JP5573008B2 - Lens unit and imaging device - Google Patents

Description

  The present invention relates to a lens unit and an imaging apparatus.

  A linear actuator is used as one of driving sources for moving optical components in the optical system of the imaging apparatus. The linear actuator is formed by linearly arranging one of a coil and a permanent magnet on a stator and mounting the other of the coil and the permanent magnet on a moving element that moves along the stator (see Patent Document 1). ).

JP 2004-191453 A

  In the linear actuator, the moving element has a structure that moves smoothly. For this reason, when the mover stops, the stop position of the mover must be maintained by feedback control based on the position of the mover, and power consumption occurs even when the mover is stopped. Further, when the power is cut off, the linear actuator cannot maintain the position of the moving element.

  Therefore, in order to solve the above problems, as a first aspect of the present invention, a holding frame that holds a lens, and a moving actuator that moves a holding frame that is connected to a mover that moves linearly with respect to the stator; When the moving actuator does not generate a driving force, when the moving actuator generates a driving force and a braking unit that contacts both the moving element and the stator and brakes the moving element against the stator Further, a lens unit is provided that includes a braking unit actuator that separates the braking unit from either the mover or the stator.

  In addition, as a second aspect of the present invention, an imaging device including the lens unit is provided.

  The above summary of the present invention does not enumerate all necessary features of the present invention. Further, a sub-combination of these feature groups can be an invention.

It is sectional drawing which shows typically the structure of the imaging device 99 whole. 3 is a perspective view of a linear motion drive unit 300. FIG. 4 is a cross-sectional view of a linear motion drive unit 300. FIG. It is a perspective view mainly showing the structure of the stator 120. FIG. 4 is a schematic diagram showing an electrical structure of a linear motion drive unit 300. FIG. 3 is a block diagram showing a control system 301 of the linear motion drive unit 300. It is a figure which shows the other structure of the lens unit.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

  FIG. 1 is a schematic cross-sectional view showing the overall structure of the image pickup apparatus 99. The imaging device 99 is formed by combining the lens unit 100 and the imaging unit 200.

  The lens unit 100 includes a lens barrel 110, a stator 120, a mover 130, a guide shaft 140, a guided portion 150, a holding frame 160, a diaphragm device 170, and a plurality of lens groups 102, 104, and 106. The lens groups 102, 104, and 106 are arranged along a common optical axis C to form the optical system 101.

  The lens barrel 110 is coupled to a mount unit 260 of the imaging unit 200 described later and is integrated with the imaging unit 200. Inside the lens barrel 110, the shaft-shaped stator 120 and the guide shaft 140 are fixed in parallel to each other in the longitudinal direction of the lens barrel 110.

  On the other hand, each of the plurality of lens groups 102, 104, and 106 is individually held by the holding frame 160. One lens group 104 is held by the holding frame 160 together with the diaphragm device 170. Part or all of the holding frame 160 is supported by the movable element 130 or the guided portion 150 so as to be movable from the stator 120 and the guide shaft 140 in the longitudinal direction of the lens barrel 110. The focal length and focal position of the optical system 101 are adjusted by the movement of the lens groups 102, 104, and 106.

  The imaging unit 200 includes an optical system including a primary mirror 240, a secondary mirror 242, a pentaprism 270, and an eyepiece optical system 290, and a control system including a focus detection unit 230, a main control unit 250, a photometry unit 280, and the like. The primary mirror 240 is between a standby position located on the optical path of incident light incident through the optical system 101 of the lens unit 100 and an imaging position (indicated by a dotted line in the figure) that rises while avoiding the incident light. To move.

  A secondary mirror 242 is disposed on the back surface of the primary mirror 240 at the standby position. The secondary mirror 242 guides part of the incident light transmitted through the primary mirror 240 to the focus detection unit 230 disposed below. Thereby, when the primary mirror 240 is in the standby position, the focus detection unit 230 detects the in-focus state of the optical system 101. When the primary mirror 240 is moved to the photographing position, the secondary mirror 242 is also retracted from the optical path of the incident light.

  Further, the primary mirror 240 at the standby position is inclined with respect to the incident light and guides most of the incident light to the focusing screen 272 disposed above. The focusing screen 272 is disposed at a focus position of the optical system 101 and forms an image formed by the optical system 101.

