Abstract:
An imaging device controller that controls an imaging device, comprising a detector and a driver, is provided. The imaging device is mounted in an image capturing apparatus. The image capturing apparatus has plural functions. The detector detects that the first function among the functions is carried out. The driver orders the imaging device to capture an optical image in a first interval before or after a detection period. The detector is detecting that the first function is carried out during the detection period. The driver orders the imaging device to capture an optical image in a second interval during the detected-period. The second interval is longer than the first interval.

Description:
The present disclosure relates to subject matter contained in Japanese Patent Application No. 2006-043496 (filed on Feb. 21, 2006), which is expressly incorporated herein, by reference, in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an imaging device controller that controls the operations of an imaging device mounted in a photographing machine, such as a digital camera. 
     2. Description of the Related Art 
     A digital camera generates and stores electronic data corresponding to an optical image by capturing an object. Power is consumed to generate and store the electronic data. In addition, a digital camera may have various additional functions, and power is consumed in the process of carrying out such functions. 
     Power used for the above operations of the digital camera is supplied by a battery, such as a storage battery. The capacity of a battery which can be re-charged is limited. Accordingly, when power charged in the battery is completely spent, the various functions of the digital camera, including photographing, cannot be carried out. 
     SUMMARY OF THE INVENTION 
     Therefore, an object of the present invention is to provide an imaging device controller and a digital camera that mitigates the power consumption. 
     According to the present invention, an imaging device controller that controls an imaging device, comprising a detector and a driver, is provided. The imaging device is mounted in an image capturing apparatus. The image capturing apparatus has plural functions. The detector detects that the first function is carried out. The first function is predetermined among the plural functions. The driver orders the imaging device to capture an optical image of an object in a first interval before or after a detection period. The detector detects that the first function is carried out during the detection period. The driver orders the imaging device to capture an optical image of an object in a second interval during the detection period. The second interval is longer than the first interval. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The objects and advantages of the present invention will be better understood from the following description, with reference to the accompanying drawings in which: 
         FIG. 1  is a block diagram showing the internal structure of a digital camera having an imaging device controller of an embodiment of the present invention; and 
         FIG. 2  is a flowchart describing the process carried out by the CPU and the AFE when the function for power conservation is switched on. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention is described below with reference to the embodiment shown in the drawings. 
     In  FIG. 1 , a digital camera  10  comprises a photographic optical system  11 , an imaging device  12 , an analog front end (AFE)  13 , a CPU  14 , an input block  15 , an anti-shake mechanism  16 , an anti-shake mechanism driver  17 , a zooming-driver  18 , a focusing-driver  19 , and other components. 
     The photographic optical system  11  is optically connected to the imaging device  12 . An optical image of an object through the photographic optical system  11  is incident to the light-receiving surface of the imaging device  12 . The imaging device  12  is, for example, a CCD area sensor. When the imaging device  12  captures the optical image of the object at the light-receiving surface, the imaging device  12  generates an image signal corresponding to the captured optical image. 
     The photographic optical system  11  comprises plural lenses, including a zoom lens  11   a  and a focus lens  11   b . The zoom lens  11   a  and the focus lens  11   b  are movable along an optical axis of the photographic optical system  11 . The zoom lens  11   a  and the focus lens  11   b  form a zoom optical system. The focal length of the photographic optical system  11  is adjusted by moving the zoom lens  11   a  and the focus lens  11   b  in relationship to each other. Further, an optical image of an object can be focused on the light-receiving surface of the imaging device  12  by moving the focus lens  11   b.    
     The movement of the zoom lens  11   a  and the focus lens  11   b  for adjusting the focal length of the photographic optical system  11  is carried out by the zooming driver  18 . The movement of the focus lens  11   b  for focusing is carried out by the focusing-driver  19 . 
