JP4333427B2 - Information signal processing method and video camera - Google Patents

Description

  The present invention relates to an information signal processing method and a video camera, and more particularly to an information signal processing method for processing a sensor signal detected by a camera shake using an angular velocity sensor in a transmission system having a finite dynamic range, and a video camera equipped with a camera shake correction apparatus. .

  Conventionally, in order to prevent image shake due to camera shake or the like that is likely to occur during handheld shooting of the video camera, the shake information of the video camera is detected by the shake detection means, and the shake is optically or electronically canceled according to the detection result. Various camera shake correction apparatuses that realize camera shake correction by doing so have been proposed.

  This camera shake correction device includes, for example, an active prism that is provided in the preceding stage of a CCD image sensor and corrects an optical axis of imaging light from a subject, an angular velocity sensor that detects an angular velocity in a vertical direction and a horizontal direction of a video camera, and the angular velocity sensor And a control unit for driving the active prism based on the output angular velocity data.

  The control unit includes a high-pass filter and an integration circuit. The high-pass filter removes a DC component from the angular velocity data, and the integration circuit converts the angular velocity data indicating the angular velocity into angle data indicating the angle of camera shake. Converted and supplied to the active prism. The active prism corrects the optical axis of the imaging light in accordance with the supplied angle data, and performs camera shake correction so that light from the same position of the subject is received at the same position of the CCD image sensor.

  However, a conventional video camera equipped with the above-described camera shake correction device has an active prism in a direction opposite to the panning or tilting direction because the camera shake correction is performed by the camera shake correction device even when panning or tilting is performed. The optical axis is corrected, a so-called swinging phenomenon occurs, and there is a problem that the position of the subject in the photographed image does not change despite panning and tilting.

  Therefore, by switching the circuit characteristics of the above-described high-pass filter, discriminating between camera shake and panning or tilting, and performing camera shake correction according to this discrimination result, video that can improve camera shake correction accuracy. A camera has been conventionally proposed (see, for example, Patent Document 1).

JP-A-7-288734 (FIG. 1)

  By the way, in recent years, video cameras have been improved in image quality, and the accuracy required for the camera shake correction function itself has increased. In particular, it has become necessary to be able to reliably correct even a small amount of camera shake, and in order to cope with this, a wide dynamic range is required for the camera shake detection means.

  However, in the conventional video camera described in Patent Document 1, when the camera shake is corrected, the angular velocity sensor detects the angular velocity in the vertical direction and the horizontal direction and supplies it to the 10-bit A / D converter through the filter and the amplifier circuit. As a result, the angular velocity detection data is formed, and the camera shake detection signal is generated from the angular velocity detection data. Therefore, the dynamic range is not sufficient for detecting the shake of minute amplitude. In order to cope with this, it is sufficient to use an A / D converter having a wide dynamic range, but this is not practical, and there are problems such as an increase in the size of a camera shake correction device and a decrease in processing speed.

  The present invention has been made in view of the above points. The sensor signal output from the angular velocity sensor is converted into a plurality of sensor signals having different gains, and the sampling point values of the plurality of sensor signals have a dynamic range. Depending on whether or not the value exceeds the sampling point value of the sensor signal with the optimal gain, or by interpolating from the values of a plurality of sampling points, it is high in the camera shake correction device without increasing the circuit scale It is an object of the present invention to provide an information signal processing method and a video camera that can ensure a dynamic range.

In order to achieve the above object, an information signal processing method according to a first aspect of the present invention is an information signal processing method for transmitting an input analog signal in a transmission system having a finite dynamic range . The first analog signal with gain is converted into one or more second analog signals with one or more second gains smaller than the first gain , and the transmission system is transmitted. A first step and a second step of separately sampling the transmitted first and one or more second analog signals with a predetermined sampling clock to generate first and one or more second digital signals, respectively. of the step, a third step of the value of the sampling points of the first and second digital signals to determine whether dolphins not exceed the dynamic range, the third step, the first If the value of the sampling points of the digital signal is determined not to exceed the dynamic range, select the value of the sampling points of the first digital signal, the third step, the first sampling of the first digital signal When it is determined that the value of the point exceeds the dynamic range and there is one second digital signal, the value of the second sampling point adjacent to one side of the first sampling point of the second digital signal is calculated. A value obtained by correcting the gain with the first gain is selected for the interpolation value calculated by using the first gain, and the value of the first sampling point of the first digital signal has a dynamic range by the third step. It is determined to exceed, and when the second digital signal is plural, the largest second gain in the second digital signal does not exceed the dynamic range Respect granted second first second interpolated value calculated by using the value of the sampling point adjacent to the single side of the sampling points of the digital signal, obtained by the gain correction in the first gain and a fourth step of selecting a value, wherein the values of the fourth selected sampling points in step outputs a time series synthesized signal.

