JP2005099831A - Electronic still camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic still camera which is small-sized and enables a sharp image to be obtained from even a dark subject and has low power consumption and has optical performance less degraded. <P>SOLUTION: The electronic still camera with a shake compensation function, which has a photographic lens 2, an imaging device 3a, an image recording means 4, and a release switch 10, is provided with an optical shake compensation means, a shake detection means, and a control means for controlling the optical shake compensation means on the basis of an output signal of the shake detection means, and shake compensation is performed at required minimum timings to prevent consumption of a battery, and a shake compensation angle is minimized. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electronic still camera, and is particularly suitable for use in an apparatus that controls an optical shake correction unit based on an output signal of a shake detection unit.

  2. Description of the Related Art Conventionally, a subject image is photographed using an image sensor, and an image signal obtained as a result is subjected to signal processing and converted into image information. Alternatively, various electronic still cameras have been proposed in which recording is performed on recording means including a hard disk.

  On the other hand, various shake correction apparatuses have been proposed for preventing adverse effects due to camera shake or the like when shooting using a shooting apparatus. In addition, as for video cameras and cameras using silver halide films, many cameras with a shake correction function have been provided on the market.

  In these cameras with shake correction function, an image signal generated by a solid-state imaging device (hereinafter referred to as a CCD) is taken out and changed in accordance with the shake of the camera to display an image without shake. A so-called electronic shake correction method or a sensor such as a vibration gyro detects shake, and based on the detection result, the apex angle of the variable apex angle prism is changed or a part of the taking lens is shifted. A so-called optical image stabilizer that prevents a captured image from shaking on the imaging surface is used.

  By the way, recent electronic still cameras have been reduced in size and weight due to the downsizing of CCD and the adoption of flash memory as a storage medium. However, when the camera is reduced in size and weight, there arises a problem that shaking such as camera shake increases when the release button is pressed or during normal holding.

  In addition, in the current electronic still camera, in order to prevent the image signal accumulated in the CCD from being electrically noised and degrading the image quality, it is converted to film sensitivity and compared to the degree equivalent to ISO75. Since a CCD with low mechanical sensitivity is used, it was easily affected by shake.

  In such a situation that is susceptible to the adverse effects of shaking, today's electronic still cameras electrically capture the image signal stored in the CCD when shooting a relatively dark subject in order to avoid the adverse effects of shaking. In order to ensure that the video signal obtained by amplification is at an appropriate level, auto gain control that automatically changes the amplification factor and strobe are provided to automatically fire the strobe. ing.

  However, when shooting a dark subject, even if an image signal corresponding to proper exposure is obtained by auto gain control, the charge accumulated in the CCD is originally small, and therefore a signal with a poor S / N ratio is amplified. There was a problem to become.

  In addition, since the amplification factor of the amplifier circuit is increased, the influence of the noise of the amplifier circuit is increased. As a result, there is a disadvantage that only an image having a poor SN ratio and a poor image quality can be obtained. Further, the above-described disadvantages are particularly noticeable when the electronic zoom, which is an advantage of the photographing apparatus using the CCD, is performed because the CCD pixels are enlarged and displayed.

  In addition, camera shake and other camera shakes affect the framing by electronic zoom, for example, when zooming equivalent to when a super telephoto lens is attached. There was a problem that even a difficult situation would occur.

  Furthermore, in today's electronic still cameras, a mechanical shutter is opened or opened just before shooting for shooting standby or for AF or AE. For this reason, when the enlargement ratio is large, there is a problem that image blur occurs due to vibration caused by the operation of the mechanical shutter. Even if the conventional shake correction device is applied, the shake correction device reacts to the vibration of the shutter and the correction means shifts in either direction, so that a sufficient correction amount cannot be obtained during actual photographing. There was a drawback.

  In addition, even if you try to obtain a proper exposure by incorporating a strobe in the electronic still camera and automatically firing the strobe, light will not reach the far subject, so when shooting a far subject, Eventually, it relied on auto gain control, and had the drawback of only obtaining images with poor image quality.

  In addition, if a strobe with a large guide number is built in so as to force the strobe light to reach far distances, there is a problem that the outer shape of the camera becomes large and the portability is impaired.

