JP2007163930A - Lens moving device and camera module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens moving device that enables the assembly cost and the component processing cost thereof to be reduced while ensuring accuracy required for positioning a lens hold frame, and to provide a camera module. <P>SOLUTION: The lens moving device is provided in which a stopper 2a is attached to the lens hold frame 2, and a stopper receiving part 10 having a female screw is provided on a lead screw 6 side. When the lens hold frame 2 is assembled in the lens moving device, the lens hold frame 2 and the stopper 10 are integrally screwed. While the lens hold frame 2 has screwed and reached the end, the lead screw and stopper receiving part are fixed. This makes it relatively easy to assemble the stopper receiving part in the lens moving device. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lens moving device, and more particularly, to a lens moving device and a camera module of an optical system having a mechanism for moving a lens group in an optical axis direction using a step motor and a lead screw.

In recent years, in an imaging apparatus such as a digital still camera, improvement in portability and usability has been demanded, and the entire apparatus has been reduced in size, and the optical system barrel and lens used in the imaging apparatus have also been reduced in size. However, there is a strong demand for higher image quality and higher pixels, and there is a demand for downsizing the optical system barrel by downsizing the lens moving device.
Recently, mobile phones equipped with a camera module that is smaller and thinner than a digital still camera are also equipped with an autofocus function and optical zoom function. Is required. Especially in camera modules for mobile phones, due to positioning accuracy and space constraints, a minimum position detection device such as a photo interrupter is used to set the optical lens reference position. In many cases, the lens movement range is set by software control based on the count of the input signal of the step motor.

As an example of a conventional lens moving device having a mechanism for stopping the rotation of the lead screw using the movement of the lens holding frame in the optical axis direction without using this photo interrupter, a D-cut flange is provided on the lead screw. Patent No. 3339039 in which the structure to be formed and the structure in which the pin-shaped stopper receiving part separate from the lead screw main body is assembled by press-fitting is described, and the stopper receiving part separate from the lead screw main body, Japanese Patent Application Laid-Open No. 2004-347920 that describes a structure that prevents biting between a lens holding frame including a female screw portion and a lead screw is known (see, for example, Patent Document 1 and Patent Document 2).
Japanese Patent No. 3339039 (page 4, FIG. 1) JP 2004-347920 A (pages 10 to 11, FIG. 1)

  However, the lead screw included in ultra-small camera modules and lens moving devices used in mobile phones and the like is generally configured to be integrated by press-fitting after the lead screw shaft and gear part are processed separately. In the former configuration of the lens moving device, there is a problem that the part processing cost increases. In addition, due to the characteristics of the processing method of the lead screw shaft and gear part, the method of forming a flange of D cut shape or the like increases the processing cost, and the method of inserting the pin-shaped stopper receiving part also increases the positional accuracy in the optical axis direction. It was difficult to secure.

Further, when a D-cut flange is formed on the lead screw, a necessary rotation angle of the lead screw cannot be secured, and there is a problem that high-precision positioning is difficult.
In the latter lens moving device, the stopper receiving portion is fitted, but it is necessary to fix the stopper receiving portion after fitting so as to sandwich the lead screw, particularly in an ultra-small camera and a lens moving device. It was difficult to use as an assembly method.

  The present invention has been made in view of the above-described points, and an object of the present invention is to provide a required lens holding frame positioning accuracy in an ultra-small lens moving device and a camera module used in a mobile phone or the like. It is an object of the present invention to provide a lens moving device and a camera module that reduce assembly costs and component processing costs while securing the above.

In order to achieve the above object, a lens moving device of the present invention includes a drive source, a lead screw that is driven to rotate according to the rotation of the drive source, and a female screw portion that is screwed with a screw portion of the lead screw. A lens holding frame that moves in the optical axis direction, and a guide member that guides the lens holding frame in the optical axis direction, and a stopper portion provided on the lens holding frame abuts on a stopper receiving portion on the lead screw side. Accordingly, in the lens moving device that positions one of the initial position and the maximum extension position of the lens holding frame, the stopper receiving portion includes a female screw portion that is screwed with the screw portion of the lead screw, and is integrated with the lead screw. It is characterized by being configured to do so.

The lens moving device of the present invention includes a drive source, a lead screw that is driven to rotate in accordance with the rotation of the drive source, a lens holding frame that moves in the optical axis direction, and a guide for guiding the lens holding frame in the optical axis direction. In the lens moving device for positioning one of the initial position or the maximum extension position of the lens holding frame by contacting the stopper receiving portion on the lead screw side with the guide member that
A nut that is screwed with a threaded portion of the lead screw and transmits a driving force to the lens holding frame; and a biasing member that biases the lens holding frame and the nut in a contacting direction.
The lens holding frame or the nut includes the stopper portion,
The stopper receiving portion includes a female screw portion that is screwed with a screw portion of the lead screw, and is configured to be integrated with the lead screw.

According to the present invention, in the above invention, the stopper receiving portion includes a first contact surface parallel to the optical axis that contacts the stopper portion, and a second contact that contacts the stopper portion and is perpendicular to the optical axis. The case of having a notch including a surface is also included.
The present invention also includes a case where the difference between the second contact surface and the end surface of the stopper receiving portion on the lens holding frame side is 0.75 times or less the screw pitch of the lead screw.
Furthermore, the lens moving device of the present invention is characterized in that in the above-mentioned invention, the rotation detecting means for detecting the rotation stop state of the lead screw based on the current or voltage state of the step motor as a driving source is used.

