Image pickup device and storage medium readable by computer

The present invention relates to an image pickup apparatus and a computer-readable storage medium which are used in a video camera or the like and have a good shake correction function such as camera shake.

[Conventional Technology] A high-magnification zoom lens is used in a video camera or the like, and a zoom ratio of 10 times or more is generally used in the field of consumer use. As the zoom ratio increases, the focal length on the long focal length side becomes large, and on the long focal length side, camera shake due to camera shake, etc., has a large effect on the captured image, and the main subject becomes the main subject. It moves unsightly on the screen. Therefore, in the field of video cameras and the like, a shake correction function for removing the influence of camera shake and the like has been put into practical use.

[0003] This runout correction function includes at least a runout detection means for detecting a runout component and a runout correction means for correcting runout according to the detection result of the detection means. Among these, as the shake detecting means, the movement of the camera is directly detected by using an electronic detection method for detecting the movement of the image by comparing images between continuous fields or between frames, an angular velocity sensor, an angular acceleration sensor, or the like. A method of measuring can be mentioned.

[0004] On the other hand, as the shake correction means, in addition to the optical shake correction means for optically adjusting the angle of the photographing optical axis in the direction in which the camera shake is removed, actually recording or outputting from the obtained image. Examples thereof include so-called electronic correction means for electronically selecting a range (cutting range) to be performed.

[0005] By the way, when a camera equipped with such a shake correction function is fixed to a tripod for shooting, the noise component from the shake detecting means causes the image that should have been stopped to fluctuate. Sometimes. Therefore, it has a runout determination means for determining whether or not it is installed and fixed in a stable place such as a tripod, and if it is determined by the determination means that the camera is fixed, the band for runout correction is limited to cause noise. A method for removing the shaking of the image has been proposed.

[0006] In this runout determination means, determination is made from the magnitude and frequency component of the runout signal detected by the runout detection means. First, when the runout frequency is lower than the predetermined threshold value A and the runout signal level is lower than the predetermined threshold value B for a predetermined time during normal runout correction, the runout correction is band-limited and unnecessary. Cut the movement. This state is called a stationary mode. On the contrary, in the stationary mode, when the runout frequency is higher than the predetermined threshold value A and the runout signal level is higher than the predetermined threshold value B, the normal correction is returned.

[0007] [Problem to be Solved by the Invention] However, in the above-mentioned conventional example, if a camera is shaken lightly with a finger during a stationary mode fixed to a tripod or the like, the camera is easily released from the stationary mode. However, there was a problem that the image would sway and give a sense of discomfort until the still mode was entered again.

[0008] Therefore, it is an object of the present invention to prevent inadvertently exiting the stationary mode during the stationary mode.

[Means for Solving the Problems] In the image pickup apparatus according to the present invention, an image pickup means for capturing a subject image and outputting an image signal, a shake detection means for detecting the shake of the image pickup means, and the shake detection. When the correction means for correcting the runout of the image signal based on the runout signal detected by the means, the runout frequency detecting means for detecting the frequency of the runout signal, and the detected runout frequency are smaller than the first threshold value. A control means is provided which limits the correction by the runout correction means and releases the limitation when the runout frequency is larger than the second threshold value.

[0010] In the storage medium according to the present invention, based on an imaging process that images a subject image and outputs an image signal, a runout detection process that detects runout of the image pickup means, and a runout signal detected by the runout detection process. The correction process for correcting the runout of the image signal, the runout frequency detection process for detecting the frequency of the runout signal, and the correction by the runout correction process when the detected runout frequency is smaller than the first threshold value are restricted. , When the runout frequency is larger than the second threshold value, the program for executing the control process for releasing the limitation is stored.

