JP4659418B2 - LENS DEVICE, IMAGING DEVICE, AND OPTICAL DEVICE - Google Patents

Description

  The present invention relates to a lens device that moves a lens in the optical axis direction, an imaging device including the lens device, and an optical device.

  In recent years, with the progress of miniaturization of digital cameras, the miniaturization of lens devices incorporated therein has also progressed. Particularly, in a digital camera incorporated in a small device such as a mobile phone or a PDA (Personal Digital Assistant), the outer diameter of the lens is molded to about several millimeters, and the miniaturization is remarkable. In such a lens apparatus, a pan focus (fixed focus) lens is mainly used, but it is required to have an auto focus and a zoom function.

For the auto focus and zoom functions, for example, a stepping motor as shown in Patent Document 1 below is used as a lens driving device. The stepping motor includes a stator that generates a magnetic field and a rotor that is rotatably provided inside the stator, and rotates the rotor according to an input drive pulse. The rotational force of the rotor is transmitted to the lens frame holding the lens via a gear, and the position of the lens is adjusted. However, in this case, the size in the direction orthogonal to the optical axis (around the optical axis) is increased by the amount of the stepping motor and the gear disposed on one side of the lens frame, which hinders downsizing of the lens device. In view of this, it has been proposed to use a hollow stepping motor in which a lens holder is incorporated in a rotor as a lens driving device. In this case, when the rotating cylinder fixed inside the rotor rotates, the rotational force is transmitted to the lens frame disposed inside the rotating cylinder, and the lens moves in the optical axis direction.
JP 2002-252963 A

  In order to correctly control the movement of the lens including the two stepping motors using the motor, it is necessary to detect that the lens has moved to the home position. However, when the lens device itself is small, there is no space for incorporating a conventional potentiometer or photosensor. As a countermeasure for such a problem, there is a method in which the movement of the lens is mechanically stopped at the end, the motor is driven for a predetermined time and then stopped, and the position is set as the home position. However, according to this method, the motor is driven in a state where the lens is mechanically stopped. At this time, vibration noise is generated, and there is a problem in terms of product quality. In addition, the power source also has a disadvantage that it involves unnecessary consumption.

  An object of this invention is to provide the lens apparatus which detects a home position efficiently, without impairing the quality as a product.

  The lens device according to the first aspect of the present invention is driven by a motor having a stator that generates a magnetic field when energized, and a hollow rotor that is rotatably provided inside the stator, and is a rotation that is fixed inside the rotor. An apparatus for moving a lens, which is movably provided inside the rotary cylinder, in the direction of the optical axis by rotating the cylinder integrally with the rotor, the fixed frame fixed to the stator, and the lens frame holding the lens; A projection formed integrally with any one of these, and formed on the other of the fixed frame and the lens frame, engages with the projection and restricts the rotation of the lens frame around the optical axis direction of the lens frame. The guide groove that guides the movement of the lens and the sections fixed to the surface of the protrusion and the wall surface of the guide groove, and the lens frame comes into contact with each other when the lens frame moves to a preset home position in the optical axis direction. A position detecting switch for outputting a communication item, characterized by comprising a.

  The protrusion has a pair of surfaces parallel to the optical axis, the guide groove has a pair of opposing walls facing the pair of surfaces of the protrusion, and the section fixed to the surface of the protrusion straddles the pair of surfaces. The sections fixed to the wall surface of the guide groove are a pair of sections fixed to the pair of opposing walls, respectively. Further, the motor is a stepping motor.

  The lens device according to the second aspect of the present invention is driven by a stepping motor having a stator that generates a magnetic field by energization and a hollow rotor that is rotatably provided inside the stator, and is fixed inside the rotor. A device that moves in the optical axis direction a lens that is movably provided inside the rotating cylinder by rotating the rotating cylinder integrally with the rotor, and is fixed to the front end or rear end of the lens frame that holds the lens. A switch pattern that is supported by a section and a fixed frame fixed to the stator and that conducts by contact with the section when the lens frame moves to the front end position or rear end position of the movement range in the optical axis direction is formed. And a switch board.

  The imaging device of the present invention includes the lens device according to the first or second mode, and includes an image sensor that captures a subject image obtained through the lens.

  An optical device according to the present invention includes the lens device described above.