In order to achieve the above object, the information signal processing method of the second invention is characterized in that the fourth step of the first invention is the value of the first sampling point of the first digital signal by the third step. Is determined to exceed the dynamic range, the interpolation value calculated by using the values of the plurality of second sampling points of the second digital signal adjacent to the first sampling point in the time series before and after On the other hand, the value obtained by correcting the gain with the first gain is selected.

In order to achieve the above object, a video camera according to a third aspect of the present invention temporarily stores a video signal obtained by imaging with an imaging device in a video signal memory and also obtains a sensor signal obtained by an angular velocity sensor. Is transmitted through a transmission system with a finite dynamic range, and the image signal corrected by image stabilization from the image signal memory is controlled by variably controlling the readout position of the image signal memory based on the image stabilization signal obtained from the transmitted sensor signal. A sensor signal obtained by an angular velocity sensor, a first sensor signal to which a first gain is applied, and one or a plurality of second gains smaller than the first gain. and one or a plurality of conversion means for converting into a second sensor signal, the first and one or more second sensor signals at a predetermined sampling clock A / D converting means for generating a first and one or more of the second digital sensor signals each sampled people in, whether the value of the sampling points of the first and second digital sensor signal exceeds the dynamic range If the data control unit for determining whether or not the value of the sampling point of the first digital sensor signal does not exceed the dynamic range, the value of the sampling point of the first digital sensor signal When the data control unit determines that the value of the first sampling point of the first digital sensor signal exceeds the dynamic range, and there is one second digital sensor signal, the second For the interpolated value calculated using the value of the second sampling point adjacent to one side of the first sampling point of the digital sensor signal, Select a value obtained by the gain correction in the first gain, the data control unit, the value of the first sampling point of the first digital sensor signal is determined to exceed the dynamic range, and the second If the digital sensor signals of a plurality adjacent on one side of the first sampling point in the second digital sensor signals largest second gain in the second digital sensor signal does not exceed the dynamic range has been granted A selection means for selecting a value obtained by correcting the gain with the first gain for the interpolated value calculated using the value of the second sampling point, and the value of the sampling point selected by the selection means And a camera shake correction signal generating unit configured to generate a camera shake correction signal based on a signal synthesized in time series.

In order to achieve the above object, the video camera of the fourth invention is characterized in that the selection means of the third invention uses the data control unit to set the dynamic range of the first sampling point value of the first digital sensor signal. When it is determined that the value exceeds the interpolated value calculated using the values of the plurality of second sampling points of the second digital sensor signal adjacent to the first sampling point before and after in time series A value obtained by performing gain correction with the first gain is selected.

  Furthermore, in order to achieve the above object, the video camera of the present invention converts the incoming light into a video signal by the image sensor, temporarily stores it in the video signal memory, and obtains the angular velocity obtained by using the angular velocity sensor. In a video camera that realizes camera shake correction by calculating the readout position of the video signal memory from the signal and changing the readout position of the video signal in the video signal memory, the output signal from the angular velocity sensor is amplified by the first gain value And a first signal amplifying means for outputting the first amplified signal, and an output signal from the angular velocity sensor is amplified with a second gain value larger than the first gain value to output a second amplified signal. Second signal amplifying means; selection means for switching the first and second amplified signals at a period twice as long as the video period for driving the video signal memory; and the first and second amplified signals selected by the selecting means The An A / D converter for sampling, a bit expansion means for correcting the gain of the first digital signal obtained by sampling the first amplified signal by the A / D converter by bit expansion, and a first output from the bit expansion means. A first memory for storing one digital signal, a second memory for storing a second digital signal obtained by sampling the second amplified signal by the A / D converter, and the first and second Memory output selection means for selecting one of the first and second digital signals respectively output from the memory, and the value of the first digital signal after gain correction output from the first memory reaches a predetermined value. Is detected, the memory output selection means selects the first digital signal output from the first memory, and the value of the first digital signal whose gain has been corrected is a predetermined value. When full, the memory output means controls the memory output selection means so as to select the second digital signal output from the second memory, and the memory output selection means selects and outputs the second digital signal. And a camera shake correction signal generating means for generating a camera shake correction signal indicating the readout position of the video signal memory based on the first or second digital signal, and the camera shake correction by changing the readout position of the video signal memory by the camera shake correction signal. It is characterized by realizing.

  According to the information signal processing method of the present invention, since a sensor signal with a small amplitude can be transmitted as a digital sensor signal with as large a gain as possible in a system with a finite dynamic range, A / D conversion means for generating a digital sensor signal is provided. As a result, a sensor signal having a small dynamic range can be used to transmit a sensor signal having a small amplitude with high accuracy.

