Abstract:
An imaging apparatus comprises: an imaging lens; an image pickup device that is placed behind the imaging lens; a lens drive portion that includes a magnet that forms a magnetic field and a coil, placed in the magnetic field, that, upon an input of a current signal, receives a force in an optical axis direction to move the imaging lens to a position corresponding to the current signal, the lens drive portion holding the imaging lens, and moving the imaging lens to the position corresponding to the current signal in the optical axis direction; and a movement control portion that, when the imaging lens is to be moved, gives to the lens drive portion, a current signal that is gradually changed from a first current signal corresponding to a first position before movement of the imaging lens, to a second current signal corresponding to a second position after movement.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to an imaging apparatus comprising an imaging lens, and an image pickup device which is placed behind the imaging lens, and also to a portable apparatus comprising the imaging apparatus. 
         [0003]    2. Description of the Related Art 
         [0004]    In many recent portable telephones, an imaging apparatus is mounted. A portable telephone itself has a small and thin structure. In the case where an imaging apparatus is mounted in a portable telephone, therefore, the imaging apparatus to be mounted in the portable telephone is requested to have a structure which is smaller and thinner than the small and thin structure of the portable telephone. 
         [0005]    In some of such imaging apparatuses which are requested to have a small and thin structure, a voice coil motor is used in order to simplify the structure of a portion for holding an imaging lens, and that of a lens drive portion which moves the imaging lens in the optical axis direction (for example, see Japanese Utility Model Registration No. 3,120,599 and JP-A-2005-50519). 
         [0006]      FIG. 1  is a view showing an example of the configuration of an imaging apparatus comprising a voice coil motor. 
         [0007]    The imaging apparatus shown in  FIG. 1  comprises: a lens module  100  having an imaging lens  10 , and a voice coil motor (hereinafter, referred to as VCM) for driving the imaging lens  10 ; an image pickup device  103  which is placed behind the imaging lens provided in the lens module  100 ; an imaging circuit  12  which produces a signal indicative of the driving direction and position of the imaging lens based on an image signal produced by the image pickup device  103 ; and a VCM driving circuit  13  which drives the VCM provided in the lens module  100  in accordance with the signal from the imaging circuit  12  indicating the driving direction and the driving position. Actually, the lens module  100  and image pickup device  103  which are shown in  FIG. 1  are integrally configured. In the following description, therefore, they are generically referred to the imaging unit  10 . 
         [0008]      FIG. 2  is a view illustrating the internal configuration of the imaging unit  10 . 
         [0009]      FIG. 2A  shows the internal configuration of the imaging unit  10 , and  FIG. 2B  shows the state where coils  102   a ,  102   b  provided respectively in VCMs in the imaging unit  10  are energized by the VCM driving circuit  13  shown in  FIG. 1 , and an imaging lens  1000  is moved together with the coils  102   a ,  102   b , by broken lines. 
         [0010]      FIGS. 2A and 2B  show the configuration where two magnets  101   a ,  101   b  provided in the imaging unit  10  shown in  FIG. 1 , and the two coils  102   a ,  102   b  which are placed in magnetic fields formed by the magnets  101   a ,  101   b , and which, upon an input of a current, receives a force in the optical axis direction to move the imaging lens  1000  to a position corresponding to the current signal are disposed on the both sides of the imaging lens  1000 . Actually, boards are fixed to a holding portion which holds the lens, and windings serving as the coils are formed on the boards, respectively. 
         [0011]    The configuration will be described with reference to  FIGS. 2A and 2B . 
         [0012]    As shown in  FIGS. 2A and 2B , the image pickup device  103  is fixed to the middle of a board  110  which is larger than the external shape of the image pickup device  103 , and springs SP 1 , SP 2  are disposed on the board  110  on the both sides across the image pickup device  103 , respectively. The two coils  102   a ,  102   b  are extensibly supported by the springs SP 1 , SP 2 , respectively, and the imaging lens  1000  is held from the both sides by the coils  102   a ,  102   b . The magnets  101   a ,  101   b  are disposed outside the coils  102   a ,  102   b . The N- and S-poles of the magnets  101   a ,  101   b  are juxtaposed. The coils  102   a ,  102   b  which are placed in the magnetic fields formed by the magnets  101   a ,  101   b  are vertically disposed across the imaging lens  1000  of  FIG. 2 . The two coils  102   a ,  102   b  and the two magnets  101   a ,  101   b  cooperate to move the imaging lens  1000  against the spring urging or in the direction of the spring urging. 