  The present invention comprises a step motor having a rotor magnetized in two poles and a stator having a two-phase coil wound around a yoke, and pulse applying means for applying a drive pulse to each of the two-phase coils, Detecting means for detecting an induced voltage generated between both terminals of at least one of the two-phase coils within a rotation angle range of the rotor at which the induced voltage is maximum, and detecting the detected induced voltage in advance. Determination means for determining whether or not the rotor is rotating in comparison with a set reference voltage, and the pulse applying means is configured to generate the induced voltage when the rotor reaches the rotation angle range. The drive pulse is applied so that a certain open time is vacant with respect to the coil in which is detected, and the detecting means detects the induced voltage within the constant open time. Rotation detecting means Teppumota have also comprise.

  Further, the camera module of the present invention includes a driving source, a lead screw, and a female screw part that is screwed with a screw part of the lead screw, a stopper part is formed, and a lens holding frame or nut that moves in the optical axis direction And a guide member that guides the lens holding frame in the optical axis direction, the stopper receiving portion includes a female screw portion that is screwed with the screw portion of the lead screw, and is configured to be integrated with the lead screw. And a control unit for driving the image pickup device and the lens moving device.

According to the lens moving device and the camera module of the present invention, since the stopper receiving portion can be easily positioned and fixed, the lens holding frame that comes into contact with the stopper receiving portion can be used without using relatively large parts such as a photo interrupter. It is possible to reduce assembly costs and component costs while ensuring positioning accuracy.
Further, according to the lens moving device and the camera module of the present invention, it is possible to prevent biting between the lens holding frame or the nut and the lead screw while ensuring the positioning accuracy of the lens holding frame.

  Further, according to the lens moving device and the camera module according to the present invention, the rotation detecting means for detecting the rotation stop state of the lead screw based on the current or voltage state of the step motor as a driving source is used. By detecting the contact of the stopper receiving portion early, it is possible to detect the initial position of the lens holding frame in a shorter time and more accurately.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a top view showing a lens moving device 1 of the present invention, and FIG. 2 is a partial cross-sectional view taken along a line AA ′ in FIG. The lens moving device 1 includes a lens holding frame 2 that moves in the optical axis direction, guide shafts 3 and 4 that play a role of restricting the moving direction of the lens holding frame and a role of rotation prevention, and a lens holding frame in the optical axis direction. Step motor 5 which is a driving source for advancing and retreating, lead screw 6 for converting a driving force in the rotation direction to a driving force in the optical axis direction, base member 7 and pressing member 8, lens 9, and stopper receiving portion 10, It is provided as its basic configuration.

The lens holding frame 2 is formed in a substantially cylindrical shape by a resin material, and includes a stopper portion 2a that comes into contact with the stopper receiving portion 10, a female screw portion 2b that engages with a lead screw, and an insertion portion 2c that inserts the guide shaft 3 therein. Then, a detent portion 2d that comes into contact with the guide shaft 4 is formed in the peripheral portion, and the lens 9 is held on the inner periphery thereof.
Each of the base member 7 and the pressing member 8 has an opening through which light passes in the center, and the guide shafts 3 and 4 are held in parallel with the optical axis direction. Further, a step motor 5 serving as a drive source for the lens moving device is fixed to the base member 7.
In addition, the detailed structure of the stopper part 2a and the stopper receiving part 10 is demonstrated based on the fragmentary perspective view of FIG. The stopper 2a is formed at the peripheral edge of the lens holding frame 2 and is disposed so as to protrude toward the base member.

  The stopper receiving portion 10 is disposed at a position facing the stopper portion 2a, and a first contact surface S1 parallel to the optical axis that contacts the stopper portion 2a and a second contact surface S2 perpendicular to the optical axis. The female screw part 10b is provided in the part screwed in the thread groove of the lead screw 6.

  A method for assembling and fixing the stopper receiving portion 10 will be described with reference to a partial side view of FIG. 4A shows a state immediately before the stopper receiving part 10 is assembled, and FIG. 4B shows a state immediately after the stopper receiving part 10 is assembled. 4A, the stopper receiving portion 10 is positioned at the tip of the lead screw 6, and the stopper portion 2a and the notch portion of the stopper receiving portion are in contact with 10a. From this state, when the stepping motor 5 is driven in the reverse direction to rotate the lead screw 6, the female screw portion 10b of the stopper receiving portion and the teeth of the lead screw are screwed together by the load of the lens holding frame 2 and the rotation restriction of the stopper portion 2a. Then, it moves to the base member side according to the rotation of the lead screw, and the stopper receiving portion 10 reaches the retracting end together with the lens holding frame 2. When the stopper receiving portion 10 reaches the retraction end, the stopper receiving portion and the lead screw 6 are fixed. As a fixing method, a small amount of adhesive is applied to the retraction end side of the lead screw, and it is relatively easy to fix when the stopper receiving portion 10 is cured when it reaches the retraction end.

  As shown in FIG. 3, the depth d of the notch 10a, which is the difference between the second contact surface S2 of the stopper receiving portion 10 and the end surface of the stopper receiving portion on the lens holding frame side, is determined by the lead screw 6. By defining the pitch p to be 0.75 p or less with respect to the pitch p, the distance between the stopper portion 2a and the stopper receiving portion 10 is 0.25p even in the state where the lead screw is drawn out only once from the position of the retracting end of the lens holding frame 2. Since the above can be ensured, it is possible to reliably avoid contact other than the retracting end, and always position the lens holding frame at a fixed position. Therefore, by defining the depth d of the notch 10a, it is possible to reliably set the initial position of the lens holding frame 2 in the optical axis direction.

  Next, the operation of the lens moving device will be described with reference to FIG.