  In addition, according to the video camera of the present invention, among sensor signals obtained by detecting camera shake with an angular velocity sensor, a sensor signal having a small amplitude is transmitted as a digital sensor signal having as large a gain as possible, and the camera shake is based on the digital sensor signal. Since the correction signal can be generated, it is possible to transmit a sensor signal with a small amplitude with high accuracy by using a comparatively small dynamic range as an A / D conversion means for generating a digital sensor signal. Without increasing the amount, it is possible to perform camera shake correction with higher accuracy than in the past.

  Furthermore, according to the present invention, since a high number of bits is effective even when a camera shake with a small amplitude, an error due to arithmetic processing by a microcomputer is small, and a camera shake correction amount can be output with high accuracy. It is possible to provide a video camera capable of improving the performance.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1A is a schematic block diagram of an embodiment of a video camera according to the present invention, and FIG. 1B is a block diagram of an embodiment of a main part of FIG.

  First, incoming image processing will be described in sequence with reference to FIG. Imaging subject light that enters from a lens (not shown) is imaged on a CCD (charge coupled device) 31 that is a solid-state imaging device, photoelectrically converted into an imaging signal, and then digitally converted by an A / D conversion unit 32 to be well known. After being shaped into a video signal by the signal processing circuit 33, it is supplied to the memory 34 and stored therein.

  On the other hand, in the shake detection portion, sensor signals output from the shake sensor 37 in the yaw direction (or yawing direction) and the shake sensor 38 in the pitch direction (or pitching direction), which are angular velocity sensors, are amplified. After being separately amplified by 39 and 40, it is directly supplied to the switch (SW) 46, while further amplified separately by the amplifiers 44 and 45 and supplied to the SW 46. The sensor signal in the yaw direction and the sensor signal in the pitch direction selected by the SW 46 are supplied to the A / D converters 41 and 42 and separately converted into digital signals, and then are sent to the microcomputer 43 (hereinafter referred to as a microcomputer). Supplied.

  The microcomputer 43 performs camera shake sensor signal processing, which will be described later, generates a camera shake correction signal, and corrects camera shake by changing the read position of the memory 34. The digital video signal read from the memory 34 is converted into an analog signal by the D / A converter 35 and then supplied to the monitor 36 to be displayed as a good subject image without camera shake.

  Next, camera shake sensor signal processing will be described with reference to FIG. 2A shows the waveform of the camera shake sensor 37 or 38, and FIG. 2B shows the output waveform obtained with the normal gain of the amplifier 39 or 40. FIG. When there is a camera shake, a sensor signal having a level corresponding to the magnitude of the camera shake is extracted from one or both of the camera shake sensors 37 and 38 according to the direction of the camera shake. Since the input signals of the amplifiers 44 and 45 are the output signals of the amplifiers 39 and 40, the output signal waveform of the amplifier 44 or 45 is an enlarged view of the normal gain waveform of FIG. Gain waveform.

  The two sensor signals, that is, the sensor signal amplified with the normal gain and the sensor signal amplified with the expansion gain, are switched by the SW 46 and digitally converted by the A / D converters 41 and 42. A D range (dynamic range) 1 is supplied to the microcomputer 43. Inside the microcomputer 43, a composite signal of the D range 2 shown by bit extension described later as shown in FIG. The small amplitude portion I in the normal gain sensor signal shown in FIG. 2B is expanded from the normal gain magnitude to the magnitude indicated by II in the synthesized signal shown in FIG. Therefore, the bit accuracy is improved. Based on this synthesized signal, a camera shake correction signal is generated.

  Next, a method for synthesizing two sensor signals having different gains will be described with reference to the block diagram of FIG. 1B, the time chart of FIG. 3, and the flowchart of FIG. FIG. 1B is a detailed block diagram of a gain signal synthesis portion inside the microcomputer 43, and for convenience of explanation, shows a processing unit 43a only for the sensor signal detected by the shake sensor 37 in the yaw direction. Yes.

  The digital sensor signal a in the yaw direction supplied from the A / D conversion unit 41 in FIG. 1A is A / D converted from the output signal of the amplifier 39 during the connection period of the terminal (0) of the SW 46. This is sensor signal data with normal gain obtained, and sensor signal data with expanded gain obtained by A / D conversion of the output signal of the amplifier 44 during the connection period of the terminal (1) of the SW 46.

  The normal gain sensor signal data is digitally amplified (gain correction) by the gain of the amplifier 44 by the bit extension unit 43b of FIG. Here, if the gain of the amplifier 44 is “2”, the above-described bit expansion unit 43b expands the normal gain sensor signal data by 1 bit and sets the LSB thereof to the same level as that of the expanded gain sensor signal data. Set to zero.

  The sensor signal data of the above-described expansion gain is directly supplied to and stored in the memory 55. The switch control (SWCTL) unit 43f controls the switching timing of the SW 46 and the storage timing in the memories 54 and 55 described above.