  In addition, in order to obtain an image signal by charge accumulation by a single CCD, an electronic still camera cuts out and displays a part of the CCD, and changes the cutout position to perform shake correction. There was a problem that anti-vibration technology could not be applied.

  Also, if you try to always perform the optical shake correction used in video cameras, etc., power consumption will increase, so the life of the battery will be reduced, and a large battery will be required by attaching a shake correction device. There was a problem that the electronic still camera became larger and alienated its portability.

  Further, when trying to always perform optical shake correction used in a video camera or the like, there is a problem that chromatic aberration is caused by the operation of the shake correction device, and the optical performance of the electronic still camera is deteriorated. This problem is particularly important in an electronic still camera that captures still images.

  In view of the above-described problems, an object of the present invention is to provide an electronic still camera with a shake correction function that consumes less power and has little optical performance deterioration.

  The electronic still camera of the present invention is an electronic still camera, in which an imaging lens, an imaging element that receives a subject image through the imaging lens and accumulates charges, and a recording that records an output from the imaging element as an image signal. Means, a release switch for starting photographing, shake correction means for optically correcting shake based on the detection result of the shake detection means, and continuously displaying an image based on the output from the image sensor. Display means, and when the images recorded by the recording means are continuously displayed without photographing the images recorded by the recording means, and when the images recorded by the recording means are photographed And switching frequency characteristics of shake correction by the shake correction means.

  Another feature of the present invention is that in an electronic still camera, an imaging lens, an imaging element that receives a subject image through the imaging lens and accumulates electric charge, and an output from the imaging element. Recording means for recording as a signal, a two-stage release switch, and shake correction means for optically correcting shake based on the detection result of the shake detection means, regardless of the state of the release switch, A first mode for operating shake correction by the shake correction means, a second mode for starting shake correction by the shake correction means when the release switch is pushed to the first stage, and the release switch. The third mode in which the shake correction by the shake correction means is started when the second stage is pressed can be selected.

  Another feature of the present invention is that the electronic still camera has a photographing lens, an image sensor that receives a subject image through the photographing lens and accumulates electric charge, and an auto gain control unit. A recording means for recording the output from the image sensor as an image signal, a release switch for starting photographing, and a shake correction means for performing optical shake correction based on a detection result of the shake detection means; On the premise that the image signal is amplified by the auto gain control means, an auto gain control priority mode for performing photographing, and a shake correction priority mode for performing photographing on the premise that the shake correction by the shake correcting means is operated. , Can be selected.

  According to the present invention, high-quality imaging can be realized with as little power as possible.

(First embodiment)
Hereinafter, a first embodiment of an electronic still camera of the present invention will be described with reference to FIGS.

  FIG. 1 is a perspective view showing an electronic still camera according to a first embodiment of the present invention. FIG. 2 is a block diagram illustrating a configuration of the electronic still camera of the present embodiment. 3 is an exploded perspective view of the lens barrel portion of the electronic still camera, FIG. 4 is a rear view of the lens barrel portion of the electronic still camera, and FIG. 5 is a timing chart for explaining the operation of the electronic still camera. It is.

  In FIG. 1, 1 is a case of an electronic still camera, 2 is a photographing lens, 3 is a CCD substrate on which a CCD 3a is fixed, 4 is a memory card, and is used as a storage medium.

  5 is an electronic circuit, 6 is an electronic viewfinder, 7 is a battery, 8 is a first vibrating gyroscope, 9 is a second vibrating gyroscope, 10 is a release switch, 13 is an external output terminal for video signals, An external output terminal 13a and a second external output terminal 13b are provided. Reference numeral 14 denotes a strobe, and 15 denotes a zoom operation switch.

  The photographic lens 2 is a so-called rear focus type zoom lens similar to that used in a video camera, and includes a zoom lens that is a moving lens and a photographic optical lens that includes a focus lens.

The photographing lens 2 includes an actuator for driving a variable power lens and a focus lens, a sensor for detecting the position of the moving lens, and a shutter.
The CCD substrate 3 is fixed to the photographing lens 2 so that a CCD 3a (not shown in FIG. 1) as an image pickup element is positioned at the focal position. The taking lens 2 is fixed in the case 1.

  The memory card 4 is provided as a storage medium for storing image information as electrical information, and is detachably fixed in the case 1 using a known flash memory.