  First, a return signal (signal in the retraction direction) of a control unit (not shown) is generated only for the time necessary for the lens holding frame 2 to reach the retraction position, and as shown in FIG. The stopper portion 2a of the frame 2 is brought into contact with the notch portion 10a of the stopper receiving portion 10. As a result, the rotation of the step motor 5 and the lead screw 6 is stopped, and the lens holding frame 2 can be positioned at the retracting end. In this state, the counter indicating the position state of the lens holding frame included in the control unit is reset, and the initial position setting is completed.

  As shown in FIG. 4C, the step motor 5 and the lead screw 6 are rotated by a drive signal (signal in the feeding direction) of a control unit (not shown), and the rotational motion is converted into a linear motion in the optical axis direction. Then, the lens holding frame 2 is extended to the first target position, and the lens holding frame 2 is held at the first target position by the drive stop signal. On the other hand, when the step motor 5 is driven in reverse by the return signal of the control unit, the lens holding frame 2 is retracted to the second target position as shown in FIG.

  Therefore, the lens holding frame is first moved to the retraction end, the counter of the control unit is reset to set the initial position, and the control unit outputs a drive signal and a return signal for driving the step motor. By integrating, the current position of the lens holding frame in the optical axis direction can be calculated.

  Next, as a variation of the lens moving device of the present invention, a nut provided with a female screw portion screwed with a screw portion of a lead screw and a biasing spring that biases the lens holding frame toward the base member are used. A lens moving device in which a first reduction gear is disposed between a step motor as a drive source and a lead screw will be described with reference to FIG.

  FIG. 5 shows another embodiment of the lens moving device according to the present invention. In contrast to the lens moving device 1, the lens moving device 21 includes a lens holding frame 22 that moves in the optical axis direction. The guide shafts 23 and 24 have a role of restricting the moving direction of the lens holding frame and a role of rotation prevention, and a step motor 25 as a drive source for moving the lens holding frame back and forth in the optical axis direction. The lead screw 26 for converting the driving force into the driving force in the optical axis direction is configured to be driven through the first reduction gear 33.

Each of the base member 27 and the pressing member 28 has an opening through which light passes at the center, and holds the guide shafts 23 and 24 parallel to the optical axis direction. Further, a step motor 25 that is a driving source of the lens moving device 21 is fixedly held on the base member 27.
The lens holding frame 22 is formed in a substantially cylindrical shape from a resin material, and holds the lens 29 on the inner periphery thereof. The lens holding frame 22 is provided with a stopper portion 22a, and an insertion portion for inserting the guide shaft 23 and a rotation preventing portion that contacts the guide shaft 24 are formed in the peripheral portion.

  Similarly to the lens moving device 1 shown in FIG. 2, the stopper receiving portion 30 includes a notch portion that comes into contact with the stopper portion 22 a and a female screw portion that engages with the lead screw 26. Prior to assembly, the stopper receiving portion 22a is a separate member from the lead screw 26, but is integrated with the lead screw during assembly. In the lens moving device 21 shown in FIG. 5, the lens holding frame 22 is configured to include the stopper portion. However, even if the nut is configured to include the stopper portion, the lens moving device is substantially the same. It has the function of.

  The nut 31 includes a female screw portion that is screwed with the lead screw, and has a function of contacting the lens holding frame 22 and transmitting a driving force. The urging spring 32 urges the lens holding frame 22 toward the base member and has a backlash removing function between the lens holding frame and the nut and between the nut and the lead screw.

  Next, the operation of the lens moving device will be described with reference to FIG.

  When the lens holding frame 22 is in a stopped state, the lens holding frame 22 is moved back and forth between the lens holding frame 22 and the nut 31 and between the nut and the lead screw 26 by the biasing force toward the base member. It is held in a stable state. When the stepping motor 25 is driven forward by a drive signal from a control unit (not shown), the speed is reduced to a predetermined speed via the first reduction gear 33 and the lead screw 26, and the lens holding frame 22 is extended to the target position. Even during the feeding operation, the nut 31 and the lead screw 26 are kept in a loose state, and the nut 31 and the lens holding frame 22 are also kept in a loose state.

  On the other hand, when the step motor 25 is driven in reverse by the return signal from the control unit, the speed is reduced to a predetermined speed via the first reduction gear 33 and the lead screw 26, and the lens holding frame 22 is retracted to the target position. Eventually, when the stopper portion 22a of the lens holding frame comes into contact with the notch portion of the stopper receiving portion 30, the lens holding frame 22 stops, and positioning in the optical axis direction at the retracting end can be performed.

  Next, as a variation of the lens moving device illustrated in FIGS. 1 and 5, a lens moving device including a rotation detection unit that detects the stop state of the lens holding frame will be described with reference to FIGS.

  FIG. 6 shows another embodiment of the lens moving device according to the present invention, in which the stopper and the stopper receiving portion abut against the above-described embodiment, and the rotation of the lead screw and the step motor stops. It is sectional drawing which shows schematic structure of the lens moving apparatus containing the rotation detection means which detects this. FIG. 7 is a top view of the step motor included in the lens moving device shown in FIG. 6, and FIG. 8 is a configuration diagram of the rotation detection device shown in FIG.

  The lens moving device 41 of this embodiment includes a lens driving device 42 built in a housing (not shown). The lens driving device 42 is used to drive the step motor 43, a rotation detection device 44 that detects the rotation of the step motor, a lens holding frame 45 that is movably disposed along the optical axis L1, and the step motor 43. Along with this, there is provided driving means 47 for moving the lens holding frame 45 along the optical axis L <b> 1 and varying the distance from the image sensor 46.