         [0013]    Namely, when a current is supplied from the external VCM driving circuit  13  to both the one coil  102   a  and other coil  102   b  which are provided in the two VCMs, a magnetic fields is generated in each of the coils  102   a ,  102   b  existing in the magnetic fields formed by the both magnets  101   a ,  101   b , an interaction between the magnet  101   a  and the coil  102   a  causes the imaging lens  1000  to be moved together with the coil  102   a , and that between the magnet  101   b  and the coil  102   b  causes the imaging lens  1000  to be moved in the optical axis direction together with the coil  102   b.    
         [0014]      FIG. 3  is a view showing a current supplied to the coil  102 , and a displacement of the imaging unit  10  incorporating the imaging lens. 
         [0015]      FIG. 3A  shows an input waveform of the current supplied to the coils  102   a ,  102   b  when the imaging unit  10  is to be moved from a position before movement to that after movement.  FIG. 3B  shows a displacement of the imaging lens  1000  which, when a current is caused to flow through the coils  102   a ,  102   b  by the input waveform, receives a force due to interactions between the currents flowing through the coils  102   a ,  102   b  and the magnets  101   a ,  101   b , to be moved in the optical axis direction. The ordinate in  FIG. 3A  indicates a driving current, and the abscissa indicates the time (second). The ordinate in  FIG. 3B  indicates the displacement of the imaging lens, and the abscissa indicates the time (second). 
         [0016]    When a current of 80 mA is supplied to each of the coils  102   a ,  102   b  in a step-like manner as shown  FIG. 3A , for example, the imaging lens  1000  is moved to a position in the vicinity of 0.45 mm from the position before movement, and is stopped there. 
         [0017]    In the structure shown in  FIG. 2 , however, the coils  102   a ,  102   b  are supported by the springs SP 1 , SP 2  so as to be extensible in the optical axis direction, and therefore, when a step-like signal is supplied to the coils  102   a ,  102   b  and the coils  102   a ,  102   b  are vigorously moved together with the imaging lens  1000 , a large external force is suddenly applied to the springs SP 1 , SP 2  supporting the coils  102   a ,  102   b . As a result, the springs SP 1 , SP 2  vibrate, and, in the case of the example shown in  FIG. 3B , the imaging unit is slowly stopped after an elapse of 0.2 seconds. 
         [0018]    In the case where a mobile unit such as an imaging lens is disposed in a small and thin structure of a portable telephone or the like, it is often that, in order to movably hold an imaging lens as shown in  FIG. 2 , the imaging lens or the like is held by using an elastic spring or the like. 
       SUMMARY OF THE INVENTION 
       [0019]    In view of the above-discussed circumstances, it is an object of the invention to provide an imaging apparatus in which, when an imaging unit is moved in the optical axis direction by a VCM, the imaging unit can be stopped within a time period that is shorter than the prior art, and a portable apparatus comprising the imaging apparatus. 
         [0020]    In order to attain the object, the imaging apparatus of the invention comprises: an imaging lens; an image pickup device that is placed behind the imaging lens; a lens drive portion that includes a magnet that forms a magnetic field and a coil, placed in the magnetic field, that, upon an input of a current signal, receives a force in an optical axis direction to move the imaging lens to a position corresponding to the current signal, the lens drive portion holding the imaging lens, and moving the imaging lens to the position corresponding to the current signal in the optical axis direction; and a movement control portion that, when the imaging lens is to be moved, gives to the lens drive portion, a current signal that is gradually changed from a first current signal corresponding to a first position before movement of the imaging lens, to a second current signal corresponding to a second position after movement. 
