JP4845823B2 - Signal processing apparatus, imaging apparatus, and control method - Google Patents

Description

  The present invention relates to a signal processing device, an imaging device, and a control method suitable for reducing noise during audio recording when recording a moving image with audio.

  In recent years, imaging devices (digital cameras) that record and reproduce images captured by a solid-state imaging device (hereinafter referred to as an imaging device) such as a CCD on a recording medium (such as a memory card having a solid-state memory device) have been developed extensively. Has become popular. The background of the spread of digital cameras includes the spread of personal computers (PCs) that can capture and process captured images from digital cameras, and increased demand for digital image information using the Internet and the like.

  In addition, the following trends are progressing in digital cameras. In other words, the number of pixels of the image sensor mounted on the digital camera is increased, the capacity of the memory card serving as a recording medium is increased, and the density and speed of the integrated circuit (IC) that handles digital signal processing of images at the center of the digital camera are increased. Is progressing.

  Recently, the following types of digital cameras have appeared. In other words, models with an increased still image size and high-speed continuous shooting function that can record several frames of still images like a movie, and a frame rate (60 frames per second) that is smaller than a still image size, just like a television receiver. This is a model that can record / play movies with

  Furthermore, in addition to the high definition of still images so far, digital cameras to which a moving image function has been added have begun to be put on the market, further raising the needs of the market. On the other hand, in the digital video camera for consumer use, the video by digital recording is very familiar by the consumer digital format standard. Along with this, not only conventional moving image shooting but also those that can use both moving image shooting and still image shooting are beginning to be marketed. Examples of the image recording method include a method of recording a still image together with a moving image on a moving image recording medium, and a method of recording a still image independent of a moving image on a recording medium independent of the moving image.

  On the other hand, a digital camera (digital still camera) whose function is still image recording and a digital video camera whose function is mainly moving image recording have started to realize the combined use of still image recording and moving image recording as functions. .

  In addition, the resolution and operation speed related to the shooting of still images and moving images in digital cameras are increasing year by year in combination with market needs for higher image quality and higher definition. Along with the improvement in resolution and operation speed, the speedup is rapidly progressing also in the technology related to the image sensor mounted on the digital camera. That is, the drive signal for driving the image pickup device is rapidly increased, and the drive frequency for all the digital signal processing circuits in the subsequent stage including the analog signal processing circuit and the AD converter is rapidly increasing.

  Recently, in addition to the improvement of image quality such as high image quality and high definition, digital cameras are increasingly required to have performance (easyness) that enables shooting with few failures in various shooting scenes. ing. Along with this, speeding up of the shutter speed for the purpose of following a subject in shooting a fast-moving subject (for example, shooting a sports scene) and preventing camera shake in shooting under low illumination (for example, indoor shooting) has progressed. Yes.

  In addition, in digital cameras, in order to enable high-sensitivity shooting in areas where strobe shooting is prohibited, such as museums and aquariums, higher sensitivity related to shooting still images and moving images has been further developed.

  A DC-DC converter is used as a power supply circuit provided in the above-described imaging apparatus (digital camera, digital video camera), and a multilayer ceramic capacitor is generally mounted in the DC-DC converter. Various techniques have been proposed for this type of technical field (see, for example, Patent Document 1 and Patent Document 2).

  In the technique described in Patent Document 2, an electrostriction phenomenon is caused by the piezoelectric characteristics of a ferroelectric ceramic composed of a ceramic having a high dielectric constant, and the electrostriction phenomenon is transmitted to the circuit board to generate sound by resonance. Has been pointed out. That is, an electrostriction phenomenon exists in principle in electronic parts such as ceramic capacitors mounted on a DC-DC converter.

  On the other hand, there has been proposed a technique for reducing sound generated due to an electrostriction phenomenon (piezoelectric phenomenon) by devising a method of mounting a ceramic capacitor on a DC-DC converter (see, for example, Patent Document 3 and Non-Patent Document 1). . However, the countermeasure for reducing the sound generated by a single component has a problem that the cost is high and the component cannot be freely selected. In addition, the noise reduction measures by devising the component mounting method have problems such as restrictions on mounting and a lack of flexibility in layout on the circuit board.

  Next, specific examples and problems of the conventional imaging apparatus (digital camera) will be described with reference to FIGS.

  FIG. 11 is a block diagram illustrating a schematic configuration of an imaging unit of an imaging apparatus according to a conventional example.

  In FIG. 11, a CCD (imaging device) 2001 in the analog signal processing area 2000 photoelectrically converts a subject image and outputs an imaging signal. The imaging circuit 2002 processes the imaging signal. The A / D converter 2003 performs A / D conversion on the imaging signal. A digital signal processing circuit 2004 records an imaging signal on a recording medium and displays an image on a liquid crystal monitor. The system control unit 2009 has a CPU for controlling the operation of the entire imaging apparatus (digital camera).

  The oscillation circuit 2005 supplies an operation clock for the timing generator 506. The oscillation circuit 2008 supplies an operation clock for the system control unit 2009. The timing generator 2006 supplies a drive pulse of the CCD 2001 to a V driver (not shown) in synchronization with the horizontal synchronization signal (HD) and the vertical synchronization signal (VD) supplied from the synchronization signal generator 2007. The V driver supplies the voltage-converted pulse to the CCD 2001.

  The timing generator 2006 supplies a sampling clock signal to the imaging circuit 2002, the A / D converter 2003, and the digital signal processing unit 2004, and also supplies an operation clock (TGCLK) to the synchronization signal generator 2007. The synchronization signal generator 2007 generates a horizontal synchronization signal (HD) and a vertical synchronization signal (VD) by counting a predetermined number of operation clocks from the timing generator 2006, and supplies the generated timing to the timing generator 2006. A system control unit 2009 controls the operation of the digital signal processing unit 2004 while setting whether or not to generate a horizontal synchronization signal (HD) and a vertical synchronization signal (VD) in the synchronization signal generator 2007 and setting a cycle.

  FIG. 12 is a block diagram illustrating a detailed configuration of the imaging circuit 2002 of the imaging unit.

  In FIG. 12, the imaging circuit 2002 includes a CDS (correlated double sampling) circuit 2002a, an amplifier 2002b, and a clamp circuit 2002c. Normally, a CDS circuit 2002a for removing a reset noise component generated during charge transfer of the CCD 2001 is provided at the subsequent stage of the CCD 2001. The CDS circuit 2002a obtains a difference between the level of the feedthrough portion and the imaging signal portion in the output signal of the CCD 2001, and thereby removes a correlation noise component of one pixel period from the imaging signal.

