JP2012163797A - Imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus with a movement mechanism of an image pickup device, which allows the movement mechanism to be thin.SOLUTION: In a movement mechanism for moving an image pickup device 3 along an optical axis of an imaging optical system, a fulcrum part 6 attached to a sheet metal 5 is arranged at a position overlapping the image pickup device 3 when viewed from a direction orthogonal to the optical axis. The sheet metal 5 is connected and fixed to a lead frame 4 extended from the image pickup device 3. An actuator part deforms the sheet metal 5 by the expansion and contraction of a piezoelectric device 7 according to an applied voltage from a drive control part to displace the image pickup device 3 in the optical axis direction.

Description

  The present invention relates to an imaging apparatus such as a still camera or a video camera, and more particularly to a technique for imaging while moving an imaging element in the optical axis direction of an imaging optical system.

In recent years, a single-lens reflex type interchangeable lens digital camera has attracted attention as well as a product having a moving image shooting function in addition to still image shooting. An apparatus equipped with a contrast detection type autofocus (AF) mechanism that is advantageous during moving image shooting has been developed.
In an imaging apparatus including a moving mechanism for an image sensor in the camera body in addition to the focus lens moving mechanism in the interchangeable lens, the focusing direction of the lens is determined by causing the image sensor to perform a wobbling operation in the photographing optical axis direction. A focusing operation is performed by scanning the focus lens based on the determination result. For example, in a configuration in which a wobbling mechanism for an image sensor is provided in the video camera body, a piezoelectric element is used for the actuator unit. By using the piezoelectric element, the configuration can be simplified, and the accuracy can be increased while the number of components is reduced.

However, even if a wobbling mechanism using a piezoelectric element is adopted, if it is placed inside the main body of a current interchangeable lens digital camera, it will cause an increase in size, and the dimension in the thickness direction will be particularly long. Is a problem.
Accordingly, an object of the present invention is to reduce the thickness of the moving mechanism in an imaging apparatus including the moving mechanism of the imaging element.

  In order to solve the above problems, an apparatus according to the present invention is an imaging apparatus having a moving mechanism that moves an imaging element along an optical axis of an imaging optical system, and an elastic member attached to the imaging element; A support member that is disposed at a position overlapping with the imaging element when viewed from a direction orthogonal to the optical axis, and an actuator that displaces the imaging element in the direction of the optical axis by deforming the elastic member. And a drive control means for the actuator unit.

  According to the present invention, the moving mechanism of the image sensor can be thinned in the optical axis direction.

In order to explain the first embodiment of the present invention in conjunction with FIGS. 2 to 5, they are a horizontal sectional top view (A) and a vertical sectional view (B) showing a configuration example of the imaging apparatus. They are a perspective view (A) when the imaging apparatus is viewed from the mount portion 1a side and a perspective view (B) when viewed from the back side. They are a front view (A), a horizontal sectional top view (B), and a vertical sectional view (C) of the imaging unit. It is the perspective view (A) of an imaging part, and the exploded perspective view (B) of the principal part. They are a front view (A) of an image pick-up part, a horizontal section top view (B-1 thru / or 3) of a principal part, and a vertical sectional view (C-1 thru / or 3) of a principal part. It is the front view (A) of the imaging part which concerns on 2nd Embodiment of this invention, the horizontal sectional top view (B-1 and 2) of the principal part, and the vertical sectional view (C) of the principal part. It is the front view (A) of the imaging part which concerns on 3rd Embodiment of this invention, the horizontal sectional top view (B) of the principal part, and the vertical sectional view (C) of the principal part. FIG. 8 is a perspective view (A) of the imaging unit in FIG. 7 and an exploded perspective view (B) of the main part. It is the rear view (A) and horizontal section top view (B) which show the positional relationship of the imaging part and finder which concern on 3rd Embodiment of this invention. It is the front view (A) of the imaging part which concerns on 4th Embodiment of this invention, and the horizontal sectional top view (B) of the principal part.

  Embodiments according to the present invention will be described with reference to the accompanying drawings. An image pickup apparatus according to the following embodiment generates image information by photoelectrically converting a subject image using an image pickup element such as a CCD (charge coupled device) sensor or a CMOS (complementary metal oxide semiconductor) sensor. A digital imaging device that records the image information.