[Embodiment of the Invention] FIG. 1 is a configuration diagram showing an embodiment of an imaging device according to the present invention. In FIG. 1, 101 is a first lens group, which is a fixed lens group for focusing. 102 is a second lens group, which is a variable magnification lens group that can move in the optical axis direction for magnification change. 103 is the aperture, 104 is the third lens group, and is the fixed lens group. 105 is the fourth lens group, which is a correction lens group that has both the function of correcting the imaging position moved by the movement of the variable magnification lens group 102 and the function of adjusting the focus, and it is also possible to move in the optical axis direction. It has become. The lens unit formed by these lens groups finally forms a variable-magnification subject image on the imaging surface of the CCD111 as an imaging sensor.

[0012] 121 is a motor, 126 is a motor driver, and the variable magnification lens group 102 is moved by driving the motor 121 by the motor driver 126. Similarly, the correction lens group 105 is moved by 125 motors and 128 motor drivers. 123 is an IG meter and 127 is an IG driver. In the present embodiment, the motors 121 and 125 are assumed to be stepping motors, and the absolute position is detected by counting the number of pulses from the reference position. When using other actuators, a position detection sensor is required if necessary.

[0013] 111 is a CCD (charge coupled device), which converts light into an electric charge. Here, the CCD 111 uses a CCD having a larger number of pixels (number of photoelectric conversion elements) than a standard CCD required for a broadcasting system (for example, the NTSC system). Reference numeral 116 denotes a CCD drive circuit, which drives the CCD 111. The CCD drive circuit 116 is devised so that the line from which the final output area is to be cut out can be selected in the V direction according to the control command from the microcomputer 117 described later.

[0014] In FIG. 3, 301 is the total image size I of the CCD._s, 302, 303, 304 are standard image sizes I according to the broadcasting system_NIs an example of. For example, when valid from the line y1 + 1 below the Δy1 line from the top line, the Δy1 line can be read out at high speed and read from y1 + 1 at the same timing as when a standard size CCD is used for the vertical synchronization signal. ..

[0015] In FIG. 1, reference numeral 112 denotes an analog signal processing unit, which performs predetermined processing on the signal obtained by CCD111 to generate an analog image signal. For example, it includes a CDS circuit (correlated double sampling circuit), an AGC circuit, and the like. Reference numeral 113 denotes an A / D converter, which converts an analog image signal into a digital image signal. 114 is a memory, which can store at least one line of digital image signals and can be read from a predetermined position (address). Reference numeral 115 denotes a digital signal processing unit, which generates a final output image signal.

[0016] The digital image signal stored in the memory 114 still has a large number of pixels as compared with the standard image size. The digital signal processing unit 115 can select the first pixel to be read from the memory 114 according to a control instruction from the microcomputer 117 described later, and is devised to read only the standard image size.

Reference numeral 117 denotes a microcomputer, which controls the entire camera system. For example, it controls motor tribes 126 and 128. In addition, the number of driven pulses is constantly monitored, and variable magnification lens position data and correction lens position data representing the absolute position from the reference position are generated. For example, if the entire stroke can be moved with 1280 pulses, it is divided equally every 10 pulses to generate 128 levels of position data. 140 is a zoom key, which is a key operated by the user when changing the focal length. The microcomputer 117 reads the signal of the zoom key 140 and controls the variable magnification lens 103 accordingly.

Reference numeral 131 denotes an angular velocity sensor, which detects a unidirectional angular velocity component of camera runout (CCD111 runout). 132 is an HPF (high-pass filter), 133 is an amplifier, and 134 is an LPF (low-pass filter), which apply predetermined frequency limitation and amplification to the angular velocity sensor output signal detected by the angular velocity sensor 131. And generate an angular velocity signal.

Reference numeral 135 denotes an angular velocity sensor, which also detects an angular velocity component in the other direction of the camera shake. 136 is an HPF (high-pass filter), 137 is an amplifier, and 138 is an LPF (low-pass filter), which have the same functions as the above 131 to 134 parts. However, both are arranged so as to detect components orthogonal to each other on the imaging surface of CCD111. Specifically, one detects the vertical (V) direction and the other detects the horizontal (H) direction.