  The amplifier 2002b amplifies the imaging signal output via the CDS circuit 2002a to a predetermined signal level in accordance with the input range of the A / D converter 2003 at the subsequent stage, and supplies the amplified signal to the clamp circuit 2002c. The clamp circuit 2002c adjusts the DC voltage level so that the shaded pixel (OB) period of the CCD 2001 becomes a predetermined black reference value.

  FIG. 13 is a timing chart showing main signals of the imaging unit.

  In FIG. 13, the operating frequency for each pixel of the CCD 2001 output is determined by the CCD drive signal generated by the timing generator 2006, and is, for example, 30 to 40 MHz.

  The timing generator 2006 outputs drive pulses H1 and H2 for charge transfer (hereinafter referred to as horizontal CCD transfer) for a horizontal line constituting a pixel block of the CCD and a reset gate signal RG, and outputs an imaging signal from the CCD 2001. Here, H1 and H2 are equal to the frequency of the CCD drive signal and are driven by a high-speed clock of 30 to 40 MHz. Further, since the horizontal transfer path of the CCD 2001 has a large capacity load, a current load of about 100 mA is generated in the power source of the timing generator 2006 that outputs H1 and H2.

  In the case of the CCD 2001, a rough breakdown of the number of pixel clocks constituting one horizontal line period is as shown in FIG. That is, a blanking period in which the driving pulses H1 and H2 for horizontal CCD transfer are stopped, and a period of pixel readout being driven (an OB (optically shielded) period + effective pixel period).

  The power supply of the timing generator 2006 generates a current load of about 100 mA during the period in which the above H1 and H2 are output. During the blanking period when H1 and H2 are stopped, the current load becomes zero, and a large load fluctuation occurs in one horizontal line cycle. In the horizontal blanking period, charge is normally transferred vertically, so that a transfer pulse is supplied from a V driver to a vertical line (hereinafter referred to as a vertical CCD) constituting a pixel block of the CCD. During that time, a current load of several tens of mA is generated.

  Capacitors and inductors connected to the power supply circuit vibrate due to fluctuations in the current load that occurs when H1 and H2 are output and when a vertical transfer pulse is output. Along with this, the vibration is transmitted to the circuit board on which the component is mounted, so that a sound matching the frequency of the current load fluctuation is generated.

  When moving image recording is performed with an imaging device (digital camera), since sound recording is also performed at the same time, there is a problem that sound (noise) generated by vibration of a component is recorded. As conventional sound countermeasures, parts with less shape distortion with respect to load fluctuations have been used. However, since parts with less shape distortion are expensive, there is a demand for a technique capable of taking sound countermeasures even with inexpensive parts.

  Next, in view of the above-described conventional problems, a specific description will be given of how a component such as a capacitor sounds under conventional operating conditions.

  FIG. 15 is a block diagram illustrating an imaging apparatus and a power supply system.

  In FIG. 15, a DC-DC converter 3003 converts the voltage of a power source 3001 such as a battery into a voltage suitable for the imaging device 3008. The charging current 3006 flows from the power supply 3001 through the path shown in the figure. The inductor 3002 accumulates current and sends power to the subsequent stage. The switch 3004 is controlled by the DC-DC converter 3003. The capacitor 3005 accumulates and smoothes the voltage-converted voltage. A current 3007 is supplied from the capacitor 3005 to the imaging device 3008. The consumption current pattern 3007-1 is determined by driving the imaging device 3008.

  When the current consumption of the imaging device 3008 increases, the DC-DC converter 3003 monitors the output voltage and constantly controls so as to keep a predetermined voltage constant. Further, when current is consumed in the imaging apparatus 3008, a voltage drop occurs, and control is performed so as to compensate for the voltage drop and maintain a constant voltage. The voltage applied to the capacitor 3005 changes due to the load fluctuation of the imaging device 3008. In the case of a ceramic capacitor, expansion and contraction are repeated, and as a result, the physical displacement is transmitted to the circuit board. As a result, when the vibration frequency of the oscillated circuit board is an audible frequency (about 50 Hz to 20 KHz), noise is heard as sound. .

  Next, the operation at the time of audio recording in the imaging apparatus will be described with reference to FIG.

  FIG. 16 is a diagram illustrating frequency characteristics during audio recording.

  In FIG. 16, the vertical axis indicates sound pressure [dB], and the horizontal axis indicates frequency [Hz]. Along with the electrostriction phenomenon of the capacitor 3005, vibration due to the consumption current pattern 3007-1 is mainly excited on the circuit board. Reference numeral 4001 denotes a voice recording band indicating a frequency at which voice is recorded. Reference numeral 4002 denotes a Nyquist frequency when A / D converting the voice. Reference numeral 4003 denotes a sampling frequency for recording sound. Reference numeral 4004 denotes an audio noise frequency generated by the circuit board vibrating due to the consumption current pattern.

  Since the voltage of the capacitor 3005 changes with the period when the load of the current consumption pattern 3007-1 is increased, and the electrostriction phenomenon occurs due to the horizontal driving frequency of the imaging device 3008, the audio noise frequency 4004 becomes the horizontal driving frequency of the imaging device 3008. ing. For example, when the horizontal drive frequency of the imaging apparatus 3008 is 3 KHz and the sampling frequency 4004 is 10 KHz, the sampling Nyquist frequency is 5 KHz. In other words, it is theoretically possible to record audio frequencies up to 5 KHz. When the horizontal drive frequency is 3 KHz, the audio noise frequency is also 3 KHz and is recorded as audio noise.

As described above, when the capacitor mounted in the DC-DC converter is a ceramic capacitor, an electrostriction phenomenon is likely to occur. Therefore, changing to a tantalum capacitor, a polymer capacitor, or the like reduces audio noise. Further, it is conceivable to shift the horizontal drive frequency of the imaging device 3008 to a sufficiently high frequency (for example, 20 KHz or more) in order to remove the audio noise frequency from the audible band. However, since the horizontal drive frequency of the imaging apparatus is predetermined by the device used, the frequency cannot be increased freely.
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 GJ4 Series ”

  As described in detail above, the conventional imaging apparatus (digital camera, digital video camera) has the following problems. That is, an electrostriction phenomenon caused by a ceramic capacitor mounted in a DC-DC converter used as a power supply circuit of the image pickup apparatus is transmitted to the circuit board, and a sound is generated by resonance. In addition, a method for reducing the sound generated due to the electrostriction phenomenon by devising a ceramic capacitor mounting method causes a limitation in mounting. Also, the method of changing the ceramic capacitor to a tantalum capacitor or a polymer capacitor has the above-mentioned problems.

  Therefore, when sound is generated with the electrostriction phenomenon caused by the electronic component as described above (squeaking phenomenon of the electronic component), there is a problem that noise is mixed into the sound during the sound recording during the moving image recording of the imaging apparatus. Therefore, conventionally, there is a demand for reducing noise during sound recording (voice recording) of an imaging apparatus by making the so-called squeaking phenomenon of electronic components (connected to a power line) constituting the power circuit of the imaging apparatus inconspicuous. .