  FIG. 3 is a time chart showing the operation of acquiring the A / D conversion data of the gain signal. As shown in FIG. 3 (a), the SWCTL unit 43f converts the A / D conversion and data acquisition pulse into 2 of the conventional acquisition pulse. The switching pulse d of SW46 shown in FIG. 5B is generated at a frequency twice that of the data acquisition pulse and at a frequency twice that of the data acquisition pulse. Are supplied to the SW 46 and controlled for switching.

  The A / D conversion and data capture pulse is supplied to the A / D conversion unit 41 as a sampling pulse and also supplied to the memories 54 and 55 as a write pulse. The switching pulse d is supplied to the SW 46 to control the switching of the SW 46, and is supplied to the memories 54 and 55 so that only one of them can be written, and the memory capable of writing can be switched alternately. Here, the memory 54 is controlled to be in a write operation enabled state during the low level period of the switching pulse d, and the memory 55 is controlled to be in a write operation enabled state during the high level period.

  The SW 46 is connected and controlled so as to select the input signal of the terminal (0) during the low level period of the switching pulse d, whereby normal gain sensor signal data from the amplifier 39 via the terminal (0) is converted into the bit extension unit 43b. After the bit expansion (gain correction), the data is stored in the memory 54 based on the data fetch pulse shown in FIG. In addition, the SW 46 is connected and controlled so as to select the input signal of the terminal (1) during the high level period of the switching pulse d, whereby the sensor signal data of the expanded gain from the amplifier 44 via the terminal (1) becomes this high signal. The data is stored in the memory 55 based on the data capture pulse in FIG.

  Therefore, the data storage states of the memories 54 and 55 are as schematically shown in FIGS. 3 (c) and 3 (d). Thereafter, the amplified sensor signal data stored in the memories 54 and 55 is selectively combined by the SW 43c as will be described later, whereby a correction use value c for use in camera shake correction schematically shown in FIG. can get.

  Next, the operation of storing data in the memories 54 and 55 and the operation of selecting and synthesizing sensor signals from the stored data will be described in more detail using the flowchart shown in FIG. First, the sensor signal data capturing operation will be described with reference to FIG. When the sensor signal (angular velocity signal) that is the output of the SW 46 shown in FIG. 1A is input to the A / D converter 41 (step S50), the sensor signal is converted into an A / D signal by the A / D converter 41. It is converted into sensor signal data (step S51).

  Next, it is determined whether or not the SW 46 is connected to the terminal (1) (step S52), and the sensor signal data from the A / D converter 41 is stored in the memory 55 within the period in which the terminal (1) is connected. (Step S54). On the other hand, if the SW 46 is connected to the terminal (0), the bit is expanded by the same gain as that of the amplifier 44 (or 45) by gain correction (step S53) and then stored in the memory 54 (step S55). In this way, the acquisition of the sensor signal data is finished (step S56).

  Next, an operation of selecting and synthesizing sensor signal data and generating a camera shake correction signal will be described with reference to FIG. When the acquisition of the sensor signal data into the memories 54 and 55 is completed according to the procedure shown in FIG. 4A, generation of a camera shake correction signal is started (step S60).

  In the data control unit 43e shown in FIG. 1B, a reference value Com for determining the magnitude of camera shake is set in advance (step S61). The default value of the reference value Com is a value corresponding to the maximum value of the D range of the amplifiers 44 and 45 and can be adjusted. First, the data control unit 43e reads out the sensor signal data subjected to gain correction (bit extension) stored in the memory 54, and the sensor signal data after the gain correction is larger than the reference value Com and 2 It is determined whether or not it continues for more than a clock (step S62). The reason for determining whether or not two clocks, that is, two or more clocks having the same period as the SW46 switching pulse, are consecutive is to prevent erroneous detection due to noise.

  If the data control unit 43e determines that the sensor signal data whose gain has been corrected is larger than the reference value Com and is continuous for two clocks or more (Yes in step S62), the sensor signal of the expanded gain stored in the memory 55 Since the data is saturated, the switch (SW) 43c is controlled so that the sensor signal data subjected to gain correction stored in the memory 54 is read from the memory 54 and supplied to the camera shake correction signal generation unit 43d ( Step S63).

  On the other hand, when the sensor signal data after gain correction stored in the memory 54 is equal to or less than the reference value Com (No in step S62), the sensor signal data of the enlarged gain stored in the memory 55 is not saturated, Since the small amplitude portion is within the D range 1 as shown in 2 (c), the data control unit 43e reads out the sensor signal data of the enlarged gain stored in the memory 55 from the memory 55, and the image stabilization signal The switch (SW) 43c is controlled to be supplied to the generation unit 43d (step S64).