         [0021]    According the imaging apparatus of the invention, when, under the control of the movement control portion, the imaging lens is held by the lens drive portion to the position before movement, the current signal that is gradually changed from a current signal corresponding to the position before movement of the imaging lens, to a current signal corresponding to the position after movement is supplied to a coil of a VCM constituting the lens drive portion, and the imaging lens is moved to the position after movement. 
         [0022]    Namely, when, under the control of the movement control portion, the imaging lens is to be moved to the position corresponding to the current signal by the VCM which is the lens drive portion, the imaging lens is slowly started to be moved, and thereafter moved to a desired position while gradually increasing the speed, and stopped there. 
         [0023]    According to the configuration, even when the imaging lens is supported by an elastic spring or the like, the imaging lens can be driven while an external force is gradually applied to the spring and the vibration is suppressed. Therefore, the imaging lens can be stopped at a predetermined position within a short time period. 
         [0024]    The movement control portion may comprise: a current signal producing circuit that produces a current signal that is changed in a step-like manner from the first current signal corresponding to the first position before movement of the imaging lens, to the second current signal corresponding to the second position after movement; and a current waveform converting circuit that receives the current signal that is produced by the current signal producing circuit and is changed in a step-like manner, produces the current signal that is gradually changed from the first current signal corresponding to the first position before movement of the imaging lens, to the second current signal corresponding to the second position after movement, and supplies the produced current signal to the lens drive portion. 
         [0025]    Alternatively, the movement control portion may comprise: a voltage signal producing circuit that produces a voltage signal that is gradually changed from a first voltage signal corresponding to the first position before movement of the imaging lens, to a second voltage signal corresponding to the second position after movement; and a voltage-current converting circuit that converts the voltage signal produced by the voltage signal producing circuit to a current signal, and supplies the current signal to the lens drive portion. 
         [0026]    In the case where the movement control portion is configured by the voltage signal producing circuit and the voltage-current converting circuit, preferably, the voltage signal producing circuit is a D-A converter that receives digital data that are gradually changed from digital data corresponding to the first position before movement of the imaging lens, to digital data corresponding to the second position after movement, and converts the input digital data to an analog voltage signal. 
         [0027]    According to the configuration, the D-A converter can be controlled by a processor such as a CPU, and hence the configuration of the periphery of the voltage signal producing circuit is simplified. When a D-A converter is used, the D-A converter and the voltage-current converting circuit in the subsequent stage can be integrated into one chip as periphery devices of the CPU. 
         [0028]    In order to attain the object, the portable apparatus of the invention is a portable apparatus comprising an imaging apparatus, the imaging apparatus comprising: an imaging lens; an image pickup device that is placed behind the imaging lens; a lens drive portion that holds the imaging lens and moves the imaging lens to a position corresponding to a current signal in an optical axis direction; and a movement control portion that, when the imaging lens is to be moved, gives to the lens drive portion, a current signal that is gradually changed from a first current signal corresponding to a first position before movement of the imaging lens, to a second current signal corresponding to a second position after movement. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]      FIG. 1  is a view showing an example of the configuration of an imaging apparatus comprising a voice coil motor; 
           [0030]      FIG. 2  is a view illustrating the internal configuration of an imaging unit  10 ; 
           [0031]      FIG. 3  is a view showing a current supplied to a coil, and a displacement of an imaging lens; 
           [0032]      FIG. 4  is a perspective view showing the configuration of the front side of a portable telephone  200  comprising the imaging apparatus of the invention; 
           [0033]      FIG. 5  is a perspective view showing the configuration of the rear side of the portable telephone  200  comprising the imaging apparatus of the invention; 
           [0034]      FIG. 6  is a view showing the configuration of the interior of the portable telephone  200  comprising the imaging apparatus of the invention; 
           [0035]      FIG. 7  is a view illustrating an example of the configuration of a VCM driving circuit; 
           [0036]      FIG. 8  is a view illustrating a second embodiment; 
           [0037]      FIG. 9  is a view illustrating an example of a case where a CPU  230  supplies digital data indicative of, for example, a function having a curve to a DAC  1321 , to obtain an output signal; and 
           [0038]      FIG. 10  is a view illustrating an example of a case where the CPU supplies digital data indicative of, for example, a function having an inclination to the DAC, to obtain a waveform of an output signal. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0039]    Hereinafter, embodiments of the invention will be described with reference to the accompanying drawings. 