  An object of the present invention is to provide a signal processing device, an imaging device, and a control method capable of reducing noise during audio recording in moving image shooting of the imaging device.

  In order to achieve the above-described object, the present invention provides a signal processing apparatus that performs band limitation on a sound signal recorded together with a video signal picked up by an image pickup means by a filter and performs analog-digital conversion and records the signal. Setting means for setting a period of a horizontal line of a video signal imaged by the means, and at the time of performing audio recording accompanying imaging by the imaging means, the setting means causes at least one of field signals constituting the frame signal to be set. When setting the horizontal line period to be different from the horizontal line period of other field signals in units of fields, the horizontal drive frequency is changed for each horizontal line period (an integer N of 1 or more), and the difference between the horizontal drive frequencies is And control means for controlling to be lower than a cutoff frequency of the filter characteristic.

  According to the present invention, when the horizontal line period is set to be different from the horizontal line period of other field signals in units of fields, the horizontal drive frequency is changed for each horizontal line period, and the difference between the horizontal drive frequencies is filtered. Lower than the characteristic cutoff frequency. As a result, the current inflow / outflow frequencies of the electronic components connected to the power supply line of the imaging apparatus can be dispersed in the time domain. Accordingly, the current is dispersed in the frequency direction as compared with the drive current at a single frequency, and the frequency dispersion of the current load fluctuation can be realized. As a result, the so-called squeaking phenomenon of the electronic component is made inconspicuous, noise during voice recording in moving image shooting of the imaging device can be reduced, and good voice recording can be performed.

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

[First Embodiment]
First, in the first embodiment of the present invention, the overall configuration of the imaging apparatus and the basic photographing process will be described with reference to FIGS. 1 to 4, and the characteristic operation of the present invention will be described in detail with reference to FIG.

  FIG. 1 is a block diagram showing the overall configuration of the imaging apparatus according to the present embodiment.

  In FIG. 1, the imaging apparatus has a known configuration except for functions (described later) of the system control circuit 50, and description of each component will be omitted or simplified as appropriate. The light beam incident on the lens 310 is imaged on the imaging unit 14 as an optical image via the aperture 312 and the shutter 12. The imaging unit 14 includes a CCD type imaging device. The A / D converter 16 converts the output signal of the imaging unit 14 from analog to digital. 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. Reference numeral 15 denotes an analog imaging signal area.

  The image processing circuit 20 performs pixel interpolation processing and color conversion processing on data from the A / D converter 16 or the memory control circuit 22, and performs arithmetic processing using the captured image data. The system control circuit 50 controls the exposure control unit 40 and the distance measurement control unit 42 based on the calculation result. The memory control circuit 22 controls the A / D converter 16, the timing generation circuit 18, the memory 30, and the like.

  The image display memory 24 stores image data for display. The image display unit 28 displays an image. The memory 30 stores still image data and moving image data with sound (moving image with sound added). The memory 30 is also used as a work area for the system control circuit 50. The compression / decompression circuit 32 performs compression / decompression processing on the image data in the memory 30 and writes it in the memory 30.

  The shutter control unit 40 controls the opening and closing of the shutter 12 in cooperation with the aperture control unit 340 based on the photometry information from the photometry unit 46. The distance measuring unit 42 performs AF (autofocus) processing and measures the in-focus state of the optical image of the subject. The photometry unit 46 performs AE (automatic exposure) processing, and measures the exposure state of the optical image of the subject.

  A system control circuit 50 (setting means, control means) controls the entire imaging apparatus. Further, the system control circuit 50 performs processing shown in each flowchart described later based on the control program, and also performs setting of a horizontal line cycle of a captured video signal, noise reduction control at the time of recording audio for moving image shooting, and the like. It has the following functions.

  The system control circuit 50 is configured to set at least one horizontal line period of a field signal constituting a frame signal to be different from the horizontal line period of other field signals in a field unit when performing audio recording during moving image shooting. The following control is performed. The horizontal drive frequency is changed every horizontal line period of an integer N equal to or greater than 1, and the difference between the horizontal drive frequencies is lower than the cut-off frequency of the low-pass filter characteristic or the cut-off frequency of the high-pass filter characteristic Control to be higher.

  Further, the system control circuit 50 sets the at least one horizontal line period of the field signal constituting the frame signal to be different from the horizontal line period of the other field signal in the field unit when performing audio recording at the time of moving image shooting. In doing so, the following control is performed. The horizontal driving frequency to be changed for each horizontal line period of an integer N equal to or greater than 1 is set to a frequency lower than the cut-off frequency of the low-pass stop filter characteristic or a frequency higher than the cut-off frequency of the high-pass stop filter characteristic.

  The system control circuit 50 performs the following control. The horizontal line period is changed by adjusting the length of a period other than the effective pixel period of the horizontal line in the CCD type image sensor that constitutes the imaging unit 14. The horizontal line period is changed by adjusting the length of the blanking period of the horizontal line. The horizontal line period is changed by adjusting the length of the empty transfer period of the horizontal line. The function of the system control circuit 50 described above will be described in detail in the operation explanation part of each embodiment.

  The memory 52 stores constants, variables, control programs, and the like for operating the system control circuit 50. The display unit 54 displays an operation state, a message, and the like. The nonvolatile memory 56 can electrically erase and record data. The mode dial 60 is used for switching between the still image shooting mode and the moving image shooting mode. The power switch 72 is used for power on / off of the imaging apparatus, switching of power on / off of the lens unit, the external strobe, and the recording media 200 and 210. The real time clock circuit 74 implements a timer function.

  The power control unit 80 includes a battery detection circuit, a DC-DC converter, a switch circuit that switches a block to be energized, and the like, and detects whether or not a battery is attached. Further, the power control unit 80 controls the DC-DC converter based on the detection result and the instruction from the system control circuit 50, and supplies a necessary voltage to each unit including the recording medium for a necessary period. Control for reducing noise during audio recording in moving image shooting accompanying vibration of the circuit board caused by electronic components mounted on the DC-DC converter will be described later.

  The I / Fs 90 and 94 manage the interface with the recording medium. The connectors 92 and 96 connect to the recording medium. The detection unit 98 detects whether or not the recording media 200 and 210 are attached to the connectors 92 and 96. The antenna / antenna 112 is connected to an external device through wired / wireless communication by the communication unit 110. The recording media 200 and 210 include a memory card, a hard disk, and the like, and include a recording unit 202, an I / F 204, a connector 206, a recording unit 212, an I / F 214, and a connector 216, respectively.