  Note that when the sensor signal data with gain correction stored in the memory 54 is equal to or less than the reference value Com, the sensor signal data with the expanded gain is selected without selecting the sensor signal data with gain correction. Compared to sensor signal data that has been gain-corrected by simple bit expansion of the digital signal by the unit 43b, the sensor signal with an expanded gain generated by A / D conversion after being amplified by the two amplifiers 39 and 44 This is because the data is data with higher resolution that is more faithful to the level of the small-amplitude portion. Therefore, even if the same 10-bit A / D converter as the conventional one is used as the A / D converter 41, for example. Therefore, it is possible to perform more accurate camera shake correction in the small amplitude portion.

  As described above, the magnitude of the camera shake is determined according to the comparison result between the sensor signal data with the gain corrected and the normal gain stored in the memory 54 and the reference value Com, and is stored in the memory 54 or the memory 55. By determining which sensor signal data is used and reading it out, the time-series synthesized signal of the D range 2 shown in FIG. 2D is obtained from the SW 43c. This combined signal corresponds to the correction use value c described above.

  Thereafter, in the camera shake correction signal generation unit 43d in FIG. 1B, DC (direct current) component removal by the high pass filter (HPF) is performed on the input sensor signal data (synthesized signal) (step S65), and HPF. Removal of pan / tilt components (step S66), integration processing (step S67) using a low-pass filter (LPF) are sequentially performed, and finally zoom gain processing (step S68) for correcting the zoom magnification is performed.

  In this way, the camera shake correction signal generated by the camera shake correction signal generation unit 43d is output to the memory 34 (step S69). The reading position of the memory 34 is controlled by the camera shake correction signal, and a video signal in which the camera shake in the yaw direction is corrected is read from the memory 34.

  Note that the processing unit 43g having the same configuration as the processing unit 43a in the yaw direction is also applied to the digital sensor signal b in the pitch direction supplied from the A / D conversion unit 42 in FIG. Then, the same processing as described above is performed in parallel, and a video signal in which the camera shake in the pitch direction is corrected is read from the memory 34.

  Next, another embodiment of the present invention will be described. 5A shows only the output of the amplifier 39 (or the amplifier 40, hereinafter referred to as the yaw direction sensor 37) shown in FIG. 1A, the same applies to the output of the pitch direction sensor 38. FIG. )), And FIG. 5B shows the output signal waveform of the amplifier 44. Since these signal waveforms are switched by the SW 46, the output signal waveform of the SW 46 is as shown in FIG.

  Here, assuming that the limit of the dynamic range of the A / D converter 41 is TH, the large amplitude signal is saturated with TH, so that the signal waveform as shown in FIG. 5D is sampled by the A / D converter 41. The The state of the sampling is shown in FIG. In FIG. 5E, p1, p2,... Represent sampling points related to the output signal waveform of the amplifier 39, and q1, q2,. The levels of these sampling points are digital signals.

  FIG. 5 (f) shows digital information in an analog waveform after interpolation processing after A / D conversion by the A / D converter 41. When the output signal of the amplifier 44 is less than the limit (saturation level) TH of the dynamic range of the A / D converter 41, information on the sampling points q1, q2,. Output signal exceeds the limit TH of the dynamic range of the A / D converter 41, that is, when the value of the sampling point q * (* is a natural number) is TH, the sampling point p1 of the output signal of the amplifier 39 , P2,...

  The interpolation method is as follows, for example.

(First interpolation method)
In this first interpolation method, information on the sampling point of the output signal of the amplifier 39 adjacent to the sampling point of the output signal of the amplifier 44 to be interpolated (eg, p5 or p6 if q5 in FIG. 5E). A value obtained by doubling the value (which is digitized after the A / D conversion and expressed in the binary system, so that only bit shift is performed) is interpolated as indicated by r5 in FIG. 5 (f).

  When interpolating with a signal at a later time, a buffer is used so that processing can be performed using a signal that comes later. More specifically, the sampling points p1, p2,... And q1, q2,. The signals shown in FIGS. 6 (a) to 6 (e) correspond to the signals shown in FIGS. 3 (a) to 3 (e), and the corrected use value is the sampling point q as shown in FIG. 6 (e). When the value of * (* is a natural number) is TH, interpolation values r5 to r8 obtained by doubling the information of the sampling point p * of the output signal of the amplifier 39 are used. These values r5 to r8 are the values shown in FIG.

  In this case, the interpolated value has a resolution of 1/2 in the amplitude direction, but has an advantage that it can be realized by a simple process called bit shift. This reduction in resolution occurs at large amplitudes. For example, in a video camera for high-definition video shooting, large-amplitude camera shake is corrected as before, and the image is high-definition. Because small camera shakes are particularly problematic, if small amplitude camera shakes are corrected with a particularly high accuracy, large amplitude camera shakes occur relatively infrequently, even if the user intends to hold them firmly. As a high-definition image is taken, the hand shake due to the fine shake is constant, so that even if this fine hand shake is corrected with high accuracy, the obtained image is a great improvement.