  According to the present invention, when the lens frame is moved to the home position, the sections fixed to the surface of the protrusion and the wall surface of the guide groove are in contact with each other and are electrically connected to the guide groove and the protrusion to detect the home position. Therefore, it is possible to eliminate the vibration noise after the home position detection as in the prior art. Further, unlike the prior art, it is not necessary to drive the motor for a predetermined time and move it to the home position, so that unnecessary power consumption can be avoided.

  1 and 2, a mobile phone 1 to which the present invention is applied is composed of a handset unit 2 and a handset unit 3 formed in a substantially rectangular thin plate shape, and a hinge portion 4 that rotatably connects these units. ing. The receiver unit 2 is provided with an antenna 5 for transmitting and receiving radio signals on the upper surface, and on the inner surface is a receiving speaker 6 for outputting the voice and ringtone of the communication partner, and an LCD 7 for displaying a telephone number and images. Is provided. A camera unit (imaging device) 8 incorporating a photographing lens is provided on the outer surface of the receiver unit 2. The cellular phone 1 can set a still image shooting mode in which a subject image is captured and recorded by the imaging device 8.

  The transmitter unit 3 has a transmitter microphone 9 for converting a speaker's voice into a digital voice signal and transmitting the voice to the other party via the antenna 5, a dial key 10a, a menu key 10b, a selection key 10c, and an enter. An operation unit 10 including a key 10d is provided. In the still image shooting mode, the selection key 10c is used for a zoom operation when shooting is performed by the imaging device 8, and the enter key 10d is used for a release operation.

  In FIG. 3, the imaging device 8 is provided with an autofocus function for moving the lens in the front-rear direction along the optical axis L1 to focus on the subject. The imaging device 8 is configured by sandwiching a cylindrical stator 13 between an upper cover 11 and a lower cover 12.

  FIG. 4 shows a state of a cross section when the imaging device 8 is cut along a straight line A1-A2. The upper cover 11 is fixed to the stator 13 and is disposed on the outer side of the front end side of the lens holder (lens frame) 14 that holds the first to third lenses 21 to 23. The lower cover 12 is fixed to the stator 13 and holds a low-pass filter 26 and a CCD substrate 27a to which a CCD image sensor 27 is fixed. The low-pass filter 26 smoothes unnecessarily dense spatial frequency components included in the passing subject light, and reduces problems such as false colors and moire. The CCD image sensor 27 images subject light that has passed through the first to third lenses 21 to 23 and the low-pass filter 26 and is imaged on the light receiving surface thereof.

  Inside the stator 13, a magnet (hollow rotor) 24, a rotating cylinder 25, and a lens holder 14 are arranged in order from the side close to the stator 13. All of these 14, 24, and 25 are formed in a cylindrical shape and are arranged coaxially with the stator 13. The stator 13 and the magnet 24 constitute a claw pole type stepping motor. When a pulse current is passed through the stator 13, the rotary cylinder 25 rotates in accordance with the input drive pulse.

  In FIG. 5, the stator 13 is composed of two layers of coil parts, an upper coil part 13a and a lower coil part 13b. Since the upper and lower coil portions 13a and 13b are configured in the same manner, the description of the configuration of the lower coil portion 13b is omitted, and only the configuration of the upper coil portion 13a will be described. The upper coil portion 13 a is formed in a cylindrical shape as a whole, with the coil 43 surrounded by the upper cover 41 and the lower cover 42. The coil 43 is formed by winding a conductive wire. The inner peripheral surfaces of the upper and lower covers 41 and 42 are provided with teeth 41a and 42a formed so as to engage with each other alternately. A gap exists between the teeth 41a and the teeth 42a.

  When a pulse current is alternately applied to the coil 43 of the upper coil portion 13a and the coil 43 of the lower coil portion 13b, a magnetic field line is generated in the coil 43 and is guided to the inside of the stator 13 by the upper and lower covers 41 and 42. When the induced magnetic field lines reach the teeth 41a and 42a, they are once released into the air and exceed the gap. Accordingly, one of the teeth 41 a and 42 a arranged so as to mesh with each other is an N pole, and the other is an S pole, and N and S magnetic fields are alternately formed along the inner peripheral surface of the stator 13.

  For example, the magnet 24 as a permanent magnet is formed into 48 poles, and 48 teeth of the upper and lower coil portions 13a and 13b are provided correspondingly. Further, the positions of the teeth 41a and 42a of the upper coil portion 13a and the positions of the teeth 41a and 42a of the lower coil portion 13b are shifted by half of the teeth. The magnet 24 rotates relative to the stator 13 by a repulsive force and an attractive force with a magnetic field formed by the stator 13.