  The aperture control unit 340 controls the aperture 312 in cooperation with the shutter control unit 40 based on the photometry information from the photometry unit 46. The distance measurement control unit 342 controls focusing of the photographing lens 310. The zoom control unit 344 controls zooming of the photographing lens 310. The lens system control unit 350 controls the entire lens unit.

  The microphone 155 is used for recording sound. The speaker 157 reproduces a recorded voice or a previously stored voice. The audio A / D / D / A conversion unit 159 A / D converts the audio input from the microphone 155 into a level and format suitable for the imaging apparatus, and transmits the output audio data. To the speaker 157. Details of the audio signal processing system (FIG. 10) including the audio A / D / D / A converter 159 will be described later.

  FIG. 2 is a flowchart showing the basic photographing process of the imaging apparatus.

  In FIG. 2, this processing is executed by the system control circuit 50 based on a program. Each part of the image pickup apparatus is initialized when the power is turned on (step S201). Next, the state of the power switch 72 is determined (step S202). If the power is OFF, the power control unit 80 performs an end process (step S203), and the process returns to step S202. If the power switch 72 is ON, it is determined whether the remaining capacity of the power supply 86 and the operation status have a problem in the operation of the imaging apparatus (step S204).

  If there is a problem, after displaying a warning (step S205), the process returns to step S202. If there is no problem, it is determined whether or not the recording media 200 and 210 are mounted, management information of the recorded image data is acquired, and whether or not the operation state has a problem in the image recording / reproducing operation (step S206). If there is a problem, after displaying a warning (step S205), the process returns to step S202. If there is no problem, the process shifts to an electronic finder mode for performing control such as increasing the number of read pixels of the image sensor 14 to a necessary rate as an electronic finder moving image (step S207).

  Next, the state of the shutter switch SW1 is determined (step S208). If the shutter switch SW1 is not pressed, the process returns to step S202. If the shutter switch SW1 is pressed, the state of the mode dial switch 60 is further determined (step S209). In the still image shooting mode, the moving image mode flag is reset (step S210), and in the moving image shooting mode, the moving image mode flag is set (step S211). Thereafter, distance measurement processing, photometry processing, and WB (white balance) detection are performed (step S212).

  Next, the state of the shutter switch SW2 is determined (step S213). If the shutter switch SW2 is pressed, the moving image mode flag is confirmed (step S214). If the flag is in the reset state, still image shooting processing is performed (step S216), and the process returns to step S202. If the flag is set, moving image shooting processing is performed (step S217), and the process returns to step S202. If the shutter switch SW2 has not been pressed, the current process is repeated until the shutter switch SW1 is released (step S215). When the shutter switch SW1 is released, the process returns to step S202.

  FIG. 3 is a flowchart illustrating still image shooting processing of the imaging apparatus.

  In FIG. 3, this processing is executed by the system control circuit 50 based on a program. After shooting conditions are set and the aperture 312 is driven to a predetermined aperture value (step S301), the CCD drive mode is set (step S302), and the electronic shutter is set (step S303). Next, exposure of the imaging unit 14 is started (step S304), the shutter 12 is closed (step S305), and exposure of the imaging unit 14 is ended (step S306). Next, an imaging signal reading process is performed (step S307), and photographed still image data is written in a predetermined area of the memory 30 (step S308). After this processing, the processing returns to the processing in FIG.

  FIG. 4 is a flowchart showing the moving image shooting process of the imaging apparatus.

  In FIG. 4, this processing is executed by the system control circuit 50 based on a program. After shooting conditions are set and the aperture 312 is driven to a predetermined aperture value (step S401), the CCD drive mode is set (step S402), and the electronic shutter is set (step S403). Next, the imaging signal readout process is started (step S404).

  First, a charge signal is read from the imaging unit 14, and one horizontal line cycle is changed (step S405). One horizontal line period can be changed to an arbitrary length. Further, the moving image data is written to a predetermined area of the memory 30 through the A / D converter 16, the image processing circuit 20, the memory control circuit 22, or directly from the A / D converter 16 through the memory control circuit 22. (Step S406).

  The AF process is continued until the moving image recording (step S406) is stopped. If the distance measurement (AF) is determined to be in focus, the photometry unit 46 performs an AE (automatic exposure) process (step S407). If it is determined that distance measurement / photometry is appropriate, the distance measurement / photometry data and / or setting parameters are stored, and the sensitivity value (Dv value), aperture value (Av value), shutter speed (Tv value), and focus are set. The resetting is performed (step S408), and the moving image recording is continued (step S406). When the shutter switch SW2 is pressed again or an operation for ending moving image recording is performed (step S409), this process ends, and the process returns to the process of FIG.

  Next, control for performing frequency dispersion of current load fluctuations during moving image shooting processing in the imaging apparatus of the present embodiment having the above-described configuration will be described with reference to FIG.

  In the present embodiment, the frequency dispersion control of the current load fluctuation makes the so-called squeaking phenomenon of the electronic components connected to the power supply line of the imaging device inconspicuous, and it is possible to reduce noise during audio recording in moving image shooting. Enable voice recording.

  The main parts of the imaging apparatus shown in FIG. 1 (analog imaging signal region 15 (including imaging unit 14 and A / D converter 16), timing generation circuit 18 and system control circuit 50) are conventional examples (FIG. 11). The function similar to that shown in FIG. That is, functions similar to those of the synchronization signal generation circuit 2007 and the oscillation circuit 2008 are built in the system control circuit 50. A function similar to that of the oscillation circuit 2005 is built in the timing generation circuit 18.

  Further, the same functions as those of the digital signal processing unit 2004 shown in the conventional example (FIG. 11) are not incorporated in a single block in FIG. 1, but the image processing unit 20, the memory control unit 22, the image display. The memory 24 is divided and incorporated.

  FIG. 5 is a timing chart showing details of one horizontal line cycle change (step S405 in FIG. 4) in the moving image shooting process of the imaging apparatus.

  In FIG. 5, in the case of a CCD type image pickup device, the number of pixel clocks constituting the horizontal line period of the image pickup signal (video signal) is roughly divided into a blanking period and a driven pixel readout period. The blanking period is a period during which the horizontal CCD transfer drive pulses (H1, H2) output from the timing generation circuit 18 are stopped. The pixel readout period is an OB (optically shielded) pixel period + an effective pixel period.

  In the present embodiment, as shown in FIG. 5, the horizontal line period is changed for each horizontal line, and the method of adjusting the length of the horizontal blanking period without affecting the pixel readout period is used. Yes. In other words, if the cycle of one horizontal line period as a reference is (tHD1 = tIMG + tBLK1), it is set to (tBLK2 = tBLK1 + Δt), so that the pixel readout period is not affected. The length can be changed.