     A diaphragm  20  and a shutter  21  are mounted between the photographic optical system  11  and the imaging device  12 . The intensity of light, made incident on the light-receiving surface of the imaging device  12 , is adjusted by adjusting the aperture ratio of the diaphragm  20 . A diaphragm driver  22  drives the diaphragm  20  so that the aperture ratio can be adjusted. An optical image reaches the light-receiving surface by opening the shutter  21 , and an optical image is shielded from the light-receiving surface by closing the shutter  21 . A shutter driver  23  drives the shutter  21  so that the shutter can open and close. 
     The imaging device  12  is supported by an anti-shake mechanism  16 . The anti-shake mechanism is formed by a base block (not depicted) and a movable block (not depicted). The base block is fixed to a camera body. The movable block holds the imaging device. 
     The movable block is mounted on the base block and the movable block is movable on a plane perpendicular to the optical axis of the photographic optical system  11 . Accordingly, the imaging device  12  is also movable on the plane perpendicular to the optical axis of the photographic optical system  11 . The movable block moves on the plane perpendicular to the optical axis of the photographic optical system  11  by control of the anti-shake mechanism driver  17  that drives the anti-shake mechanism  16 . 
     The anti-shake mechanism driver  17  comprises a shake-sensor (not depicted). The shake-sensor detects the direction and length of a shake of the digital camera  10 . The anti-shake mechanism driver  17  drives the movable block to move in the opposite direction of the detected shake direction for the same length as the detected shake length. 
     A relative location where an optical image of an object is in focus on the light-receiving surface is shifted according to a user&#39;s hand shake. The influence of such a shift is canceled by moving the imaging device  12  via the movable block. 
     Incidentally, the zooming-driver  18 , the focusing-driver  19 , the diaphragm  22 , the shutter driver  23 , and the anti-shake mechanism driver  17  are all connected to the CPU  14 . The CPU  14  controls the operations of the zooming-driver  18 , the focusing-driver  19 , the diaphragm  22 , the shutter driver  23 , and the anti-shake mechanism driver  17 . 
     The imaging device  12  is electrically connected to the CPU  14  via the AFE  13 . A clock signal is sent from the CPU  14  to the AFE  13 . The AFE  13  generates a frame signal and an imaging device driving signal based on the received clock signal. The imaging device driving signal is sent to the imaging device  12 . The imaging device  12  is driven based on the imaging device driving signal to generate an image signal corresponding to the frame signal. 
     The generated image signal is sent to the AFE  13 . The AFE  13  carries out correlated double sampling and gain adjustment on the image signal. In addition, the image signal is converted into image data, which is digital data. The image data is sent to the CPU  14 . 
     The CPU  14  is connected to a dynamic random access memory (DRAM)  24 . The DRAM is used as a work memory for signal processing carried out by the CPU  14 . The image data sent to the CPU  14  is temporarily stored in the DRAM  24 . The CPU  14  carries out predetermined signal processing for the image data stored in the DRAM  24 . 
     The CPU  14  is connected to a monitor  25 . The image data, having undergone predetermined signal processing, is sent to the monitor  25 , which is able to display an image corresponding to the received image data. 
     The CPU  14  is connected to a card-interface  26  which can be connected to a memory card (not depicted). When a release operation, as described later, is carried out, the image data, having undergone predetermined signal processing, is stored in the memory card. 
     The CPU  14  is connected to the input block  15 , where a user inputs operational commands. The input block  15  comprises a power button (not depicted), a zoom button (not depicted), a release button (not depicted), and other buttons. The CPU  14  orders each component of the digital camera  10  to carry out a necessary operation according to a user&#39;s command input to the input block  15 , as described below. 
     By pushing on the power button, power of the digital camera  10  is switched on and off. When power of the digital camera  10  is switched on, each component of the digital camera  10  starts. 
     For example, when power is switched on, the digital camera  10  starts the predetermined operations for a stand-by mode. In the stand-by mode, the imaging device  12  is driven and the capture of an optical image is initiated. Further, as described later, the object captured by the imaging device  12  is displayed on the monitor  25 . 
     Further for example, when power is switched on, the zooming-driver  18  and the focusing-driver  19  move the zoom lens  11   a  and the focus lens  11   b  to predetermined lens starting positions. Incidentally, the zoom lens  11   a  and the focus lens  11   b  are located and stored in predetermined storage positions while power is switched off. 
