JP2009071426A - Image device, its method for recording moving video with sound, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image device of which power supply portion for an image device can be manufactured at a low cost and in which noise due to electronic parts connected to the power supply line can be made inconspicuous, and to provide its method for recording moving video with sound and a program. <P>SOLUTION: A digital camera 100 comprises an image pick-up portion 14 for outputting field signals during photographing moving video, a microphone 155tp for recording outside sound, a timing generating circuit 18 for generating a driving pulse for field signal output, a power supply controlling portion 80 for controlling power supply for driving pulse generation, and a system controlling circuit 50 for controlling the whole camera. The system controlling circuit 50 varies the HD period for controlling drive of driving pulses H1 and H2 for horizontal line output for each period. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an imaging apparatus, a moving image recording method with sound, and a program, and more particularly, to an imaging device that captures a subject image with a solid-state image sensor such as a CCD, a moving image recording method with sound, and a program.

  In recent years, an image pickup apparatus such as a digital camera that records and reproduces an image picked up by a solid-state image pickup device such as a CCD using a memory card having a solid-state memory element as a recording medium has been actively developed and widely spread.

  The background of such spread is the spread of personal computers (PCs) that can capture and process video captured by a digital camera, and the demand for digital image information using the Internet and the like has increased.

  On the other hand, recently, the number of pixels of the image sensor of a digital camera is increased, the capacity of a memory card serving as a recording medium is increased, and the density (high speed) of an IC (integrated circuit) that handles digital signal processing of images at the center of the digital camera Etc. are progressing. For this reason, recent digital cameras have an increased still image size and a high-speed continuous shooting function, and can record several frames of still images like moving images. Furthermore, although the image size is smaller than when recording a still image, recording and reproduction of a moving image can be performed at a frame rate (60 frames per second) just like a television.

  In this way, digital cameras not only with higher definition of still images that could be recorded than before but also with the function of moving image recording have begun to be marketed, and this has further stimulated market needs.

  On the other hand, consumer video cameras have become very familiar with digital storage video because of the consumer digital format standard. In addition to the conventional video recording function, still image recording function is also used. Video cameras that can be used are beginning to be marketed.

  In other words, it has become possible for a digital still camera whose function is still image storage and a digital video camera whose function is moving image storage to execute both still image storage and moving image storage, respectively. As described above, as a storage method for executing both still image storage and moving image storage, a storage method for storing still images in a storage medium for moving images, a storage medium for moving images, Are known that store only still images in an independent storage medium.

  Furthermore, the resolution and operation speed related to still image and video shooting are increasing year by year, coupled with market needs such as high image quality and high definition, and along with this, a series of driving solid-state image sensors of digital cameras. The driving speed of digital signal processing circuits is rapidly increasing.

  Recently, in addition to the improvement of image quality such as high image quality and high definition, speeding up of the shutter speed has been advanced in order to prevent failure in shooting in various shooting scenes. The failure described on the left is, for example, a case where the subject cannot be tracked well when shooting a fast-moving subject such as a sports scene, or camera shake occurs during shooting in low-light indoor shooting. On the other hand, in order to enable high-sensitivity photography in areas where strobe photography is prohibited, such as museums and aquariums, the demand for higher sensitivity related to photography of still images and moving images is further increasing.

  In order to respond to the demand for higher sensitivity related to the shooting of still images and moving images, recent digital cameras and digital video cameras use a DCDC converter or a multilayer ceramic capacitor as a power supply circuit (for example, Patent Document 1). , 2).

  FIG. 12 is a block diagram schematically showing an imaging unit of a conventional digital camera.

  In FIG. 12, the digital camera 1000 includes a CCD 501, an image signal circuit 502 that processes a CCD output signal from the CCD 501, an analog signal processing area 500 including an AD converter 503, and a digital signal processing unit 504.

  The AD converter 503 converts the analog imaging signal processed by the imaging circuit 502 into a digital signal. The digital signal processing unit 504 stores the digitally converted imaging signal in a storage medium (not shown) or displays it on a liquid crystal monitor (not shown).

  The digital camera 1000 also includes an oscillation circuit (OSC1) 505, a timing generator (TG) 506, a V driver (Vdr) 510, and a synchronization signal generator (SSG) 507. Furthermore, the digital camera 1000 includes an oscillation circuit (OSC2) 508 and a system control unit 509 including a CPU for controlling the operation of the entire digital camera 1000.

  The oscillation circuit 505 supplies an operation clock for the timing generator 506, and the oscillation circuit 508 supplies an operation clock for the system control unit 509. The timing generator 506 supplies the drive pulse of the CCD 501 to the V driver 510 in synchronization with the horizontal synchronization signal (HD) and the vertical synchronization signal (VD) supplied from the synchronization signal generator 507. The V driver 510 converts the drive pulse into a voltage and supplies it to the CCD 501.

  The timing generator 506 supplies a sampling clock signal to the image pickup circuit 502, the A / D converter 503, and the digital signal processing unit 504, respectively, and an operation clock (TGCLK) to the synchronization signal generator 507. Supply.

  On the other hand, the synchronization signal generator 507 generates a horizontal synchronization signal (HD) and a vertical synchronization signal (VD) and supplies them to the timing generator 506. The horizontal synchronizing signal (HD) and the vertical synchronizing signal (VD) are generated by counting a predetermined number of operation clocks from the timing generator 506 in the synchronizing signal generator 507.

  The system control unit 509 controls the operation of the digital signal processing unit 504 as well as the presence / absence of generation of a horizontal synchronization signal (HD) and a vertical synchronization signal (VD) and a cycle setting for the synchronization signal generator 507. is doing.

  FIG. 13 is a block diagram showing in detail the internal configuration of the imaging circuit 502 in FIG.

  In FIG. 13, the imaging circuit 502 includes a CDS (correlated double sampling) circuit 600, an amplifier 601, and a clamp circuit 602.

  The CDS circuit 600 removes a reset noise component generated when the CCD output signal is transferred from the CCD 501. Specifically, the CDS circuit 600 is configured by a noise removal circuit that obtains a difference between the level of the feedthrough portion and the imaging signal portion of the CCD output signal and thereby eliminates a correlation noise component of one pixel period from the imaging signal. Is done.

  The amplifier 601 amplifies the imaging signal output via the CDS circuit 600 to a predetermined signal level according to the input range of the A / D converter 503 and then supplies the amplified signal to the clamp circuit 602.

  The clamp circuit 602 adjusts the DC voltage level of the amplified imaging signal so that the light-shielded pixel (OB) period of the CCD 501 becomes a predetermined black reference value.

  FIG. 14 is a diagram illustrating a timing chart of main signals transmitted / received between circuits constituting the digital camera 1000.

  In FIG. 14, the value of the operating frequency of the CCD output signal (OSC 1) output from the CCD 501 for each pixel is determined by the drive pulse generated and supplied by the timing generator 506. For example, this frequency is preferably set to be in the range of 30 to 40 MHz.

  Further, the timing generator 506 supplies drive pulses H 1 and H 2 for horizontal line output of the CCD 501 and the reset gate signal RG to the CCD 501, and causes the CDS circuit 600 to output an imaging signal.

  Here, the frequency values of the drive pulses H1 and H2 are equal to the value of the operating frequency of the CCD output signal and are driven by a high-speed clock of 30 to 40 MHz. In addition, since the horizontal line output transfer path of the CCD 501 has a large capacitive load, a current load of about 100 mA is generated in the power source of the timing generator 506 that outputs the drive pulses H1 and H2.

  As shown in FIG. 15, a driving frequency (hereinafter referred to as “horizontal driving frequency”) 1501 at the time of horizontal line output is supplied by a blanking period 1502 in which the supply of the drive pulses H1 and H2 is stopped and the drive pulses H1 and H2. A period of pixel readout (OB period 1503 + effective pixel period 1504) is defined as one cycle.

  That is, the current load 1505 generated in the power source of the timing generator 506 by the horizontal line output is generated while the drive pulses H1 and H2 are being output, and a large load fluctuation of about 100 mA is generated every cycle as described above. To do.

  Further, during the blanking period, the drive pulse V of the CCD 501 is supplied from the V driver 510, whereby the vertical line output of the CCD 501 is performed.

  Here, as described above, the DC / DC converter is used as the power source of the timing generator 506, and the capacitor used for this is made of a ferroelectric ceramic. For this reason, when an electric field is applied to the capacitor of the power supply of the timing generator 506, a so-called electrostriction phenomenon occurs in which distortion occurs. The distortion due to the electrostriction phenomenon is transmitted to the substrate on which the capacitor is mounted and resonates to generate sound noise. That is, a so-called squeaking phenomenon occurs in an electronic component connected to the power supply line.