  The electronic circuit 5 is fixed in the case 1. In the present embodiment, the electronic circuit 5 includes a microcomputer and reads an image signal obtained by the CCD 3a. Then, the read image signal is converted into a format for storing in the memory card 4 and stored in the memory card 4.

  The electronic circuit 5 controls an autofocus operation (hereinafter referred to as AF), exposure control (hereinafter referred to as AE), zooming operation, and shake correction operation with respect to the photographing lens 2.

  Further, the electronic circuit 5 causes the strobe to emit light with an intensity corresponding to the illuminance of the subject, and displays an image captured on the CCD 3 a on the electronic viewfinder 6. In addition, an image signal is output to an external personal computer or a television monitor via the output terminal 13.

  An electronic viewfinder (hereinafter referred to as EVF) 6 is an EVF using a known liquid crystal, and displays an image captured on the CCD 3a as well as shooting information such as a shooting mode and focal length information.

  The battery 7 is a known battery such as a lithium ion battery or an alkaline manganese battery, and is detachably housed in the case 1. The battery 7 is electrically connected to the above-described electronic circuit 5 by operating a power switch (not shown), and supplies driving power.

  The first vibrating gyroscope 8 is a vibrating gyroscope using a piezoelectric element, and its sensitivity axis is fixed to the case 1 with the vertical direction (hereinafter referred to as the pitch direction) of the screen. When vibration is applied to the electronic still camera due to camera shake or the like, the angular velocity in the pitch direction is detected, and the detection output is transmitted to the electronic circuit 5 described above.

  Similarly, the second vibration gyro 9 is a vibration gyro using a piezoelectric element, and its sensitivity axis is fixed to the case 1 in the horizontal direction of the screen (hereinafter referred to as the yaw direction). When vibration is applied to the electronic still camera due to the shake, the angular velocity in the yaw direction due to the vibration is detected, and the detection output is transmitted to the electronic circuit 5 described above.

  The release switch 10 is a well-known two-stage switch and is fixed to the case 1. When the release switch 10 is pushed down to the first stage (hereinafter referred to as release SW1), the shutter provided in the taking lens 2 is opened by the operation of the electronic circuit 5, and AF and AE are performed to perform the electronic still camera. Is in shooting standby mode.

  Further, when the release switch 10 is pushed to the second stage (hereinafter referred to as release SW2), after the clear shutter operation of the CCD 3a is performed by the operation of the electronic circuit 5, the photographed image is accumulated in the form of charge on the CCD. To be recorded.

  The output terminal 13 is used for transferring captured image data of the electronic still camera to a personal computer, displaying an image captured by the electronic still camera on an external monitor, and displaying an image displayed on the EVF 6 on the external monitor. FIG. 1 shows a pin type terminal.

  The strobe 14 is fixed to the case 1 and automatically emits light in synchronism with the timing of shooting according to the shooting mode and the illuminance of the subject by the action of the electronic circuit 5.

Next, the configuration of the photographing device unit of the electronic still camera of the present embodiment will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the part common to above-mentioned FIG.
In FIG. 2, 2 is a photographing lens, 2a is a first fixed lens, 2b is a first moving lens that is a variable power lens, 2c is a second fixed lens, and 2d is a second moving lens that is a focus lens. Reference numeral 2e denotes a shutter, 3a denotes a CCD, 16 denotes a variable apex angle prism, and 17 denotes a lens barrel.

  18a is a first link, 19a is a first stepping motor, 20 is a first microcomputer, 21a is a first reset sensor, 21b is a second reset sensor, 8 and 9 are vibration gyros, and 22 is a first gyro. , 23 is a second drive circuit, and 24 is a second microcomputer.

  Reference numeral 25 denotes a third drive circuit, 26 denotes a video signal processing circuit, 27 denotes a video output processing circuit, 28 denotes a digital output processing circuit, 4 denotes a memory card, 6 denotes an EVF, and 10 denotes a release switch. In FIG. 2, the zoom operation switch 15 is not shown.

  The photographic lens 2 is, for example, a photographic lens with a shake correction function as proposed by the present applicant in Japanese Patent Laid-Open No. 6-138419. The first fixed lens 2a and the second fixed lens 2c are fixed to the photographing lens 2 of the present embodiment, and the first moving lens 2b and the second movable lens 2d move in the optical axis direction. It is supported freely.