  As a specific operation, in the imaging signal readout process (step S404) in FIG. 4 described above, an active period of horizontal blanking corresponding to (tBLK2 = tBLK1 + Δt) is given from the system control circuit 50 to the timing generation circuit 18. Set. The timing generation circuit 18 receives the set horizontal blanking active period information (PBLK) and interlocks with the timing change at the end of the horizontal blanking period. The timing generation circuit 18 has a function of relatively changing the drive start timings of all horizontal system timing signals supplied to the CCD elements, analog signal processing circuits, and the A / D converter 16 in the imaging unit 14.

  As an example in FIG. 5, a clamp pulse (CLPOB) indicating an OB pixel period is used to adjust a DC voltage level so that an OB (optically shielded) pixel level becomes a black reference value of an imaging signal. Also, the timing position is changed in conjunction with the expansion of PBLK.

  Since the length of one horizontal line period can be changed by changing the horizontal blanking period, the cycle in which H1, H2, and the vertical transfer pulse are output for each horizontal line period can be changed. Along with this, the cycle of the current load of the timing generation circuit 18 changes.

  That is, as described above, a current load of about 100 mA is generated during the period when H1 and H2 are output from the timing generation circuit 18, and the current load is zero during the blanking period when H1 and H2 are not output. By changing the blanking period of one horizontal pulse, the generation cycle of the current load generated by H1 and H2 and the current load generated by the vertical transfer pulse is changed, and the frequency dispersion of the current load fluctuation can be realized.

  For example, if Δt = (tHD1) / 2, tHD2 = tIMG + tBLK1 + (tHD1) /2=1.5*tHD1. As a result, tHD2 can be made 1.5 times longer than one horizontal line period (tHD1), and the current load cycle is also 1.5 times longer. By changing Δt to an arbitrary time for each horizontal line period, frequency dispersion of current load fluctuations can be realized.

  In this embodiment, a method of adjusting the length of the horizontal blanking period without affecting the pixel readout period is used with the change of the horizontal line period for each field signal. In the case of this method, all the horizontal timing signals supplied to the CCD element, the analog signal processing circuit, and the A / D converter 16 in the imaging unit 14 are interlocked with the timing change at the end of the horizontal blanking period. It is necessary to change the drive start timing. The timing generation circuit 18 is provided with a function for that purpose, but it is also assumed that the timing generation circuit 18 does not have such a function.

  If the timing generation circuit 18 can change the timing in a programmable manner for all the related horizontal timing signals, it is not impossible to change the timing all at once during the immediately preceding vertical blanking. In this case, the task of the system control circuit 50 becomes heavy accordingly. In addition, if there is a timing signal that cannot be changed at a fixed timing, or if there is a timing signal that does not immediately change even if the change is set, this method cannot change the horizontal line period for each field signal.

  As described above, according to the present embodiment, when performing audio recording at the time of moving image shooting, at least one horizontal line cycle of a field signal constituting a frame signal is set to a horizontal line cycle of another field signal in units of fields. The following control is performed when setting differently. Control such as changing the horizontal drive frequency for each horizontal line period of an integer N of 1 or more is performed.

  This makes it possible to disperse the current inflow / outflow frequencies of electronic components (decoupling capacitors, coupling inductors) connected to the power supply line of the imaging device in the time domain. Along with this, the current / voltage accumulation and discharge frequency changes with time, so the current is distributed in the frequency direction compared to the drive current at a single frequency, and the frequency dispersion of the current load fluctuation is realized. Can do.

  As a result, the so-called squeaking phenomenon of electronic components connected to the power supply line of the imaging device is made inconspicuous, noise during audio recording during imaging of the imaging device can be reduced, and good audio recording can be performed. Become.

[Second Embodiment]
The second embodiment of the present invention is different from the first embodiment in the points described below. Since the other elements of the present embodiment are the same as the corresponding ones of the first embodiment (FIG. 1), description thereof is omitted.

  In this embodiment, the control described below makes the so-called squeak phenomenon of electronic components connected to the power supply line of the imaging device inconspicuous, and enables noise reduction during audio recording in moving image shooting, and good audio recording Is possible.

  In the present embodiment, the setting for changing the horizontal line period for each field signal is made in the timing generation circuit 18 of the imaging apparatus by a method different from that of the first embodiment.

  As described above, in the case of a CCD type imaging device, the number of pixel clocks constituting the horizontal line period of the imaging signal (video signal) is roughly divided into a blanking period and a driven pixel readout period. However, blanking period: a period in which the drive pulses (H1, H2) for horizontal CCD transfer are stopped. Pixel readout period: OB pixel period + effective pixel period.

  In this embodiment, the blanking period is not changed as it is, and the horizontal line cycle is changed by adding an empty transfer period of the horizontal CCD to the end of the pixel readout period (OB pixel period + effective pixel period). . Horizontal CCD empty transfer refers to the following state. Charges exposed and accumulated in the light-receiving pixel unit are read out to the horizontal CCD unit, transferred from the horizontal CCD unit and read out, and further, driving pulses (H1, H2) for horizontal CCD transfer to the horizontal CCD unit. Is an idle reading state in which there is no accumulated charge when the signal is continuously sent.

  FIG. 6 is a timing chart showing the change of the horizontal line cycle by adjusting the length of the horizontal CCD empty transfer period for each field signal of the imaging apparatus according to the present embodiment.

  In FIG. 6, an extra empty transfer period is provided at the end of the effective pixel period of one horizontal line, and the number of pixel clocks in the empty transfer period of one horizontal line is (Δtx). The number of pixel clocks in the empty transfer period of the next one horizontal line is changed to (Δtx + n) by adding n clocks to the number of pixel clocks Δtx in the empty transfer period of one horizontal line.

  As specific operations, the following two settings are performed in the imaging signal readout process (step S404) shown in FIG. That is, the system control circuit 50 sets the timing generation circuit 18 so that the horizontal CCD transfer drive pulses (H1, H2) corresponding to the horizontal synchronization signal HD are maintained until the next HD input. In addition, the setting for resetting the drive start timings of all the horizontal system timing signals supplied to the CCD element, the analog signal processing circuit, and the A / D converter 16 in the imaging unit 14 at the next horizontal synchronization signal HD input is performed. Do.

  Thereby, it is not necessary to change the timing of each field, such as the timing of the clamp pulse (CLPOB) indicating the OB pixel period as shown in the first embodiment.

  The length adjustment of the horizontal CCD empty transfer period for each field signal is a period adjustment in the portion after the effective pixel period of the horizontal CCD ends, and does not stop the charge transfer in the middle of the effective pixel period. Therefore, there is no fear that an adverse effect is caused when the next field signal is read by the transfer residual charge of the horizontal CCD. In addition, the original image to be displayed on the display unit of the imaging apparatus is not affected at all.

  The present embodiment is the same as the first embodiment with respect to changing one horizontal line period, but the generation period of the current load of the timing generation circuit 18 is different from the first embodiment. However, the generation period of the current load generated by the vertical transfer pulse is the same as that in the first embodiment.