  The image displayed on the focusing screen 272 is observed from the eyepiece optical system 290 via the pentaprism 270. As a result, the image on the focusing screen 272 can be viewed as a normal image from the eyepiece optical system 290.

  Between the pentaprism 270 and the eyepiece optical system 290, a half mirror 292 that superimposes the display image formed on the finder LCD 294 on the image of the focusing screen 272 is disposed. Thereby, at the exit end of the eyepiece optical system 290, the image on the focusing screen 272 and the image on the finder LCD 294 can be seen together. The finder LCD 294 displays information such as shooting conditions and setting conditions of the imaging device 99 and ready light of the flash device.

  A part of the light emitted from the pentaprism 270 is guided to the photometry unit 280. The photometry unit 280 measures the intensity of incident light, its distribution, and the like, and refers to the measurement result when determining imaging conditions.

  In the imaging unit 200, a shutter 220, an optical filter 212, and an imaging element 210 are arranged along the optical axis C behind the main mirror 240 with respect to the incident light from the lens unit 100. When the release switch of the imaging unit 200 is pressed, first, the primary mirror 240 moves to the imaging position and retracts from the optical path of the incident light. Thereby, the incident light enters toward the shutter 220. Further, when the shutter 220 is opened, the incident light goes straight and enters the image sensor 210. As a result, the image on which the optical system 101 is formed is converted into an electrical signal in the image sensor 210.

  Note that the imaging unit 200 includes a main LCD 296 arranged on the back surface of the lens unit 100 so as to face the outside. The main LCD 296 can display various setting information for the image capturing unit 200 and can display an image formed on the image sensor 210 when the primary mirror 240 is moved to the photographing position. It is also used when reproducing an image captured by the image sensor 210.

  The main controller 250 comprehensively controls the above operation. In addition, the autofocus mechanism that drives the lens unit 100 is controlled with reference to the distance information to the subject detected by the focus detection unit 230 on the imaging unit 200 side.

  FIG. 2 is a perspective view of the linear motion drive unit 300 in the lens unit 100. FIG. 2 shows one lens group 106 and a member that drives a holding frame 160 that holds the lens group 106. In FIG. 2, the same elements as those in FIG.

  In the linear motion drive unit 300, the holding frame 160 that holds the lens group 106 is supported by the mover 130 and the guided unit 150 that are integrally disposed at symmetrical positions of a substantially circular frame. The mover 130 is inserted through the stator 120 and moves along the extending direction of the stator 120. The guided portion 150 is also inserted through the guide shaft 140 and moves along the guide shaft 140.

  As will be described later, a driving force for moving the holding frame 160 is generated between the stator 120 and the mover 130. For this reason, a cable 121 that supplies power is coupled to the stator 120.

  The holding frame 160 and the guided portion 150 move according to the mover 130. Since the stator 120 and the guide shaft 140 are arranged in parallel with the optical axis C of the optical system 101, the lens group 106 held by the holding frame 160 moves along the optical axis C.

  FIG. 3 is a cross-sectional view of the linear motion drive unit 300. The stator 120 includes an outer cylinder 122 and a core 128, and a plurality of coils 124. The mover 130 includes a mover main body 138, a bearing portion 132 attached to the mover main body 138, a permanent magnet 134, and a braking portion actuator 136.

  In the stator 120, the outer cylinder 122 and the core 128 are arranged coaxially with each other. Each of the plurality of coils 124 is wound around the core 128 inside the outer cylinder 122 and arranged in the longitudinal direction of the stator 120. In addition, from the viewpoint of improving the controllability of the linear motion drive unit 300, the outer cylinder 122 and the core 128 are preferably non-magnetic.

  In the mover 130, the mover main body 138 has an inner diameter larger than the outer diameter of the stator 120, and the inner surface of the mover 130 is separated from the stator 120. A pair of bearing portions 132 are arranged at both inner ends of the mover 130, and the mover 130 is supported from the stator 120 via the bearing portion 132. Thereby, the mover 130 moves smoothly along the stator 120.