  When the zoom operation switch 15 described in FIG. 1 is operated, the first moving lens 2b moves in the optical axis direction by the power of a zoom motor (not shown). The second moving lens 2d moves in the optical axis direction by the power of a focus motor (not shown) along with zooming and autofocus operations. The shutter 2e opens and closes in conjunction with the operation of the release switch 10.

  A CCD 3 a is fixed to the photographing lens 2. Further, the taking lens 2 includes a variable apex angle prism 16, a lens barrel 17 that supports the variable apex angle prism 16, a first link 18a, a second link 18b (not shown), a first stepping motor 19a, An optical axis deflection mechanism comprising a second stepping motor 19b (not shown) is provided.

  In this optical axis deflection mechanism, for example, when the first stepping motor 19a for deflecting the optical axis in the pitch direction rotates, the lead screw provided on the output shaft of the first stepping motor 19a rotates. The rack meshed with each other moves in the optical axis direction. Thus, the apex angle of the variable apex angle prism 16 is changed in the pitch direction via the first link 18a, and the direction of the light beam incident on the photographing lens 2 is changed.

  The deflection of the optical axis in the yaw direction is performed in the same manner, and the rotation of the second stepping motor 19b for deflecting the optical axis in the yaw direction is transmitted to the variable apex prism 16 by the second link 18b. Thereby, the apex angle of the yaw method of the variable apex angle prism 16 is changed, and the direction of the light beam incident on the photographing lens 2 is deflected in the yaw direction.

  The first microcomputer 20 controls the shake correction operation, and includes first and second reset switches for detecting the reset position of the variable apex angle prism 16, and vibrations in the pitch and yaw directions. The first and second vibrating gyros to be detected, the first drive circuit 22, the second drive circuit 23, and the second microcomputer 24 for controlling the operation of the electronic still camera are electrically connected. .

  As a result, when the power switch is turned on, the first microcomputer 20 first detects the reset position of the variable apex angle prism 16 in the pitch and yaw directions, and the second reset sensor 21a and the second reset sensor 21a. Based on the output signal of the reset sensor 21b, a drive pulse is sent to the first drive circuit 22 and the second drive circuit 23, and the first and second reset sensors 21a and 21b are changed until the states of the first and second reset sensors 21a and 21b change. The second stepping motors 19a and 19b are driven, and a counter provided in the first microcomputer 20 that counts the pitch and yaw positions at the positions is reset.

  Next, the first microcomputer 20 sets the first and second pulses by the number of pulses stored in the first microcomputer 20 in advance so that the apex angle of the variable apex angle prism 16 is 0 ° in both pitch and yaw. The second stepping motors 19a and 19b are driven to enter a standby state.

  When the first microcomputer 20 receives a start command for shake correction operation from the second microcomputer 24, the first microcomputer 20 detects the shake in the pitch direction and the second vibration gyro 8 detects the shake in the yaw direction. Processing such as integration is performed on the output signal of the vibration gyro 9 to calculate a target vertex angle in each direction of the variable apex angle prism 16 so that the apex angle of the variable apex angle prism 16 tracks the target apex angle. The first and second stepping motors 19a and 19b are driven to perform shake correction.

  The second microcomputer 24 includes a shutter drive circuit 25, a video signal processing circuit 26, a memory card 4, a first output signal processing circuit 27, a second output signal processing circuit 28, and a strobe control circuit 14a. The release switch 10 of the release switch 10 is electrically connected to the release SW 2 and the first microcomputer 20.

  The second microcomputer 24 outputs a signal to the shutter drive circuit 25 in accordance with the operation of the release switch 10 to control the opening / closing of the shutter 2e. In addition, the video signal processing circuit 26 is controlled to read an image signal, the CCD 3a is controlled to be reset, and the read pixel signal is output to an enlarged range. Perform electronic zoom.

  Further, the second microcomputer 24 outputs a signal to the memory card 4 to store the input of the video signal processing circuit 26, and the video data stored in the memory card 4 is transferred to the first output signal processing circuit 27, the second 2 output signal processing circuit 28 or EVF 6.