  As shown in FIG. 7, the step motor 43 has a rotor 50 magnetized in two poles and having a step angle of 180 °, and a stator 53 in which two-phase coils A and B are wound around yokes 51 and 52. is doing. The stator 53 is formed with elongated holes 54 and 55 that serve as spaces for winding the coils A and B. A region extending from the elongated holes 54 and 55 to one side surface of the stator 53 is the yokes 51 and 52. It has become. Coils A and B are wound around the yokes 51 and 52, respectively.

  Further, the stator 53 has a rotor insertion hole 50a through which the rotor 50 is inserted, an insertion hole 50b through which a lead screw 75 described later is inserted, and a fixing insertion hole (not shown) through which a fixing screw 60 for fixing the stator 53 is inserted. Is formed.

  Furthermore, two notches 56 for stabilizing the stop position of the rotor 50 are formed in the stator 53 around the axis L2 of the rotor 50 with an interval of 180 °. A recess for cutting the magnetic path is formed in the upper portion of the stator 53. And between this recess and the rotor insertion hole 50a, between the two long holes 54 and 55 and the rotor insertion hole 50a, it is the pole part 57 magnetically cut | disconnected.

  In the step motor 43 configured as described above, the rotor 50 rotates at a step angle of 180 ° by a magnetic action generated by applying a predetermined drive pulse by a motor driver 90 described later. This rotation principle will be described in detail later.

  A terminal on one end side of the coil A is a1, a terminal on the other end side is a2, a terminal on one end side of the coil B is b1, and a terminal on the other end side is b2. Also, drive pulses applied to the terminals a1 and a2 are A1 and A2, and drive pulses applied to the terminals b1 and b2 are B1 and B2.

  As shown in FIG. 6, the step motor 43 configured as described above is supported in a state where the bottom surface of the stator 53 is placed on the support member 61, and a cover portion disposed above the stator 53. It is fixed to 62 by the fixing screw 60.

  The support member 61 is made of, for example, a non-magnetic material, and functions as a gear support that rotatably supports various gears described later in addition to supporting the step motor 43. The support member 61 is fixed on the base member 63. The base member 63 is formed, for example, in a rectangular shape when viewed from above, and is fixed by a fixing screw 65 while being placed on the upper surface of the circuit board 64. At this time, the fixing screw 65 also fixes the hard support plate 66 laminated on the back surface of the circuit board 64 in an insulating state.

  On the circuit board 64, the rotation detection device 44 and the image sensor 46 (for example, a semiconductor device such as a CCD or a CMOS) are mounted. The image sensor 46 is mounted so as to be accommodated in an opening 63 a formed in a step shape on the base member 63. The circuit board 64 is bent at approximately 90 ° at one end and is fastened together with the fixing screw 60 that fixes the step motor 43. At this time, the fixing screw 60 fixes the circuit board 64 with the coil block 67 sandwiched between the circuit board 64 and the stator 53. This facilitates wiring work of a motor lead (not shown) between the circuit board 64 and the coils A and B.

  The cover part 62 is formed so as to cover the upper parts of the step motor 43, the support member 61, the base member 63, and the like described above, and these are built in a space between the circuit board 64. The cover portion 62 is formed with a daylighting hole 62 a that becomes incident light of the lens holding frame 45 at a position corresponding to the upper side of the image sensor 46.

  The lens holding frame 45 is disposed above the image sensor 46, and includes a cylindrical lens holder portion 70 and one or a plurality of lenses R fixed to the inner peripheral surface of the lens holder portion 70. It is configured. Note that the installation positions of the image sensor 46 and the daylighting hole 62a are adjusted so as to be arranged on the optical axis L1 of the lens R.

  A pair of sliding portions 71 and 72 are provided on the outer periphery of the lens holder portion 70 so as to face each other with the optical axis L1 interposed therebetween. The pair of sliding portions 71 and 72 are formed with guide holes 71a and 72a such as through holes and grooves through which the pair of guide shafts 73 and 74 can be inserted, respectively.

  The pair of guide shafts 73 and 74 are, for example, round bars, and are arranged in parallel with the optical axis L1 at a position sandwiching the lens holding frame 45 therebetween, and both ends are fixed to the cover portion 62 and the base member 63, respectively. Has been. That is, the lens holding frame 45 is supported in a state of being spanned between the pair of guide shafts 73 and 74, and is disposed so as to be positioned between the imaging element 46 and the daylighting hole 62a. The pair of guide shafts 73, 74 and the pair of guide holes 71a, 72a are slidable. Thereby, the lens holding frame 45 can be moved along the pair of guide shafts 73 and 74 in the direction of the optical axis L1.

  Further, of the pair of sliding portions 71 and 72, one sliding portion 71 is formed so as to extend in a direction away from the lens holding frame 45, and the tip 71b thereof is connected to the threaded portion 75a of the lead screw 75. A nut 76 to be screwed is provided in a press-fit state.

  The lead screw 75 is disposed so as to be parallel to the optical axis L <b> 1 at a position adjacent to one of the pair of guide shafts 73 and 74. At this time, the lead screw 75 is disposed in a state of penetrating through the insertion hole 50 b formed in the stator 53 of the step motor 43. Further, both ends of the lead screw 75 are rotatably supported by the cover portion 62 and the base member 63, respectively. As a result, the lead screw 75 can rotate about an axis L3 parallel to the optical axis L1.

  A stopper portion 71c is provided on the upper surface of one sliding portion 71, and when the lens holding frame 45 is moved closest to the subject side, the stopper portion 71c and the notch portion of the stopper receiving portion 77 come into contact with each other. It is configured as follows. In this embodiment, the position at this time is set as the reference position of the lens R.