  When a pulse current is applied to the stator 13, the magnet 24 rotates with one pole as one step and rotates once in 48 steps. When the forward direction of the rotation direction of the magnet 24 is clockwise D1, in order to rotate the magnet 24 in the forward direction, the forward direction of the upper coil portion 13a, the reverse direction of the lower coil portion 13b, and the reverse direction of the upper coil portion 13a. The energization is repeated in the order of the direction and the forward direction of the lower coil portion 13b. On the other hand, in order to rotate the magnet 24 in the reverse direction, the energization is repeated in the order of the forward direction of the upper coil portion 13a, the forward direction of the lower coil portion 13b, the reverse direction of the upper coil portion 13a, and the reverse direction of the lower coil portion 13b. . In the imaging device 8, when a forward pulse current is applied to the stator 13, the lens holder 14 moves in the forward direction.

  In FIG. 4, the rotating cylinder 25 is fixed to the inside of the magnet 24, and is rotated with the rotation of the magnet 24. A helicoid 25 a is formed on the inner peripheral surface of the rotating cylinder 25, and meshes with the helicoid 14 a formed on the outer peripheral surface of the lens holder 14.

  When a pulse current is applied to the stator 13, the rotating body 25 rotates together with the magnet 24 once in 48 steps. The helicoid 25a on the rotating cylinder 25 side is provided two more times (96 steps) than the helicoid 14a on the lens holder 14 side, and the lens holder 14 can move for 96 steps. The rotational force of the rotary cylinder 25 is converted into a force in the optical axis direction by the helicoids 14a and 25a. This force in the optical axis direction is transmitted to the lens holder 14, and the lens holder 14 moves in the optical axis direction. For example, the lens holder 14 moves about 1.25 mm in the optical axis direction with a full stroke (96 steps), and moves about 13 μm in the front-rear direction in one step.

  A cylindrical fixed frame 15 whose outer peripheral surface is fixed to the upper cover 11 is disposed outside the front end of the lens holder 14. In the imaging device 8, a rotation stop mechanism is provided that prevents the lens holder 14 from rotating with respect to the stator 13 when the lens holder 14 moves in the optical axis direction, thereby preventing the optical axis L 1 from shifting. In FIG. 6, the rotation stopping mechanism includes a protrusion 31 provided integrally on the outer peripheral surface of the lens holder 14 and a guide groove 32 provided on the inner peripheral surface of the fixed frame 15. The protrusion 31 has a pair of surfaces 31a and 31b parallel to the optical axis L1, and the guide groove 32 has a pair of opposing walls 32a and 32b facing the pair of surfaces 31a and 31b of the protrusion 31. By fitting the protrusions 31 and the guide grooves 32, the lens holder 14 moves only in the optical axis direction while being guided by the guide grooves 32.

  In the present embodiment, the rotation stop mechanism is provided with a position detection switch 33 that detects that the lens holder 14 has moved to the home position. The position detection switch 33 includes a section 34 fixed to the surface of the protrusion 31 and a section 35 fixed to the wall surface of the guide groove 32. For example, the section 34 on the protrusion 31 side is a single section bent so as to straddle the pair of surfaces 31 a and 31 b of the protrusion 31, and is provided at the rear end of the protrusion 31. The section 35 on the guide groove 32 side is a pair of sections 35 a and 35 b fixed to the pair of opposing walls 32 a and 32 b of the guide groove 32, respectively, and is provided at the rear end of the guide groove 32.

  The lens holder 14 is between a first position P1 (see FIG. 4) where the tip is retracted to the CCD image sensor 27 side and a second position P2 (see FIG. 7) protruding from the first position P1 to the subject side. It can be moved in the optical axis direction. For example, when the tip of the lens holder 14 is at the second position P2, the position detection switch 33 is turned on when the section 34 on the projection 31 side contacts the pair of sections 35a and 35b on the guide groove 32 side. When the holder 14 is at a position other than the second position P2, the section 34 on the projection 31 side and the sections 35a and 35b on the guide groove 32 side are in a non-contact off state. When the lens holder 14 reaches the second position P2 with the rotation of the rotary cylinder 25, the position detection switch 33 is turned on, and it is detected that the lens holder 14 is at the home position.

  In FIG. 8, the CPU 50 controls each unit of the mobile phone 1 in accordance with operation signals input from the operation unit 10 and the position detection switch 33. The taking lens 51 includes first to third lenses 21 to 23 and is moved along the optical axis direction by energizing the stator 13. The stator 13 is controlled based on a pulse signal input from the drive pulse generation circuit 52.