  The guided portion 150 also has an inner diameter larger than the outer diameter of the guide shaft 140, and the inner surface of the guided portion 150 is separated from the surface of the guide shaft 140. A pair of bearing portions 152 are disposed at both inner ends of the guided portion 150, and the guided portion 150 is supported from the guide shaft 140 via the bearing portion 152. Thereby, the guided part 150 moves smoothly along the guide shaft 140.

  The permanent magnet 134 has an annular shape that surrounds the stator 120 in the middle of the movable body 138. Further, the permanent magnet 134 is magnetized so that the polarity is reversed at both ends of the stator 120 in the longitudinal direction. However, the direction of the permanent magnet 134 is not particularly limited, and the polarity of the longitudinal direction of the stator 120 may be arranged opposite to the illustrated direction.

  The pair of brake unit actuators 136 are fixed on the upper surface of the movable element main body 138 and on the lower surface of the pair of brake section actuators 136 with the outer surface of the stator 120. As a result, the surface of the braking portion actuator 136 becomes a braking portion, and the mover 130 is fixed to the stator 120.

  Further, the brake portion actuator 136 is controlled from the outside and operates to reduce the thickness. Accordingly, one surface of the braking portion actuator 136 is separated from the surface of the stator 120 and does not prevent the mover 130 from moving along the stator 120.

  As described above, the brake unit actuator 136 releases the brake of the mover 130 with respect to the stator 120 during the period in which the mover 130 moves with respect to the stator 120 in the linear drive unit 300. When the movement of the mover relative to the stator 120 in the linear drive unit 300 stops, the mover 130 is fixed to the stator 120. Thereby, when the needle | mover 130 stops, the position is hold | maintained.

  For example, the brake unit actuator 136 can be formed as a piezoelectric element that changes its thickness when a voltage is applied. That is, the piezoelectric element can be formed such that the braking portion actuator 136 reduces the thickness when a driving voltage is applied. Thereby, when the linear motion drive unit 300 is not driving the mover 130, the brake unit actuator 136 holds the position of the mover 130 as a brake unit.

  Thereby, when the mover 130 is not moved in the linear drive unit 300, the mover 130 autonomously holds the stop position without supplying electric power or the like. When the mover 130 is driven in the linear drive unit 300, a driving voltage is applied in parallel to the brake unit actuator 136, and the brake of the mover 130 by the brake unit actuator 136 is released. Therefore, the mover 130 moves smoothly.

  The brake section actuator 136 that operates as described above can be formed of a bimetal that changes its shape when heated. Furthermore, even when a shape memory alloy that is heated to the recovery temperature and recovers the memory shape is used, the brake portion actuator 136 can be formed.

  Bimetal or shape memory alloy can be controlled by turning on and off the power supply with a heater or the like. In addition, when the linear motion drive unit 300 is operating by operating it with the heat generated by the coils disposed in the stator 120, the brake 130 is controlled to be released simultaneously by the braking unit actuator 136. Can be executed autonomously.

  In the above example, one end of the holding frame 160 is driven by the movable element 130 and the other end is the guided portion 150 driven by the movable element 130. However, a pair of movable elements 130 are arranged and the holding frame 160 is arranged. May be driven. In that case, it goes without saying that the stator 120 should be arranged in place of the guide shaft 140.

  FIG. 4 is a perspective view of the linear drive unit 300 and shows the internal structures of the stator 120 and the mover 130 exposed. Elements common to FIGS. 1 to 3 are denoted by the same reference numerals, and redundant description is omitted.

  The stator 120 has a plurality of coils 124 arranged along a core 128. Each of the coils 124 individually generates a magnetic field when supplied with a drive current. In the mover 130, the permanent magnet 134 surrounds the coil 124 from the outside of the outer cylinder 122. Further, in the mover 130, the braking portion actuator 136 is disposed before and after the permanent magnet 134 in the moving direction of the mover 130.

  FIG. 5 is a schematic diagram illustrating the electrical structure of the linear motion drive unit 300. In addition, the same reference number is attached | subjected to the same element as another figure, and the overlapping description is abbreviate | omitted.

  The coil 124 is individually wound around the core 128, and is connected to three phases of the U phase, the V phase, and the W phase as shown by dotted lines in the drawing. In the illustrated example, three sets of three phases of U phase, V phase, and W phase are shown, but it is needless to say that it is not limited to three phases or three sets, depending on the moving distance required for the mover 130. Arranged. Further, the connection of the coil 124 is not limited to the three-phase connection, and may be a three-phase connection or more or a two-phase connection.

