distance due to variations in assembling due to variations in dimensions and characteristics of the imaging optical system including the prism and the components of the holding members of the imaging optical system. The position in the optical axis direction (the Y direction) of the imaging optical system necessary for obtaining the in-focus state may be shifted. The adjustment data for adjusting this deviation for each product is fc adjustment data. The fc adjustment data is also stored in the adjustment value memory 112 in advance.

  In step S5 in FIG. 16, the AF adjustment data from the adjustment value memory 112 is added to the distance measurement data (AFD) obtained in step S4. In step S6, the lens driving amount (LD value) is obtained, and in step S7, the fc adjustment data from the adjustment value memory 112 is added to obtain the final driving amount.

  In step S8, a voltage corresponding to the lens driving amount is applied to the piezoelectric actuator 80, thereby focusing the prism unit 30. Further, in step S9, imaging is performed. The imaged data is subjected to image processing in step S10, subjected to compression processing in step S11, and then recorded as image data in, for example, a recording medium 116 (shown in FIG. 14) in step S12. Finally, in step S13, the position of the prism unit 30 is driven to an infinite position by the piezoelectric actuator 80, and the process returns to step S1.

  Since the imaging device 10 can finely adjust the position of the focus surface by the fc adjustment, the prism unit is caused by variations in the parts of the components inevitably generated when the imaging device 10 is assembled, the shape accuracy of the components, and the like. The positional deviation between the 30 imaging surfaces 45 and the light receiving surface of the image sensor 32 can be minimized. For this reason, the imaging device 10 can form a high-quality image.

  FIG. 18 and FIG. 19 show a second embodiment of the present invention, which is an example provided with a focus detection means for detecting a focus state instead of using the distance measuring device 101. The focus detection means of this embodiment is adapted to obtain an optimum focus state by so-called hill climbing control (schematically shown in FIG. 18).

  FIG. 19 shows the flow of focusing processing using hill climbing control. If it is detected in step S20 of FIG. 19 that the release button has been pressed, it is determined in step S21 whether or not the macro mode is set. If it is not the macro mode, the process proceeds to the following step S25.

  In the macro mode, the driving amount of the prism unit 30 corresponding to macro imaging is calculated in step S22. In step S23, the fc adjustment value obtained in the same manner as in the first embodiment is added. After that, in step S24, a predetermined voltage is applied to the piezoelectric actuator 80, so that the prism unit 30 moves all at once to the macro imaging position, and then the process proceeds to step S25 where imaging for focusing is performed.

  After imaging is performed in step S25, the contrast of the image is detected in step S26, and further, in step S27, it is determined whether or not the contrast value is a peak. If the contrast value is not a peak, the prism unit 30 is moved by one step in the first direction by the piezoelectric actuator 80 in step S28.

  That is, as shown in FIG. 18, when the prism unit 30 moves in the first direction from the start value and the contrast value exceeds the peak, the prism unit 30 moves in the second direction opposite to the previous value. Stop one step back. This position is the just focus position. In this manner, so-called hill climbing control is performed by a series of processes from step S25 to step S28, and the prism unit 30 is focused.

  After focusing is completed, imaging is performed in step S29. The imaged data is subjected to image processing in step S30, compressed in step S31, and then recorded as image data in, for example, the recording medium 116 (shown in FIG. 14) in step S32. After that, the process returns to step S20.

  Similarly to the first embodiment, the imaging apparatus 10 of the second embodiment can finely adjust the position of the focus surface by fc adjustment based on the adjustment value from the adjustment value memory 112. Therefore, the imaging apparatus 10 Thus, the positional deviation between the imaging surface 45 of the prism unit 30 and the light receiving surface of the image sensor 32 due to variations in the parts of the component inevitably generated during assembly, the shape accuracy of the component, and the like can be minimized. For this reason, the imaging device 10 can form a high-quality image.

  FIG. 20 shows an example in which the imaging apparatus of the present invention is incorporated in a camera-equipped mobile phone 160 as an example of imaging equipment. By incorporating the imaging device 10 into the camera-equipped mobile phone 160, the camera-equipped mobile phone 160 can be reduced in size and thickness, and the image quality can be improved.