  A CCD image sensor 27 is disposed behind the photographic lens 51. The CCD image sensor 27 is driven by a CCD driver 53, images subject light that has passed through the photographing lens 51 and is imaged on its light receiving surface, and outputs an analog imaging signal. An imaging signal from the CCD image sensor 27 is sent to an analog signal processing unit 54 including a CDS / AMP circuit and an A / D converter. The analog signal processing unit 54 performs A / D conversion after performing correlated double sampling processing and amplification processing for removing noise on the imaging signal, and converts the imaging signal into image data. This image data is sent to the digital signal processing unit 55. The digital signal processing unit 55 performs various processes such as white balance adjustment, γ correction, data format conversion, and data compression / decompression. The VRAM 56 is used as a work memory of the digital signal processing unit 55, and image data being processed is written therein.

  The LCD driver 57 drives the LCD 7 based on image data input via the digital signal processing unit 55. Under the still image shooting mode, image data obtained by imaging by the CCD image sensor 27 is input to the LCD driver 57 one after another, and the subject image being shot is displayed on the LCD 7 as a through image. When the return button 10d is half-pressed in the still image shooting mode, autofocus control is executed in response to this.

  The AF detection circuit 60 compares the contrast of the image data written in the VRAM 56 and detects the optimum focus position of the photographic lens 51. The autofocus control by the AF detection circuit 60 will be described. First, imaging is performed by the CCD image sensor 27 in response to the release operation, and image data generated based on the imaging signal is input to the AF detection circuit 60. Next, a forward pulse current is applied to the stator 13 to move the lens holder 14 forward by one step. Then, imaging is performed again by the CCD image sensor 27, and image data obtained by this imaging is input to the AF detection circuit 60 as in the previous imaging. The AF detection circuit 60 compares the contrast of the two input image data to determine which image data has the higher contrast, and inputs the determination result to the CPU 50. In the CPU 50, when the contrast of the previous image data is larger, a reverse pulse current for returning the lens holder by one step backward is supplied to the stator 13, and the contrast of the subsequent image data is larger. For this, a forward pulse current that moves the lens holder 14 forward by one step is supplied to the stator 13.

  The above-described process for comparing the contrast of the image data is continued for 96 steps at maximum until the contrast of the previous image data and the subsequent image data is inverted. When the contrast is reversed, a pulse current in a direction opposite to the direction in which the stator 13 is energized immediately before is supplied to the stator 13 to return the lens holder 14 by one step. The position of the lens holder 14 at this time has the maximum contrast and is the optimum focus position of the photographic lens 51.

  In the present embodiment, when the autofocus control is executed, it is detected that the lens holder 14 is at the home position. When the lens holder 14 moves to the second position P2 and the contact between the protrusion 31 and the guide groove 32 is conducted, the position detection switch 33 sends an on signal indicating that the lens holder 14 is at the home position to the CPU 50. . The CPU 50 receives the on signal and executes autofocus control.

  When the return button 10d is fully pressed subsequent to the half-pressing operation of the return button 10d, the image data for one frame imaged in response thereto is subjected to various processes by the digital signal processing unit 55. Thereafter, it is recorded in the SDRAM 58 as photographed image data.

  The operation of the above embodiment will be described. When shooting a still image using the mobile phone 1, after setting the still image shooting mode, framing is performed while confirming the through image of the subject displayed on the LCD 7, and then the enter key 10d is operated. Perform the release operation. When the enter key 10d is pressed halfway, a forward pulse current is applied to the stator 13 in response to this, and the lens holder 14 is moved in the forward direction. At this time, the rotation of the lens holder 14 is restricted by the fitting between the projection 31 on the lens holder 14 side and the guide groove 32 on the fixed frame 15 side. When the lens holder 14 moves to the front end position P2, contact between the section 34 on the projection 31 side and the sections 35a and 35b on the guide groove 32 side is detected, and an ON signal is output from the position detection switch 33. In response to this ON signal, autofocus control is executed. By this autofocus control, the photographic lens 51 is moved to an optimum focus position. Thereafter, the subject is photographed in response to pressing the enter key 10d fully.