[First Embodiment]
The imaging apparatus according to the first embodiment of the present invention will be described below with reference to FIGS.
1A and 1B show an imaging device without an imaging lens, FIG. 1A is a horizontal sectional top view, and FIG. 1B is a vertical sectional view.
The main body 1 of the imaging apparatus has a mount 1a on the lens mounting surface. This surface is a reference surface with respect to the optical axis direction (z direction in FIG. 1) of the imaging optical system (not shown). The sensor base plate 2 supports the entire moving mechanism of the image sensor 3 described later. The sensor base plate 2 is attached to the main body 1 so that the sensor base plate 2 is located at a predetermined distance from the mount portion 1a and the flatness perpendicular to the optical axis of the imaging optical system is obtained. For example, the height in the z direction can be adjusted by sandwiching the adjusting washers 2a at three positions between the sensor base plate 2 and the main body 1. 2A and 2B are a perspective view illustrating an external appearance example when the imaging apparatus is viewed from the front side and a perspective view illustrating an external appearance example when viewed from the back side.
Light is imaged from the subject through the imaging optical system on the imaging device 3, and the image projected on the imaging surface inside the imaging device is converted into an electrical signal. Since this imaging surface is on the planned imaging surface of the lens, a focused image is taken. The imaging device 3 has a so-called electronic shutter function, and has an electronic front curtain as an electronic shutter that starts image signal capturing and an electronic rear curtain that stops capturing. That is, the image sensor 3 starts accumulating the image charge by the operation of the electronic front curtain, and ends the accumulation after a predetermined time by the operation of the electronic rear curtain. Thereafter, a charge readout operation for the accumulated image is performed, and the imaging signal is sent to a signal processing circuit (not shown).

FIG. 3 shows a configuration example of an imaging unit including a moving mechanism of the imaging device 3. 3A is a front view when viewed from the optical axis direction, FIG. 3B is a top view in horizontal section, and FIG. 3C is a vertical section view. 4A is a perspective view of the imaging unit, and FIG. 4B is an exploded perspective view thereof.
The lead frame 4 is a frame member that extends from the image sensor 3 and includes a flat portion 4a and arm portions 4b on both sides thereof. The arm portion 4b has a thin substantially U-shape that extends in a direction substantially orthogonal to the longitudinal direction of the flat portion 4a. As shown in FIG. 3A, both ends of the flat portion 4a are wide, and the arms 4b are bent from the wide ends as shown in FIG. 4B. . The lead frame 4 is a member formed integrally with a package constituting the image pickup device 3, and specifically, a sheet metal member including a terminal (lead) for outputting an image pickup signal to the outside as a part thereof.

  The sheet metal 5 is an elastic member attached to the lead frame 4 of the image pickup device 3 and is processed by bending a rectangular plate material with 42 alloy material which is an alloy of nickel and iron in this example. The sheet metal 5 has a thin, substantially U-shaped configuration including a flat portion 5a and arm portions 5b bent at substantially right angles from both ends thereof. As shown in FIG. 4B, two sets of sheet metal 5 are arranged above and below the image sensor 3. The arm portion 5b is fixed to the arm portion 4b of the lead frame 4 with high accuracy by soldering in a state where the imaging surface of the imaging element 3 and the flat surface portion 5a are substantially parallel. The sheet metal 5 and the image sensor 3 are arranged so that their positions overlap each other when viewed from the vertical direction orthogonal to the optical axis direction, and the sheet metal 5 is within the thickness of the image sensor 3. The sheet metal 5 is elastically deformed by the piezoelectric element 7 constituting the actuator unit. With this configuration, the sheet metal 5 can be bent in the front-rear direction (thickness direction) with its central portion as the center while the imaging surface of the imaging device 3 is maintained perpendicular to the optical axis direction.

  The sheet metal 5 is fixed in a plane orthogonal to the optical axis direction by joining to the fulcrum portion 6. A fulcrum portion 6 that is a support member of the sheet metal 5 is disposed around the imaging element 3 in a plane orthogonal to the optical axis. In this example, as shown in FIG. 3A, four fulcrum portions 6 are arranged above and below the image sensor 3, and one sheet metal 5 is supported by a pair of fulcrum portions. Since the thickness of the fulcrum part 6 in the optical axis direction overlaps the thickness of the imaging element 3 in the optical axis direction when viewed from the direction orthogonal to the optical axis, the thickness of the entire imaging part can be kept small. As shown in FIGS. 3B and 3C, the fulcrum portion 6 is attached to the sensor base plate 2 so as to be adjustable with the two fulcrum adjustment plates 6a interposed therebetween. Of the imaging device relative to the reference plane is determined. Two fulcrum adjusting plates 6a are provided at each end of the fulcrum part 6, and are arranged in a total of eight places in this example. Each fulcrum portion 6 supports the sheet metal 5 and the imaging element 3 at a position approximately equidistant from the central portion in the longitudinal direction of the fulcrum portion 6 without any problem in bending deformation of the piezoelectric element 7.