  Further, the second computer 24 determines the shutter time based on the luminance signal of the subject obtained from the video signal processing circuit 26. If necessary, a signal is output to the strobe control circuit 14a to cause the strobe 14 to emit light in synchronization with photographing. Furthermore, the second microcomputer 24 controls the operations of the first output signal processing circuit 27 and the second output signal processing circuit 28. It also controls autofocus and zooming.

  The video processing circuit 26 sequentially reads out the image signal stored in the CCD 3a, outputs it as a video signal to the memory card 4 or the EVF 6, and resets the CCD 3a at a predetermined timing or at the command of the second microcomputer 24. I do.

  The first output signal processing circuit 27 is electrically connected to the second microcomputer 24, the video signal processing circuit 26, the memory card 4, the EVF 6, and the first external output terminal 13a. Then, according to the command signal of the second microcomputer 24, the signal from the video signal processing circuit 26 is output to the first external output terminal 13a, or the video data stored in the memory card 4 is transferred to the video signal of one screen. Or output after conversion.

  The second output signal processing circuit 28 is electrically connected to the second microcomputer 24, the memory card 4, and the second external output terminal 13b, and the video data stored in the memory card 4 is unit by screen. To output as personal computer file data.

  In the present embodiment, the above-described photographic lens 2 is configured as shown in FIG. Here, the first stepping motor 19a and the second stepping motor 19b are formed in a substantially arc shape. Further, when viewed from the direction of the CCD 3a, the photographing lens 2 is formed in a shape having few protrusions as shown in FIG. 4, and is devised so that it can be arranged in an extremely small space.

Next, the operation of the electronic still camera according to the present embodiment will be described with reference to FIG.
FIG. 5 is a timing chart showing the operation of the electronic still camera according to the first embodiment. In the following description, since AF and data storage are not directly related to the object and effect of the present invention, detailed description thereof is omitted.

  As shown in FIG. 5, after the power switch is turned on at time t0, when the release SW1, which is the first stage of the release switch 10, is turned on at time t1, the second microcomputer 24 opens the shutter. The image obtained by the CCD 3a is displayed on the EVF 6 as a finder image. A video signal is output from the first external output terminal 13a.

  When the release SW2 is pressed at time t2 and shooting is performed, the first microcomputer 24 resets the CCD 3a at time t3 after a predetermined short time, and the first microcomputer 20 performs shake correction. Start command is output and shake correction is started.

  After the reset of the CCD 3a, the second microcomputer 24 outputs a shutter close signal to the shutter control circuit 25 at time t4 when the exposure time calculated in advance by the luminance signal output of the video signal processing circuit 26 has elapsed. The shutter 2e is closed, and a shake correction stop is output to the first microcomputer 20 to stop the shake correction.

  At the same time, the second microcomputer 24 outputs an image signal reading command signal stored in the CCD 3 a to the video processing circuit 26. The video processing circuit 26 reads an image signal from the CCD 3a and outputs it to the memory card 4 and the EVF 6 as a one-screen video signal.

  The memory card 4 stores the input video signal, and the EVF 6 displays the video signal. FIG. 5 is an example in which only one shooting is performed, and the release switch 10 is turned off at time t5. If the release switch 10 is still ON, if the release SW1 is ON, the photographed image is displayed for a predetermined time, and then the state returns to the state at time t1, and the shutter is opened again to enable the next photographing. To do.

  On the other hand, if the release SW2 is ON, the shutter is opened immediately after reading the image signal from the CCD 3a. At the same time, continuous shooting can be performed by returning to the state at time t2.

  The first microcomputer 20 records a shake signal during photographing obtained from the outputs of the first and second vibrating gyros 8 and 9 and outputs it to the second microcomputer 24. The second microcomputer 24 can also store the shake signal when the image is taken in the memory card 4 in pairs with the image data.

  In this way, by using the shake signal stored in the memory card 4 and processing the image data on the personal computer, it is possible to correct the occurrence of chromatic aberration and the curvature of the image plane caused by the shake correction.

  In the present embodiment, EVF 6 is used as a finder. However, a known optical finder may be used. In addition, by combining the electronic still camera described in this embodiment with an optical viewfinder, an electronic still camera capable of shooting a good image with shake correction can be manufactured with extremely low power. it can.