  FIG. 6 is a block diagram showing the control system 301 of the linear motion drive unit 300. The control system 301 includes a position calculation unit 320, a drive circuit 330, and a switch control unit 340. The control system 301 is included in the control unit 250 of the imaging unit 200.

  The position calculation unit 320 refers to the position of the mover 130 detected by the encoder 310 arranged in the linear drive unit 300 and turns on the drive circuit 330 when moving the mover 130. Drive circuit 330 includes a three-phase command generator 332 and a DC voltage generator 334. Three-phase command generator 332 generates a drive current to be supplied to coil 124. The DC voltage generation unit 334 generates a drive voltage to be applied to the brake unit actuator 136. Further, the switch control unit 340 couples the three-phase command generation unit 332 and the DC voltage generation unit 334 to the coil 124 or the braking unit actuator 136 in accordance with an instruction from the position calculation unit 320.

  When the switch SW0 is closed, the driving voltage of the braking section actuator 136 is applied to the braking section actuator 136 after the polarity is inverted by the inverting amplifier 350. As a result, the thickness of the braking portion actuator 136 decreases, and the braking portion actuator 136 is separated from the surface of the stator 120 from one surface of the braking portion actuator 136. As a result, the movable element 130 can move smoothly during a period in which the drive current is supplied to any of the coils 124 described later.

  When the control unit 250 indicates the target position of the mover 130, the position calculation unit 320 refers to the encoder 310 and the drive current supplied to the coil 124 depends on the distance and direction to the target position. The drive amount of the linear motion drive unit 300 is calculated. The three-phase command generation unit 332 generates a drive current for each of the U phase, the V phase, and the W phase according to the calculation result, and gives a three-phase command value to the corresponding current amplifier.

  The switch control unit 340 controls on / off of the plurality of switches SW1 to SW9 of the switch unit S according to the calculation result of the position calculation unit. Thereby, the current Iu, Iv, Iw is energized to any one of the coils 124, and the linear drive unit 300 is operated. The current amplifier may be provided with a series resistor that senses overcurrent for overcurrent protection.

  The schedule for supplying drive current to the coil 124 is shown in Table 1 below. In Table 1, the switch numbers from the switches SW1 to SW9 corresponding to the coils 124 are described in the column direction, and the distance La (unit: mm) to the target position of the slider is described in the row direction. In the table, ◯ indicates the energized state of the coil, and x indicates the non-energized state. The numerical value of the magnet position indicates the length of one coil 124 in the moving direction of the mover 130 in millimeters. The length of each coil 124 is 10 mm.

  In this way, by sequentially supplying the drive current to the plurality of coils 124, the mover 130 on which the permanent magnet 134 is mounted can be moved. In addition, the moving direction of the mover 130 can be reversed by reversing the order of the coils 124 that supply the drive current.

  Furthermore, while the drive current is supplied to any one of the coils 124, the braking of the mover 130 by the braking section actuator 136 is released. Accordingly, the mover 130 that has received the driving force moves smoothly and moves the holding frame 160.

  When the supply of the drive current to all of the coils 124 is interrupted, the switch control unit 340 brings all the switches SW1 to SW9 except the switch SW0 into a conductive state. As a result, the linear drive unit 300 enters the coil short mode and stops at the back electromotive force generated by the relative movement of the permanent magnet 134 and the coil 124.

  Further, when the drive current is not supplied to any of the coils 124, the drive voltage for opening the brake section actuator 136 is not supplied. As a result, the brake portion actuator 136 contacts both the mover 130 and the stator 120 to brake the mover 130. Since this braking is maintained without receiving drive power from the outside, the stop position of the mover 130 is maintained regardless of whether the power source or the like is on or off. Further, by stopping the mover 130, power is not consumed.

  FIG. 7 is a cross-sectional view showing another structure of the lens unit 100. FIG. 7 shows a cross section orthogonal to the optical axis C. In FIG. 7, the same reference numerals are assigned to elements common to the other embodiments, and redundant description is omitted. This lens unit 100 has a unique structure in that the brake part actuator 136 of the mover 130 is disposed between the mover main body 138 and the lens barrel 110.