         [0040]      FIGS. 4 to 6  are views showing an example of the configuration of a portable telephone  200  comprising the imaging apparatus of the invention. 
         [0041]      FIGS. 4 and 5  are perspective views respectively showing the surface and rear face of the portable telephone  200 . 
         [0042]    The portable telephone  200  is configured by an upper portion  210  and a lower portion  220 , and foldable. 
         [0043]    The upper portion  210  of the portable telephone  200  comprises a display screen  211 , an earpiece  212 , an antenna  213 , and a camera imaging lens  214  placed on the rear face. The lower portion  220  comprises operation keys  221  and a mouthpiece  222 . 
         [0044]      FIG. 6  is a block diagram showing the internal configuration of the portable telephone the appearance of which is shown in  FIGS. 4 and 5 . 
         [0045]    The portable telephone  200  is configured so that the whole is controlled by a CPU  230 . To the CPU  230 , connected are: a RAM  231  which is a volatile memory; a ROM  232  which is a nonvolatile memory; a display portion  233  comprising the display screen  211  shown in  FIG. 4 ; the operation keys  221  shown also in  FIG. 4 ; a rewritable ROM  234  which is a rewritable nonvolatile memory; and a power supply portion  235 . 
         [0046]    The ROM  232  stores programs which are to be executed by the CPU  230 , etc. The rewritable ROM  234  stores programs which are downloaded by packet communication. The programs stored in the ROM  232  and the rewritable ROM  234  are executed by the CPU  230 , whereby operations of various portions of the portable telephone  200  are controlled. The RAM  231  is used as a work space for transmission of data to the external, etc. 
         [0047]    The display portion  233  comprises the display screen  211  shown in  FIG. 4 , and an image is displayed on the display screen  211  in accordance with instructions from the CPU  230 . According to operation instructions through the operation keys  221 , the CPU  230  executes a process corresponding to the operation. 
         [0048]    A battery (not shown) is loaded into the power supply portion  235 , and the power from the battery is supplied to the CPU  230 , and various portions of the portable telephone  200  under the control of the CPU  230 . 
         [0049]    As components for realizing the telephone function, the portable telephone  200  comprises the antenna  213  which is shown also in  FIGS. 4 and 5 , a transmission/reception portion  241 , a signal process portion  242 , and a communication portion  243 . The communication portion  243  includes: a microphone  243   a  which is placed in the mouthpiece  222  of  FIG. 4 ; and a speaker  243   b  which is placed in the earpiece  212 . 
         [0050]    The transmission/reception portion  241  is a circuit component which is in charge of transmission and reception of a radio wave through the antenna  213 . A signal which is obtained in the transmission/reception portion  241  as result of reception of a radio wave at the antenna  213  is supplied to the signal process portion  242 , and subjected to a signal process to be output as a sound from the speaker  243   b  of the communication portion  243 . A sound which is picked up by the microphone  243   a  of the communication portion  243  is subjected to a signal process in the signal process portion  242 , and output as a radio wave from the antenna  213  through the transmission/reception portion  241 . 
         [0051]    The portable telephone  200  has also a packet communication function. A packet signal received through the antenna  213  and the transmission/reception portion  241  is subjected to an adequate signal process in the signal process portion  242 , and then once stored into the RAM  231 . In the case of a downloaded program, it is stored into the rewritable ROM  234 . The packet data in the RAM  231  are displayed on the display screen  211  (see  FIG. 4 ) of the display portion  233  by the CPU  230  which receives instructions through the operation keys  221 , or programs stored in the rewritable ROM are executed. 
         [0052]    A packet communication document or the like which is prepared through the operation keys  221  is once stored in the RAM  231  at the timing of preparation, sent to the signal process portion  242  in accordance with transmission instructions from the operation keys  221  to be subjected to a transmission signal process, and then transmitted as a radio wave through the transmission/reception portion  241  and the antenna  213 . 
         [0053]    The portable telephone  200  has an image function, and, as a component which plays a role of the image function, comprises an imaging apparatus  1  having the configuration which has been described as the prior art example. 