  As described above, in the first embodiment of the present invention, the shake correction is performed at the minimum necessary timing, so that battery consumption can be prevented and the shake correction angle can be minimized. Can do. Further, since the shake correction angle can be minimized, it is possible to prevent the optical performance from being deteriorated by the operation of the shake correction mechanism. As a result, it is possible to obtain a sharp image even when a dark subject is photographed despite the small size and low power consumption.

(Second Embodiment)
Next, a second embodiment of the electronic still camera of the present invention will be described with reference to FIGS. In FIG. 6, the same components as those in the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.

  In FIG. 6, reference numeral 11 denotes a shake correction mode setting switch, which is provided on the surface of the case 1 of the electronic still camera shown in FIG. 1, and repeatedly presses the second microcomputer 24 to correct the shake. And the display mode is set.

  Next, FIGS. 7 to 9 are flowcharts for explaining the shake correction operation of the electronic still camera. FIG. 10 is a timing chart for explaining the operation of the first mode of the electronic still camera, FIG. 11 is a timing chart for explaining the operation of the second mode, and FIG. 12 shows the operation of the third mode. It is a timing chart for explaining.

  As shown in FIGS. 6 to 12, in the second embodiment of the present invention, a shake correction and display mode setting switch 11 is provided so that the operation mode of shake correction and display on the EVF 6 can be switched. This is an electronic still camera.

  In addition, the same code | symbol is attached | subjected to the same structure as the above-mentioned 1st Embodiment, and detailed description is abbreviate | omitted.

  In the second embodiment, three shake correction and display modes can be set. In the first mode, the image obtained by the CCD 3a is always displayed on the EVF 6 regardless of the release switch 10, and during that time, the shake correction operation is always turned on with a frequency characteristic having no gain for a relatively low frequency, and the release is performed. In this mode, when the image to be recorded is recorded with the SW2 turned ON, the frequency characteristic of the control circuit that controls the shake correction mechanism is switched to a characteristic that follows low-frequency shake.

  In the second mode, the image obtained by the CCD 3 a is always displayed on the EVF 6 regardless of the release switch 10. The shake correction operation is started when the release SW1 is turned on, and the frequency characteristics are switched in conjunction with the release SW2. Furthermore, the third mode is a mode in which the shake correction operation is not always performed.

Next, the operation of the electronic still camera according to the present embodiment will be described with reference to the flowcharts shown in FIGS.
When the power switch of the electronic still camera is operated to turn on the power (step S100), the second microcomputer 24 turns on the EVF 6 (step S101). Next, the state of the mode SW is monitored to determine whether or not the mode SW setting is the third mode (step S102).

  If the mode SW setting is not the third mode, it is further determined whether or not the mode SW setting is the first mode (step S103). As a result of this determination, when the mode SW is set to the first mode, the first shake correction and display mode of the electronic still camera is set.

  When the first shake correction and display mode is set, the second microcomputer 24 causes the first microcomputer to set the frequency characteristic of the shake correction operation to a default value with no gain on the relatively low frequency side. A command is sent to 20 (step S104).

  Next, the second microcomputer 24 instructs the first microcomputer 20 to start a shake correction operation (step S105), and the shake correction operation is started. Next, the second microcomputer 24 opens the shutter (step S106), starts storing image signals in the CCD 3a, and starts projecting a finder image on the EVF 6.

  Next, the second microcomputer 24 monitors whether or not the release SW1 is turned on (step S107). When the release SW1 is turned on, autofocus (step S108) and exposure setting (step S109) are performed, and it is monitored whether the release SW2 is turned on (step S110).

  When the release SW2 is turned on, the second microcomputer 24 outputs a frequency characteristic switching command signal to the first microcomputer 20 that controls shake correction (step S112). The first microcomputer 20 changes the frequency characteristic of shake correction to a characteristic having a gain up to a relatively low frequency for photographing.

  This change in the frequency characteristic is performed by changing the target apex angle of the variable apex angle prism, which is an optical shake correction unit, based on the outputs of the first and second vibration gyros 8 and 9 performed in the first microcomputer 20. This is done by changing the constant of the digital filter to be calculated.

  Next, the second microcomputer 24 resets the CCD 3a (step S113), and closes the shutter 2e at a timing in accordance with the exposure setting performed in advance 109 from the end of the reset (step S114).