  Hereinafter, the principle of generating the sound noise will be described in detail with reference to FIG.

  In FIG. 16A, the power source 800 of the timing generator 506 is an optimum value for supplying the timing generator 506 with a supply power source 801 made of a battery or the like and a voltage of a charging current 806 supplied from the supply power source 801. And a DCDC controller 803 for converting the voltage into a voltage. The power source 800 includes a switch 804 controlled by the DCDC controller 803, a ceramic capacitor 805a for accumulating and smoothing the voltage converted by the DCDC controller 803, and a horizontal line output, and a vertical line output (not shown). The capacitor 805b is provided. The power supply 800 further includes an inductor 802 for accumulating current and sending electric power 807 to the digital camera 1000.

  On the other hand, the power 807 sent from the inductor 802 is consumed by the timing generator 506.

  The power source 800 monitors the output voltage by the DCDC controller 803 and controls it to be a predetermined voltage. Therefore, even when the current consumption increases in the timing generator 506 and a voltage drop occurs, control is performed so as to compensate for the voltage drop and keep the voltage constant. That is, the voltage applied to the ceramic capacitors 805a and 805b mainly responds to the fluctuation of the current load 1505 of the timing generator 506 having a large fluctuation, and, for example, as in a current consumption pattern 807-1 shown in FIG. Change. As described above, when the voltages applied to the ceramic capacitors 805a and 805b change, an electrostriction phenomenon occurs in which the ceramic capacitors 805a and 805b repeatedly expand and contract (reset) as a single component. For this reason, vibration due to the expansion and contraction is also transmitted to the substrate on which the ceramic capacitors 805a and 805b are surface-mounted. Furthermore, when the transmitted vibration is in an audible frequency range (generally about 50 Hz to 20 KHz), audio noise is generated.

  That is, when the current loads 1505 and 1506 generated by the output of the horizontal line output drive pulses H1 and H2 and the vertical line output drive pulse V fluctuate, the ceramic capacitors 805a and 805b in the power supply 800 vibrate. As a result, the substrate on which the ceramic capacitors 805a and 805b are surface-mounted vibrates, thereby generating a sound that matches the frequency of fluctuation of the current load.

  The generated sound is recorded as audio noise when a moving image with audio is recorded by the digital camera 1000 as shown in FIG. Hereinafter, only audio noise generated in the ceramic capacitor 805a will be described for the sake of simplicity.

  FIG. 17 is a graph showing the spectrum of audio recorded during the moving image shooting process by the digital camera 1000, where the vertical axis indicates sound pressure and the horizontal axis indicates frequency.

  As described above, vibration is excited by the consumption current pattern 807-1 (FIG. 16B) on the substrate excited by the electrostriction phenomenon of the ceramic capacitor 805a.

  As shown in FIG. 17, the spectrum of the sound recorded during the moving image shooting process by the conventional digital camera includes a sound recording band 1701 indicating the frequency at which the sound is recorded and a sound recording band when the sound is converted from analog to digital. Nyquist frequency 1702. Further, this audio spectrum includes a sampling frequency 1703 for recording audio and an audio noise frequency 1704 generated by the substrate vibrating due to the consumption current pattern 807-1.

  The audio noise frequency 1704 is a frequency of audio noise generated when the voltage of the ceramic capacitor 805a changes and an electrostriction phenomenon occurs in synchronization with the period of the consumption current pattern 807-1. As described above with reference to FIG. 16, this electrostriction phenomenon occurs mainly due to fluctuations in the current load 1505 during horizontal line output. Therefore, the audio noise frequency 1504 matches the horizontal drive frequency 1501. Here, when the horizontal drive frequency 1501 of the digital camera 1000 is 3 KHz and the sampling frequency 1703 is 10 KHz, the sampling Nyquist frequency 1702 is 5 KHz. In other words, it is theoretically possible to record audio frequencies up to 5 KHz. At this time, the audio noise frequency 1704 is 3 KHz which is the same as the horizontal drive frequency 1501. That is, audio noise generated by the electrostriction phenomenon is recorded when a moving image with audio is recorded by the conventional digital camera 1000.

In order to prevent the recording of the audio noise, a method of shifting the horizontal drive frequency 1501 to a sufficiently high frequency (for example, 20 KHz or more) is known in order to remove the audio noise frequency 1704 from the audible band. There is also known a method of using a component (for example, a piezoelectric, a tantalum capacitor, a polymer capacitor, or the like, which is less susceptible to electrostriction) in place of the ceramic capacitor 805a, which has less shape distortion with respect to voltage load variation. Furthermore, a method of devising a method for mounting the ceramic capacitor 805a on the substrate is also known (see, for example, Patent Document 3 and Non-Patent Document 1).
JP-A-2005-109151 Japanese Patent Application Laid-Open No. 08-115843 JP 2003-324030 A Murata Manufacturing Co., Ltd. “Chip multilayer ceramic capacitors that do not sound: About the GJ4 series”

  However, the method of removing the audio noise frequency 1704 from the audible band may not be adopted because the horizontal drive frequency 1501 of the digital camera 1000 is predetermined by the device used. In addition, parts such as tantalum capacitors and polymer capacitors, which have less shape distortion with respect to fluctuations in voltage load, are generally more expensive than ceramic capacitors, so there is a problem that using such parts leads to an increase in the cost of the entire device. . Similarly, when adopting a method for preventing recording of audio noise by devising a mounting method, there is a problem that mounting restrictions are large, and the degree of freedom in board layout and the like and the degree of freedom in component selection are lost.

  An object of the present invention is to provide an imaging apparatus capable of manufacturing a power supply unit used in the imaging apparatus at a low cost and making an electronic component connected to the power supply line inconspicuous, a moving image recording method with audio, and a program thereof Is to provide.

  In order to achieve the above object, the imaging apparatus according to claim 1 accumulates electric charges on the imaging plane according to a frame rate during moving image shooting, and the accumulated electric charges are stored in a plurality of horizontal lines and vertical lines. An imaging unit that divides and outputs a field signal, an audio recording unit that records external audio during the moving image shooting, a pulse generation unit that generates a drive pulse for outputting the field signal, and the pulse In the imaging apparatus including a power supply control unit that controls supply of drive power for generation and a drive cycle setting unit that sets a drive cycle of the drive pulse, the drive cycle setting unit includes the drive cycle of the drive pulse Is variable for each period.

  In order to achieve the above object, the moving image recording method with sound according to claim 8, during moving image shooting, charges are accumulated on the imaging plane in accordance with a frame rate, and the accumulated charges are separated from horizontal and vertical lines. An imaging unit that divides and outputs a plurality of field signals, an audio recording unit that records external audio during the moving image shooting, and a pulse generation unit that generates a drive pulse for outputting the field signal; In the moving image recording method with sound of the imaging apparatus, the power supply control unit that controls the supply of the driving power for generating the pulse, and the driving cycle setting unit that sets the driving cycle of the driving pulse, the driving cycle setting The drive cycle of the drive pulse is varied in each unit.

  In order to achieve the above object, the program according to claim 9 accumulates charges on the imaging plane according to a frame rate during moving image shooting, and stores the accumulated charges in a plurality of fields including horizontal lines and vertical lines. An imaging unit that divides and outputs signals, an audio recording unit that records external audio during the moving image shooting, a pulse generation unit that generates a drive pulse for outputting the field signal, and the pulse generation In a program for causing a computer to execute a moving image recording method with sound of an imaging apparatus, comprising: a power supply control unit that controls supply of drive power for driving; and a drive cycle setting unit that sets a drive cycle of the drive pulse. The attached moving image recording method is characterized in that the drive cycle of the drive pulse is varied for each cycle by the drive cycle setting unit.

  According to the imaging apparatus according to claim 1, the moving image recording method with sound according to claim 8, and the program according to claim 9, the charges accumulated on the imaging plane according to the frame rate during moving image shooting are represented by a horizontal line and a vertical line. The drive cycle of the output drive pulse when the signal is divided into a plurality of field signals and output from the imaging unit is varied for each cycle. As a result, even if an inexpensive capacitor made of a ferroelectric ceramic is included in the power supply control unit, fluctuations in current load that occur when the power supply control unit controls the supply of drive power for generating drive pulses. Thus, the frequency of voice noise generated by the electrostriction phenomenon of the capacitor can be dispersed in the time domain. That is, it is possible to provide an imaging apparatus capable of manufacturing a power supply unit used in the imaging apparatus at a low cost and making an electronic component connected to the power supply line inconspicuous, a moving image recording method with audio, and a program thereof.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram schematically showing a digital camera as an imaging apparatus according to an embodiment of the present invention.

