JP4792773B2 - Camera phone - Google Patents

Description

  The present invention relates to a camera-equipped mobile phone, and more particularly to a camera-equipped mobile phone having an autofocus function.

  With camera-equipped mobile phones, as the number of pixels of the image sensor becomes 1 million pixels or more, an autofocus function has been required. In order to realize this autofocus function, an actuator is used that can move the lens in the optical axis direction by the interaction between the magnetic field generated by the current flowing in the coil and the magnetic field generated by the permanent magnet. For example, the external dimensions of an actuator mounted on a camera-equipped mobile phone are about 10 mm in length, about 10 mm in width, and about 5 mm in thickness.

  In the actuator attached to the camera-equipped mobile phone, the current flowing through the coil is rapidly changed in order to move the lens to the focus position during autofocus. As a result, the lens moves to the focus position. However, since the lens is supported by the spring so as to be movable in the optical axis direction, when the current changes suddenly, the lens does not stop immediately at the focus position but mechanically vibrates in the optical axis direction. This vibration is said to be a transient response, and focusing cannot be performed if the vibration amplitude is large. Since it takes time for the transient response to converge, there is a problem that autofocusing takes time.

For example, the vibration amplitude of a lens that can be focused is a maximum of 9 μm.
The present invention has been made in view of these problems, and an object thereof is to provide a camera-equipped mobile phone in which the time required for autofocus is reduced.

In order to achieve the above object, a camera-equipped mobile phone according to the present invention is fixed to a holder having a cylindrical portion with a lens attached to one end thereof and to the holder so as to be positioned around the cylindrical portion of the holder. Provided on both sides in the optical axis direction of the cylindrical portion of the holder, the holder being radially positioned, and displaceable in the optical axis direction A pair of leaf springs to be supported and a sheet-like electrode for supplying electricity to the coil, and by energizing the coil through the sheet-like electrode, the magnetic field of the permanent magnet and the current flowing through the coil A camera-equipped mobile phone comprising an actuator capable of adjusting the position of the lens in the direction of the optical axis by interaction with a magnetic field by
The actuator further includes a transient response suppressing unit that suppresses a transient response in which the lens vibrates in the optical axis direction due to a sudden change in the current flowing through the coil.
The transient response suppressing means includes a capacitor attached to the sheet-like electrode and connected in parallel to the coil.

  In the camera-equipped mobile phone having the above-described configuration, the transient response suppression unit suppresses a transient response in which the lens vibrates in the optical axis direction due to a sudden change in the current flowing through the coil for focusing. Thereby, the time until the transient response converges can be shortened, and the time required for autofocus can be shortened.

In addition, since the lens is moved to the focus position, a sudden change in the current flowing through the coil can be easily mitigated, and a transient response can be suppressed.
Further, since the capacitor is attached to the sheet-like electrode, it is possible to connect the capacitor without increasing the outer dimension of the actuator, and it is possible to easily mitigate a rapid change in the current flowing through the coil.

Further, in the mobile phone with a camera present invention, the transient response suppression means further having a capacitor connected in parallel to a power source for supplying a current to the coil, a resistor and connected in series with said power supply Is preferred.

Also by this, since the lens is moved to the focus position, a sudden change in the current flowing through the coil can be easily mitigated, and a transient response can be suppressed.

  In the camera-equipped mobile phone according to the present invention, the transient response suppressing means attenuates the vibration amplitude of the lens due to the transient response to 9 μm at the maximum during a maximum of 90 msec from the change of the current flowing through the coil. It is preferable.

  Thereby, vibration with a large amplitude due to a transient response can be converged in a short time, and the time required for autofocus can be shortened.

  Hereinafter, a camera-equipped mobile phone according to the present invention will be described with reference to the accompanying drawings. In the present specification, the terms “upper” and “lower” are used as appropriate. The direction of the arrow shown in FIG. 4 is the upward direction, and the opposite direction of the arrow is the downward direction.