  Thereafter, the second microcomputer 24 outputs a command signal to the video signal processing circuit 26, and transfers the image signal stored in the CCD 3a to the memory card 4 (step S115).

  When the transfer is completed, the second microcomputer 24 opens the shutter (step S116), displays the finder image on the EVF 6 again, and sets the frequency characteristics of shake correction to the first microcomputer 20 so that the gain is reduced to a relatively low frequency. A signal for instructing a change to the original characteristic that is not present is output (step S117).

  Next, it is confirmed whether or not the power is turned off (step S118). If the power is turned off, the power is turned off in step S150. If the power is not turned off, the process returns to step 102 and the same operation is repeated again.

Here, the operation with respect to the time of the first mode in the second embodiment of the present invention will be described with reference to the timing chart shown in FIG.
When the power switch is turned on at time t0, the second microcomputer 24 opens the shutter, and the image obtained by the CCD 3a is copied to the EVF 6 as a finder image, and the video is output from the first output terminal 13a. Output a signal.

When mode selection is performed at time t1, the second microcomputer 24 outputs a shake correction start command to the first microcomputer 20, and shake correction is started.
Next, when the release SW1 is turned on at time t2, the first microcomputer 24 performs AF and AE.

  Next, when the release SW 2 is pressed at time t 3 and shooting is performed, the second microcomputer 24 outputs a shake correction frequency characteristic change command to the first microcomputer 20. The shake correction operation expands the characteristics to the low frequency region side, and the second microcomputer 24 resets the CCD 3a.

  After the reset of the CCD 3a, the second microcomputer 24 outputs a shutter close signal to the shutter control circuit 25 at the time t4 when the exposure time calculated in advance by the luminance signal output of the video signal processing circuit 26 has elapsed. Then, the shutter 2e is closed and a command for returning the frequency characteristic of the shake correction to the first microcomputer 20 is output to the first microcomputer 20, and the shake correction is changed to a characteristic having relatively no gain on the low frequency side.

  At the same time, the second microcomputer 24 outputs a command signal for reading the image signal stored in the CCD 3a to the video processing circuit 26. The video processing circuit reads the image signal from the CCD 3a, and displays one screen. Are output to the memory card 4 and the EVF 6 as video signals. The memory card 4 stores the input image signal, and the EVF 6 displays it.

  Although the release SW2 is turned off at time t5, the second microcomputer 24 finishes reading the image signal from the CCD 3a at time t6, opens the shutter again, and performs standby for the next shooting. Next, when the release SW1 is turned off at time t7 and the power supply SW is turned off at time t8, all the operations are finished.

  FIG. 10 is an example in which only one shooting is performed, and the release switch 10 is turned off at time t5. If the release switch 10 is still ON, the photographed video is displayed for a predetermined time if the release SW1 is ON, and then the state returns to the state at time t2 to enable the next shooting or the release SW2 is ON. If so, the shutter can be opened immediately after reading the image signal from the CCD 3a, and at the same time, the state can be returned to the time t3 for continuous shooting.

  In the first mode of the second embodiment of the present invention, a super-telephoto lens or an image magnified at a high magnification by an electronic zoom can be viewed with EVF in a state where shake correction is performed. Therefore, accurate framing can be performed, facilitating framing, and the influence of image blur due to the influence of driving such as shake and shutter can be suppressed as much as possible. In addition, since the image magnified at a high magnification can be displayed as an easy-to-see finder image, the electronic still camera can be used as a telescope by the finder image.

  In addition, by switching the frequency mode of shake correction at the time of shooting, the shake correction can be made to follow low-frequency large-amplitude shake from a position where the optical shake correction means has not substantially changed the optical axis. A large correction amount can be ensured, good shake correction can be performed, and a high-quality image can be obtained.

  Next, the second mode of the second embodiment of the electronic still camera according to the present invention will be described with reference to the flowchart of FIG. The second mode of the second embodiment is to turn on the shake correction operation only while the release SW1 is being pressed.

  7 to 9, when the second microcomputer 24 detects that the second mode is set in step S103, the process proceeds to step S119 in FIG. In this case, the second microcomputer 24 opens the shutter, starts storing image signals in the CCD 3a, and starts displaying a finder image on the EVF 6.