  The camera-equipped mobile phone 160 may be provided with the distance measuring device 101 (FIG. 15) of the above-described embodiment, and the focus control unit 100 may perform focusing. When the distance measuring device 101 is not used, focusing by the above-described hill climbing control (FIGS. 18 and 19) is performed.

  21 to 23 show different examples of the prism units 30a, 30b, and 30c applied to the imaging apparatus of the present invention. Each of the prism units 30a, 30b, and 30c can be switched and focused between the standard imaging position P1 and the macro imaging position P2 by a piezoelectric actuator similar to that of the imaging apparatus of the above embodiment.

  In the prism unit 30a shown in FIG. 21, the surfaces 201 to 206 of the first prism 41a and the second prism 42a are all free-form surfaces. The light incident from the first surface 201 is refracted by the first surface 201, totally reflected by the second surface 202, refracted by the third surface 203, and then refracted by the fourth surface 204. Further, the light is totally reflected by the fifth surface 205, then totally reflected by the sixth surface 206, refracted by the fifth surface 205, and then imaged on the imaging surface 45.

  The decentering prism 210 of the prism unit 30b shown in FIG. 22 has a first surface 211, a second surface 212, and a third surface 213 that are free-form surfaces. The light incident through the diaphragm member 214 is refracted by the first surface 211 and incident on the eccentric prism 210, is internally reflected by the second surface 212, is incident again on the first surface 211, and is totally reflected this time. Internally reflected by the third surface 213, totally reflected by the first surface 211 three times, again internally reflected by the third surface 213, refracted by the first surface 211 and imaged by the imaging surface 45 four times. To do.

  In the prism unit 30c shown in FIG. 23, the surfaces 231 to 238 of the first prism 221 and the second prism 222 are all free-form surfaces. The light incident from the first surface 231 is refracted by the first surface 231, totally reflected by the second surface 232, further totally reflected by the third surface 233, and then refracted by the fourth surface 234 and the fifth surface 235. Further, after being totally reflected by the sixth surface 236 and the seventh surface 237, it is refracted by the eighth surface 238 and forms an image on the imaging surface 45.

  In implementing this invention, the components of the invention, including the prism optical system, imaging device, regulating means, piezoelectric element, displacement magnifying mechanism, displacement direction converting means, displacement transmitting member, and focus control means, are included in this invention. Needless to say, various modifications can be made without departing from the scope of the present invention.

1 is a perspective view of a digital camera including an imaging device according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing the inside of the digital camera shown in FIG. 1. The side view of the prism unit of the digital camera shown by FIG. FIG. 4 is an exploded perspective view of the prism unit shown in FIG. 3. FIG. 4 is a perspective view of a first prism of the prism unit shown in FIG. 3. FIG. 4 is a perspective view of a second prism of the prism unit shown in FIG. 3. FIG. 4 is a perspective view of a diaphragm member of the prism unit shown in FIG. 3. FIG. 4 is a front view of a diaphragm member of the prism unit shown in FIG. 3. FIG. 4 is a rear view of a diaphragm member of the prism unit shown in FIG. 3. FIG. 4 is a perspective view of the prism unit shown in FIG. 3. The perspective view of the imaging device incorporated in the digital camera shown by FIG. FIG. 12 is an exploded perspective view of the imaging apparatus shown in FIG. 11. The side view of the imaging device shown by FIG. The perspective view of the piezoelectric actuator used for the imaging device shown in FIG. FIG. 2 is a block diagram showing a circuit configuration and the like of the digital camera shown in FIG. 1. 2 is a flowchart of a focusing process of the digital camera shown in FIG. The figure which shows the relationship between the ranging data of the digital camera shown by FIG. 1, and object distance. The figure which shows the relationship between the lens drive position at the time of performing hill-climbing control, and a contrast value. 9 is a flowchart of a focusing process of a digital camera showing a second embodiment of the present invention. The perspective view which shows the mobile phone with a camera as another example of the apparatus for imaging. Sectional drawing which shows the other example of a prism optical system typically. Sectional drawing which shows the further another example of a prism optical system typically. Sectional drawing which shows the further another example of a prism optical system typically.