  That is, the stopper receiving portion 77 is provided at the extended end of the lens holding frame 45 and comes into contact with the stopper portion 71c of the lens holding frame 45 that has moved to stop the movement of the lens holding frame 45, and the lead screw 75 and The rotation of the reduction gear mechanism 80 and the rotor 50 is stopped.

  Further, a driven gear 75b integrally formed with the lead screw 75 is formed on the cover portion 62 side of the lead screw 75, and a thread groove is formed on the outer peripheral surface on the base member 63 side beyond the insertion hole 50b. Thus, the screw portion 75a is formed. As described above, the nut 76 press-fitted into one sliding portion 71 is screwed into the screw portion 75a. At this time, since the lens holding frame 45 is supported by the pair of guide shafts 73 and 74, when the lead screw 75 is rotated around the axis L3, the nut 76 is not rotated by the lead screw 75. It moves in the direction of the axis L3. That is, the rotational motion is converted into a linear motion.

  The driven gear 75 b of the lead screw 75 is connected to a drive gear 81 fixed to the rotor 50 of the step motor 43 via the reduction gear mechanism 80, and rotates about the axis L <b> 2 as the rotor 50 rotates. It is like that.

  Specifically, first, the rotor 50 of the step motor 43 is rotatably supported at both ends by the cover 62 and the support member 61, and the drive gear 81 is integrally molded on the outer peripheral surface, for example. . The drive gear 81 is meshed with a first reduction gear 82 whose both ends are rotatably supported by the cover portion 62 and the support member 61. Further, the first reduction gear 82 is integrally formed with a second reduction gear 83 having a small diameter. The driven gear 75 b is engaged with the second reduction gear 83. Thereby, the rotational force of the rotor 50 is transmitted to the lead screw 75 after being decelerated by the drive gear 81, the first reduction gear 82, the second reduction gear 83, and the driven gear 75b.

  That is, the first reduction gear 82 and the second reduction gear 83 constitute the reduction gear mechanism 80. The drive gear 81, the reduction gear mechanism 80, the lead screw 75, and the nut 76 constitute the drive means 47 that moves the lens holding frame 45 as the rotor 50 rotates.

  As shown in FIG. 8, the rotation detection device 44 includes a motor driver (pulse applying means) 90 that applies drive pulses to the two-phase coils A and B, and at least one of the two-phase coils A and B. Detecting means 91 for detecting an induced voltage generated between both terminals a1, a2 or b1, b2 of the coil within a rotation angle range of the rotor 50 where the induced voltage is maximum, and the detected induced voltage is preset. A DSP (digital signal processor) (determination means) 92 that determines whether or not the rotor 50 is rotating as compared with the reference voltage is provided. When the DSP 92 determines that the stopper portion 71c comes into contact with the stopper receiving portion 77, the rotation of the lead screw 75 stops, and the rotor 50 stopped via the reduction gear mechanism 80 is in a non-rotating state, the lens It is set as a reference position.

In addition, when the rotor 50 reaches the rotation angle range described above, the motor driver 90 sends a drive pulse to the coils A and B from which the induced voltage is detected with a certain open time t _OFF. It is designed to be applied. The detection means 91 is adapted to detect an induced voltage in the constant opening time t _OFF.
The detecting means 91 detects the terminal voltage generated at both terminals a1, a2 or b1, b2 of the coils A and B each time the rotor 50 rotates by one step, and the induced voltage is calculated from the difference between the two terminal voltages. An A / D conversion circuit (calculation unit) 93 for calculation is provided.

The DSP 92 includes a CPU 94 and a ROM 95 and a RAM 96 in which the above-described reference voltage, various programs, fixed data, and the like are stored.
In the present embodiment, an A / D conversion circuit 93 is built in the DSP 92. The CPU 94, ROM 95, RAM 96, and A / D conversion circuit 93 are electrically connected to each other via a bus.
The principle of detecting the rotation of the rotor 50 by the rotation detecting device 44 configured as described above will be described in detail later.

  First, the rotation principle of the step motor 43 will be described below with reference to FIGS. First, a case where the rotor 50 is rotated clockwise (CW direction) will be described. 9 and 10, the polarities of the drive pulses applied to the coils A and B are illustrated.

  First, as shown in FIG. 9A, the drive pulses having the polarities shown in the drawings are applied to the coils A and B when the rotation angle of the rotor 50 is 0 °. As a result of this application, a magnetic field is generated in the stator 53 so as to have an N pole on the upper left side and an S pole on the upper right side. As a result, the S pole and the N pole of the rotor 50 rotate in the clockwise direction by receiving a repulsive force / attraction force from the S pole and the N pole of the magnetic field generated in the stator 53.

  Next, when the rotor 50 rotates 90 °, the polarity of the drive pulse applied to the coil B is reversed as shown in FIG. As a result, a magnetic field is generated in the stator 53 such that the intermediate portion of the yokes 51 and 52 is the S pole and the upper left and right sides of the stator 53 are the N pole. As a result, the rotor 50 is further rotated in the clockwise direction, and the rotor 50 is rotated 180 ° as shown in FIG. 9C.

  When the rotor 50 rotates 180 °, the drive pulse applied to the coil A is reversed as shown in FIG. If the drive pulse applied to the coil A is not reversed when the rotor 50 rotates 180 °, the rotation gradually converges around the notch 56 as shown in FIG. Stopped. On the other hand, when the drive pulse is inverted as described above, a magnetic field is generated in the stator 53 such that the upper left side is the S pole and the upper right side is the N pole, as shown in FIG. To do. As a result, the S pole and N pole of the rotor 50 receive repulsive force and attractive force from the S pole and N pole of the stator 53, respectively, and further rotate clockwise.