  In this example, the switching output by SW is substituted with the value obtained from the value before or after the point to be interpolated in the sampled signal. Become. This is practically not a problem when the change in the signal of the camera shake detection output is sufficiently slow with respect to the sampling period.

(Second interpolation method)
In the second interpolation method, the information of the sampling points (for example, p5 and p6) of the output signal of the amplifier 39 adjacent to the sampling point (for example, q5) of the output signal of the amplifier 44 to be interpolated is added to obtain r5. Interpolate. In this case, since the interpolation is performed from the information at the time points before and after the point to be interpolated, the information at the time point q5 is predicted. According to this method, for example, when the value of p5 is “6” and the value of p6 is “7”, the added value is “13”, which is a predicted interpolated value, but as in the first interpolation method. However, the resolution is not reduced.

  Each waveform according to the second interpolation method is specifically shown for p1, p2,... And q1, q2,. The signals shown in FIGS. 7A to 7E correspond to the signals shown in FIGS. 3A to 3E, and the corrected use value is the sampling point q as shown in FIG. 7E. When the value of * (* is a natural number) is TH, interpolated values r5 to r8 obtained by adding the information of the sampling points of the output signal of the amplifier 39 adjacent to the sampling point are used.

  As described above, according to the first and second interpolation methods, a small amplitude signal is input to the A / D converters 41 and 42 with a large gain. For large-amplitude signals that saturate with respect to the dynamic range, a smaller gain signal is placed at the adjacent sampling point and interpolated from the signal, enabling high-accuracy correction for small-amplitude camera shake. At the same time, it is possible to drive the correction means with an amount corresponding to the large amplitude by the signal generated by interpolation even for a large amplitude camera shake.

  In the first interpolation method, the signal to be interpolated is a signal at a point shifted by the sampling period from the point to be interpolated, but the interpolated signal and the interpolated signal are not affected by this time lag. In order to match the time point, a delay circuit for the sampling period may be inserted before the input to the SW 46 at the output of either the amplifier 39 or the amplifier 44.

  Also, when interpolating with information created from the previous sampling point (specifically, for example, in FIG. 5 (e), when interpolating by multiplying the signal at time q5 by the signal p5), When inserting a delay circuit 47 (and 48) for one sample period on the side of the amplifier 44 (and 45) as shown in FIG. 8 and interpolating with information created from a later sampling point (specifically, for example, FIG. 5). In (e), when the signal at the point of q5 is interpolated by doubling the signal of p6), as shown in FIG. 9, the delay circuit 49 (and for one sample period) is placed on the amplifier 39 (and 40) side. 50) may be inserted.

  In the above embodiment, two amplifiers 39 and 44 (or amplifiers 40 and 45) are prepared to generate two sensor signals having different gains from the output sensor signal of one sensor 37 (or 38). However, in order to obtain a waveform as shown in FIG. 5C, the output sensor signal of one sensor 37 (or 38) may be amplitude modulated (AM modulated) to obtain two sensor signals.

  That is, as shown in FIG. 10, the sensor signals output from the sensors 37 and 38 are amplitude-modulated by the AM modulators 101 and 102 and supplied to the A / D converters 41 and 42. The switching pulse d of SW46 is supplied to the AM modulators 101 and 102 as a carrier wave. As a result, the AM modulators 101 and 102 output a waveform in which two sensor signals having different gains are synthesized in a time-series manner with the period of the switching pulse as an AM modulated wave. Here, the sensor output may be appropriately amplified by a preamplifier or the like provided at the subsequent stage of the sensors 37 and 38.

  Further, in the above embodiment, it has been described that signals of two different gains are sequentially sampled. However, the present invention is not limited to signals of two gains. For example, as shown in FIG. And 203 may be used to switch signals of three gains by SW206. Here, assuming that interpolation is performed using a later sampling point, the time points of the original signals sampled by the delay circuits 204 and 205 are aligned at the time of interpolation as in FIG.

  For example, if the gain of the amplifier 201 that first amplifies the output sensor signal of the camera shake sensor is “1”, among the amplifiers 202 and 203 that amplify the output sensor signal of the amplifier 201, the gain of the amplifier 202 is “2”. The gain of the amplifier 203 is “4”. FIG. 12 shows a diagram corresponding to a combination of FIGS. 5E and 5F for the output sensor signals of these three gain amplifiers 201 to 203.

  In FIG. 12, the time alignment by the delay circuits 204 and 205 is also reflected. When the information at the sampling point of the maximum gain does not reach the saturation level TH of the A / D converter 41 (or 42) (for example, s1, s2), that information is used and when the saturation level TH is reached ( For example, s3, s4, etc. are interpolated by bit shift or the like using information on the next highest gain sample point (for example, t3 with respect to s3) (for example, v3 is obtained). When it has reached (for example, both s7 and t7 are saturated), interpolation is performed using information (for example, u7) of the minimum gain sample point (for example, v7 is obtained).

