Optical member driving device, camera device, and electronic apparatus

An optical member driving device is described that includes a fixed portion having a plate-like base with a through hole, a movable portion having a spring plate to place an optical member on it, and a SMA driving portion having a SMA wire and driving the movable portion. The spring plate has a spring plate main body and two arm portions extending from the spring plate main body and fixed on a plate surface of the base. The spring plate main body is entirely located inside the through hole when viewed from a normal direction of the plate surface.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority to Chinese patent application CN201910991907.1, filed on Oct. 18, 2019, the contents of which are incorporated herein by reference herein.

TECHNICAL FIELD

The present invention relates to an optical member driving device used in electronic apparatus such as smartphones, a camera device, and an electronic apparatus.

BACKGROUND

Various camera devices equipped with OIS (Optical Image Stabilizer) function have been proposed. As a document disclosing a technique related to this type of device, Chinese patent No. 108174104 (hereinafter referred to as “Patent Document 1”) can be taken. The imaging device disclosed in Patent Document 1 is a device in which an OIS base, which is a fixed portion, and a lead, which is a movable portion supporting the lens, are connected and integrated via two pairs of SMA (Shape Memory Alloy) wires which contract in the X-axis and Y-axis directions due to heat generation caused by electric current. This imaging device realizes hand shake correction by controlling the supply of electric current to the SMA wire.

However, the technique of Patent Document 1 has a problem that the width in the Z-axis direction becomes thick, since in its constitution the OIS base and the lead are laminated in the Z-axis direction, which is the optical axis direction

SUMMARY

In accordance with a first aspect of the present disclosure, there is provided an optical member driving device including: a fixed portion having a plate-like base with a through hole; a movable portion having a spring plate for placing an optical member; and a SMA driving portion having a SMA wire and driving the movable portion. The spring plate has a spring plate main body and two arm portions extending from the spring plate main body and fixed on a plate surface of the base. The spring plate main body is entirely located inside the through hole when viewed from a normal direction of the plate surface.

In accordance with a second aspect of the present disclosure, there is provided a camera device including the optical member driving device described above, a lens assembly as the optical member, an AF lens assembly allowing light from a subject to pass through, and an image sensor receiving light having passed through the AF lens assembly. The lens assembly is arranged between the subject and the AF lens assembly.

In accordance with a third aspect of the present disclosure, there is provided a camera device including the optical member driving device described above, a lens assembly as the optical member, an AF lens assembly allowing light from a subject to pass through, and an image sensor receiving light having passed through the AF lens assembly. The lens assembly is arranged between the AF lens assembly and the image sensor.

In accordance with a fourth aspect of the present disclosure, there is provided a camera device including the optical member driving device described above, an AF lens body allowing light from a subject to pass through, and an image sensor as the optical member receiving light having passed through the AF lens body.

In accordance with a fifth aspect of the present disclosure, there is provided an electronic apparatus including the camera device described above.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present disclosure are explained with reference to drawings. As shown inFIGS. 1A and 1B, the camera device1is accommodated in the housing of the smartphone70. The camera device1includes: an OIS lens assembly3and an AF lens assembly8which are optical members; a prism81which is an optical path bending element; an image sensor83which is a photoelectric conversion element; an OIS lens driving device10to drive the OIS lens assembly3; a prism device91to accommodate the prism81; and an AF lens driving device92to drive the AF lens assembly8. OIS is an abbreviation for Optical Image Stabilization. AF is an abbreviation for Autofocus.

Hereinafter, the optical axis direction along the optical axis of the OIS lens body30of the OIS lens assembly3is appropriately referred to as a Z direction, one direction orthogonal to the Z direction is appropriately referred to as an X direction, and a direction orthogonal to both the Z direction and the X direction is appropriately referred to as a Y direction. Further, the +Z side of the optical axis of the OIS lens body30, which is the side of the subject, may be referred to as a front side, and the −Z side, which is the side on which the prism81on the opposite side of the subject is provided, may be referred to as a rear side. Further, the +Y side may be referred to as an upper side, the −Y side may be referred to as a lower side, the +X side may be referred to as a left side, and the −X side may be referred to as a right side.