Explanation of symbols

1. Digital camera (imaging equipment)
DESCRIPTION OF SYMBOLS 10 ... Imaging device 11 ... Image processing circuit 12 ... Recording part (recording means)
30, 30a, 30b, 30c ... Prism unit 32 ... Imaging element 41 ... First prism 42 ... Second prism 45 ... Imaging surface 75, 76 ... Guide member (regulating means)
80 ... Piezoelectric actuator (drive unit)
84, 85 ... refractive member (displacement magnifying mechanism, displacement direction converting means)
86, 87 ... communication member (displacement direction conversion means, displacement transmission member)
101 ... Distance measuring device (focus control means)
112 ... Adjustment value memory (Adjustment value recording means)
S25 to S28: Steps for hill climbing control (focus control means)
160 ... Mobile phone with camera (imaging device)

Claims (11)

A prism unit that forms an imaging optical system for entering a light beam from an object and forming an object image on the imaging surface. The prism unit has at least two free-form reflecting surfaces and enters the light beam from the object. A prism unit including a prism optical system in which an incident optical axis for performing and an exit optical axis for emitting a light beam from the imaging optical system to the imaging surface are substantially parallel and spaced apart from each other;
An image sensor that is disposed on the imaging plane and converts an object image formed by the prism unit into an electrical signal;
Restricting means for restricting the prism unit to a predetermined position in a plane parallel to the light receiving surface of the image sensor;
A piezoelectric element formed by laminating a plurality of piezoelectric bodies in a direction parallel to the light receiving surface of the imaging element;
A displacement enlarging mechanism for enlarging the expansion and contraction displacement of the piezoelectric element;
A displacement direction converting means for converting the direction of expansion / contraction displacement of the piezoelectric element into a direction orthogonal to the light receiving surface of the imaging element;
A displacement transmitting member that transmits the displacement expanded and direction-converted by the displacement enlarging mechanism and the displacement direction converting means to the prism unit and moving the prism unit in a direction perpendicular to the light receiving surface of the image sensor;
A focus control means for controlling a focus state of the prism unit by applying a predetermined voltage to the piezoelectric element;
An imaging apparatus comprising: Processing means for performing predetermined electrical processing on an electrical signal obtained by the imaging apparatus according to claim 1 to obtain image data;
Recording means for recording the image data from the processing means on an applied information recording medium;
An imaging apparatus comprising:   The imaging apparatus according to claim 1, wherein the plurality of piezoelectric bodies are stacked in a direction in which the incident optical axis and the emission optical axis are aligned.   The prism unit has two prisms, and each prism has at least one free-form reflecting surface, a light incident surface having refractive power, and a light emitting surface having refractive power, The imaging apparatus according to claim 1, further comprising a diaphragm member disposed between the prisms.   The imaging apparatus according to claim 1, wherein the displacement magnifying mechanism and the displacement direction conversion unit are configured by members common to each other.   The displacement enlarging mechanism and the displacement direction converting means are respectively disposed so as to extend in the stacking direction of the piezoelectric elements with the piezoelectric element interposed therebetween, and substantially center portions are refracted, and both ends of the piezoelectric elements in the stacking direction are arranged. 6. A pair of refracting members that connect surfaces, and a connecting member that is refracted in a substantially central portion and communicates with the substantially central portion of each of the pair of refracting members at both ends. Imaging device.   The focus control unit selectively switches the prism unit between a first position in a direction orthogonal to the light receiving surface of the image sensor and a second position farther from the light receiving surface than the first position. The imaging apparatus according to claim 1, wherein control for positioning the prism unit is performed.   The first position is a standard imaging position for performing imaging corresponding to a case where the position of an object to be imaged is between a predetermined position and approximately infinity, and the second position is an imaging The imaging apparatus according to claim 7, wherein the imaging apparatus is a macro imaging position for performing imaging corresponding to a case where a position of an object to be processed is closer than the predetermined position.   The distance measuring means for measuring the distance to the object is further provided, and the focus control means performs the focus control by inputting a distance detection signal from the distance measuring means. The imaging device described.   2. The focus detection unit according to claim 1, further comprising a focus detection unit for detecting a focus state, wherein the focus control unit inputs the focus detection signal from the focus detection unit and performs the focus control. Imaging device.   adjustment value recording means for recording fc adjustment data for fc adjustment, wherein the focus control means is a voltage applied to the piezoelectric element in consideration of the fc adjustment data from the adjustment value recording means The imaging apparatus according to claim 1, wherein:

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