     Further for example, when power is switched on, the anti-shake mechanism driver moves the movable block so that the imaging device  12  moves to a predetermined imaging device starting position. Incidentally, the imaging device starting position is the intersection point of the light-receiving surface and the optical axis of the photographic optical system  11 . The imaging device  12  is moved so that a central point of the light-receiving surface can agree with the imaging device starting position. Incidentally, the imaging device  12  is located at a predetermined storage position. 
     By continuously pushing on the zoom button, zooming-operation is carried out. In the zooming-operation, the zooming-driver  18  moves the zoom lens  11   a  and the focus lens  11   b  along the optical axis of the photographic optical system  11 . As described above, by moving the zoom lens  11   a  and the focus lens  11   b  in relationship to each other along the optical axis, the focal length of the photographic optical system  11  is adjusted. 
     By depressing on the release button halfway during stand-by mode, exposure adjustment and focusing operation are carried out. In the exposure adjustment, adjustment of the aperture ratio of the diaphragm  20 , adjustment of shutter speed, and gain adjustment for the image signal are carried out. In the focusing operation, the location of the focus lens  11   b  is adjusted. Further, by fully depressing the release button, the release operations, such as opening and closing the shutter  21 , capturing by the imaging device  12 , and storing the image data in the memory card, are carried out. 
     Next, control of the operations carried out by the CPU  14  during stand-by mode is explained below. In stand-by mode, a thru-image is displayed on the monitor  25 . Incidentally, the thru-image is a real-time optical image of an object captured by the imaging device  12 . 
     During stand-by mode, a clock signal, of which frequency is 36 MHz, is sent from the CPU  14  to the AFE  13 . When the AFE  13  receives the 36 MHz clock signal, the AFE  13  generates a frame signal, of which frequency is 30 Hz, and a driving signal corresponding to the frame signal of which frequency is 30 Hz. The generated driving signal is sent to the imaging device  12 . Incidentally, in stand-by mode the CPU  14  controls the shutter driver  23  so that the shutter  21  is left open. 
     The imaging device  12  starts to capture an optical image of an object based on the driving signal, and then one frame of an image signal is generated. Incidentally, the frequency of the frame signal is the same as the frequency of the image signal. Consequently, one frame of an image signal is generated per 1/30 second. 
     The generated image signal is sent to the CPU  14  via the AFE  13 , as described above. The CPU  14  sends the image data to the monitor  25  after carrying out the predetermined signal processing for the received image signal. Accordingly, an image successively updated per 1/30 second is displayed as the thru-image on the monitor  25 . 
     The digital camera  10  has a function for power saving. When the function for power saving is switched off, the CPU  14  controls the AFE  13  as described above in stand-by mode. When the function for power saving is switched on, the CPU  14  carries out another control for the AFE  13 . 
     As described above, a thru-image, based on an optical image captured per 1/30 second, is displayed on the monitor  25  in stand-by mode. On the other hand, when the function for power saving is switched on, a thru-image, based on an optical image captured per 1/15 second is displayed on the monitor  25  while the focal length of the photographic optical system  11  is adjusted by the zooming-driver  18 , the zoom lens  11   a  and the focus lens  11   b  are moved to the lens starting position, or the imaging device  12  is moved to the imaging device starting position. 
     Incidentally, the movements of the zoom lens  11   a  and the focus lens  11   b  by the zooming-driver  18 , the movements of the zoom lens  11   a  and the focus lens  11   b  to the lens starting position, and the movement of the imaging device  12  to the imaging device starting position are detected by the CPU  14 . For example, the movements of the zoom lens  11   a  and the focus lens  11   b  by the zooming-driver  18  is detected by the CPU  14  based on a command input to the zoom button. The movements of the zoom lens  11   a  and the focus lens  11   b  to the lens starting position is detected when the power is switched on and each component of the digital camera  10  is ordered to start. 