  That is, by setting the number of pixel clocks in the empty transfer period of one horizontal line to (Δtx) or (Δtx + n), the period during which the load current of the horizontal CCD transfer drive pulses (H1, H2) is generated becomes longer. Although the length of the blanking period is the same, since the period in which the load currents H1 and H2 are generated changes, the period for each horizontal line period changes and the current load period can be dispersed.

  As described above, according to the present embodiment, the so-called squeaking phenomenon of electronic components connected to the power supply line of the imaging device is made inconspicuous, and noise can be reduced during audio recording in moving image shooting of the imaging device. It is possible to perform good voice recording.

[Third Embodiment]
The third embodiment of the present invention differs from the first embodiment in the points described below. Since the other elements of the present embodiment are the same as the corresponding ones of the first embodiment (FIG. 1), description thereof is omitted.

  In this embodiment, the control described below makes the so-called squeak phenomenon of electronic components connected to the power supply line of the imaging device inconspicuous, and enables noise reduction during audio recording in moving image shooting, and good audio recording Is possible.

  FIG. 7 is a flowchart showing still image recording processing and moving image recording processing with sound of the imaging apparatus according to the present embodiment.

  In FIG. 7, recording an image while recording sound with the imaging apparatus is generally in the case of moving image shooting, and in the case of still image shooting, the moving image shooting will be described. As the operator powers on the imaging apparatus (step S701), the system control circuit 50 shifts to imaging preparation including initialization of the imaging apparatus and power supply to each unit (step S702). The system control circuit 50 sets the initial value of the horizontal driving frequency of the CCD and the like in a state where it is ready for photographing (step S703). Since there is no shooting instruction from the normal operator at the power-on timing, the mode is a confirmation mode for the shot image.

  In general, shooting is started by an operation of a release switch, shutter switch SW1, shutter switch SW2, etc. of the imaging apparatus as a trigger. Therefore, after the power is turned on, the above shooting preparation is performed in order to display a predetermined image for shooting confirmation on a display unit such as an electronic viewfinder. Thereafter, the imaging apparatus including the CCD is initialized. As a result, the preparation for photographing is made so that the operator can recognize it.

  As the shooting mode is selected by the operator, the system control circuit 50 determines whether the shooting mode is still image recording or moving image recording (step S704). When the shooting mode is still image recording by still image shooting, the processing after step S301 is performed. When the shooting mode is moving image recording by moving image shooting, the processing after step S705 is performed. Note that when performing moving image shooting while displaying a subject for preparation for shooting on the display unit of the imaging apparatus, processing similar to that for moving image shooting is performed.

  When the shooting mode is moving image recording, the system control circuit 50 sets shooting conditions (step S705). Specifically, the photographed image size, the frame rate of the moving image to be recorded, and the like are set as photographing conditions. The system control circuit 50 determines the driving method of the imaging apparatus based on the set photographing condition, and changes the horizontal driving frequency of the CCD set to the initial value to a predetermined horizontal driving frequency.

  For example, for each horizontal drive frequency, the cycle of the first horizontal interval is t, the second horizontal interval is 2t, and the third horizontal interval is t. Set. In this embodiment, the time of each horizontal section is set as t, 2t, t..., But the time setting of each horizontal section can be arbitrarily changed. The following settings are made to match the time settings of each horizontal section.

  First, the system control circuit 50 performs setting for reading the first field signal to the imaging unit 14 by the timing generation circuit 18 (step S707). Next, the system control circuit 50 sets the period of the horizontal and vertical synchronization signals supplied from the built-in synchronization signal generation unit to the timing generation circuit 18 and starts the supply (step S708).

  The system control circuit 50 starts and executes the reading of the first field signal from the imaging unit 14 by the timing generation circuit 18 in synchronization with the horizontal and vertical synchronization signals (step S709). The system control circuit 50 converts the moving image data read from the imaging unit 14 and the audio data input from the microphone 155 and subjected to analog-digital conversion (A / D conversion) by the audio A / D / D / A conversion unit 159. Record in the memory 30. When the series of processes is completed, the process returns to the process of FIG.

  As described above, the sound noise frequency can be dispersed by driving the image pickup apparatus by changing the frequency for each horizontal drive frequency when shooting and recording moving images with sound. The manner in which the audio noise frequency is dispersed and reduced is shown in FIG. 8 below.

  As described in the conventional example (FIG. 15), the vibration due to the current consumption pattern mainly due to the electrostriction phenomenon of the capacitor mounted on the DC-DC converter that is the power supply circuit of the imaging device is mounted on the imaging device. Excited by the circuit board.

  FIG. 8 is a diagram illustrating frequency characteristics at the time of voice recording (during voice recording) of the imaging apparatus according to the present embodiment.

  In FIG. 8, the vertical axis indicates sound pressure [dB], and the horizontal axis indicates frequency [Hz]. Reference numeral 1501 denotes a voice recording band indicating a frequency at which voice is recorded. Reference numeral 1502 denotes a Nyquist frequency when the audio is converted from analog to digital (A / D conversion). Reference numeral 1503 denotes an audio sampling frequency for recording audio. Reference numeral 1504 denotes a frequency of sound noise generated by the circuit board vibrating due to the consumption current pattern. Reference numeral 902 denotes a horizontal driving frequency of the imaging apparatus obtained by shifting the horizontal driving frequency by the method of the second embodiment.

  Since the voltage of the capacitor changes with the period when the load of the current consumption pattern increases, and the electrostriction phenomenon occurs due to the horizontal drive frequency of the image pickup apparatus, the audio noise frequency 1504 is the horizontal drive frequency of the image pickup apparatus. For example, when the audio sampling frequency 1503 is set to 10 KHz and the audio noise frequency 1504 is generated, when the horizontal drive frequency is changed for each horizontal line period, the audio frequency spectrum is weighted by the entire time Is assumed. Since the audio noise frequency 1504 is distributed into the audio noise frequency (horizontal drive frequency) 902 and the suppressed audio noise frequency 903, the overall energy is suppressed to half.

  All the noise energy of the noise with respect to the original voice is kept as it is, but the voice noise frequency is dispersed, and noise can be reduced as a way of hearing for human beings. Similarly, the shifted audio noise frequency 902 has half the time-weighted energy, and the frequency peak can be reduced. As a result, it is possible to reduce audio noise caused by recording a peak notably as noise, particularly during audio recording of moving image shooting.

  As described above, according to the present embodiment, the so-called squeaking phenomenon of electronic components connected to the power supply line of the imaging device is made inconspicuous, and noise can be reduced during audio recording in moving image shooting of the imaging device. It is possible to perform good voice recording.