  In the above embodiment, the projection 31 is provided on the lens holder 14 and the guide groove 32 is provided on the fixed frame 15. However, as shown in FIG. 9, the guide groove 65 is provided on the lens holder 63 and the projection 64 is provided on the fixed frame 62. The arrangement of the protrusions and the guide grooves may be reversed. In this case, the position detection switch 66 is bent, for example, so as to straddle the pair of sections 67a and 67b fixed to the pair of surfaces of the protrusion 64 and the pair of opposing walls of the guide groove 65, for example. It consists of a section 68.

  In the above embodiment, the position detection switch 33 is constituted by the section 34 fixed to the protrusion 31 of the lens holder 14 and the pair of sections 35a and 35b fixed to the guide groove 32 of the fixed frame 15, as shown in FIG. As described above, the position detection switch 70 may be composed of a section fixed to a projection (not shown) and a switch substrate 71 on which a switch pattern is formed. In this case, the switch substrate 71 is formed in a concave shape so as to be attached to the guide groove 73, and a pair of terminals 76a and 76b are mounted on the pair of opposed surfaces 71a and 71b. When the lens holder moves while being guided by the guide groove 73 to which the switch substrate 71 is fixed and reaches the home position, the pair of terminals 76a and 76b come into contact with each other while sandwiching the protrusion-side segment, and the switch pattern becomes conductive. With this conduction, a switch-on signal is sent to the CPU.

  In the above-described embodiment, the example in which the autofocus control is performed after the lens holder 14 is moved to the home position has been described. However, not only the autofocus control but also the zoom control may be performed, for example.

  In the above embodiment, a claw pole type stepping motor is used as an actuator for driving the lens holder 14, but the actuator is not limited to this.

  In the above embodiment, the image pickup apparatus (digital camera) 8 having the CCD image sensor 26 has been described as an example. However, the present invention is not limited to this image pickup apparatus, and image projection such as a silver salt camera using a film or a photosensitive plate, a projector, or the like. The present invention can be applied to an apparatus. The present invention can also be applied to a pickup lens used for reading data on an optical medium such as a CD-ROM or DVD.

It is a perspective view which shows the front surface of a mobile telephone. It is a perspective view which shows the back surface of a mobile telephone. It is a perspective view which shows the imaging device of this invention. It is sectional drawing when cut | disconnecting the imaging device shown in FIG. 3 in the surface which passes along straight line A1-A2. It is explanatory drawing which shows the structure of a hollow stepping motor. It is explanatory drawing which shows the structure of a position detection switch. It is explanatory drawing which shows the movement range of the optical axis direction of a lens. It is a block diagram which shows the electric constitution of a mobile telephone. It is explanatory drawing which shows the structure of another position detection switch. It is explanatory drawing which shows a switch board | substrate.

Explanation of symbols

8 Imaging device 13 Stator 14 Lens holder 15 Fixed frame 24 Magnet 25 Rotating body 31 Protrusion 32 Guide groove 33 Position detection switch 34, Intersections 35a, 35b (on the guide groove side)

Claims (5)

By being driven by a motor having a stator that generates a magnetic field by energization and a hollow rotor rotatably provided inside the stator, and rotating a rotating cylinder fixed to the inside of the rotor integrally with the rotor In the lens device for moving the lens provided movably in the rotating cylinder in the optical axis direction,
A protrusion having a pair of surfaces parallel to the optical axis , provided integrally with either the fixed frame fixed to the stator or the lens frame holding the lens;
A lens that is formed on the other of the fixed frame and the lens frame , has a pair of opposing walls facing the pair of surfaces of the protrusion, and engages with the protrusion to restrict the rotation of the lens frame around the optical axis. A guide groove for guiding the movement of the frame in the optical axis direction;
A piece provided on one of the protrusion and the guide groove and bent so as to straddle a pair of surfaces of the protrusion or a pair of opposing walls of the guide groove; and the protrusion and the guide provided on the other with the groove consists of a pair of sections that are respectively fixed to the pair of surface or a pair of opposed walls of the guide groove of the protrusion, the lens frame to a preset home position in the optical axis direction A lens device comprising: a position detection switch that outputs a conduction signal by bringing the one piece and the pair of pieces into contact with each other when moved. The lens device according to claim 1 , wherein the section on the fixed frame side is provided on a switch board attached to the fixed frame . It said motor according to claim 1 Symbol placement of the lens apparatus characterized in that it is a stepping motor. Comprising a lens device according to any one of claims 1 to 3, an imaging apparatus characterized by having an image sensor that captures a subject image obtained through the lens. An optical device comprising the lens device according to any one of claims 1 to 3 .

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