  In this way, by performing A / D conversion and performing interpolation so that a plurality of gains are switched and sampled, minute fluctuations detected by the sensor can be detected with a very large resolution with high accuracy. A slightly large variation is detected with a medium resolution, and the accuracy of the resolution is rough even for a very large variation. Therefore, it is possible to realize both of detecting minute fluctuations with high accuracy and covering a wide fluctuation range. Although switching of three gains has been described above, switching of four or more gains can be similarly realized.

  Further, in the above embodiment, the description has been made so that a signal with a particularly small amplitude is transmitted with high accuracy in a transmission system having a finite dynamic range such as the A / D converters 41 and 42. However, the present invention is not limited to this. The present invention is not limited, and can be applied to, for example, a transmission system using a non-linear circuit described below.

  FIG. 13 is a block diagram showing another embodiment of the main part of the present invention. In the figure, the same components as those in FIG. 1A are denoted by the same reference numerals, and the description thereof is omitted. In the embodiment shown in FIG. 13, using coring circuits 71 and 72 as a kind of non-linear circuit, a sensor signal that passes through the coring circuits 71 and 72, and a delay circuit 51 that does not pass through the coring circuits 71 and 72. , 52 is used to switch the sensor signal delayed at 52 with SW 46. The input / output characteristics of the coring circuits 71 and 72 have a dead band with respect to a small amplitude of the input as shown in FIG. 14A, for example. The slope of the input / output characteristics other than the dead band is shown in FIG. It is set to 1.

  FIG. 15 is a signal waveform diagram for explaining the operation of the circuit shown in FIG. The signal waveforms shown in FIGS. 15A to 15F correspond to the signal waveforms shown in FIGS. 5A to 5E. FIG. 15A shows a large amplitude sensor signal waveform output from the amplifier 39 that does not pass through the coring circuit 71 (or 72), and FIG. 15B shows a coring to which the large amplitude sensor signal is supplied. The output sensor signal waveform of the circuit 71 (or 72) is shown.

  These sensor signals are alternately switched by the SW 46 in FIG. 13, output as shown in FIG. 15C, input to the A / D converter 41 (or 42), and sampled in synchronization with this switching. . Here, assuming that the limit of the dynamic range of the A / D converter 41 is TH, the large amplitude signal is saturated with TH, so that a signal waveform as shown in FIG. 15D is sampled by the A / D converter 41. The Therefore, the sampling points are as shown in FIG.

  Here, as in FIG. 5, the sampling points q5, q6, q7, and q8 where the signal waveform of large amplitude is saturated at the limit (saturation level) TH of the dynamic range of the A / D converter 41 (or 42). Is interpolated using the output sensor signal of the coring circuit 71 (or 72) at the sampling points n5 to n9.

For example, with respect to the signal at the sampling point q5 in FIG.
m5 = TH + {(n5 + n6) / 2}
M5 calculated based on is created and interpolated.

  In the above description, since the slope of the input / output characteristics other than the non-linear dead zone is set to 1 as shown in FIG. 14A, signals up to twice the threshold TH can be passed. If there is a possibility that a signal having an amplitude larger than twice TH is input at the input of the A / D converters 41 and 42, as shown in FIG. If the slope of the output characteristic is made smaller than 1, it is possible to pass through the coring circuits 71 and 72 while keeping the amplitude smaller than TH, so that it can be doubled by interpolating by expanding the information of those sampling points. Passing up to the above large amplitude can be covered.

1 is a schematic block diagram of an embodiment of a video camera of the present invention and a block diagram of a main part. It is a figure explaining the process of the camera-shake sensor signal of the video camera of FIG. 2 is a time chart for explaining an operation of capturing a camera shake sensor signal of the video camera in FIG. 1. It is a flowchart of one embodiment for generating a camera shake correction signal in the present invention. 2 is a signal waveform diagram for explaining the operation of FIG. 1 in more detail with respect to a large peak portion in the camera shake sensor signal of the video camera of FIG. FIG. 6 is an explanatory time chart illustrating an example of an operation for capturing a camera shake sensor signal in FIG. 5. FIG. 6 is a time chart for explaining another example of the camera shake sensor signal capturing operation of FIG. 5. FIG. 3 is a block diagram showing an example of matching the time points of an interpolation signal and an interpolated signal so as not to cause a time lag in the main part of the video camera of the present invention. FIG. 11 is a block diagram of another example in which the time points of the interpolation signal and the interpolated signal are matched so as not to cause a time lag in the main part of the video camera of the present invention. FIG. 10 is a block diagram of another example for obtaining sensor signals having two different gains in the main part of the video camera of the present invention. It is a block diagram of an example of the principal part of the video camera of this invention using the sensor signal of three gains. It is a figure which shows an example of the signal waveform and sampling point of the principal part of FIG. It is a block diagram of other embodiment of the principal part of the video camera of this invention. It is a figure which shows each example of the input-output characteristic of the coring circuit in FIG. FIG. 14 is a signal waveform diagram illustrating the operation of FIG. 13 in more detail with respect to a large peak portion in the camera shake sensor signal of the video camera of FIG. 13.