         [0054]    An image portion of the imaging apparatus  1  comprises the imaging unit  10  shown in  FIG. 1 . An object image which is taken through the imaging lens  1000  in the imaging unit  10  is picked up by the image pickup device  103  to produce image data. The image data obtained in the image pickup device  103  are process by the imaging circuit  12  to be converted to digital image data, and then once stored into the RAM  231  through the CPU  230 . In accordance with an operation on the operation keys  221 , the data are displayed on the display screen  211  of the display portion  233 . 
         [0055]    The image portion of the portable telephone  200  of the embodiment comprises the imaging unit  10  having the configuration shown in  FIG. 1 . Therefore, a VCM driving circuit  131  for driving the coils  102   a ,  102   b  in the imaging unit  10  is disposed in an output portion of the CPU  230 . 
         [0056]    In the embodiment, the lens drive portion in the invention is configured by VCMs comprising the magnets  101   a ,  101   b  and the coils  102   a ,  102   b , and an example of the movement control portion in the invention is configured by the CPU  230  and the VCM driving circuit  131 . 
         [0057]    In the VCM driving circuit  131  in the embodiment, a current signal producing circuit and a current waveform converting circuit are disposed. When the imaging lens  1000  is to be moved, the VCM driving circuit  131  gives a current signal which is gradually changed from a current signal corresponding to a position before movement of the imaging lens  1000 , to a current signal corresponding to a position after movement, to each of the coils  102   a ,  102   b  of the VCMs serving as an example of the lens drive portion in the invention. 
         [0058]    In the embodiment, when the CPU  230  supplies a control signal corresponding to the driving amount, a step-like current signal (see the waveform in  FIG. 6 ) is produced in accordance with the control signal by the current signal producing circuit of the VCM driving circuit  131 , and the produced step-like current signal is supplied to the current waveform converting circuit in the subsequent stage. The current signal producing circuit and the current waveform converting circuit can be simply configured by using circuit devices such as transistors. In order to describe this, a circuit example of the current waveform converting circuit will be described later. When the step-like current signal is supplied from the current signal producing circuit in the preceding stage to the current waveform converting circuit, the current signal which is gradually changed from the current signal corresponding to the position before movement of the imaging lens  1000 , to the current signal corresponding to the position after movement is produced in the current waveform converting circuit in the VCM driving circuit  131 , and the produced current signal is supplied to the coil  102 . 
         [0059]    When the current signal which is gradually changed from the current signal corresponding to the position before movement of the imaging lens, to the current signal corresponding to the position after movement is supplied to each of the coils  102   a ,  102   b  as described above, the imaging lens  1000  is slowly started to be moved so as not to apply a large force to the springs, and thereafter moved to a predetermined position while gradually increasing the speed, and stopped there. Unlike the prior art, the phenomenon that the imaging unit  10  vibrates and a prolonged time must elapse before the unit stops does not occur. As a result, at a photo opportunity, the user can adequately perform in-focus imaging with using the imaging apparatus  1  provided in the portable telephone  200 . 
         [0060]    A specific circuit example of the current waveform converting circuit provided in the above-described VCM driving circuit  131  will be described with reference to  FIG. 7 . 
         [0061]      FIG. 7  is a view illustrating an example of the configuration of the current waveform converting circuit  131 . 
         [0062]      FIG. 7A  shows the specific circuit configuration example of the current waveform converting circuit provided in the VCM driving circuit  131 .  FIG. 7B  shows a response output waveform obtained when a step-like current signal is supplied from the current signal producing circuit in the preceding stage of the VCM driving circuit  131  to the circuit shown in  FIG. 7A .  FIG. 7C  shows a displacement of the imaging lens  1000  which, when the coils  102   a ,  102   b  are energized by the current signal having the response output waveform, receives a force due to interactions between the coils  102   a ,  102   b  and the magnets  101   a ,  101   b , and is moved in the optical axis direction together with the coils  102   a ,  102   b . The ordinate in  FIG. 7B  indicates a driving current (mA), and the abscissa indicates the time (second). The ordinate in  FIG. 7C  indicates the displacement (mm) of the imaging lens, and the abscissa indicates the time (second). 