  Next, when the rotor 50 rotates 270 °, the drive pulse applied to the coil B is reversed as shown in FIG. As a result, a magnetic field is generated in the stator 53 such that the intermediate portion between the yokes 51 and 52 has an N pole and the upper left and right sides of the stator 53 have an S pole. As a result, as shown in FIG. 9F, the rotor 50 further rotates and makes one rotation. Thus, the rotor 50 can be rotated clockwise by changing the drive pulse applied to each of the coils A and B in a timely manner according to the rotation angle of the rotor 50.

  When the rotor 50 rotates 360 ° (one rotation), the drive pulse applied to the coil A is changed to the state shown in FIG. If not changed, as shown in FIG. 9 (f), the rotation gradually converges around the notch 56 as in the case of 180 ° rotation, and a stop state is reached.

  Next, a case where the rotor 50 is rotated counterclockwise (CCW direction) will be described with reference to FIG. In this case, the basic principle is the same as in the case of rotating clockwise as described above, except that the polarity and order of the applied pulses are different.

  That is, as shown in FIG. 10A, the drive pulses having the polarities shown in the drawings are applied to the coils A and B when the rotation angle of the rotor 50 is 0 °. As a result of this application, a magnetic field is generated in the stator 53 so as to be an S pole on the upper left side and an N pole on the upper right side. As a result, the S pole and N pole of the rotor 50 receive a repulsive force / attraction force from the S pole and N pole of the magnetic field generated in the stator 53 and rotate counterclockwise.

  Next, when the rotor 50 rotates 90 °, the polarity of the drive pulse applied to the coil A is reversed as shown in FIG. As a result, a magnetic field is generated in the stator 53 such that the intermediate portion of the yokes 51 and 52 is the S pole and the upper left and right sides of the stator 53 are the N pole. As a result, the rotor 50 is further rotated counterclockwise, and the rotor 50 is rotated 180 ° as shown in FIG.

  When the rotor 50 rotates 180 °, the drive pulse applied to the coil B is reversed as shown in FIG. As a result, a magnetic field is generated in the stator 53 such that the upper left side is an N pole and the upper right side is an S pole. As a result, the S pole and N pole of the rotor 50 receive repulsive force and attractive force from the S pole and N pole of the stator 53, respectively, and further rotate counterclockwise.

  When the drive pulse applied to the coil B is not reversed when the rotor 50 rotates 180 °, the rotation gradually converges around the notch 56 as shown in FIG. Stop.

  Next, when the rotor 50 rotates 270 °, the polarity of the drive pulse applied to the coil A is reversed as shown in FIG. As a result, a magnetic field is generated in the stator 53 such that the intermediate portion between the yokes 51 and 52 has an N pole and the upper left and right sides of the stator 53 have an S pole. As a result, as shown in FIG. 10F, the rotor 50 further rotates and makes one rotation. Thus, the rotor 50 can be rotated counterclockwise by changing the drive pulses applied to the coils A and B in a timely manner according to the rotation angle of the rotor 50.

  When the rotor 50 rotates 360 ° (one rotation), the drive pulse can be further rotated by changing the drive pulse to the state shown in FIG. In the case where the reversal is not performed, as shown in FIG. 10 (f), a stop state is gradually started around the notch 56 as in the case of the clockwise rotation.

  In the case of 90 ° step driving, it is possible to keep the rotor 50 stationary at rotor rotation angles of 90 ° and 270 ° by continuously inputting drive pulses P1 and P3 described later.

  Next, the principle of detecting the rotation of the rotor 50 by the rotation detector 44 will be described.

  First, the induced voltage generated in the coils A and B will be described below. Since this induced voltage is derived by the rotational speed of the rotor 50 and the coil linkage magnetic flux, these will be described first with reference to FIGS. Note that the case where the rotor 50 is rotated counterclockwise (CCW direction) as shown in FIG. 15 will be described as an example.

  Here, the interlinkage magnetic fluxes of the coils A and B (magnetic flux received from the rotor 10 when the coils A and B are not excited) with respect to the rotation angle of the rotor 50 are shown in FIG. FIG. 12 shows the rotational speed of the rotor 50 with respect to the above, and FIG. 13 shows drive pulse waveforms applied to both terminals a1, a2, b1, and b2 of the coils A and B, respectively. At this time, the magnetic flux in the arrow direction shown in FIG. 15 is positive.

  First, as shown in FIG. 11, it can be seen that the flux linkages generated in both coils A and B are out of phase by 60 °. Further, it can be seen that the range in which the amount of change in the interlinkage magnetic flux is large, that is, the range in which the inclination is large, is within the range of the rotor rotation angle of approximately 90 ° to 210 ° and the range of 270 ° to 10 °.

  Next, as shown in FIG. 12, it can be seen that the rotational speed of the rotor 50 increases every 90 °, starting from 0 °. This is because, as shown in FIGS. 13 and 14, the drive pulse is switched at the rotation angle (every 90 °) at which the torque is maximized, so that the rotation speed immediately after the pulse switch is maximized.

  That is, as shown in FIG. 13, the range of the rotor rotation angle from 0 ° to 90 ° is P1 pulse, the range of the rotor rotation angle is from 90 ° to 180 °, the P2 pulse, and the range of the rotor rotation angle is from 180 ° to 270 °. Is a P3 pulse, and a rotor rotation angle range of 270 ° to 360 ° is a P4 pulse. As shown in FIG. 14, the torque waveform of the rotor 50 is the same as that of the P1 pulse and the P3 pulse. The P4 pulse has the same waveform.