[Fourth Embodiment]
The fourth embodiment of the present invention is different from the first embodiment in the points described below. Since the other elements of the present embodiment are the same as the corresponding ones of the first embodiment (FIG. 1), description thereof is omitted.

  In this embodiment, the control described below makes the so-called squeak phenomenon of electronic components connected to the power supply line of the imaging device inconspicuous, and enables noise reduction during audio recording in moving image shooting, and good audio recording Is possible.

  FIG. 9 is a diagram illustrating frequency characteristics at the time of voice recording (during voice recording) of the imaging apparatus according to the present embodiment, (a) is a frequency characteristic before adding attenuation characteristics, and (b) is It is a frequency characteristic after adding attenuation characteristics.

  In FIG. 9, the vertical axis represents sound pressure [dB], and the horizontal axis represents frequency [Hz]. Reference numeral 1501 denotes a voice recording band indicating a frequency at which voice is recorded. Reference numeral 1502 denotes a Nyquist frequency when the audio is converted from analog to digital (A / D conversion). Reference numeral 1503 denotes a sampling frequency for recording sound. Reference numeral 1504 denotes a frequency of sound noise generated by the circuit board vibrating due to the consumption current pattern.

  Since the voltage of the capacitor changes with the period when the load of the current consumption pattern increases, and the electrostriction phenomenon occurs due to the horizontal drive frequency of the image pickup apparatus, the audio noise frequency 1504 is the horizontal drive frequency of the image pickup apparatus. Reference numeral 1601 denotes an audio noise frequency obtained by superimposing a filter attenuation characteristic on the audio noise frequency 902. Reference numeral 1603 denotes a filter frequency characteristic applied before A / D conversion. Reference numeral 1604 denotes an attenuation amount due to filter characteristics at the audio noise frequency 902.

  That is, FIG. 9A shows a state where the sound noise frequency (horizontal drive frequency) 902 and the sound noise frequency 1504 are distributed. FIG. 9B shows a state where the audio noise frequency 903 is suppressed and the audio noise frequency 1601 obtained by superimposing the filter attenuation characteristic on the audio noise frequency 902 is dispersed.

  FIG. 10 is a block diagram illustrating a configuration of an audio signal processing system of the imaging apparatus.

  In FIG. 10, the microphone amplifier 1701 sets the audio signal input from the microphone 155 to a level suitable for the subsequent stage. The filter 1703 performs band limitation on the audio signal transmitted from the microphone amplifier 1701 and converts it into a characteristic suitable for A / D conversion at the subsequent stage. The A / D conversion unit 1705 of the audio A / D / D / A conversion unit 159 performs analog-digital conversion (A / D conversion) on the audio signal and converts it into a format that can be easily processed by the system control circuit 50.

  The D / A conversion unit 1711 of the audio A / D / D / A conversion unit 159 performs digital / analog (D / A conversion) on the audio signal transmitted from the system control circuit 50. The filter 1709 applies filter characteristics to the D / A converted audio signal. The output amplifier 1707 converts the sound signal from the speaker 157 to a level suitable for sounding.

  The audio signal input from the microphone 155 is input to the system control circuit 50 via the microphone amplifier 1701, the filter 1703, and the A / D conversion unit 1705. When a signal having the audio noise frequency 1504 (FIG. 9) is generated, the frequency is dispersed for each period under the control of the system control circuit 50. That is, the audio noise frequency 1504 is reduced and distributed to the audio noise frequency 903 and audio noise frequency 902 levels. At this time, the filter 1703 converts the level of the audio noise frequency 902 in the frequency domain based on the frequency characteristics determined in advance by the system control circuit 50.

  The system control circuit 50 determines the frequency characteristic and the sampling frequency of the A / D converter 1705. The sampling frequency can be changed by the operator from the operation unit of the imaging apparatus, and a predetermined frequency is selected. The frequency characteristics of the filter 1703 can be changed according to the state at the time of voice recording simultaneously with the selected frequency. In general, a low-pass filter called a wind filter is frequently used.

  For example, it is assumed that the filter 1703 is set to have a low-frequency rejection filter configuration by the system control circuit 50 and has a filter frequency characteristic 1603. The shifted audio noise frequency 902 is suppressed like the audio noise frequency 1601 by the attenuation 1604 due to the filter characteristics. In this way, it is possible to further suppress the dispersed audio noise by moving the audio noise frequency by changing the horizontal drive frequency of the imaging device to the attenuation region of the cutoff frequency of the predetermined filter characteristic. Become.

  The filter 1703 may be arranged as a digital filter after the A / D converter 1705. Further, although the filter 1703 is configured as a low-frequency rejection filter, it may be configured as a high-frequency rejection filter or a band-pass filter. In this case, noise may be reduced by frequency dispersion in a frequency region having a characteristic of attenuating the frequency. Of course, the frequency attenuation characteristic includes the meaning of relative attenuation when the entire signal has gain.

  It is possible to effectively attenuate the sound noise generated by the vibration caused by the electronic component (capacitor) of the power supply circuit due to the load fluctuation of the image pickup device being transmitted to the circuit board by the control of the present embodiment. In addition, it is possible to realize voice noise reduction at a low cost without incurring costs.

  As described above, according to the present embodiment, the so-called squeaking phenomenon of electronic components connected to the power supply line of the imaging device is made inconspicuous, and noise can be reduced during audio recording in moving image shooting of the imaging device. It is possible to perform good voice recording.

[Other embodiments]
In each of the above embodiments, the type of the imaging device is not mentioned, but the present invention can be applied to either a digital camera or a digital video camera.

1 is a block diagram illustrating an overall configuration of an imaging apparatus according to a first embodiment of the present invention. It is a flowchart which shows the imaging | photography basic process of an imaging device. It is a flowchart which shows the still image shooting process of an imaging device. It is a flowchart which shows the moving image shooting process of an imaging device. It is a timing diagram showing details of one horizontal line cycle change of moving image shooting processing of the imaging device. FIG. 10 is a timing chart showing a change in the horizontal line cycle by adjusting the length of the horizontal CCD empty transfer period for each field signal of the imaging apparatus according to the second embodiment of the present invention. It is a flowchart which shows the still image recording process and moving image recording process with a sound of the imaging device which concerns on the 3rd Embodiment of this invention. It is a figure which shows the frequency characteristic at the time of the audio recording of an imaging device. It is a figure which shows the frequency characteristic at the time of the audio | voice recording of the imaging device which concerns on the 3rd Embodiment of this invention, (a) is a frequency characteristic before adding attenuation | damping characteristic, (b) considers attenuation | damping characteristic. This is the frequency characteristic after It is a block diagram which shows the structure of the audio | voice signal processing system of an imaging device. It is a block diagram which shows schematic structure of the imaging part of the imaging device which concerns on a prior art example. It is a block diagram which shows the detailed structure of the imaging circuit of an imaging part. It is a timing diagram which shows the main signals of an imaging part. FIG. 5 is a timing chart showing a rough breakdown of the number of pixel clocks constituting one horizontal line period. It is a block diagram which shows an imaging device and a power supply system. It is a figure which shows the frequency characteristic at the time of audio | voice recording.