         [0063]    First, the CPU  230  supplies the control signal indicating the driving amount to the VCM driving circuit  131 , the current signal producing circuit in the VCM driving circuit  131  produces the step-like current signal, and the produced step-like current signal is supplied to the current waveform converting circuit in the subsequent stage. Then, a current signal having a current waveform shown in  FIG. 7B  is output. 
         [0064]    Hereinafter, the configuration of the circuit shown in  FIG. 7A  will be described. 
         [0065]    The current waveform converting circuit provided in the VCM driving circuit  131  shown in  FIG. 7A  is configured by a transistor TR, a resistor R, and a capacitor C. The collector of the transistor TR is connected to the CPU  230 , and the emitter of the transistor TR is connected to the coil  102  provided in the VCMs. By contrast, the base of the transistor TR is connected to the capacitor C, and the capacitor C is connected to the ground GND. The base and collector of the transistor TR are connected to each other through the resistor R. 
         [0066]    Next, the operation of the current waveform converting circuit shown in  FIG. 7A  will be described. 
         [0067]    When the step-like current signal is supplied from the current signal producing circuit in the preceding stage to the collector of the transistor TR which is the input end of the current waveform converting circuit of  FIG. 7A , a current is supplied through the resistor R to the base of the transistor TR, and the base potential is raised to produce a potential difference between the base and the emitter. Therefore, the transistor TR enters the operation state. 
         [0068]    The capacitor C is disposed between the base of the transistor TR of the current waveform converting circuit of  FIG. 7A  and the ground GND. Even the step-like signal is input into the collector of the resistor R, therefore, the base potential is not immediately raised, but gradually raised by the integration function of the capacitor C. Accordingly, the base potential of the transistor TR is gradually raised, and the potential difference between the base and the emitter is gradually increased. Therefore, the current signal which is output from the emitter of the transistor TR is gradually changed and increased. 
         [0069]    In this way, the step-like current is supplied to the collector of the transistor TR shown in  FIG. 7A . Then, a current signal which is gradually changed as shown in  FIG. 7B  is supplied to the coils  102   a ,  102   b . In accordance with the current signal which is gradually changed, therefore, the imaging lens is gradually started to be moved, so that the movement of the imaging lens  1000  can be started without largely affecting the springs SP 1 , SP 2  supporting the coils  102   a ,  102   b.    
         [0070]    Unlike the prior art, the phenomenon that a large external force is suddenly applied to the springs SP 1 , SP 2  supporting the coils  102   a ,  102   b  does not occur. Therefore, the imaging lens can be stopped within a time period which is shorter than the prior art, for example, within 0.05 seconds as shown in  FIG. 7C . 
         [0071]    As described above, according to the invention, an imaging apparatus in which, when an imaging unit is moved in the optical axis direction by a VCM, the imaging unit can be stopped within a time period that is shorter than the prior art, and a portable apparatus comprising the imaging apparatus can be realized. 
         [0072]    When an imaging apparatus is to be mounted in the portable telephone, the imaging apparatus is requested to have a small and thin structure as described in the prior art column. Therefore, it is desirable that the VCM driving circuit  131  is made small as far as possible by integrating it into one chip. 
         [0073]    In the first embodiment, however, the current signal producing circuit in the VCM driving circuit  131 , and the current waveform converting circuit shown in  FIG. 7A  are configured by the transistor TR, the capacitor C, and the resistor R, and hence the circuits are somewhat difficult to be integrated. In the current waveform converting circuit shown in  FIG. 7A , particularly, the capacity of the capacitance is so large that the circuit cannot be integrated. For example, a digital-analog converter (hereinafter, referred to as DAC) which can be easily controlled by the CPU  230  may be used in place of the current signal producing circuit. In this case, the control of the CPU  230  can be simplified, and the VCM driving circuit can be integrated so as to achieve miniaturization. 
         [0074]      FIG. 8  is a view illustrating a second embodiment in which miniaturization can be realized. 