  As described above, since the drive pulse is sequentially switched at the position where each torque is the largest (position where the rotor rotation angle is every 90 °), the rotation speed immediately after the pulse switching is increased, and the rotation speed of the rotor 50 is The waveform is shown in FIG.

  Next, the induced voltage generated in the coil A is shown in FIG. Note that the voltage in the direction of the arrow shown in FIG. 17 is positive. As shown in FIG. 16, the induced voltage has a negative peak around the rotor rotation angle of about 90 ° to 150 °, and a positive peak around the rotor rotation angle of 270 ° to 330 °. I know that. That is, since the induced voltage is a value obtained by multiplying the gradient of the coil linkage magnetic flux by the rotation speed of the rotor 50, the induced voltage is most in the above range where the gradient of the coil linkage flux is large and the rotation speed of the rotor 50 is fast. A large induced voltage is generated.

  Here, when the rotor 50 is not rotating, since the rotation speed is “0”, no induced voltage is generated. That is, whether or not the rotor 50 is rotating can be determined based on whether or not the induced voltage is generated.

  The rotation detection device 44 of the present embodiment performs rotation detection based on such a principle to determine whether or not the rotor 50 is rotating from the induced voltage. Further, in order to detect the induced voltage with high accuracy, detection is performed within a rotation angle range where the induced voltage reaches a peak. That is, the rotation angle range of the rotor 50 in which the induced voltage is maximum is in the vicinity of 90 ° to 150 ° and in the vicinity of 270 ° to 330 °, and thus detection is performed in this range.

Then, as shown in FIG. 13, when the rotor 50 reaches this rotational angle range, the motor driver 90 applies a drive pulse in a state in which the above-described constant opening time t _OFF is left (opened). Have been adjusted so that.

In the present embodiment, by applying a driving pulse spaced only open time t _OFF in coil A, and an example of the case of applying a continuous drive pulse is not open time t _OFF the coil B.

Finally, an outline of the camera module 101 including the lens moving device will be described with reference to FIG.
FIG. 18 is a block diagram of a camera module including the lens moving device 1 described above. The camera module 101 is necessary for the lens moving device 1, the transmission mechanism 102 that transmits the driving force of the step motor 5 to the lens holding frame, and the step motor 5 that is a driving source for driving the lens holding frame 2 including the lens 9. A motor driver 103 that outputs a drive signal, a CPU and a memory, a control unit 104 that controls the lens moving device based on a video signal to be described later, an image sensor 105 that converts light converged by the lens into an electrical signal, and imaging The signal processing unit 106 processes a signal output from the element and outputs it as a video signal to the control unit. The display unit 107 is provided in an electronic device in which the camera module 101 is incorporated, and displays image information obtained by the image sensor 105, other control information, and the like.
The step motor 5 of the lens moving device is driven via a motor driver 103, and a drive command is sent to the motor driver 103 from a control unit 104 as control means. The control unit 104 includes a CPU and a memory, and has a counter function for holding the position of the lens holding frame. The step motor 5 is driven in a predetermined state. Information on the image sensor 105 is input to the control unit 104 via the signal processing unit 106, and image information is sent from the control unit 104 to the display unit 107.

  In response to a command from the control unit 104, the stepping motor 5 is driven so as to retract the lens holding frame 2, and the counter of the control unit 104 is reset when the stepping motor 5 is moved to the retracting end. Thereafter, the lens holding frame 2 is set to the initial position, and a transition is made to the shooting preparation state. In response to a shooting request from the photographer, the control unit 104 calculates a focus evaluation value from the contrast included in the image information output from the image sensor 105, repeats the focus determination and the lens movement, and executes shooting.

FIG. 19 is a block diagram of the camera module 201 including the lens moving device 41 described above. The camera module 201 includes a lens R and a lens holding frame 70, a transmission mechanism 202, a motor driver 203 that outputs a necessary driving signal to a step motor 43 that is a driving source for driving the lens, a position of the lens holding frame 70, A rotation detection unit 204 that detects a state, a CPU and a memory, a control unit 205 that controls the lens moving device 41 based on the rotation detection unit 204 and a video signal described later, and converts light converged by the lens into an electrical signal. An image sensor 206 and a signal processing unit 207 that processes a signal output from the image sensor and outputs it as a video signal to the control unit. The display unit 208 is provided in an electronic device in which the camera module 201 is incorporated, and displays image information obtained by the image sensor 206, other control information, and the like.
A step motor 43 of the lens moving device is driven via a motor driver 203, and a drive command is sent to the motor driver 203 from a control unit 205 as a control means. The control unit 205 includes a CPU and a memory, and has a counter function. The control unit 205 drives the step motor 43 in a predetermined state according to the rotation state output from the rotation detection unit 204. Further, information on the image sensor 206 is input to the control unit 205 via the signal processing unit 207, and imaging information is sent from the control unit 205 to the display unit 208.

  In response to a command from the control unit 205, the rotation detecting means 204 drives the stepping motor 43 in the direction in which the lens holding frame 45 is retracted, detects the rotation stop state, resets the counter, and then extends the lens holding frame 45. Drive in the direction. In response to a shooting request from the photographer, the control unit 205 calculates a focus evaluation value from the contrast included in the image information, repeats focus determination and lens movement, and executes shooting.