Explanation of symbols

31 CCD (solid-state image sensor)
32, 41, 42 A / D converter 33 Signal processing circuit 34, 54, 55 Memory 35 D / A converter 36 Monitor 37, 38 Camera shake sensor 39, 40, 44, 45, 201, 202, 203 Amplifier 43 Microcomputer (Microcomputer)
43a, 43g Sensor signal processing unit 43b Bit extension unit 43c, 46, 206 Switch (SW)
43d Camera shake correction signal generation unit 43e Data control unit 43f Switch control (SWCTL) unit 47-52, 204, 205 Delay circuit 71, 72 Coring circuit 101, 102 AM modulator

Claims (4)

An information signal processing method for transmitting an input analog signal through a transmission system having a finite dynamic range,
The input analog signal is converted into a first analog signal to which a first gain is applied, and one or more second analog signals to which one or more second gains smaller than the first gain are applied. A first step of converting and transmitting the transmission system;
A second step of separately sampling the transmitted first and one or more second analog signals with a predetermined sampling clock to generate first and one or more second digital signals, respectively;
A third step of determining whether a value of a sampling point of the first and second digital signals exceeds the dynamic range ;
If it is determined by the third step that the value of the sampling point of the first digital signal does not exceed the dynamic range, the value of the sampling point of the first digital signal is selected, and the third point If it is determined that the value of the first sampling point of the first digital signal exceeds the dynamic range and the number of the second digital signal is one, the step of A value obtained by performing gain correction with the first gain is selected with respect to an interpolation value calculated using a value of a second sampling point adjacent to one side of the first sampling point, and the third gain is selected. By this step, it is determined that the value of the first sampling point of the first digital signal exceeds the dynamic range, and the second digital signal is duplicated. The case, the adjacent on one side of the first sampling point of greatest said second of said second digital signal gain is assigned in the second digital signal does not exceed the dynamic range against calculated interpolation value with the value of the second sampling point, and a fourth step of selecting a value obtained by the gain correction in the first gain is selected by said fourth step And outputting a signal obtained by synthesizing the values of the sampling points in time series. In the fourth step, when it is determined in the third step that the value of the first sampling point of the first digital signal exceeds the dynamic range, the time series of the first sampling point In particular, a value obtained by performing gain correction with the first gain is selected with respect to an interpolation value calculated using values of a plurality of second sampling points of the second digital signal adjacent to each other in the front-rear direction. The information signal processing method according to claim 1 . The video signal obtained by imaging with the image sensor is temporarily stored in the video signal memory, and the sensor signal obtained by the angular velocity sensor is transmitted by a transmission system having a finite dynamic range. Based on the obtained camera shake correction signal, by variably controlling the readout position of the video signal memory, a video camera that reads the video signal corrected for camera shake from the video signal memory,
The sensor signal obtained by the angular velocity sensor is a first sensor signal to which a first gain is given, and one or more second gains to which one or more second gains smaller than the first gain are given. conversion means for converting into a second sensor signal,
A / D conversion means for separately sampling the first and one or more second sensor signals with a predetermined sampling clock to generate first and one or more second digital sensor signals, respectively.
A data control unit for determining whether a value of a sampling point of the first and second digital sensor signals exceeds the dynamic range ;
When the data control unit determines that the value of the sampling point of the first digital sensor signal does not exceed the dynamic range, the value of the sampling point of the first digital sensor signal is selected, and the data When the controller determines that the value of the first sampling point of the first digital sensor signal exceeds the dynamic range, and there is one second digital sensor signal, the second digital sensor signal For the interpolated value calculated using the value of the second sampling point adjacent to one side of the first sampling point of the sensor signal, a value obtained by gain correction with the first gain is selected, wherein the data controller, the value of the first sampling point of the first digital sensor signal is determined to exceed the dynamic range, or The case second digital sensor signals of a plurality, the largest said second gain is assigned a second digital sensor signal in the second digital sensor signal does not exceed the dynamic range selection means for selecting a value obtained by the gain correction in the first to the second interpolated value calculated by using the value of the sampling point adjacent to the single side of the sampling point, the first gain,
And a camera shake correction signal generating unit configured to generate the camera shake correction signal based on a time-sequentially synthesized signal of sampling point values selected by the selecting unit. When the data control unit determines that the value of the first sampling point of the first digital sensor signal exceeds the dynamic range, the selection unit performs time series of the first sampling point. Selecting a value obtained by correcting the gain with the first gain for the interpolated value calculated using the values of a plurality of second sampling points of the second digital sensor signal adjacent to the front and rear. The video camera according to claim 3 .

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