[0020] The microcomputer 117 has a built-in A / D converter, and the angular velocity signal in two directions is converted into a digital signal by the built-in A / D converter and becomes angular velocity data. Further, the angular velocity data is subjected to predetermined signal processing to generate vertical and horizontal runout correction signals. The microcomputer 117 transmits the vertical runout correction signal to the CCD drive circuit 116 and the horizontal runout correction signal to the digital signal processing unit 115. As described above, the CCD drive circuit 116 and the digital signal processing unit 115 each change the cutting position according to the runout correction signal.

[0021] As a result of the above series of operations, the total image size I is as shown in FIG._sStandard image size I from 301, for example 302, 304_NCan be cut out by shifting it from the center, and as a result, it becomes possible to correct the runout due to camera shake or the like.

[0022] Reference numeral 143 is a storage medium according to the present invention for storing the control program of the microcomputer. The control program includes a program for executing the processes shown in FIGS. 2 and 4 described later. As the storage medium 143, a semiconductor memory, an optical disk, a magneto-optical disk, a magnetic medium, or the like may be used. Further, they may be configured and used in ROM, RAM, CD-ROM, memory card, floppy disk, magnetic tape, magnetic card and the like.

Next, signal processing for converting the angular velocity data in the microcomputer 117 into a runout correction signal will be described with reference to FIG. Since the same processing is performed in the vertical direction and the horizontal direction, one direction will be described here. First, the angular velocity data is taken in by the process 201. Processing 202 is an HPF (High Pass Filter), which mainly cuts off the direct current component from the angular velocity data. Therefore, the cutoff frequency is low enough. Process 210 is an HPF (High Pass Filter) and 213 is a cutoff frequency table. The HPF210 can select the cutoff frequency from the cutoff frequency table 213.

[0024] The process 203 is an integrator, and outputs an angular displacement signal by integrating the HPF output. Process 204 multiplies the zoom gain and outputs the correction amount. When the camera is shaken by the angular displacement θ, the focal length 1 and the subject movement amount Δx on the imaging surface are Δx = 1 × tan θ ......... (1), so each focal length Multiply the distance-matched gain here. Reference numeral 205 denotes focal length data, and as described above, the position of the variable magnification lens is actually represented by a finite number (for example, 0 to 128).

[0025] 207 is a zoom gain table, and the focal length data and the zoom gain are associated with each other and stored in the ROM area. The zoom gain 204 reads the gain of the focal length data 205 from the zoom gain table 207. The process 206 is a limiter, which limits the output value of the zoom gain 204 and outputs the correction amount. Reference numeral 208 denotes a limiter table, in which the focal length data and the limiter value (the number of pixels to be shifted) are associated with each other and stored in the ROM area. The limiter 206 reads the limiter value corresponding to the focal length data 205 from the limiter table 207, compares the output of the zoom gain 204 with the limiter value, and outputs the limiter value as a correction amount when it is larger than the limiter value.

Reference numeral 211 denotes a runout frequency detector, which detects a runout frequency component from the output signal of the HPF202. The runout frequency detector 211 outputs the most detected frequency data. Reference numeral 212 denotes a runout state discriminator, which discriminates the runout state from the output signal of the HPF202 and the runout frequency data from the runout frequency detector 211, and controls the cutoff frequency of the HPF210. In the present embodiment, the runout discriminator switches between the correction mode and the stationary mode. The correction mode is a mode for normal runout correction, and the static mode is a mode in which the image that should have been stopped sways due to noise of the runout detection system when installed in a stable place such as a tripod. This is a mode that limits the band of the shake correction and removes the shake of the image due to noise in order to prevent the noise.

[0027] In the stationary mode, the cutoff frequency of the HPF210 is changed in order to limit the runout correction band. Specifically, in the normal mode, the cutoff frequency of the HPF210 is set sufficiently low, and in the static mode, it is set to a value required for noise removal. Further, each cutoff frequency is set to a predetermined value in advance.