It is a top view which shows one Embodiment of the lens moving apparatus which concerns on this invention. It is a fragmentary sectional view around the lead screw of the lens moving device shown in FIG. It is a fragmentary perspective view of the stopper part periphery of the lens moving apparatus shown in FIG. It is explanatory drawing explaining the assembly method of the stopper receiving part of the lens moving apparatus shown in FIG. It is a side view which shows other embodiment of the lens moving apparatus which concerns on this invention. It is sectional drawing which shows one Embodiment of the lens drive device containing the rotation detection apparatus of the step motor which concerns on this invention. FIG. 7 is a top view of the lens moving device shown in FIG. 6. It is a block diagram of the rotation detection apparatus shown in FIG. It is explanatory drawing which shows the clockwise rotation operation | movement of the step motor shown in FIG. It is explanatory drawing which shows the rotation operation | movement of the counterclockwise direction of the step motor shown in FIG. In the step motor shown in FIG. 7, it is the figure which showed the relationship between a rotor rotational angle and the coil linkage magnetic flux received from a rotor. In the step motor shown in FIG. 7, it is the figure which showed the relationship between the rotor rotation angle at the time of normal rotation, and the rotational speed of a rotor. In the step motor shown in FIG. 7, it is the figure which showed the relationship between a rotor rotation angle and the drive pulse applied to each coil. FIG. 8 is a diagram showing a relationship between a rotor rotation angle and torque in the step motor shown in FIG. 7. FIG. 15 is a diagram for defining the direction of magnetic flux in FIGS. 11 to 14. In the step motor shown in FIG. 7, it is the figure which showed the relationship between the rotor rotation angle at the time of normal rotation, and the induced voltage generate | occur | produced between coil terminals. In FIG. 16, it is a figure for defining the direction of a voltage. It is the block diagram which showed the outline of the camera module containing the lens moving apparatus by this invention. It is the block diagram which showed the outline of the camera module containing the lens moving apparatus which has a rotation detection means by this invention.

Explanation of symbols

1, 21, 41 Lens moving device 2, 22 Lens holding frame 2a, 22a Stopper
3, 4, 23, 24 Guide shaft 5, 25 Step motor 6, 26 Lead screw 7, 27 Base member 8, 28 Holding member 9, 29 Lens 10, 30 Stopper receiving portion 31 Nut 32 Energizing spring 33 First reduction gear 101, 201 Camera module

Claims (8)

A driving source; a lead screw that is rotationally driven according to the rotation of the driving source; a lens holding frame that includes a female screw portion that is screwed with a screw portion of the lead screw; and a lens holding frame that moves in the optical axis direction; A guide member for guiding in the optical axis direction is provided, and a stopper portion provided on the lens holding frame abuts on a stopper receiving portion on the lead screw side, thereby positioning one of the initial position or the maximum extension position of the lens holding frame. In the lens moving device that performs
The stopper receiving portion includes a female screw portion that is screwed with a screw portion of the lead screw, and is configured to be integrated with the lead screw. A driving source; a lead screw that is driven to rotate according to the rotation of the driving source; a lens holding frame that moves in the optical axis direction; and a guide member that guides the lens holding frame in the optical axis direction. In the lens moving device that positions one of the initial position or the maximum extension position of the lens holding frame by contacting the stopper receiving part on the lead screw side,
A nut that is screwed with a threaded portion of the lead screw and transmits a driving force to the lens holding frame;
An urging member for urging the lens holding frame and the nut in a contact direction;
The lens holding frame or the nut includes the stopper portion,
The stopper receiving portion includes a female screw portion that is screwed with a screw portion of the lead screw, and is configured to be integrated with the lead screw.   The stopper receiving portion has a first abutting surface parallel to the optical axis that abuts on the stopper portion and a notch portion that abuts on the stopper portion and includes a second abutting surface perpendicular to the optical axis. 3. The lens moving device according to 1 or 2.   The lens moving device according to claim 3, wherein a difference between the second contact surface and an end surface of the stopper receiving portion on the lens holding frame side is not more than 0.75 times the screw pitch of the lead screw.   The lens moving device according to any one of claims 1 to 4, further comprising a rotation detection unit that detects a rotation stop state of the lead screw based on a current or voltage state of a step motor serving as a drive source. A step motor having a rotor magnetized in two poles and a stator having a two-phase coil wound around a yoke, and a pulse applying means for applying a drive pulse to each of the two-phase coils; Detecting means for detecting an induced voltage generated between both terminals of at least one of the coils within a rotation angle range of the rotor at which the induced voltage is maximized, and a reference for which the detected induced voltage is set in advance Determining means for determining whether or not the rotor is rotating in comparison with voltage,
The pulse applying means applies the drive pulse so that a certain open time is provided to the coil from which the induced voltage is detected when the rotor reaches the rotation angle range, and the detection means The lens moving device according to claim 1, further comprising a step motor rotation detecting unit that detects the induced voltage within the predetermined opening time.   A drive source, a lead screw, a lens holding frame that includes a female screw portion that is screwed with a screw portion of the lead screw, and includes a lens holding frame that moves in the optical axis direction, and a guide member that guides the lens holding frame in the optical axis direction. The camera module containing the lens moving device as described in any one of Claims 1 and 3-6 including the control part which controls the image pick-up element and the said lens moving device.   A drive source, a lead screw, a lens holding frame, a guide member that guides the lens holding frame in the optical axis direction, and a female screw portion that engages with a screw portion of the lead screw move in the optical axis direction. 7. A lens moving device including a nut and a biasing member that biases the lens holding frame and the nut in a contact direction, and further includes a control unit that controls the imaging device and the lens moving device. A camera module including the lens moving device according to claim 1.

Images