The piezoelectric elements 7 are respectively disposed on the sheet metal 5, and in this example, a thin plate-shaped piezoelectric ceramic element using a material such as PZT is used. The piezoelectric element 7 includes a piezoelectric element 7a provided on one surface of the flat portion 5a of the sheet metal 5 and a piezoelectric element 7b provided on the back surface thereof. That is, the piezoelectric elements 7a and 7b attached to the front and back surfaces of the flat portion 5a of the sheet metal 5 and the sheet metal 5 sandwiched therebetween constitute a driving means. The piezoelectric elements 7a and 7b are controlled in their expansion and contraction direction and size by controlling the applied voltage and current direction by a drive control unit (see 100 in FIG. 5A). In this example, when a constant voltage is applied to each piezoelectric ceramic element by a connection method called a parallel type, the front and rear piezoelectric ceramic elements expand and contract in opposite directions.
A counterweight 8 serving as an inertial body is attached to the central portion of the sheet metal 5 and has heat dissipation performance at the same time. The counterweight 8 is made of a material having a large specific gravity, such as brass, and good heat dissipation, and has a shape with a large number of fins (not shown). The mass is obtained by dividing the product of the mass of the image sensor 3 and the stroke by the stroke of the counterweight 8, and is designed as a mass that cancels vibration caused by the movement of the image sensor 3 during driving. The counterweight 8 has a thickness in the optical axis direction that is equal to or less than the thickness of the image sensor 3 and is arranged so that they overlap when viewed from a direction orthogonal to the optical axis direction. That is, consideration is given so as not to increase the thickness of the entire imaging unit. Further, as shown in FIG. 3A, the counterweight 8 is fixed to the sheet metal 5 with only two upper and lower points at the center of the front surface (subject side) of the sheet metal 5 as attachment portions 9. For this reason, the bending deformation of the sheet metal 5 due to the driving of the piezoelectric element 7 is not affected.

FIG. 5 shows the operation of the moving mechanism of the image sensor 3. FIG. 5A is a front view similar to FIG. 3A, (B-1 to 3) are horizontal sectional top views, and (C-1 to 3) are vertical sectional views. P indicates a planned imaging plane of the focus lens. In the following description, the direction in which the image sensor 3 moves to the subject side is assumed to be the front.
FIGS. 5B-1 and 5C-1 show a state where the image sensor 3 is at the reference position. 5 (B-2) and (C-2) show a state in which the image sensor 3 has moved forward, and FIGS. 5 (B-3) and (C-3) show a state in which the image sensor 3 has moved back. For example, the application of a positive voltage from the drive control unit 100 causes the piezoelectric element 7a to contract and the piezoelectric element 7b to expand, so that the sheet metal 5 is deformed into a concave state on the front side. Therefore, the image pickup device 3 having the lead frame 4 fixed to the metal plate 5 by soldering at the top and bottom of FIG. 5A advances as shown in FIGS. 5B-2 and C-2.
Conversely, the application of a negative voltage from the drive control circuit causes the piezoelectric element 7a to expand and the piezoelectric element 7b to contract, so that the sheet metal 5 is moved to the front side as shown in FIGS. 5B-3 and (C-3). The image pickup device 3 is moved backward by being deformed into a convex shape. Since the amount of displacement is controlled according to the magnitude of the applied voltage, the fulcrum portion 6 is displaced between the center of the flat portion 5a of the sheet metal 5 and the arm portions 5b at both ends.

  In the first embodiment, a plurality of actuator units are arranged on opposite sides of the image sensor 3 with the image sensor interposed therebetween in the short side direction. When the piezoelectric elements 7a and 7b are expanded and contracted by voltage application, the plane part 5a of the sheet metal 5 is bent and deformed, and the moving mechanism of the imaging element 3 configured by using the sheet metal 5, the fulcrum part 6, and the piezoelectric elements 7a and 7b. 5b is displaced back and forth. Therefore, the imaging device 3 moves forward or backward in the optical axis direction from the flange back position of the imaging lens while maintaining the imaging surface orthogonal to the optical axis direction. At that time, the counterweight 8 moves backward or forward, that is, the image sensor 3 and the counterweight 8 move in opposite directions. The stroke control of the moving mechanism is performed by changing the expansion / contraction amount of the piezoelectric elements 7 a and 7 b by voltage control by the drive control unit 100.