  In FIG. 1, a digital camera 100 includes an image pickup unit 14 in an analog image pickup signal area 15 that converts an optical image from a lens 310 into an electric signal, and a shutter 12 that controls an exposure amount to the image pickup unit 14 using a diaphragm function. Is provided. The digital camera 100 further includes a shutter control unit 40 and a distance measuring unit 42 that control the aperture of the shutter 12 and a D / A converter 26.

  Specifically, the light beam incident on the lens 310 is guided to the diaphragm 312 and the shutter 12 and is formed on the imaging unit 14 including the CCD 501 (FIG. 12) as a subject image. A plurality of horizontal lines and vertical lines are set in advance on the image pickup unit 14, and a subject image (frame image) formed on the image pickup unit 14 during exposure is photoelectrically converted in the horizontal lines and vertical lines, and a plurality of images are obtained. Is output as a field signal.

  In the analog imaging signal area 15, in addition to the imaging unit 14, an A / D converter 16 that converts an analog signal output into a digital signal exists.

  Further, the digital camera 100 includes a memory control circuit 22, a system control circuit 50 that controls the entire digital camera 100, a timing generation circuit 18 (pulse generation unit) that is controlled by the system control circuit 50, and an image processing circuit 20. Is provided.

  The timing generation circuit 18 supplies a clock signal and a control signal to the imaging unit 14, the A / D converter 16, and the D / A converter 26.

  The image processing circuit 20 performs predetermined pixel interpolation processing and color conversion processing on the data from the A / D converter 16 or the data from the memory control circuit 22.

  In the image processing circuit 20, predetermined calculation processing is performed using the captured image data as necessary, and the system control circuit 50 performs the shutter control unit 40 and the distance measurement unit 42 based on the obtained calculation result. The aperture of the shutter 12 is controlled by controlling. As a result, TTL (through the lens) AF (autofocus) processing, AE (automatic exposure) processing, and EF (flash dimming) processing can be performed.

  Further, the image processing circuit 20 performs predetermined arithmetic processing using the captured image data, and also performs TTL AWB (auto white balance) processing based on the obtained arithmetic result.

  In the present embodiment, the digital camera 100 includes the distance measuring unit 42 and the photometric unit 46, but is not limited thereto. For example, when the digital camera 100 does not include the distance measuring unit 42 and the photometric unit 46, the image processing circuit 20 may be used to perform AF (autofocus) processing and AE (automatic exposure) processing. Further, even when the distance measuring unit 42 and the photometric unit 46 are provided as in the digital camera 100 according to the present embodiment, AF (autofocus) processing, AE (automatic exposure) using the image processing circuit 20 is used. ) You may make it use each process of a process together.

  The digital camera 100 further includes a memory control circuit 22, an image display memory 24, a memory 30, and a compression / decompression circuit 32.

  The memory control circuit 22 controls the A / D converter 16, the timing generation circuit 18, the image processing circuit 20, the image display memory 24, the D / A converter 26, the memory 30, and the compression / decompression circuit 32. Data of the A / D converter 16 is written into the image display memory 24 or the memory 30 through the image processing circuit 20 and the memory control circuit 22 or only through the memory control circuit 22.

  The digital camera 100 also includes an image display unit 28 composed of a TFT, LCD, or the like. The image display unit 28 displays the display image data written in the image display memory 24 via the D / A converter 26. Thus, the electronic viewfinder function can be realized by sequentially displaying the image data captured using the image display unit 28. The image display unit 28 can arbitrarily turn on / off the display according to an instruction from the system control circuit 50. When the display is turned off, the power consumption of the digital camera 100 can be significantly reduced. I can do it.

  The memory 30 is a memory for storing captured still images and moving images, and has a sufficient storage capacity for storing a predetermined number of still images and moving images for a predetermined time. Thereby, even in the case of continuous shooting or panoramic shooting in which a plurality of still images are continuously shot, it is possible to write a large amount of images to the memory 30 at high speed. The memory 30 can also be used as a work area for the system control circuit 50.

  The compression / decompression circuit 32 compresses and decompresses image data by adaptive discrete cosine transform (ADCT) or the like. Specifically, the compression / decompression circuit 32 reads an image stored in the memory 30, performs compression processing or decompression processing, and writes the processed data to the memory 30.

  The shutter control unit 40 controls the shutter 12 in cooperation with the aperture control unit 340 that controls the aperture 312 based on the photometric information from the photometry unit 46.

  When performing the AF (autofocus) processing, the distance measuring unit 42 causes the light beam incident on the lens 310 to enter the distance measuring unit 42 through the aperture 312 and the distance measuring sub mirror (not shown) to form an optical image. Image and measure the in-focus state of the image.

  When the photometry unit 46 performs an AE (automatic exposure) process, the light beam incident on the lens 310 is incident on the photometry unit 46 through the aperture 312 and the photometry lens (not shown) to form an optical image. Measure the exposure state of the image.

  The system control circuit 50 controls the shutter control unit 40, the aperture control unit 340, and the distance measurement control unit 342 based on the calculation result obtained by calculating the image data captured by the imaging unit 14 by the image processing circuit 20. It is also possible to perform exposure control and AF (autofocus) control using the video TTL method.

  Furthermore, AF (autofocus) control may be performed by using both the measurement result by the distance measuring unit 42 and the calculation result obtained by calculating the image data captured by the imaging unit 14 by the image processing circuit 20.

  The exposure control may be performed using both the measurement result by the photometry unit 46 and the calculation result obtained by calculating the image data captured by the imaging unit 14 by the image processing circuit 20.

  The digital camera 100 further includes a memory 52 and a display unit 54. Here, the memory 52 stores constants, variables, programs, and the like for the operation of the system control circuit 50. The display unit 54 is configured by a liquid crystal display device, a speaker, and the like that display an operation state, a message, and the like using characters, images, sounds, and the like according to execution of a program by the system control circuit 50.

  In the present embodiment, the display unit 54 is composed of an LCD, and is arranged at a position near the operation unit of the digital camera 100 where it can be easily seen. However, the display unit 54 may be configured by a plurality of LCDs as long as the display unit 54 is disposed at a position near the operation unit of the digital camera 100 that is easily visible. In addition, the display unit 54 may be configured by a combination of an LCD, an LED, a sound generating element, and the like instead of a single LCD.

  The display content of the display unit 54 includes single shot / continuous shooting display, self-timer display, compression rate display, number of recorded pixels, number of recorded pixels, number of remaining shots displayed, shutter speed display, aperture value display, exposure correction Display, red-eye reduction display, macro shooting display. Also, the display content of the display unit 54 includes a buzzer setting display, a clock battery remaining amount display, a battery remaining amount display, an error display, an information display by a multi-digit number, a display state of the recording media 200 and 210, and a lens unit. There are 300 attachment / detachment status display, communication I / F operation display, and date / time display. Further, the display content of the display unit 54 includes a display indicating a connection state with an external computer, a focus display, a shooting preparation completion display, a camera shake warning display, a flash charge display, a flash charge completion display, a shutter speed display, and an aperture value display. There is an exposure compensation display. The display content of the display unit 54 includes a recording medium writing operation display.

  The digital camera 100 further includes a nonvolatile memory 56 such as an electrically erasable / recordable EEPROM, a power switch 72, a real-time clock circuit 74, and a power control unit 80.

  The digital camera 100 also includes a mode dial switch 60, a shutter switch (SW1) 62, a shutter switch (SW2) 64, a playback switch 66, and an operation unit 70. These are used as an operation means composed of one or a plurality of combinations such as a switch, a dial, a touch panel, pointing by line-of-sight detection, a voice recognition device, etc. for inputting various operation instructions of the system control circuit 50.

  The mode dial switch 60 is a mode changeover switch for distinguishing between starting of the normal still image shooting mode and the moving image shooting mode. The shutter switch (SW1) 62 is turned ON during the operation of a shutter button (not shown), and AF (autofocus) processing, AE (automatic exposure) processing, AWB (auto white balance) processing, EF (flash dimming) processing, etc. Instruct the start of operation.

  The shutter switch (SW2) 64 is turned on when the operation of a shutter button (not shown) is completed, and the mode of the photographing operation of the digital camera 100 is shifted according to the state of the mode dial switch 60. Specifically, when the state of the mode dial switch 60 is OFF, the mode shifts to the still image shooting operation mode, and when the mode dial switch 60 is ON, the mode dial switch 60 shifts to the moving image shooting operation mode. Next, after shifting to each shooting operation mode, the shutter switch (SW2) 64 gives an instruction to start the shooting process. Here, in the photographing process, the following series of processes is performed. First, an exposure process is performed in which a signal read from the imaging unit 12 is written into the memory 30 via the A / D converter 16 and the memory control circuit 22. Further, the shutter switch (SW2) 64 reads out the image data from the development process using the calculation in the image processing circuit 20 and the memory control circuit 22 and the memory 30 and performs the compression in the compression / decompression circuit 32. Finally, the shutter switch (SW2) 64 performs a recording process for writing image data to the recording media 200 and 210 such as a memory card and a hard disk.