         [0075]      FIG. 8  is a view showing an example in which, in consideration of integration into one-chip for miniaturizing a VCM driving circuit  132 , the VCM driving circuit  132  is configured by a DAC  1321  that is an example of the current signal producing circuit in the invention, and a voltage-current converting circuit  1322 . 
         [0076]    Also when, as shown in  FIG. 8 , the VCM driving circuit  132  is configured by: the DAC  1321  that outputs a stair-like voltage signal in accordance with the increase of stair-like digital data supplied from the CPU  230 ; and the voltage-current converting circuit  1322  that converts a voltage signal supplied from the DAC  1321  into a current signal, it is possible to attain effects which are equivalent to those attained by the waveform conversion using the circuit of  FIG. 7A . 
         [0077]    When the DAC  1321  is used, the CPU  230  can read out one of many functions stored in an internal memory or the like, and with elapse of time supplies digital data indicating the function to the DAC  1321 , thereby enabling the DAC  1321  to output a voltage signal which is gradually changed in accordance with the curve of the function. The voltage signal output from the DAC  1321  is converted into a current signal by the voltage-current converting circuit  1322  in the subsequent stage, so that the current signal corresponding to the waveform of the voltage signal output from the DAC  1321  can be supplied to the coil  102 . 
         [0078]    The CPU  230  can control the DAC  1321  in the preceding stage of the VCM driving circuit  132  so as to output a voltage signal which is gradually increased with elapse of time in the form of various kinds of curves. Therefore, the voltage-current converting circuit in the subsequent stage of the VCM driving circuit  132  can output a current signal which is gradually increased in the form of various kinds of curves. 
         [0079]    Finally, the operation of the VCM driving circuit  132  will be described with using an output example where the CPU  230  supplies digital data which are gradually changed from digital data corresponding to a position before movement to those corresponding to a position after movement, to the VCM driving circuit  132 , thereby causing the VCM driving circuit  132  to output a current signal. 
         [0080]      FIGS. 9 and 10  are views illustrating an output waveform in the case where the CPU  230  supplies digital data which are gradually increased with elapse of time, to the VCM driving circuit  132 , thereby causing the VCM driving circuit  132  to output a current signal which is gradually changed. 
         [0081]    The abscissas of  FIGS. 9A and 10A  indicate the time, and the ordinates indicate a driving current (mA). The abscissas of  FIGS. 9B and 10B  indicate the time (second), and the ordinates indicate the lens displacement (mm). 
         [0082]      FIG. 9  shows an example in the case where the CPU  230  supplies digital data which are gradually changed from digital data corresponding to a position before movement to those corresponding to a position after movement, to the DAC  1321 , the voltage-current converting circuit  1322  outputs a current signal having a curve corresponding to the change of the digital data, and the current signal is supplied to the coil  102 . 
         [0083]    According to the configuration, the phenomenon that a current is suddenly supplied to the coil  102  does not occur, and the imaging unit does not vibrate. Therefore, the imaging unit is gradually moved from the position before movement to that after movement, and immediately stopped there. 
         [0084]      FIG. 10  shows an example in the case where digital data which are gradually changed in a curve different from that in the example of  FIG. 9  are supplied to the DAC  1321 , the voltage-current converting circuit  1322  outputs a current signal having a curve corresponding to the change of the digital data, and the current signal is supplied to the coil  102 . 
         [0085]    Also in the case where the current signal shown in  FIG. 10  is supplied to the coil  102 , it is possible to attain effects which are equivalent to those attained by the example of  FIG. 9 . 
         [0086]    In any case, the phenomenon that a step-like current is suddenly supplied to apply a large external force to the coil does not occur. Even when the imaging lens is extensibly supported by the springs, therefore, the imaging lens does not vibrate together with the springs, and the imaging lens can be stopped at a predetermined position within a short time period. 
         [0087]    As described above, according to the invention, an imaging apparatus in which, when an imaging unit is moved in the optical axis direction by a VCM, the imaging unit can be stopped within a time period that is shorter than the prior art, and a portable apparatus comprising the imaging apparatus can be realized. 
         [0088]    The entire disclosure of each and every foreign patent application from which the benefit of foreign priority has been claimed in the present application is incorporated herein by reference, as if fully set forth.