On the other hand, for the two fulcrum portions 6, the ratio between the moving stroke of the image sensor 3 and the moving stroke of the counter weight 8 can be changed by adjusting the distance in the longitudinal direction of the sheet metal 5. Further, in the width direction orthogonal to the longitudinal direction of the sheet metal 5, the position of the fulcrum part 6 in the optical axis direction can be changed by the fulcrum adjusting plate 6 a. That is, twisting the sheet metal 5 changes the way the imaging surface of the imaging device 3 falls. In this way, the position of the fulcrum portion 6 can be finely adjusted in the front-rear and left-right directions, or in the tilt direction, so that manufacturing variations of parts can be reduced. That is, the imaging surface of the imaging device 3 can be adjusted so as to be the reference position of the flange back distance without being inclined with respect to the optical axis in the manufacturing process. Furthermore, since the actuator units are arranged above and below the image sensor 3 and the respective movement strokes can be controlled independently, the inclination of the imaging surface with respect to the optical axis can be adjusted.
As described above, the fulcrum portion 6 that supports the sheet metal 5 is disposed at a position overlapping the image pickup device 3 when viewed from the direction orthogonal to the optical axis, so that the imaging portion in the optical axis direction can be thinned.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. In the second embodiment, the structure of the lead frame 4, the method of supporting the image sensor 3 by the sheet metal 5, and the counterweight 8 are different from those of the first embodiment. In the following, differences will be mainly described, and the same components as in the first embodiment will be described using the same reference numerals, and detailed description thereof will be omitted. Note that the method of omitting such description is the same in the embodiments described later.
FIG. 6A is a front view of the imaging unit, FIGS. 6B-1 and 6B-2 are horizontal sectional top views, and FIG. 6C is a vertical sectional view. 6B-1 shows a state where the image sensor 3 is at the reference position, and FIG. 6B-2 shows a state where the image sensor 3 has advanced.

Both ends of the lead frame 4 are fixed to the central portion of the shaft 10. Both ends of the sheet metal 5 are connected and fixed to the ends of the shafts 10 and are arranged above and below the image sensor 3. When, for example, the sheet metal 5 is deformed so as to be recessed forward by applying a voltage to the piezoelectric elements 7 a and 7 b attached to the sheet metal 5, the imaging element 3 connected and fixed to the sheet metal 5 up and down via the shaft 10 moves forward ( (See FIG. 6 (B-2)). As a result, a displacement occurs between the center of the flat portion 5 a of the sheet metal 5 and the tip portion connected and fixed to the shaft 10.
The counterweights 8a and 8b are attached to both the front and back surfaces of the flat portion 5a of the sheet metal 5, respectively. The counterweight 8a is located on the front side, and the counterweight 8b is located on the back side. The counterweights 8 a and 8 b are arranged symmetrically with respect to the flat portion 5 a of the sheet metal 5, and the inertial mass is distributed to both the front and back surfaces of the sheet metal 5. Thereby, in 2nd Embodiment, the thickness of each counterweight in an optical axis direction can be made small.

[Third Embodiment]
Next, an imaging apparatus according to a third embodiment of the present invention will be described with reference to FIGS. In the third embodiment, the structure of the lead frame 4 and the positional relationship of the sheet metal 5 with respect to the image sensor 3 are different from those in the first embodiment.
7A and 7B show an imaging unit according to the third embodiment. FIG. 7A is a front view, FIG. 7B is a horizontal cross-sectional top view, and FIG. 7C is a vertical cross-sectional view. The lead frame 4 has a flat portion 4a and arm portions 4b bent substantially at right angles from the wide upper and lower end portions thereof, and has a thin substantially U-shape.
FIG. 8A is a perspective view of the imaging unit, and FIG. 8B is an exploded perspective view thereof. The arm portion 4b of the lead frame 4 is bent from the wide portion of the flat portion 4a, extends in the longitudinal direction thereof, and is fixed to the arm portion 5b of the sheet metal 5 with high accuracy by soldering. Each sheet metal 5 is arranged on both the left and right sides of the image sensor 3 in a plane orthogonal to the optical axis, and is attached to the lead frame 4 in a state where the image pickup surface of the image sensor 3 and the flat portion 5a of the sheet metal 5 are substantially parallel. It has been. The sheet metal 5 is disposed so as to overlap the image sensor 3 when viewed from the left-right direction orthogonal to the optical axis, and is within the thickness of the image sensor 3.