Explanation of symbols

DESCRIPTION OF SYMBOLS 14 Image pick-up part 30 Memory 50 System control circuit 155 Microphone 157 Speaker 159 Audio | voice A / D * D / A converter 1701 Microphone amplifier 1703 Filter 1705 A / D converter 1707 Output amplifier 1709 Filter 1711 D / A converter

Claims (14)

In a signal processing apparatus that performs band limitation with a filter on an audio signal recorded together with a video signal imaged by an imaging unit, and performs analog-digital conversion to record,
Setting means for setting a period of a horizontal line of the video signal imaged by the imaging means;
When performing audio recording accompanying imaging by the imaging unit, the setting unit sets at least one horizontal line period of the field signal constituting the frame signal to be different from the horizontal line period of other field signals in units of fields. Control means for changing the horizontal driving frequency for each horizontal line period (an integer N of 1 or more) and controlling the difference between the horizontal driving frequencies to be lower than the cutoff frequency of the filter characteristics, A signal processing apparatus comprising: In a signal processing apparatus that performs band limitation with a filter on an audio signal recorded together with a video signal imaged by an imaging unit, and performs analog-digital conversion to record,
Setting means for setting a period of a horizontal line of the video signal imaged by the imaging means;
When performing audio recording accompanying imaging by the imaging unit, the setting unit sets at least one horizontal line period of the field signal constituting the frame signal to be different from the horizontal line period of other field signals in units of fields. Control means for changing the horizontal driving frequency for each horizontal line period (an integer N of 1 or more) and controlling the difference between the horizontal driving frequencies to be higher than the cutoff frequency of the filter characteristic. A signal processing apparatus comprising: In a signal processing apparatus that performs band limitation with a filter on an audio signal recorded together with a video signal imaged by an imaging unit, and performs analog-digital conversion to record,
Setting means for setting a period of a horizontal line of the video signal imaged by the imaging means;
When performing audio recording accompanying imaging by the imaging unit, the setting unit sets at least one horizontal line period of the field signal constituting the frame signal to be different from the horizontal line period of other field signals in units of fields. And a control means for setting a horizontal drive frequency to be changed for each horizontal line period (integer N equal to or greater than 1) to a frequency lower than the cutoff frequency of the filter characteristic. . In a signal processing apparatus that performs band limitation with a filter on an audio signal recorded together with a video signal imaged by an imaging unit, and performs analog-digital conversion to record,
Setting means for setting a period of a horizontal line of the video signal imaged by the imaging means;
When performing audio recording accompanying imaging by the imaging unit, the setting unit sets at least one horizontal line period of the field signal constituting the frame signal to be different from the horizontal line period of other field signals in units of fields. Control means for setting a horizontal drive frequency to be changed for each horizontal line period (integer N equal to or greater than 1) to a frequency higher than the cutoff frequency of the filter characteristic. .   The signal processing apparatus according to claim 1, wherein the filter is configured as a low-frequency rejection filter.   The signal processing apparatus according to claim 2, wherein the filter is configured as a high-frequency rejection filter.   5. The setting unit according to claim 1, wherein the setting unit changes a horizontal line period by adjusting a length of a period other than an effective pixel period of a horizontal line in a CCD type imaging device constituting the imaging unit. The signal processing device according to any one of the above.   The said setting means changes a horizontal line period by adjusting the length of the blanking period of the horizontal line in the CCD type image pick-up element which comprises the said image pickup means. The signal processing apparatus as described.   The said setting means changes a horizontal line period by adjusting the length of the empty transfer period of the horizontal line in the CCD type image sensor which comprises the said image pickup means. The signal processing apparatus as described.   An image pickup apparatus comprising the signal processing device according to any one of claims 1 to 9, and capable of recording a moving image to which sound is added. In a control method of a signal processing apparatus that performs band limitation on a sound signal recorded together with a video signal picked up by an image pickup means by a low-frequency blocking filter and performs analog-digital conversion to record,
A setting step for setting a period of a horizontal line of the video signal imaged by the imaging means;
When performing audio recording accompanying imaging by the imaging means, the setting step sets at least one horizontal line period of the field signal constituting the frame signal to be different from the horizontal line period of other field signals in units of fields. In this case, the control step of changing the horizontal drive frequency for each horizontal line period (an integer N of 1 or more) and controlling the difference between the horizontal drive frequencies to be lower than the cut-off frequency of the low-frequency rejection filter characteristic. And a control method comprising: In a control method for a signal processing apparatus that performs band limitation on an audio signal recorded together with a video signal imaged by an imaging means by a high-frequency blocking filter and performs analog-digital conversion and recording,
A setting step for setting a period of a horizontal line of the video signal imaged by the imaging means;
When performing audio recording accompanying imaging by the imaging means, the setting step sets at least one horizontal line period of the field signal constituting the frame signal to be different from the horizontal line period of other field signals in units of fields. In this case, the control step of changing the horizontal drive frequency for each horizontal line period (integer N greater than or equal to 1) and controlling the difference between the horizontal drive frequencies to be higher than the cutoff frequency of the high-frequency rejection filter characteristic. And a control method comprising: In a control method of a signal processing apparatus that performs band limitation on a sound signal recorded together with a video signal picked up by an image pickup means by a low-frequency blocking filter and performs analog-digital conversion to record,
A setting step for setting a period of a horizontal line of the video signal imaged by the imaging means;
When performing audio recording accompanying imaging by the imaging means, the setting step sets at least one horizontal line period of the field signal constituting the frame signal to be different from the horizontal line period of other field signals in units of fields. And a control step of setting a horizontal driving frequency to be changed for each horizontal line period (an integer N equal to or greater than 1) to a frequency lower than the cut-off frequency of the low-frequency blocking filter characteristic. Control method. In a control method for a signal processing apparatus that performs band limitation on an audio signal recorded together with a video signal imaged by an imaging means by a high-frequency blocking filter and performs analog-digital conversion and recording,
A setting step for setting a period of a horizontal line of the video signal imaged by the imaging means;
When performing audio recording accompanying imaging by the imaging means, the setting step sets at least one horizontal line period of the field signal constituting the frame signal to be different from the horizontal line period of other field signals in units of fields. And a control step of setting a horizontal driving frequency that is changed every horizontal line period (an integer N equal to or greater than 1) to a frequency that is higher than a cutoff frequency of the high-frequency rejection filter characteristic. Control method.

Images