  An example of a camera-equipped mobile phone to which the present invention can be applied will be described with reference to FIG. The camera-equipped mobile phone 1 in FIG. 1 shows a folded state. A camera module 2 is attached to a predetermined position of the camera-equipped mobile phone 1. Thus, the user can take a picture using the camera-equipped mobile phone 1.

  Next, an outline of the configuration of the camera module 2 will be described with reference to FIG. The camera module 2 is combined with the substrate 4, the image sensor 7 placed on the substrate 4, the electronic component 8 placed on the substrate 4 at a distance from the image sensor 7, and the substrate 4. It has the sealing member 6 which forms the sealed space which seals the image pick-up element 7 and the electronic component 8, and the actuator 3 mounted on the sealing member 6. FIG.

  Hereinafter, as an example of a camera-equipped mobile phone to which the present invention can be applied, a basic configuration of an actuator 3 that is provided in an auto-focusable camera-equipped mobile phone 1 and that can move a lens in the optical axis direction will be described.

  As shown in FIGS. 2, 3 and 4, the basic configuration of the actuator 3 includes a cylindrical portion 11 to which the lens 5 is attached at one end, and a flange portion 12 provided on the outer periphery of the other end of the cylindrical portion 11. A holder 10 having a coil; a coil 20 provided in the flange portion 12 of the holder 10 with a space around the cylindrical portion 11; and an inner cylindrical portion having an insertion hole 35 through which the cylindrical portion 11 of the holder 10 is inserted. 31, the outer cylinder part 32 provided outside the inner cylinder part 31 at a predetermined interval, and the end part of the inner cylinder part 31 and the outer cylinder part 32 opposite to the flange part 12 of the holder 10 are integrally formed. A circular yoke 30 having a connecting portion 34 to be connected, and configured to house the coil 20 in a predetermined space between the inner cylinder portion 31 and the outer cylinder portion 32; 30 is spaced from the coil 20 on the inner peripheral surface of the outer cylindrical portion 32. A plurality of permanent magnets 40 arranged so as to face each other; the permanent magnets 40 are arranged so as to be coupled in a state of being in contact with the surface of the permanent magnet 40 opposite to the coupling part 34 of the circular yoke 30. An upper leaf spring 60U and a lower leaf spring 60L, which are provided on both sides of the cylindrical portion 11 of the holder 10 in the optical axis direction and support the holder 10 so as to be displaceable in the optical axis direction. A pair of leaf springs 60; a stopper 70 fitted to the holder 10 so as to sandwich the upper leaf spring 60U between the holder 10; and the optical axis direction outer side of each of the stopper 70 and the lower leaf spring 60L. The plate spring 60 is sandwiched between both end surfaces of the yoke 30 in the optical axis direction, and at least a portion corresponding to the lens 5 attached to the holder 10 has an opening. That a pair of support frames and cover 80 and the base 85 forming a; to power coil 20, a sheet-like electrode 90 disposed between the lower leaf spring 60L and the base 85; and a.

Hereinafter, the operation of the actuator 3 having the above basic configuration will be described.
In FIG. 2, the direction of the magnetic field is from the permanent magnet 40 to the inner cylindrical portion 31 of the yoke 30. When a current flows counterclockwise when the coil 20 is viewed from above with the holder 10 in the initial position, an upward electromagnetic force is generated in the coil 20, that is, the holder 10. The holder 10 is displaced in the optical axis direction until the electromagnetic force and the elastic force of the leaf spring 60 that changes according to the displacement of the holder 10 are balanced. The electromagnetic force is controlled by the amount of current flowing through the coil 20. Therefore, the holder 10, that is, the lens 5 can be displaced to an arbitrary position (focus position) by controlling the current.

  Autofocus is performed according to the following procedure. First, the contrast of the image detected by the image sensor 7 is converted into an electric signal (waveform) in the entire range in which the lens 5 is movable. Next, the electric signal (waveform) is amplified by a high pass filter. The position of the lens where the waveform is most undulating is determined as the focus position. Next, the lens 5 is moved to the focus position by flowing a predetermined current through the coil 20 and then stopped, so that autofocus is possible. However, in order to quickly move the lens 5 to the focus position, it is necessary to rapidly increase a predetermined current in the coil 20, so that vibration occurs in the lens 5 at the focus position. As a result, there is a problem that focusing cannot be performed until the vibration is converged.