FIG. 9A is a rear view when the imaging unit is viewed from the side opposite to the imaging optical system, and FIG. 9B is a horizontal sectional top view.
The viewfinder 12 constitutes an optical system for observing a subject, and is arranged above the image pickup unit as shown in FIG. Piezoelectric elements 7 (7a and 7b) attached to the sheet metal 5 are lines connecting the left and right sides of the image sensor 3, that is, the center of the image sensor 3 and the viewfinder 12 (see vertical line V in FIG. 9A). Are arranged in a direction perpendicular to the horizontal axis (see horizontal line H).
In the third embodiment, the positional relationship between the image sensor 3 and the finder 12 in a plane orthogonal to the optical axis is taken into consideration, and the moving mechanism of the image sensor 3 is set so as not to interfere with the finder 12 in position. Can be placed sideways.

[Fourth Embodiment]
Next, an imaging device according to a fourth embodiment of the present invention will be described with reference to FIG. In 4th Embodiment, the support method of the image pick-up element 3 by the sheet metal 5, the structure of the sheet metal 5, and the fulcrum part 6 differ from 2nd Embodiment.
FIG. 10A is a front view of the imaging unit, and FIG. 10B is a horizontal sectional top view.
The image sensor 3 is attached to a sheet metal 5 and its attachment portion 11 is shown in FIG. In this example, the imaging element 3 is fixed to the sheet metal 5 with only the upper and lower two points in the center of the front surface of the sheet metal 5 being attached positions, so that the bending deformation of the sheet metal 5 by the imaging element 3 is not affected.
The sheet metal 5 has a crank shape, and includes a flat surface portion 5a, a step portion 5b bent at a substantially right angle from both sides thereof, and a flat front end portion 5c which is further bent and positioned at the tip. The sheet metal 5 is elastically deformed by the piezoelectric elements 7a and 7b attached to the front and back surfaces of the flat plate portion 5a.

The fulcrum parts 6 are arranged on the left and right sides of the image sensor 3 as shown in FIG. The fulcrum portion 6 is a pair of support members that sandwich the front end portion 5c of the sheet metal 5 from the front and the back, and is arranged so that the thickness in the optical axis direction overlaps the thickness in the optical axis direction of the image pickup device 3. As a result, the thickness can be kept small. Further, the counterweights 8a and 8b are respectively attached to the front and back by the attachment portion 9 at the tip portion 5c closer to the end than the two fulcrum portions 6.
The piezoelectric elements 7 a and 7 b are controlled in their deflection direction and size by controlling the applied voltage and current direction by the drive control unit 100. For example, when the sheet metal 5 is deformed so as to be recessed in the front side, the image pickup device 3 fixed to the sheet metal 5 with the attachment portion 11 moves backward. As a result, displacement occurs between the center of the flat surface portion 5a of the sheet metal 5 and the tip portion 5c to which the counterweights 8a and 8b are attached.
In the fourth embodiment, in a configuration in which the piezoelectric elements 7 a and 7 b are attached to the flat surface portion 5 a of the sheet metal 5 located on the back surface of the image sensor 3, the fulcrum part 6 of the sheet metal 5 is arranged in the lateral direction of the image sensor 3. The thickness can be reduced.

3 Image sensor 4 Lead frame 5 Sheet metal (elastic member)
6 fulcrum (support member)
7 Piezoelectric element 8 Counterweight (Inertial body)
12 Finder 100 Drive controller

Claims (6)

An imaging apparatus having a moving mechanism for moving an imaging element along an optical axis of an imaging optical system,
An elastic member attached to the image sensor;
A support member that is disposed at a position overlapping with the imaging element when viewed from a direction orthogonal to the optical axis and supports the elastic member;
An actuator unit that displaces the image sensor in the direction of the optical axis by deforming the elastic member;
An image pickup apparatus comprising drive control means for the actuator unit. Connecting the elastic member to a frame member extending from the image sensor;
The imaging apparatus according to claim 1, wherein the support member is disposed around the imaging element in a plane orthogonal to the optical axis and attached to the elastic member.   The imaging apparatus according to claim 1, wherein the actuator unit includes piezoelectric elements respectively provided on both surfaces of the elastic member in the optical axis direction.   4. The image pickup apparatus according to claim 1, wherein the plurality of actuator units are arranged on opposite sides of the image pickup element in a short side direction of the image pickup element. 5. A viewfinder for observing the subject
The imaging according to any one of claims 1 to 3, wherein the actuator unit is arranged in a direction orthogonal to a line connecting the center of the imaging device and the viewfinder as viewed from the optical axis direction. apparatus.   The imaging device according to claim 1, further comprising an inertial body attached to the elastic member.

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