  The structure of the brake section actuator 136 itself is the same as that described with reference to FIG. 3, and when not driven from the outside, one surface is fixed to the mover body 138 and the other surface is the lens barrel. It is pressed against the inner surface of 110. Thereby, the mover 130 and the guided portion 150 are braked over a large area with respect to the inner surface of the lens barrel 110 and do not move.

  When the mover 130 moves relative to the stator 120, the braking portion actuator 136 is driven, and the thickness of the braking portion actuator 136 is reduced in the radial direction of the lens barrel 110. As a result, the movable element 130 and the guided portion 150 are released from braking on the lens barrel 110 and smoothly move along the stator 120 or the guide shaft 140.

  Note that the piezoelectric element, bimetal, shape memory alloy, or the like can be used as the brake section actuator 136 as in the other embodiments. In addition, the structure of the stator 120 and the mover 130 is not changed except for the arrangement of the brake section actuator 136.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  The order of execution of each process such as operations, procedures, steps, and stages in the apparatus, system, program, and method shown in the claims, the description, and the drawings is particularly “before” or “prior to”. It should be noted that the output of the previous process may be realized in any order unless used in a subsequent process. Regarding the operation flow in the claims, the description, and the drawings, even if it is described using “first”, “next”, etc. for convenience, it means that it is essential to carry out in this order. It is not a thing.

99 imaging device, 100 lens unit, 101 optical system, 102, 104, 106 lens group, 110 lens barrel, 120 stator, 121 cable, 122 outer cylinder, 124 coil, 128 core, 130 mover, 132, 152 bearing part , 134 Permanent magnet, 136 Actuator for brake part, 138 Movable body, 140 Guide shaft, 150 Guided part, 160 Holding frame, 170 Aperture device, 200 Imaging part, 210 Imaging element, 212 Optical filter, 220 Shutter, 230 Focus Detection unit, 240 primary mirror, 242 secondary mirror, 250 control unit, 260 mount unit, 270 pentaprism, 272 focusing screen, 280 photometry unit, 290 eyepiece optical system, 292 half mirror, 294 finder LCD, 296 main LCD, 300 Dynamic drive unit, 301 control system 310 encoder, 320 position calculating unit, 330 drive circuit, 332 a three-phase command generating unit, 334 a DC voltage generating unit, 340 switch controller, 350 inverting amplifier

Claims (9)

A holding frame for holding the lens;
The shaft-shaped stator is inserted and includes an insertion portion having an inner diameter larger than the outer diameter of the stator , connected to the holding frame, and provided so as to be linearly movable along the axial direction, A mover having a length shorter than the stator in the axial direction ;
A moving actuator that is provided in the insertion portion and generates a driving force between the stator and the mover to move the mover relative to the stator by the action of a permanent magnet and a coil ;
An actuator for a braking portion provided on an inner surface of the insertion portion and extending or contracting;
With
When the actuator for movement does not generate a driving force, the actuator for braking unit contacts the outer surface of the stator to brake the movable element with respect to the stator, and the actuator for movement in the event of a force, spaced apart from the outer surface of the stator by subtracting the brake actuator thickness prevents a put lens unit that the mover moves along the stator.   The lens unit according to claim 1, wherein the brake unit actuator includes a piezoelectric element that expands or contracts when a voltage is applied thereto.   The lens unit according to claim 2, wherein the voltage is applied to the brake unit actuator when the actuator is separated from the outer surface of the stator.   4. The lens unit according to claim 2, wherein the braking section actuator is operated by electric power supplied in parallel with the moving actuator. 5.   The lens unit according to claim 1, wherein the braking portion actuator includes a bimetal that is deformed when heated.   The lens unit according to claim 1, wherein the braking section actuator includes a shape memory alloy that is heated to a recovery temperature to recover a memory shape.   The lens unit according to claim 5, wherein the braking portion actuator is operated by heat propagated from the moving actuator.   7. The lens unit according to claim 5, wherein the brake unit actuator is operated by a heater that raises the temperature with electric power supplied in parallel with the moving actuator. 8.   An imaging device comprising the lens unit according to any one of claims 1 to 8.

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