As shown inFIG. 1A,FIG. 1B, andFIG. 2, in the camera device1, the prism device91is arranged on the rear side of the OIS lens driving device10, and the AF lens driving device92is arranged on the lower side of the prism device91. The OIS lens driving device10supports the OIS lens assembly3. A prism81is arranged in the prism device91, the incident surface thereof faces an OIS lens assembly3, and the emission surface thereof faces an AF lens assembly8. In the AF lens driving device92, the AF lens assembly8is arranged so that the direction along the optical axis of the AF lens body becomes Y direction. An image sensor83is arranged on the lower side of the AF lens driving device92. The light from the subject passes through the OIS lens assembly3and is reflected downward by the prism81. The light reflected by the prism81passes through the AF lens assembly8and is converged on the image sensor83. The image sensor83photoelectrically photoelectrically converts the light and outputs the converted signal as an image signal. The camera device1is required to reduce the dimension in the Z direction so that the dimension in the Z direction, which is the thickness direction of the smartphone70, is reduced. Therefore, it is also required to reduce the thickness of the OIS lens driving device10, which is the dimension in the Z direction.

As shown inFIG. 3toFIG. 6, the OIS lens driving device10includes a casing2, a SMA driving portion4, a spring plate5, and a base6. The details of the configuration of each portion will be described below. An accommodation space is formed by the casing2and the base6and accommodates the SMA driving portion4, the spring plate5, and the OIS lens assembly3.

The casing2has a square-shaped front wall23and a side wall24slightly extending backward from the periphery of the front wall23to form a box-like body, and is provided with a through hole27at the center of the front wall23. The through hole27has such a shape that four corners of a square have been removed. A plurality of recessed portions25,26recessed on the front side are provided at the rear end of the side wall24. The OIS lens assembly3has an OIS lens body30which is a main body thereof and is an optical member main body, and a flange portion31provided around the OIS lens body30. The flange portion31is a square plate with a perfect circular hole in the center, and the OIS lens body30is fixed to the inner circumference of this hole.

The SMA driving portion4has a SMA wire41extending in one direction, and a fixed-side end portion42and a movable-side end portion43on both sides thereof. One end and the other end of the SMA wire41are respectively fixed to the fixed-side end portion42and the movable-side end portion43. Further, the fixed-side end portion42and the movable-side end portion43are formed of a conductive material, and serve as electric connection portions when electric current is applied to the SMA wire41.

The spring plate5has a main body portion51with an approximately square outer shape and two arm portions55extending outward from two parallel end edges of the main body portion51. A through hole57is provided in the center of the main body portion51. The four corners of the main body portion51are cut out as notches520and530at each diagonal portion.

The arm portion55protrudes from the base end at a position on the side close to the notch530at the end edge in the X-direction of the main body portion51, extends to the notch520along the end edge in the X-direction, turns around the outside of the notch520to bend toward the side of the end edge in the Y-direction, and extends toward a direction outwardly away from the end edge. The tip end of the arm portion55is provided with a connection piece56.

The first pin53is provided in the notch530so as to protrude diagonally outward from the main body portion51. The first pin53has a pentagonal shape. The first pin53is integrally formed with the main body portion51of the spring plate5.

The base6has a rectangular plate-like shape. A through hole67is provided in the center of the base6. The through hole67has such a shape that four corners of a square have been removed. Two second pins62are respectively provided in the upper right corner and the lower left corner of the front surface of the base6. The second pin62has a rectangular plate-like shape and one end surface thereof is substantially flush with the outer end surface of the base6.

Of the members described above, the casing2and the base6form a fixed portion, the spring plate5and the OIS lens assembly3form a movable portion which is movable relative to the fixed portion. The fixed portion and the movable portion are connected via four SMA driving portions4.

It will be described in more detail. The rear end portion of the side wall24of the casing2is joined to the circumference of the front surface of the base6. The spring plate5is arranged on the front surface of the base6in a narrow space surrounded by the casing2and the base6. As shown inFIG. 9, the main body portion51of the spring plate5is entirely located inside the through hole67when viewed from the normal direction of the plate surface. The two first pins53of the spring plate5project out to the outside of the corner cut portion of the through hole67of the base6, and the portion which has projected out overlaps with the base6, but is not in contact with the base6in the present embodiment. The OIS lens assembly3is supported by placing the flange portion31on the main body portion51.