  The playback switch 66 instructs the start of a playback operation for reading an image shot in the shooting mode state from the memory 30 or the recording media 200 and 210 and displaying it on the image display unit 28.

  The operation unit 70 includes various buttons and a touch panel. Specifically, the operation unit 70 includes a menu button, a set button, a macro button, a multi-screen playback page break button, a flash setting button, a single shooting / continuous shooting / self-timer switching button, a menu movement + (plus) button, Menu movement-There is a (minus) button. Further, the operation unit includes a playback image movement + (plus) button, a playback image-(minus) button, a shooting image quality selection button, an exposure correction button, and a date / time setting button. The operation unit also includes a selection / switch button for setting selection and switching of various functions when performing shooting and playback in panoramic mode, etc., and determination of various functions when performing shooting and playback in panoramic mode and the like. There is a decision / execution button to set execution. Further, the operation unit includes an image display ON / OFF switch for setting ON / OFF of the image display unit 28 and a quick review ON / OFF switch for setting a quick review function for automatically reproducing image data captured immediately after shooting. . The operation unit includes a compression mode switch that is a switch for selecting a compression rate for JPEG compression or for selecting a CCD RAW mode in which a signal from the imaging unit is directly digitized and recorded on a recording medium. Further, the operation unit includes a playback switch that can set each function mode such as a playback mode, a multi-screen playback / erase mode, and a PC connection mode.

  The operation unit includes an AF mode setting switch for switching the AF operation mode when the shutter switch SW1 is pressed to either the one-shot AF mode or the servo AF mode. Here, the one-shot AF mode refers to a mode in which the in-focus state is maintained after focusing by an AF operation started by pressing the shutter switch SW1. The servo AF mode is a mode in which the AF operation is continuously performed while the shutter switch SW1 is pressed.

  In this embodiment, a menu or a playback image is selected by a menu movement + (plus) button, a menu movement-(minus) button, a playback image movement + (plus) button, or a playback image-(minus) button. However, menus and playback images may be selected using a rotary dial switch. This makes it possible to select menus and playback images more easily.

  The power switch 72 sets on / off of the power of the digital camera 100. The power switch 72 is used to turn on / off the power of various devices externally attached to the digital camera 100, such as the lens unit 300 connected to the digital camera 100, the external strobe, and the recording media 200 and 210. Also good.

  In the real-time clock circuit 74, the system control circuit 50 measures elapsed time and realizes various timer functions.

  The power control unit 80 (power supply control unit) includes a battery detection circuit (not shown), a DC-DC converter, a switch circuit that switches a block to be energized, and the like. Here, the battery detection circuit detects whether or not a battery is attached, the type of battery, and the remaining battery level. Further, the power supply control unit 80 controls the DC-DC converter based on the detection result and an instruction from the system control circuit 50, and supplies a necessary voltage to each unit including the recording medium for a necessary period.

  Furthermore, the digital camera 100 includes connectors 82 and 84, and a power supply device 86 including a primary battery such as an alkaline battery or a lithium battery, a secondary battery such as a NiCd battery, a NiMH battery, or a Li battery, an AC adapter, or the like. The digital camera 100 also includes interfaces 90 and 94 for recording media such as a memory card and a hard disk, and connectors 92 and 96 for connecting to a recording medium such as a memory card and a hard disk. Furthermore, the digital camera 100 includes a recording medium attachment / detachment detection unit 98 that detects whether or not the recording mediums 200 and 210 are attached to the connectors 92 and 96.

  The digital camera 100 further includes a connection unit 112 that is communicably connected to another device using a communication unit 110 that is a USB.

  The communication unit 110 is not limited to the present embodiment as long as it has a communication function. For example, the communication unit 110 may be configured by RS232C, IEEE1394, P1284, SCSI, modem, LAN, wireless communication, or the like. . Similarly, the connection unit 112 only needs to be able to communicate with other devices. For example, when the communication unit 110 has a wired communication function, the connection unit 112 includes a connector, and the communication unit 110 has a wireless communication function. If it is, it is composed of an antenna.

  The digital camera 100 further includes an interface 120 for connecting to the lens unit 300, a connector 122 for electrically connecting to the lens unit 300, and a lens mount 106 for mounting the lens unit 300.

  The recording medium 200 includes a recording unit 202 composed of a semiconductor memory, a magnetic disk, and the like, an interface 204 with the digital camera 100, and a connector 206 that connects to the digital camera 100. Similarly, the recording medium 210 includes a recording unit 212 composed of a semiconductor memory, a magnetic disk, or the like, an interface 214 with the digital camera 100, and a connector 216 that connects to the digital camera 100.

  The lens unit 300 includes a photographic lens 310, an aperture 312, a connector 322 for connecting to the digital camera 100 by electrical communication, an aperture controller 340, and a lens mount 306.

  Note that the connector 322 may be configured to perform not only electrical communication but also optical communication, voice communication, and the like.

  The aperture control unit 340 controls the aperture 312 in cooperation with the shutter control unit 40 that controls the shutter 12 based on the photometry information from the photometry unit 46.

  The lens mount 306 is mounted in a state where the optical axis of the lens unit 300 is aligned with the optical axis of the digital camera 100 by being attached to the lens mount 106 on the digital camera 100 side.

  The lens unit 300 further includes a distance measurement control unit 342 that controls focusing of the photographing lens 310, a zoom control unit 344 that controls zooming of the photographing lens 310, and a lens system control circuit 350 that controls the entire lens unit 300. Prepare.

  The lens system control circuit 350 includes a memory for storing operation constants, variables, programs and the like, identification information such as a number unique to the lens unit 300, management information, function information such as an open aperture value, a minimum aperture value, a focal length, A non-volatile memory is also provided for holding current and past set values.

  The digital camera 100 further includes a microphone 155 (audio recording unit) for recording audio, a speaker 157 for reproducing recorded audio or audio previously stored in the apparatus, and an audio analog-to-digital converter 159. Externally. This audio analog-to-digital conversion device 159 converts the audio input from the microphone 155 to analog-digital conversion to the optimum level and format for the device and sends it out, and also converts the audio data output from the device to digital-analog and sends it to the speaker 157 .

  FIG. 2 is a flowchart showing a flow of a photographing process performed by the system control circuit 50 in FIG.

  In FIG. 2, first, a predetermined initial setting necessary for each part of the digital camera 100 is performed by initializing flags, control variables, and the like when the power is turned on such as battery replacement (step S201).

  Next, it is determined whether the power of the digital camera 100 is turned on or off by the power switch 72 (step S202). As a result, if the power is set to off (NO in step S202), an end process is performed (step S203), and the process returns to step S202. Here, in the present embodiment, the termination process includes termination of image display by the image display unit 28, recording of necessary parameters and setting values including a flag, a control variable, and the like in the nonvolatile memory 56, power supply This means shutting off the power of each part of the digital camera 100 by the control unit 80.

  On the other hand, if the power switch 72 is set to power on (YES in step S202), the remaining capacity and operation status of the power supply device 86 configured by a battery or the like by the power control unit 80 may cause a problem in the operation of the digital camera 100. It is determined whether or not there is (step S204). If there is a problem as a result of this determination (YES in step S204), a predetermined warning is displayed by image or sound using the display unit 54 (step S205), and the process returns to step S202.

  On the other hand, if there is no problem in the remaining capacity of the power supply device 86 (NO in step S204), the process proceeds to step S206.

  Thereafter, it is determined whether or not there is a problem in the recording / reproducing operation of the image data recorded on the recording media 200 and 210 (step S206). Specifically, the determination is to acquire management information of image data recorded on the recording media 200 and 210, an operating state of the recording media 200 and 210, and an operating state of the digital camera 100 when the recording medium is attached. It is done by.

  As a result of the determination, if there is a problem in the recording / reproducing operation (NO in step S206), a predetermined warning is displayed by an image or sound using the display unit 54 (step S205), and then the process returns to step S202.

  On the other hand, if there is no problem in the recording / reproducing operation (YES in step S206), the electronic finder mode is entered (step S207). Here, the electronic viewfinder mode is a mode for performing the following processing. First, with the shutter 12 open, the number of readout pixels is reduced to a signal with a number of lines suitable for viewfinder display by a method such as line thinning or line addition of the imaging unit 14 via the timing generation circuit 18. Next, finder mode driving is performed to speed up to a necessary rate as a finder moving image, and exposure processing for writing image data to the memory 30 via the A / D converter 16 and the memory control circuit 22 is performed. . Thereafter, the image processing circuit 20 or the memory control circuit 22 performs development processing on the image data written in the exposure processing. Finally, the image data after the arithmetic processing is sequentially displayed as a finder image.