  Hereinafter, a preferred embodiment of the camera-equipped mobile phone 1 according to the present invention will be described in detail. As described above, in the camera-equipped mobile phone 1 having the actuator 3 having the above basic configuration, the position of the lens 5 is controlled by controlling the current flowing through the coil 20 as described above. In other words, the coil 20 of the actuator 3 is connected to a drive circuit for current control.

  In the actuator 3, the lens 5 is attached to a holder 10 that is supported by plate springs 60 on the top and bottom. Accordingly, the lens 5 and the holder 10 are supported by the leaf spring 60 so as to be movable in the optical axis direction.

  In the camera-equipped mobile phone 1 having the actuator 3 having the above basic configuration, the actuator 3 is controlled using a general-purpose driver IC (not shown). FIG. 5 shows a transient response in the camera-equipped mobile phone 1 having the actuator 3 having the above basic configuration. The three waveforms shown in FIG. 5 represent the voltage, the position of the lens 5 (holder 10), and the current in order from the top. The horizontal axis represents time, and the interval between adjacent broken lines represents 50 msec.

  As shown in FIG. 5, in order to move the lens 5 to the focus position during auto-focusing, the current flowing through the coil 20 is rapidly changed. Thereby, the lens 5 is moved to the focus position. However, the lens 5 is supported by the leaf spring 60 via the holder 10 so as to be movable in the optical axis direction. Therefore, when the current changes rapidly, the lens 5 does not stop immediately at the focus position, but a transient response that mechanically vibrates in the optical axis direction occurs. When the amplitude of vibration due to a transient response is large, focusing cannot be performed until the vibration converges. As this transient response takes time to converge, there is a problem that it takes time to autofocus.

  More specifically, when the current for controlling the movement of the lens 5 changes suddenly in order to move the lens 5 to the focus position, the current waveform rises earlier. The holder 10 moves suddenly, and the acceleration causes a transient response in which the lens 5 greatly vibrates in the optical axis direction at the focus position. Focusing cannot be performed while the amplitude of the vibration due to the transient response is larger than the predetermined amplitude. The width of A in FIG. 5 indicates the time from when the current starts to flow through the coil 20 until it converges to the amplitude of vibration that enables autofocus. Specifically, focusing is possible if the vibration amplitude of the lens 5 due to the transient response converges to a maximum of 9 μm. In the actuator having this basic configuration, as indicated by A in FIG. 5, there is a problem that the vibration amplitude of the lens 5 does not converge to 9 μm unless 300 msec elapses from the time when the current changes.

  In view of this problem, the present inventor has devised a camera-equipped mobile phone 1 that shortens the time required for autofocus. Hereinafter, an actuator 3 attached to the camera-equipped mobile phone 1 will be described as a preferred embodiment of the camera-equipped mobile phone 1.

  In the present embodiment, the actuator 3 having the basic configuration described above has a transient response in which the lens 5 vibrates in the optical axis direction due to a sudden change in the current flowing through the coil 20 in order to move the lens 5 to the focus position. A transient response suppressing unit is further provided. Also in this embodiment, the coil 20 of the actuator 3 is connected to a drive circuit for current control.

A first embodiment for suppressing a transient response using the drive circuit 100 shown in FIG. 6 will be described. The drive circuit 100 includes a power supply 130 that supplies current to the coil 20 and a capacitor 111 that is connected in parallel to the coil 20 as the transient response suppression unit 110. In the present embodiment, the capacitor 111 has a capacitance of 22 μF to 100 μF. In addition, as shown in FIG. 8 described later, in this embodiment, the capacitor 111 has a configuration attached to the sheet-like electrode 90.

  Hereinafter, the case where the connection position of the capacitor 111 is on the sheet-like electrode 90 will be described.