The arm portion55of the spring plate5projects out to the outside of the through hole67of the base6, and the connection piece56at the tip end of the arm portion55is bonded to the front surface of the base6. The end surface on the outer side of the connection piece56is fixed so as to be substantially flush with the end surface of the outer shape of the base6, and is exposed to the outside via the recessed portion25of the casing2. Further, the end surface on the outer side of the second pin62is also exposed to the outside via the recessed portion26of the casing2. The elastic force of the two arm portions55of the spring plate5is balanced at the position where the main body portion51is in the center of the through hole57. This position is referred to as initial position. Since the arm portion55extends in approximately X-direction and Y-direction, the main body portion51can move in the in-plane direction of XY. Further, since it is smaller than the through hole67, it can move with a small driving force without contacting with the base6.

The four SMA driving portions4are arranged along respective end edges of the base6on the front surface side of the base6. The fixed-side end portion42of the SMA driving portion4is provided on the second pin62. The movable-side end portion43of the SMA driving portion4is provided on the first pin53. As shown inFIG. 4, the SMA wire41of the SMA driving portion4is located in front of the main body portion51and the arm portion55of the spring plate5in the normal direction of the plate surface of the spring plate5.

Four second pins62and two connection pieces56are connected to an external power source. Thereby, an electric current path of the external power source→the second pin62→the fixed-side end portion42→the SMA wire41→movable-side end portion43→the first pin53→the main body portion51→the arm portion55→the connection piece56→the external power source is formed, and electric current is supplied to the SMA wire41. In each of the four SMA driving portions4, the SMA wire41contracts due to heat generated by being supplied with electric current and drives the movable portion. As for the movable portion, the main body portion of the spring plate5on which the OIS lens assembly3has been placed moves in the in-plane direction of XY.

The above description is the details of the configuration of the present embodiment. The OIS lens driving device10, which constitutes the optical member driving device of the present embodiment, includes a fixed portion having plate-like base6with a through hole67; a movable portion having a spring plate5for placing an optical member; and a SMA driving portion4having a SMA wire41and driving the movable portion. The spring plate5has a main body portion51of the spring plate5and two arm portions55extending from the main body portion51of the spring plate5and fixed on a plate surface of the base6. The main body portion51of the spring plate5is entirely located inside the through hole67when viewed from a normal direction of the plate surface. Therefore, the thickness of the OIS lens driving device10excluding the casing2in the optical direction is the thicknesses of the base6, of the spring plate5and of the SMA driving portion4only, and can be reduced. Therefore, according to the present embodiment, it is possible to provide an optical member driving device, a camera device, and an electronic apparatus in which the width thereof in the optical axis direction are small.

It is to be noted that, in the embodiment described above, SMA wires41of four SMA driving portions4may be provided at the same height as the spring plate5in a normal direction of the plate surface of the spring plate5. For example, if the SMA wire41of the SMA driving portion4is laid between the main body portion51and the arm portion55on the side where the connection piece56is located, the SMA wire41can be arranged at the same height as the spring plate5without interfering with the arm portion55and the SMA wire41. With such a configuration, the width of the optical member driving device in the optical direction can be further reduced. In addition, the floating of the spring plate5can be suppressed.

Further, in the above embodiment, the number of the SMA wires41of each of the four SMA driving portions4is set to two, and these two SMA wires41may be provided on both the front side and the rear side of the spring plate5in the normal direction of the plate surface of the spring plate5. The force that the SMA wire41pulls the spring plate5forward and the force that the SMA wire41pulls the spring plate5backward are counterbalanced. Therefore, the floating of the spring plate5can be suppressed.

Further, in the above embodiment, the movable portion or the OIS lens assembly3on the movable portion may be slid with a sliding portion provided on the rear surface of the front wall23of the casing2. Further, the flange portion31may be slid with the fixed-side end portion42of the SMA driving portion4or another fixed portion. Further, the first pin53or the movable-side end portion43of the SMA driving portion4may be slid with respect to the base6.

Further, in the above embodiment, the OIS lens assembly3is arranged between the subject and the AF lens assembly8. In this embodiment, a prism81is further arranged between the OIS lens assembly3and the AF lens assembly8. The OIS lens assembly3may be configured to be arranged between the AF lens assembly8and the image sensor83.

Further, in the above embodiment, the OIS lens body30is used as an optical member, and the optical member driving device is for driving the OIS lens assembly3, but the image sensor83may be used as the optical member, and the optical member driving device may drive the image sensor83. That is, the OIS lens assembly3may be eliminated, and a combination of the AF lens assembly8and the AF lens driving device92for focus adjustment, and the image sensor83and the optical member driving device for hand shake correction may be used.