  Thereafter, it is detected by the shutter switch (SW1) 62 whether or not the shutter button has been turned on within a predetermined time. If the shutter button has not been turned on (NO in step S208), the process returns to step S202.

  On the other hand, when the ON state of the shutter button is detected (YES in step S208), it is detected whether the mode dial switch 60 is in the still image shooting mode or the moving image shooting mode (step S209). If the result of this detection is that the mode dial switch 60 is in the still image shooting mode (YES in step S209), the moving image mode flag is reset (step S211), and the process proceeds to step S212. On the other hand, when the mode dial switch 60 is in the moving image shooting mode (NO in step S209), the moving image mode flag is set (step S210), and the process proceeds to step S212.

  Thereafter, in step S212, distance measurement, photometry, and WB (white balance) detection are performed. Specifically, the photographing lens 310 is focused on the subject by the distance measurement process, the aperture value (Av value) and the shutter time (Tv value) are determined by the photometry process, and then the WB process is performed. In addition, various signals are exchanged between the system control circuit 50 and the aperture control unit 340 or the distance measurement control unit 342 during such processing by the interface 120, the connector 122, the connector 322, the interface 320, and the lens system control circuit 350. Done through.

  Further, after the distance measurement and the photometry are performed, an AF (autofocus) process is started using the imaging unit 14, the distance measurement unit 42, and the distance measurement control unit 342. Here, the AF processing is performed by causing a light beam incident on the lens 310 to enter the distance measuring unit 42 through the aperture 312, the lens mounts 306 and 106, the mirror 130, and a distance measuring sub mirror (not shown), thereby optically. A process for determining the in-focus state of an image formed as an image. This processing is performed until the lens 310 is driven using the distance measurement control unit 342 and the in-focus state is detected using the distance measurement unit 42 until ranging (AF) is determined to be in focus.

  Thereafter, when an in-focus state is detected by the AF process, the system control circuit 50 determines a focused distance measurement point from a plurality of distance measurement points in the shooting screen. The distance measurement data and / or setting parameters together with the determined distance measurement point data are stored in the internal memory (not shown) or the memory 52 of the system control circuit 50.

  Subsequently, the system control circuit 50 uses the photometry unit 46 to start AE (automatic exposure) processing. Here, the AE process specifically refers to the following process. First, the light beam incident on the lens 310 is incident on the photometry unit 46 via the aperture 312 and a photometry lens (not shown). Next, the exposure state of the image is measured from the light beam incident on the photometry unit 46. As a result of this measurement, photometric processing is performed using the shutter control unit 40 until exposure (AE) is determined to be appropriate.

  When it is determined that the exposure is appropriate by the AE process, the system control circuit 50 stores the photometric data and / or the setting parameter in the internal memory or the memory 52 of the system control circuit 50. Further, a sensitivity value (Dv value), an aperture value (Av value), and a shutter speed (Tv value) are determined according to the exposure result detected in the photometric process S212.

  Further, the system control circuit 50 determines the charge accumulation time of the imaging unit 14 according to the determined shutter speed (Tv value). Further, the system control circuit 50 determines the input D range of the A / D converter 16 according to the determined sensitivity value (Dv value).

  Next, the system control circuit 50 performs a predetermined calculation process using the image data captured by the image processing circuit 20 after the AF process and the AE process. Thereafter, the system control circuit 50 stores WB setting parameters for WB processing in the internal memory or the memory 52 of the system control circuit 50 based on the obtained calculation result.

  If it is detected that the shutter switch (SW2) 64 is turned on after completion of the operation of the shutter button (YES in step S213), it is confirmed whether the moving image mode flag is turned on or off (step S214). ). In this embodiment, when actually shooting a movie, the movie mode flag is on and the following movie shooting process is performed, but when shooting a movie while displaying a subject for shooting preparation, the following You may make it perform the process similar to a video recording process.

  When the moving image mode flag is off (NO in step S214), after the still image shooting process is performed (step S216), the process returns to step S202. On the other hand, when the moving image mode flag is on (YES in step S214), after moving image shooting processing is performed (step S217), the processing returns to step S202.

  On the other hand, when it is detected that the shutter switch (SW2) 64 is off (NO in step S213), it is detected whether or not the shutter button is released from the user's hand and the shutter switch (SW1) 62 is turned off. (Step S215). Thereafter, the processing from step S213 is repeated until the shutter switch (SW1) 62 is turned off (YES in step S215), and then the processing returns to step S202.

  FIG. 3 is a flowchart showing the flow of the procedure of the still image shooting process in step S216 of FIG. 2 executed by the system control circuit 50.

  Various signals are exchanged between the system control circuit 50 and the aperture control unit 340 or the distance measurement control unit 342 in this processing through the interface 120, the connector 122, the connector 322, the interface 320, and the lens system control circuit 350. .

  In FIG. 3, first, shooting conditions are set (step S301). Here, specifically, the aperture control unit 340 controls the aperture according to exposure conditions such as aperture value (Av value) and shutter speed (Tv value) and photometric data stored in the internal memory of the system control circuit 50 or the memory 52. 312 is driven to a predetermined aperture value.

  Next, the CCD drive mode of the timing generation circuit 18 is set (step S302) and the electronic shutter is set (step S303), and then charge accumulation is started in the CCD of the imaging unit 14 (step S304). The exposure of the imaging unit 14 starts from this charge accumulation.

  Thereafter, after the exposure of the imaging unit 14 is finished according to the photometric data, the shutter 12 is closed by the shutter control unit 40 (step S305), and the charge accumulation of the CCD of the imaging unit 14 is finished (step S306). Thereby, the exposure of the imaging unit 14 is completed.

  Thereafter, the imaging signal is read out (step S307). Specifically, the charge signal is read out from the image pickup unit 14 and passed through the A / D converter 16, the image processing circuit 20, and the memory control circuit 22 (or directly from the A / D converter 16 through the memory control circuit 22. ) Acquire an imaging signal.

  Next, after the still image recording process is performed in which the imaging signal is written as a photographed still image data in a predetermined area of the memory 30 (step S308), the still image photographing process (step S216) is terminated, and the photographing of FIG. Return to processing.

  Here, in the still image recording process in step S <b> 308, the system control circuit 50 not only writes image data in a predetermined area of the memory 30. Specifically, first, a part of the written image data is read through the memory control circuit 22. Thereafter, WB (white balance) integration calculation processing and OB (optical black) integration calculation processing necessary for performing the development processing are performed, and the calculation result is stored in the internal memory or the memory 52 of the system control circuit 50.

  Further, the system control circuit 50 reads out the image data written in a predetermined area of the memory 30 using the memory control circuit 22 (also the image processing circuit 20 if necessary), and performs various processes. Specifically, various development processes including an AWB (auto white balance) process, a gamma conversion process, and a color conversion process are performed using calculation results stored in the internal memory of the system control circuit 50 or the memory 52.

  Further, the system control circuit 50 reads out the image data written in a predetermined area of the memory 30, and the compression / decompression circuit 32 performs image compression processing according to the set mode. Further, a process of writing the compressed / decompressed image data into an empty area of the image storage buffer area of the memory 30 is also performed.

  Thereafter, the system control circuit 50 applies the recording media 200 and 210 to the image data stored in the image storage buffer area of the memory 30 by the photographing process of FIG. 2 via the interfaces 90 and 94 and the connectors 92 and 96. The following recording process is started.

  This recording process is performed on the image data every time image data is newly photographed in the empty area of the image storage buffer area of the memory 30 by the photographing process.

  Note that while writing image data to the recording media 200 and 210, in order to clearly indicate that the writing operation is being performed, the display unit 54 performs a recording medium writing operation display such as blinking an LED. Further, an image obtained by resizing the image data recorded on the recording media 200 and 210 to an image size suitable for the image display unit 28 is separately generated, and this is displayed on the image display unit 28 for a predetermined captured image display time. To do.

  Next, the moving image shooting process in step S217 of FIG. 2 will be described.

  FIG. 4 is a block diagram showing the internal configuration of the analog imaging signal area 15 and the timing generation circuit 18 of FIG.

  In FIG. 4, the analog imaging signal processing area 15 includes an imaging unit 14 that includes a CCD 14 a and an imaging circuit 14 b that processes a CCD output signal from the CCD 14 a, and an A / D converter 16.