Next, the operation of the runout state discriminator 212 will be described with reference to FIG. The process of FIG. 4 is repeatedly executed at a predetermined cycle. In addition, processes 403 to 406 are executed independently in the horizontal direction and the vertical direction. Process 402 determines whether or not the mode is currently stationary. When the correction mode is determined by the process 402, the process proceeds to the process 408.

[0029] In the process 408, both the angular velocities S of P and Y have a predetermined threshold value S._eDetermine if it is smaller. Here, P (pitch) is the vertical direction, and Y (yaw) is the horizontal direction. In process 409, it is determined whether or not the runout frequencies f of P and Y are both equal to or less than a predetermined threshold value fg. If both are judged to be fg or less in process 409, the process proceeds to process 410. In process 409, 1 is added to the value of memory Count and saved. In process 411, it is determined whether or not the value of the memory Count is equal to the predetermined value ch. If it is determined in process 411 that it is equal, it moves to process 412, and if it is determined that it is not equal, it ends in process 407.

[0030] In the process 412, the mode shifts to the stationary mode. Specifically, the cutoff frequency of the HPF210 is changed to the value that should be set in the stationary mode. When the conditions are not satisfied in processes 408 and 409, and after executing process 412, the process proceeds to process 413. Save memory Count0 in process 413 and initialize it.

[0031] When the stationary mode is determined by the process 402, the process proceeds to the process 403. In process 403, it is determined whether or not the angular velocity S is smaller than the predetermined threshold value Sa. If it is judged to be large in process 408, it moves to process 404. In the process 404, it is determined whether or not the runout frequency f is smaller than the predetermined threshold value fb. If it is determined in process 404 that it is fb or higher, it moves to process 406. In process 406, the mode shifts to the correction mode. Specifically, change the cutoff frequency of HPF210 to the value that should be set in the correction mode.

[0032] The present embodiment is characterized in that the values of the threshold values fb and fg are different. This is because if you give the camera a shake that lightly flicks the camera with your finger while in static mode, the image will still sway and give you a sense of discomfort until you easily exit the static mode and re-enter the static mode. This is to prevent. That is, by setting the threshold value fb to a value larger than the threshold value fg, it is easy to enter the stationary mode and it is difficult to exit.

Although the cutoff frequency of the HPF 210 is variable in the present embodiment, the characteristics of the integrator 203 may be variable, and the characteristics of both the HPF and the integrator may be variable. Further, in the present embodiment, an electronic shake correction system by cutting out from CCD111 has been described as an example, but a system that corrects runout by shifting a part of the lenses in the lens group and a system having a high refractive index It is clear that the present invention is also effective in the case of an optical runout correction means such as a system that corrects runout by changing the apex angle of a prism (variable apex angle prism (VAP)) in which a liquid is sealed.

[Effect of the Invention] As described above, according to the present invention, it is easy to enter a mode for limiting correction such as a stationary mode fixed to a tripod or the like, and it is possible to make it difficult to pull out. If you give the camera a shake that lightly flicks it with your finger, you can easily exit the static mode as in the past, and the image will sway and give you a sense of discomfort until you enter the static mode again. It can be effectively prevented and good runout correction can be realized.

BRIEF DESCRIPTION OF THE DRAWINGS [Fig. 1] Fig. 1 is a configuration diagram showing an embodiment of an imaging device according to the present invention.

FIG. 2 is a block diagram showing signal processing for converting angular velocity data into a runout correction signal.

FIG. 3 is a configuration diagram showing an imaging surface of a CCD.

FIG. 4 is a flowchart showing the operation of the runout state discriminator.

[Code description] 102 Second lens group (variable lens group) 111 CCD115 Digital signal processing unit 116 CCD drive circuit 117 Microcomputer 131, 135 Angular velocity sensor 143 Storage medium 132, 136 HPF301 All image sizes 302 to 304 Standard image size