  As shown in FIG. 7, the sheet-like electrode 90 provided to supply power to the coil 20 between the lower leaf spring 60L and the base 85 is a ring formed in a substantially circular ring shape made of a polyimide sheet material. And a projecting portion 92 extending radially outward from the ring-shaped portion 91.

  Two terminal portions 93 made of copper are provided on one surface of the sheet-like electrode 90 from the extending portion 92 to the ring-shaped portion 91.

  Furthermore, an adhesive layer (not shown) for adhering the sheet electrode 90 to the lower surface of the lower leaf spring 60L is provided on the other surface of the sheet electrode 90, and a ring-shaped portion 91 and a ring-shaped extension portion 92 are formed. It is provided in the vicinity of the connecting portion with the portion 91 and in the vicinity of the distal end portion of the extending portion 92.

Further, the extending portion 92 extends to the outside of the base 85 through the insertion hole 88 of the base 85. The extension part 92 is connected to the substrate 4 or the like, for example, and can serve to supply a current to the coil 20. (See Figs. 2 and 4)
Electric power can be supplied to the coil 20 by soldering the tip of the lead portion 21 of the coil 20 to the terminal portion 93 provided on the ring-shaped portion 91 of the sheet-like electrode 90.

  As shown in FIG. 8, the capacitor 111 as the transient response suppressing unit 110 is attached on the extension portion 92 so as to be connected in parallel with the coil 20. Specifically, the capacitor 111 is connected in parallel with the coil 20 by connecting the terminals of the capacitor 111 to the two terminal portions 93 of the extending portion 92, respectively.

  As described above, according to the camera-equipped mobile phone 1 having the actuator 3 according to the preferred embodiment of the present invention, the coil 111 is used to move the lens 5 to the focus position by the capacitor 111 constituting the transient response suppressing means 110. Alleviates sudden changes in the flowing current. Thereby, the transient response in which the lens 5 vibrates in the optical axis direction can be suppressed, and the time until the transient response converges can be shortened.

  FIG. 9 shows a state of transient response in the camera-equipped mobile phone 1 of the present embodiment. The three waveforms shown in FIG. 9 represent the voltage, the position of the lens 5 (holder 10), and the current in order from the top as in FIG. The horizontal axis represents time, and the interval between adjacent broken lines represents 50 msec. In the present embodiment, a capacitor 111 having a capacitance of 47 μF is connected to the coil 20 in parallel. As shown in FIG. 9, the rise of the current waveform can be delayed by the transient response suppressing means 110 of the present invention. Thereby, the amplitude of vibration of the lens 5 due to the transient response can be reduced. The width of A in FIG. 5 indicates the time from when the current starts to flow through the coil 20 until it converges to the amplitude of vibration that enables autofocus. Comparing A in FIG. 5 with B in FIG. 10, it can be seen that the time until the transient response converges is shortened. Thereby, the time required for focusing can be shortened.

  Further, by connecting a capacitor 111 in parallel to the driving circuit 100 of the lens 5, a transient response is suppressed. Thereby, it is not necessary to make a new driver IC for suppressing the transient response, and the time required for focusing can be shortened even if the general-purpose driver IC attached to the conventional actuator is used as it is.

  A second embodiment for suppressing the transient response using the drive circuit 101 shown in FIG. 10 will be described. The drive circuit 101 includes a capacitor 121 connected in parallel to a power supply 130 that supplies current to the coil 20 as a transient response suppressing unit 120 and a resistor 122 connected in series to the power supply 130. The transient response suppression unit 120 is connected to the drive circuit 101 so as to be in series with the coil 20. Such a transient response suppressing means 120 also relieves a sudden change in the current flowing through the coil 20. As a result, it is possible to reduce the time from when the current starts to flow to the coil 20 until the transient response of the lens 5 (holder 10) converges, and the time required for focusing can be reduced.

  In this embodiment, the case where the capacitor 111 has a capacitance of 22 μF to 100 μF has been described. However, the camera-equipped mobile phone of the present invention is not limited to this, and the transient response converges according to the configuration of the drive circuit. Alternatively, a capacitor having a capacitance suitable for shortening the time to do so may be used.