  Further, the image processing unit 20, the memory control unit 22, and the image display memory 24 are configured, and a signal processing unit 20a that stores the digitally-converted imaging signal in a storage medium or displays it on a liquid crystal monitor is provided.

  Further, the timing generation circuit 18 includes an oscillation circuit (OSC1) 18a, a synchronization signal generator (step SSG) 50a, and an oscillation circuit (OSC2) 50b.

  The digital camera 100 further includes an oscillation circuit (OSC1) 18a and a V driver 14b connected to the CCD 14.

  The oscillation circuit 18 a supplies an operation clock for the timing generation circuit 18, and the oscillation circuit 18 a supplies an operation clock for the system control circuit 50.

  The system control circuit 50 (drive cycle setting unit) sets the number of cycles of the horizontal synchronization signal (HD) and the vertical synchronization signal (VD) generated by the synchronization signal generator 50a.

  The synchronization signal generator 50a supplies the timing generation circuit 18 with the horizontal synchronization signal and the vertical synchronization signal having the set number of periods.

  The timing generation circuit 18 supplies the drive pulse of the CCD 14a to the V driver 14b in synchronization with the horizontal synchronization signal (HD) and the vertical synchronization signal (VD) supplied from the synchronization signal generator 50a. The V driver 14b converts the drive pulse into a voltage and supplies it to the CCD 14a. In the present embodiment, drive pulses H1 and H2 are supplied to the CCD 14a as drive pulses for horizontal line output of the field signal. Further, a drive pulse V is supplied to the CCD 14a as a drive pulse for vertical line output of the field signal.

  The timing generation circuit 18 supplies a sampling clock signal to the imaging circuit 14b, the A / D converter 16, and the digital signal processing unit 20a, respectively, and an operation clock (TGCLK) to the synchronization signal generator 50a. Supply.

  On the other hand, the synchronization signal generator 50 a generates a horizontal synchronization signal (HD) and a vertical synchronization signal (VD) and supplies them to the timing generation circuit 18. The horizontal synchronization signal (HD) and the vertical synchronization signal (VD) are generated by counting a predetermined number of operation clocks from the timing generation circuit 18 in the synchronization signal generator 50a.

  The system control circuit 50 controls the operation of the digital signal processing unit 20a as well as the presence / absence of generation of the horizontal synchronization signal (HD) and the vertical synchronization signal (VD) and the period setting for the synchronization signal generator 50a. is doing.

  Next, frequency dispersion of current load fluctuations in the moving image shooting processing according to the embodiment of the present invention will be described.

  FIG. 5 is a timing chart used to explain the change timing of the horizontal drive frequency in the moving image shooting process in step S217 of FIG.

  In FIG. 5, the HD cycle for controlling all of the horizontal timing signals of the digital camera 100 is the blanking period and the pixel readout period of the drive pulses H1 and H2 for horizontal line output of the field signal output from the imaging unit 14. Composed. Here, the blanking period is a period during which the supply of the driving pulses H1 and H2 from the timing generation circuit 18 to the CCD 14a is stopped. The pixel readout period refers to a period in which the CCD 14a is being driven by the supply of the drive pulses H1 and H2, and more specifically includes two periods, an OB period and an effective pixel period. Here, the effective pixel period refers to a period during which horizontal line output of the field signal output from the imaging unit 14 is actually performed, and the OB period refers to optical shielding of the CCD 14a after the supply of the drive pulses H1 and H2. Refers to the period of time.

  On the other hand, the drive pulse V for vertical line output of the field signal output from the imaging unit 14 is controlled to be supplied to the CCD 14a in a certain period of the blanking period constituting the HD cycle. That is, the supply control of the drive pulse V to the CCD 14a is interlocked with the HD cycle.

  In this embodiment, as shown in FIG. 5, the HD cycle for each drive pulse H1, H2 for horizontal line output is varied for each cycle, and the length of the horizontal blanking period is not affected without affecting the pixel readout period. The method of adjusting the height is used.

  That is, the blanking time during the one horizontal line period is alternately set between (tBLK1) and a time (tBLK2) shifted by Δt from this time. This makes it possible to vary the length of the HD cycle of each drive pulse H1, H2 for horizontal line output without affecting the pixel readout period.

  Specifically, in the initial setting in step S201 of FIG. 2, the CCD drive setting and the initial setting of the period of the horizontal line period are performed. After that, when the moving image mode flag is ON in step S214, The moving image shooting process shown in FIG.

  First, shooting condition settings such as a shot image size and a frame rate of a moving image to be recorded are set (see step S2005 in FIG. 10). Next, the blanking time (tBLK2 = tBLK1 + Δt) for each of the drive pulse signals H1 and H2 is varied in accordance with the blanking time (tBLK1) of the reference HD period set in step S201 and the shooting conditions. Thereafter, a pulse signal (PBLK) indicating active period information of the blanking time after the variable is transmitted to the timing generation circuit 18.

  When receiving the pulse signal (PBLK) from the system control circuit 50, the timing generation circuit 18 changes the end timing of the blanking period of the HD cycle based on the received signal. As a result, the drive start timings of all horizontal system timing signals used in the CCD 14a, the imaging circuit 14b, the A / D converter 16 and the like are relatively changed. Specifically, in order to adjust the DC voltage level so that the optically shielded OB pixel level becomes the black reference value of the imaging signal, the timing position of the clamp pulse signal (CLPOB) indicating the OB period is set to the pulse signal ( PBLK) is changed to a position linked to the extension (see FIG. 5).

  Thus, the system control circuit 50 can vary the HD cycle by changing the blanking period for each of the drive pulses H1 and H2 for controlling the horizontal line output. In addition, the supply timing of the drive pulse V controlled in conjunction with the HD cycle to the CCD 14a can be varied. Furthermore, the cycle of the current load of the power supply control unit 80 that controls the supply of the drive currents of the drive pulses H1, H2, and V generated by the timing generation circuit 18 can be changed.

  FIG. 6 is a detailed block diagram of the power supply control unit 80 that controls the supply of the drive current of the drive pulses H1, H2, and V and its peripheral components.

  In FIG. 6, a power control unit 80 includes a DCDC controller 401 that converts the voltage of power supplied from the power supply device 86 to an optimal value for supplying to the timing generation circuit 18, and a switch controlled by the DCDC controller 401. 402. Further, the power supply controller 80 accumulates and smoothes the voltage converted by the DCDC controller 401, accumulates a ceramic capacitor 403a for outputting a horizontal line and a capacitor 403b (not shown) for outputting a vertical line, and generates timing. And an inductor 404 for sending power to the circuit 18.

  The power transmitted from the inductor 404 is mainly consumed by the timing generation circuit 18. Further, the DCDC controller 401 controls so that the electric power sent to the timing generation circuit 18 becomes a predetermined voltage. For this reason, even if the current consumption increases in the timing generation circuit 18 and a voltage drop occurs, the DCDC controller 401 controls to compensate for the voltage drop and keep the voltage constant. That is, the voltage applied to the ceramic capacitors 403a and 403b responds to fluctuations in the load current of the timing generation circuit 18.

  The ceramic capacitors 403a and 403b are made of a ferroelectric ceramic, and a so-called electrostriction phenomenon occurs in which distortion occurs when an electric field is applied thereto. When this electrostriction phenomenon occurs, the entire substrate on which the ceramic capacitors 403a and 403b are mounted vibrates, resulting in audio noise.

  In this embodiment, the ceramic capacitors 403a and 403b and the inductor 404 are included in the power supply control unit 80, but instead of these, a decoupling capacitor and a coupling inductor connected to the power supply device 86 in line. May be used.

  FIG. 7 is a timing chart showing the load current of the timing generation circuit 18.

  Here, in the present embodiment, the load current of the timing generation circuit 18 that causes the audio noise is mainly due to the drive currents of the drive pulses H1 and H2, and is affected by the drive current of the drive pulse V. Is small and negligible. Therefore, in the following description, the drive current supplied from the DCDC controller 401 refers only to the drive currents of the drive pulses H1 and H2.

  In FIG. 7, as described above with reference to FIG. 5, when the blanking period of the drive pulses H1 and H2 changes from tBLK1 to tBLK2, the HD cycle changes from tHD1 to tHD2. During the blanking period, since the drive currents of the drive pulses H1 and H2 are not required in the timing generation circuit 18, the cycle of the drive current supplied from the DCDC controller 401 to the timing generation circuit 18 also changes. Further, the load current Vdr to the timing generation circuit 18 that is delayed by Δtdr with respect to the drive current supply cycle by the DCDC controller 401 also changes from TvL1 to TvL2.