     When the CPU  14  detects these movements, a clock signal, of which frequency is 18 MHz, is sent from the CPU  14  to the AFE  13 . When the AFE  13  receives the 18 MHz clock signal, the AFE  13  generates a frame signal, of which frequency is 15 Hz, and a driving signal corresponding to the frame signal of which frequency is also 15 Hz. The generated driving signal is sent to the imaging device  12 . Accordingly, the imaging device  12  then captures an optical image of an object per 1/15 second, which is half the frequency of the stand-by mode. 
     After the zooming-driver  18  moves the zoom lens  11   a  and the focus lens  11   b , the zoom lens  11   a  and the focus lens  11   b  moves to their respective starting positions, and the imaging device  12  moves to the imaging device starting position, the frequency of the clock signal is reset to 36 MHz. Accordingly, the imaging device  12  then captures an optical image of an object per 1/30 second. 
     Next, the process that the CPU  14  and the AFE  13  carry out when the function for power conservation is selected is explained below, using the flowchart of  FIG. 2 . 
     The process starts when power of the digital camera  10  is switched on. Incidentally, the process is repeated until power of the digital camera  10  is switched off. 
     At step S 100 , each component of the digital camera  10  is ordered to start. For example, the movements of the zoom lens  11   a  and the focus lens  11   b  to the lens starting position and the movement of the imaging device  12  to the imaging device starting position are initiated, as described above. 
     At step S 101 , the AFE  13  sends the driving signal to the imaging device  12 , at which point the imaging device  12  commences to be driven. Incidentally, the imaging device  12  may commence to be driven simultaneously with the movements of the lenses  11   a  and  11   b  and the imaging device  12  to their respective starting positions. 
     In addition at step S 101 , a clock signal, of which frequency is 18 MHz, is sent from the CPU  14  to the AFE  13 . Upon receipt of the lower frequency clock signal, the AFE  13  sends a driving signal corresponding to a frame signal of 15 Hz to the imaging device  12 . The imaging device  12  generates an image signal per 1/15 second in synchronicity with the frame signal of 15 Hz. The predetermined signal processing is carried out for the generated image signal, and the image data based on the image signal is sent to the monitor  25 . 
     After the imaging device  12  has commenced to be driven, the process proceeds to step S 102 . At step S 102 , it is determined whether the zoom lens  11   a  and focus lens  11   b  have reached their respective starting positions. 
     When it is determined that the zoom lens  11   a  and the focus lens  11   b  have not reached their respective starting positions, the process returns to step S 102  and step S 102  is repeated until both lenses  11   a  and  11   b  reach their respective starting positions. Once both lenses  11   a  and  11   b  have reached their respective starting positions, the process proceeds to step S 103 . 
     At step S 103 , it is determined whether or not the imaging device  12  has reached the imaging device starting position in the anti-shake mechanism  16 . When it is determined that the imaging device  12  has not reached the imaging device starting position, the process returns to step S 102  and steps S 102  and S 103  are repeated until the imaging device  12  reaches the imaging device starting position. Once the imaging device  12  has reached the imaging device starting position, the process proceeds to step S 104 . 
     At step S 104 , the frequency of the clock signal sent from the CPU  14  to the AFE  13  is changed to 36 MHz. Upon receipt of the higher frequency clock signal, the AFE  13  sends a driving signal corresponding to a frame signal of 30 Hz to the imaging device  12 . The imaging device  12  generates an image signal per 1/30 second in synchronicity with the frame signal of 30 Hz. The predetermined signal processing is carried out for the generated image signal, and the image data based on the image signal is sent to the monitor  25 . 
     At step S 105 , it is determined whether or not the user has input a command for zooming-operation. When the command input for zooming-operation is not detected, the process returns to step S 105  and the step S 105  is repeated until the command input is detected. When the input command is detected, the process proceeds to step S 106 . 
     At step S 106 , the frequency of the clock signal sent from the CPU  14  to the AFE  13  is changed to 18 MHz. Upon receipt of the lower frequency clock signal, the AFE sends a driving signal corresponding to a frame signal of 15 Hz to the imaging device  12 . The imaging device  12  generates an image signal per 1/15 second in synchronicity with the frame signal of 15 Hz. The predetermined signal processing is carried out for the generated image signal, and the image data based on the image signal is sent to the monitor  25 . 