  In this embodiment, the drive circuit having the transient response suppression means 110 (see FIG. 6) and the drive circuit having the transient response suppression means 120 (see FIG. 10) have been described separately. The telephone is not limited to this, and may be a drive circuit having both transient response suppressing means 110 and 120.

It is a perspective view which shows the external appearance of embodiment of the mobile phone with a camera which concerns on this invention. It is sectional drawing of the camera module shown in FIG. It is a perspective view of the actuator of the present invention. It is a disassembled perspective view which shows the basic composition of an actuator. It is a graph which shows the transient response in the mobile phone with a camera which has an actuator which consists of the said basic composition. 1 is a circuit diagram showing a first embodiment of the present invention. It is a top view which shows a sheet-like electrode. It is a top view of a sheet-like electrode, and shows a state where a capacitor is attached on the sheet-like electrode. It is a graph which shows the transient response in the mobile telephone with a camera of this invention. It is a circuit diagram which shows 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mobile phone with a camera 2 Camera module 3 Actuator 4 Board | substrate 5 Lens 6 Sealing member 7 Image pick-up element 8 Electronic component 10 Holder 11 Cylindrical part 12 Flange part 20 Coil 21 Pull-out part 30 Yoke 31 Inner cylinder part 32 Outer cylinder part 34 Connection Portion 35 insertion hole 40 permanent magnet 50 magnetic member 60 leaf spring 60U upper leaf spring 60L lower leaf spring 70 stopper 80 cover 85 base 88 insertion hole 90 sheet electrode 91 ring portion 92 extension portion 93 terminal portion 100 drive circuit 101 drive Circuit 110 Transient response suppression means 111 Capacitor 120 Transient response suppression means 121 Capacitor 122 Resistance 130 Power supply

Claims (4)

A holder having a cylindrical portion with a lens attached to one end thereof, a coil fixed to the holder so as to be located around the cylindrical portion of the holder, and a yoke having a permanent magnet facing the coil A pair of leaf springs provided on both sides of the cylindrical portion of the holder in the optical axis direction and supporting the holder so as to be displaceable in the optical axis direction with the holder positioned in a radial direction, and for supplying electricity to the coil A sheet-like electrode, and adjusting the position of the lens in the optical axis direction by the interaction between the magnetic field of the permanent magnet and the magnetic field caused by the current flowing through the coil by energizing the coil through the sheet-like electrode. A camera-equipped mobile phone with a possible actuator,
The actuator further includes a transient response suppressing unit that suppresses a transient response in which the lens vibrates in the optical axis direction due to a sudden change in the current flowing through the coil.
The camera-equipped mobile phone, wherein the transient response suppression means includes a capacitor attached to the sheet-like electrode and connected in parallel to the coil. 2. The camera-equipped mobile phone according to claim 1 , wherein the transient response suppression unit further includes a capacitor connected in parallel to a power source that supplies current to the coil, and a resistor connected in series to the power source. 3. The camera-equipped mobile phone according to claim 1, wherein the transient response suppressing unit attenuates the vibration amplitude of the lens due to the transient response to 9 μm at the maximum during a maximum of 90 msec from a change in the current flowing through the coil. phone. A holder having a cylindrical portion with a lens attached to one end thereof, a coil fixed to the holder so as to be located around the cylindrical portion of the holder, and a yoke having a permanent magnet facing the coil A pair of leaf springs provided on both sides of the cylindrical portion of the holder in the optical axis direction and supporting the holder so as to be displaceable in the optical axis direction with the holder positioned in a radial direction, and for supplying electricity to the coil A sheet-like electrode, and adjusting the position of the lens in the optical axis direction by the interaction between the magnetic field of the permanent magnet and the magnetic field caused by the current flowing through the coil by energizing the coil through the sheet-like electrode. A possible camera actuator,
The camera actuator further includes a transient response suppressing unit that suppresses a transient response in which the lens vibrates in the optical axis direction due to a sudden change in the current flowing through the coil.
The transient response suppressing means comprises a capacitor attached to the sheet-like electrode and connected in parallel to the coil.

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