  In this embodiment, the case where the blanking periods of the drive pulses H1 and H2 change in two ways, tBLK1 and tBLK2, has been described. However, the drive pulses H1 and H2 may change in four ways, tBLK1 to tBLK4. Further, the blanking periods of the drive pulses H1 and H2 may change differently.

  As described above, by changing the blanking period of the drive pulses H1 and H2, frequency dispersion of current load fluctuations generated in the timing generation circuit 18 can be realized. Even if the drive current of the drive pulse V is approximately the same as the drive currents of the drive pulses H1 and H2, the HD cycle also changes due to the change in the blanking period. Therefore, when the DCDC controller 401 supplies the drive current of the drive pulse V linked to the HD cycle, the fluctuation cycle of the load current generated in the power supply control unit 80 can be changed, so that the above frequency dispersion is realized reliably. can do.

  For example, if Δt = (tHD1) / 2, tHD2 = tIMG + tBLK1 + (tHD1) /2=1.5*tHD1, which can be 1.5 times longer than the period of the reference HD cycle, The period is also 1.5 times. Thus, since the value of Δt for adjusting the blanking period for each HD cycle can be changed to an arbitrary value, the frequency of the current load generated in the power supply control unit 80 can be reliably dispersed.

  In the present embodiment, the blanking period of the HD cycle for each of the drive pulses H1 and H2 is adjusted in order to disperse the frequency of the current load generated in the power supply control unit 80 without affecting the pixel readout period. When such adjustment is performed, driving of all horizontal system timing signals supplied to the CCD 14a, the imaging circuit 14B, the A / D converter 16 and the like is started in conjunction with the change of the HD cycle for each of the driving pulses H1 and H2. Need to change timing.

  However, as in the present embodiment, there may be a case where the timings of all the horizontal timing signals cannot be freely changed simply by adjusting the blanking period.

  Specifically, as long as the timing generation circuit 18 can change the timing in a programmable manner with respect to all related horizontal system timing signals, the drive pulses H1, H2, and V are all in the blanking period. It is not impossible to change them all at once. However, in this case, the task of the system control circuit 50 becomes heavy. Also, if there are some horizontal timing signals that cannot be changed because the timing is fixed, or those that do not change immediately even after changing settings, this method should be used. I can't.

  Hereinafter, a method of changing the HD cycle for controlling these pulses, not for each of the drive pulses H1, H2, will be described as a modification of the present invention.

  In the HD cycle in this modification, the blanking period of the drive pulses H1 and H2 is not variable, but an empty transfer period (variable period) related to the horizontal line output is provided at the end of the pixel readout period (OB period + effective pixel period). to add.

  Here, the idle transfer related to the horizontal line output is the horizontal line output when the drive pulses H1 and H2 are continuously supplied to the CCD 14a after all the accumulated charges of the CCD 14a are output as field signals, that is, in the idle reading state. The output of

  FIG. 8 is a modification of the timing chart used to explain the change timing of the horizontal drive frequency in the moving image shooting process in step S217 of FIG.

  In FIG. 8, the HD cycle according to this modification is composed of a blanking period of drive pulses H1 and H2 for a horizontal line output of the CCD 14a, and a pixel readout period (= OB period + effective pixel period + empty transfer period). The For example, when the number of pixel clocks in the effective pixel period set by the initial setting is Δtx, the pixel readout period in the HD cycle is changed by adding the number n of pixel clocks in the empty transfer period to the end of the effective pixel period.

  Specifically, the system control circuit 50 sets the HD cycle in accordance with the captured image size being set in the shooting conditions set in step S2005 of FIG. Next, supply of drive pulses H1 and H2 from the timing generation circuit 18 to the CCD 14a is started based on the HD cycle. Thereafter, the drive pulses H1 and H2 are continuously supplied even after the effective pixel period of the current HD cycle, and supplied to the CCD 14a, the image sensor 14b, the A / D converter 16 and the like when the next HD cycle starts. Reset the drive start timings of all horizontal timing signals.

  Thus, the drive timings of all the horizontal system timing signals including the drive pulses H1 and H2 are set according to the HD cycle variably set by the system control circuit 50. As a result, the task of the system control circuit 50 can be lightened compared to the embodiment, and the setting of the horizontal system timing signal can be performed quickly and reliably.

  In addition, the HD cycle adjustment in this modification is performed by setting the empty transfer period to start after the horizontal line output in the effective pixel period is completed. During the effective pixel period, the horizontal line output is stopped and the empty line period is stopped. It is not set to start the transfer period. Accordingly, since the residual charge of the CCD 14a is not output as a horizontal line output during the idle transfer period, there is an adverse effect when the next field signal is read out, or the original image contributing to the display is affected. Can be prevented.

  FIG. 9 is a modification of the timing chart showing the load current of the timing generation circuit 18.

  In FIG. 9, the time excluding the blanking time in the HD cycle is tIMG1 (= (effective pixel period) + (OB period) + (empty transfer period Δtx)) and tIMG2 (= (effective pixel period) + (OB period) + (empty transfer period Δtx + Δtn)) are alternately set. That is, as the idle transfer period increases by (Δtn), the HD cycle changes from tHD1 to tHD2.

  According to this modification, the blanking period is constant, but the tIMG period is changed. Thereby, the period during which the drive currents of the drive pulses H1 and H2 flow can be changed, and as a result, the cycle in which the load current Vdr to the timing generation circuit 18 flows can be changed.

  In this modification, the case in which the time excluding the blanking time of the HD period changes in two ways, tIMG1 and tIMG2, may be changed in four ways, tIMG1 to tIMG4. Further, the HD periods of the drive pulses H1, H2 may change differently.

  Further, the present embodiment and the modification thereof are the same in that the generation period of the current load in the power supply control unit 80 is variable and the generation period of the current load generated by the drive pulse V is the same. The generation period of the current load is different.

  That is, in the present modification (FIG. 9), the time for supplying the drive pulses H1 and H2 to the CCD 14a is longer than that in the present embodiment (FIG. 7). However, this is longer than in the present embodiment.

  Next, a moving image shooting process when the current load cycle of the horizontal line is varied using the method described in the present embodiment and its modification will be described.

  FIG. 10 is a flowchart showing the flow of the procedure of the moving image shooting process in step S217 of FIG. 2 executed by the system control circuit 50.

  In FIG. 10, first, shooting conditions are set (step S2005). Here, specifically, the setting of the captured image size, the frame rate of the moving image to be recorded, and the like are set.

  Next, the period of the HD cycle of the drive pulses H1 and H2 supplied by the timing generation circuit 18 is set based on the set photographing condition (step S2006). Specifically, the repetition of the cycle is set with tHD as the first period of the HD cycle, 2tHD1 twice as long as tHD1 as the second period, and time tHD1 as the third period again. Note that the setting of the period of the HD cycle in step S2006 is not limited to the above setting method, and can be arbitrarily changed.

  Next, field signal readout setting is performed (step S2007). Specifically, a plurality of horizontal lines and vertical lines are set as pixel lines for performing photoelectric conversion of the captured image whose size is set in step S2005.

  Thereafter, the HD cycle is set (step S2008). Specifically, a process of setting the blanking period of the HD cycle for each drive pulse H1, H2 (FIG. 5), or a process of setting the empty transfer period added to the HD cycle for each cycle (FIG. 7). )I do.

  Thereafter, the supply of the drive pulses H1, H2, and V controlled in the set HD cycle from the timing generation circuit 18 to the CCD 14a is started (step S2009). This process is performed, for example, in the case of the modification described above with reference to FIG. First, the system control circuit 50 sets an idle transfer period of HD cycle. Thereafter, the synchronization signal generator 50 a generates a horizontal synchronization signal and a vertical synchronization signal based on the set HD cycle, and supplies them to the timing generation circuit 18. The timing generation circuit 18 generates drive pulses H1 and H2 synchronized with the horizontal synchronization signal and a drive pulse V synchronized with the vertical synchronization signal, and supplies them to the CCD 14a.

  When the output of the field signal is started by the CCD 14a based on the drive pulses H1, H2, and V supplied in step S2009 (YES in step S2010), moving image shooting is started (step S2011). During this moving image shooting, charges are accumulated by the CCD 14a according to the frame rate set in step S2005, and external sound is recorded by the microphone 155 at a predetermined sampling frequency.

  Thereafter, when the supply of the drive pulses H1 and H2 for one cycle is completed (YES in step S2012), moving image recording for recording the field signal (first field signal) output from the CCD 14a during the supply period is performed (step S2012). S2013). In parallel with this process, A / D conversion and other processes are performed on the analog audio data obtained by the audio recording process by the microphone 155 during the supply period, and then the process is performed in synchronization with the first field signal. Later audio data is stored.

  Thereafter, the processing from step S2012 is repeated until moving image shooting is completed (NO in step S2014).