     At step S 107 , the zooming-driver  18  begins driving the zoom lens  11   a  and focus lens  11   b , thus adjusting the focal length of the photographic optical system  11 . At step S 108 , it is determined whether or not the input command for zooming-operation is still detected. When the input command is still detected, the process returns to step S 107  and steps S 107  and S 108  are repeated until the input command is no longer detected. Once detection of the input command has ceased, the process returns to step S 104  and steps S 104 -S 108  are repeated. 
     In the above embodiment, when a predetermined function is carried out, the frequency of the frame signal is lowered and the interval of capturing an optical image is expanded. Accordingly, as the frequency for capturing an optical image is lowered, less power is consumed by the entire digital camera  10  and more power is conserved. 
     The frequency of capturing an optical image is lowered so that motion resolution may be lowered. However, it is not necessary in general to keep motion resolution at a high level when the zooming-driver  18  is operated to move the zoom lens  11   a  and focus lens  11   b , when the zoom lens  11   a  and focus lens  11   b  are moved to their respective starting positions, and when the imaging device  12  is moved to the imaging device starting position. Accordingly, utility of the digital camera  10  is maintained in such operations for moving lenses  11   a  and  11   b  or the imaging device  12 , even if an interval of capturing an optical image is expanded. 
     In addition, the expanded interval of capturing an optical image is changed back to a shorter interval once the predetermined function has been carried out. Accordingly, utility of the digital camera  10  is maintained. 
     Further, the above described operations for power conservation can be suspended by switching off the power conservation function. Accordingly, even if a user desires to see the thru-image during a zooming-operation, utility of the digital camera  10  is prevented from lowering by automatically switching off the power conservation function. 
     The frequency of the frame signal is changed from a higher to lower level when the lenses  11   a  and  11   b  are moved for zooming-operations, when the lenses  11   a  and  11   b  are moved to the lens starting position, and when the imaging device  12  is moved to the imaging device starting position, in the above embodiment. However, the frequency may also be changed while other functions, not requiring high motion resolution, are carried out. For example, a function in which a user carries out without viewing the thru-image, or a function the user carries out without requiring synchronization of the changing frame signal. 
     The zoom lens  11   a  and the focus lens  11   b  start to be moved for focal length adjustment, after lowering a frequency of the frame signal, in the above embodiment. However, the frequency of the frame signal may be reduced once the zoom lens  11   a  and focus lens  11   b  commence movement for focal length adjustment. Of course, it is preferable for power consumption purposes to lower the frequency in advance of the movement of lenses  11   a  and  11   b.    
     The lenses  11   a  and  11   b , and the imaging device  12  move to the lens starting position and the imaging device starting position, respectively, as soon as power of the digital camera  10  is switched on, in the above embodiment. These movements may be carried out based on an input command in stand-by mode, and the frequency of the frame signal may be lowered when the CPU  14  detects such an input command. 
     The anti-shake mechanism  16  supports the imaging device  12  in the above embodiment. However, the anti-shake mechanism may support an anti-shake lens in the photographic optical system  11 . The influence of a shift according to user&#39;s hand shake can also be canceled by moving the lens for an anti-shake. 
     The imaging device  12 , which receives the frame signal, generates one frame of the image signal in the above embodiment. However, the same effect of the above embodiment can be achieved if the imaging device generates one field of the image signal. 
     The frequency of the frame signal is changed to either 30 Hz or 15 Hz in the above embodiment. However, it is not limited to either 30 Hz or 15 Hz. The same effect of the above embodiment can be achieved if the frequency of the frame signal chosen for the function for power conservation is lower than the frequency of the frame signal in the stand-by mode. 
     Although the embodiments of the present invention have been described herein with reference to the accompanying drawings, obviously many modifications and changes may be made by those skilled in this art without departing from the scope of the invention.