  On the other hand, when the moving image shooting is completed (YES in step S2014), the supply of the driving pulses H1, H2, V from the timing generation circuit 18 to the CCD 14a is ended (step S2015), and the processing returns to the shooting processing in FIG.

  In this process, while the drive pulses H1 and H2 are being supplied (steps S2009 to S2015), moving image shooting and recording of external sound by the microphone 155 are performed (steps S2011 to S2014). For this reason, audio noise caused by the ceramic capacitors 403a and 403b generated during the supply of the drive pulses H1 and H2 is mixed in the audio data recorded in step S2013.

  Next, audio noise recorded by the microphone 155 will be described.

  FIG. 11 is a graph showing the spectrum of audio recorded during the moving image shooting process of FIG. 10, where the vertical axis indicates sound pressure and the horizontal axis indicates frequency.

  In FIG. 11, the spectrum of the sound recorded during the moving image shooting process of FIG. 10 is the sound recording band 701 indicating the sound recording frequency by the microphone 155 and when the recorded sound is A / D converted by the analog / digital converter 159. Nyquist frequency 702. Further, this spectrum has a sampling frequency 703 when the microphone 155 records sound, and HD periods 704 and 705 before and after the frequency shift performed by any of the methods described above with reference to FIGS.

  As described above with reference to FIG. 6, the audio noise is generated due to electrostriction occurring in the ceramic capacitors 403 a and 403 b due to a change in load current of the timing generation circuit 18. Here, in the present embodiment, the current supplied by the timing generation circuit 18 is mainly the drive current of the drive pulses H1 and H2. Further, the load period of these drive currents is an HD period that is shifted every period. Therefore, the audio noise frequency 704 substantially matches the frequencies 704 and 705.

  Here, when the frequency spectrum of the audio is weighted by the entire time, the generation time of the audio noise substantially matching the frequencies 704 and 705 is half that in the case where the HD cycle is not shifted as in the prior art. That is, the energy of the voice noise is the same as in the conventional case, but the frequency dispersion is performed, so that the noise can be reduced as a way of hearing. In addition, since the peak value of the voice noise that substantially matches the frequencies 704 and 705 is half that of the conventional case, the microphone 155 has a characteristic of recording significantly when the peak value of the voice noise is equal to or higher than a certain value. If it is, the recorded audio noise can be reliably reduced.

  As described above, although the audio noise reduction method in the moving image shooting process has been described in the present embodiment, the present method is not limited to the moving image shooting process, and for example, is applied to the processing in the electronic finder mode. You can also

  Further, in this processing, the audio noise is reduced by changing the HD cycle, but the present invention is not limited to this. For example, when the current load of the vertical line output is large or equivalent to the current load of the horizontal line output, not only the HD cycle but also the VD cycle may be changed similarly.

  Further, the control performed in the present invention may be performed by a hardware circuit, and part or all of the control may be performed by software.

  Moreover, you may achieve the objective of this invention by performing the following processes. That is, a storage medium that records a program code of software that realizes the functions of the above-described embodiments is supplied to a system or apparatus, and a computer (or CPU, MPU, etc.) of the system or apparatus is stored in the storage medium. This is the process of reading the code.

  In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the program code and the storage medium storing the program code constitute the present invention.

  Moreover, the following can be used as a storage medium for supplying the program code. For example, floppy (registered trademark) disk, hard disk, magneto-optical disk, CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD + RW, magnetic tape, nonvolatile memory card, ROM or the like. Alternatively, the program code may be downloaded via a network.

  Further, the present invention includes a case where the function of the above-described embodiment is realized by executing the program code read by the computer. In addition, an OS (operating system) running on the computer performs part or all of the actual processing based on an instruction of the program code, and the functions of the above-described embodiments are realized by the processing. Is also included.

  Furthermore, a case where the functions of the above-described embodiment are realized by the following processing is also included in the present invention. That is, the program code read from the storage medium is written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer. Thereafter, based on the instruction of the program code, the CPU or the like provided in the function expansion board or function expansion unit performs part or all of the actual processing.

1 is a block diagram schematically showing a digital camera as an imaging apparatus according to an embodiment of the present invention. 2 is a flowchart showing a flow of a photographing process performed by a system control circuit in FIG. 1. 3 is a flowchart showing a flow of a procedure of a still image shooting process in step S216 of FIG. 2 executed by a system control circuit. FIG. 2 is a block diagram illustrating an internal configuration of an analog imaging signal area and timing generation circuit in FIG. 1. 3 is a timing chart used to explain the timing of changing the horizontal drive frequency in the moving image shooting process in step S217 of FIG. FIG. 4 is a detailed block diagram of a power supply control unit that controls the supply of drive currents of drive pulses H1, H2, and V and its peripheral components. It is a timing chart which shows the load current of a timing generation circuit. It is a modification of the timing chart used for demonstrating the change timing of the horizontal drive frequency in the moving image shooting process of step S217 of FIG. It is a modification of the timing chart which shows the load current of a timing generation circuit. It is a flowchart which shows the flow of the procedure of the moving image shooting process of step S217 of FIG. 2 performed by a system control circuit. It is a graph which shows the spectrum of the audio | voice recorded in the moving image shooting process of FIG. 10, A vertical axis | shaft shows a sound pressure and a horizontal axis shows a frequency. It is a block diagram which shows schematically the imaging part of the conventional digital camera. It is a block diagram which shows the internal structure of the imaging circuit in FIG. 12 in detail. It is a figure which shows the timing chart of the main signal transmitted / received between the circuits which comprise a digital camera. It is a timing chart used for demonstrating the horizontal drive frequency in the conventional video recording processing. FIG. 2 is a diagram used to explain the principle of generating sound noise from a power source of a timing generator, where FIG. Indicates a pattern. It is a graph which shows the spectrum of the audio | voice recorded at the time of the video recording process by a digital camera, A vertical axis | shaft shows a sound pressure and a horizontal axis shows a frequency.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Digital camera 14 Imaging part 15 Analog imaging signal area 16 A / D converter 50 System control circuit 18 Timing generation circuit 80 Power supply control part 86 Power supply device

Claims (9)

During moving image shooting, an image pickup unit that accumulates electric charges on the imaging surface according to a frame rate, divides the accumulated electric charges into a plurality of field signals composed of horizontal lines and vertical lines, and outputs the moving image. A sound recording unit that records external sound, a pulse generation unit that generates a drive pulse for outputting the field signal, a power supply control unit that controls supply of drive power for generating the pulse, In an imaging apparatus having a drive cycle setting unit for setting a drive cycle of the drive pulse,
The image pickup apparatus, wherein the drive cycle setting unit varies the drive cycle of the drive pulse for each cycle.   2. The imaging apparatus according to claim 1, wherein the driving pulse whose driving cycle is variable is a driving pulse for outputting a horizontal line of the field signal.   The imaging apparatus according to claim 1, wherein the drive cycle setting unit varies one period constituting the drive cycle for each of the drive pulses. The driving cycle includes an effective pixel period for the imaging unit,
The imaging apparatus according to claim 3, wherein the one period is set before or after the effective pixel period.   The imaging apparatus according to claim 3, wherein the one period is a blanking period of the imaging unit, which is one of the periods constituting the driving cycle.   The imaging apparatus according to claim 1, wherein the drive cycle setting unit adds a variable period as a period constituting the drive cycle.   The imaging apparatus according to claim 6, wherein the variable period is an empty transfer period of the imaging unit. During moving image shooting, an image pickup unit that accumulates electric charges on the imaging surface according to a frame rate, divides the accumulated electric charges into a plurality of field signals composed of horizontal lines and vertical lines, and outputs the moving image. A sound recording unit that records external sound, a pulse generation unit that generates a drive pulse for outputting the field signal, a power supply control unit that controls supply of drive power for generating the pulse, In the moving image recording method with sound of the imaging device having a drive cycle setting unit for setting a drive cycle of the drive pulse,
The moving image recording method with sound, wherein the drive cycle setting unit varies the drive cycle of the drive pulse for each cycle. During moving image shooting, an image pickup unit that accumulates electric charges on the imaging surface according to a frame rate, divides the accumulated electric charges into a plurality of field signals composed of horizontal lines and vertical lines, and outputs the moving image. A sound recording unit that records external sound, a pulse generation unit that generates a drive pulse for outputting the field signal, a power supply control unit that controls supply of drive power for generating the pulse, In a program for causing a computer to execute a moving image recording method with sound of an imaging apparatus having a driving cycle setting unit that sets a driving cycle of the driving pulse, the moving image recording method with sound includes:
The program characterized in that the drive cycle setting unit varies the drive cycle of the drive pulse for each cycle.

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