  Next, it is monitored whether or not the release SW1 is turned on (step S120). When the release SW1 is turned on, the frequency characteristics of the shake correction operation in the first microcomputer 20 have no gain on the relatively low frequency side. A command is sent to set the default value (step S121).

  Next, the second microcomputer 24 instructs the first microcomputer 20 to start a shake correction operation (step S122), and the shake correction operation is started.

  Next, the second microcomputer 24 performs autofocus (step S123) and exposure setting (step S124), and monitors whether the release SW2 is turned on (step S125).

  If the release SW2 is not turned on, AF, AE, and release SW2 are continuously monitored. When the release SW2 is turned on, the second microcomputer 24 instructs the first microcomputer 20 that controls shake correction to switch the frequency characteristic. A signal is output (step S126), and the frequency characteristic of shake correction is changed to a characteristic having a gain up to a relatively low frequency for photographing. The change of the frequency characteristic is a process of calculating the target vertex angle of the variable vertex angle prism which is an optical correction means based on the outputs of the first and second vibrating gyros 8 and 9 performed in the first microcomputer. This is done by changing the constant of the digital filter.

  Next, the second microcomputer 24 resets the CCD 3a (step S127), and closes the shutter 2e at the timing matched with the exposure setting performed in advance (step S124) from the end of the reset (step S128).

  Thereafter, the second microcomputer 24 outputs a command signal to the video signal processing circuit 26, and transfers the image signal stored in the CCD 3a to the memory card 4 (step S129).

  When the transfer is completed, the second microcomputer 24 detects the state of the release SW1 (step S130), and stops the shake correction when the release SW1 is OFF (step S132). Then, after confirming whether or not the power is turned off ((step S118)), the process returns to step S102 and the same operation is repeated.

If the release SW1 remains on, the second microcomputer 24 opens the shutter (step S119), displays a finder image on the EVF 6 again, and checks whether the power is turned off ( (Step S118), it returns to step (102) again and repeats the same operation.
Here, the operation with respect to time in the second mode in the second embodiment of the present invention will be described with reference to a timing chart shown in FIG.

  When the power switch is turned on at time t0, the second microcomputer 24 opens the shutter and projects the image obtained by the CCD 3a on the EVF 6 as a finder image. A video signal is output from the first output terminal 13a.

When the mode is selected at time t1, the second microcomputer 24 recognizes that the second mode has been selected.
When the release SW1 is turned on at time t2, the second microcomputer 24 outputs a shake correction start command to the first microcomputer 20, and shake correction is started. At this time, the shake correction is set to a characteristic having relatively no gain on the low frequency side. At this time, AF and AE are also performed.

  Next, when the release SW2 is pressed at time t3 and shooting is performed, the second microcomputer 24 outputs a shake correction frequency characteristic change command to the first microcomputer 20, and the shake correction operation is low. Expand the characteristics to the frequency domain side. Further, the second microcomputer 24 resets the CCD 3a.

  After the reset of the CCD 3a, the second microcomputer 24 outputs a shutter closing signal to the shutter control circuit 25 at the time t4 when the exposure time calculated in advance by the luminance signal output of the video signal processing circuit 26 has elapsed. While closing the shutter 2e, a command for returning the frequency characteristic of shake correction to the first microcomputer 20 is output. As a result, the shake correction is changed to a characteristic having relatively no gain on the low frequency side.

  At the same time, the second microcomputer 24 outputs a command signal for reading the image signal stored in the CCD 3a to the video processing circuit 26. The video processing circuit reads the image signal from the CCD 3a, and the image of one screen is displayed. The signal is output to the memory card 4 and the EVF 6 as a signal. The memory card 4 stores this image signal, and the EVF 6 displays it.

  Although the release SW2 is turned off at time t5, the second microcomputer 24 finishes reading the image signal from the CCD 3a at time t6, opens the shutter again, stands by for the next shooting, and releases at time t7. When SW1 is turned off and the power supply SW is turned off at time t8, all operations are terminated.

  As described above, in the second shooting mode of the present embodiment, since the shake correction is activated only when the release SW 1 is turned on, it is possible to suppress battery consumption.

Next, the third mode of the second embodiment will be described with reference to FIG.
In the third mode of the second embodiment of the electronic still camera according to the present invention, the shake correction operation is turned on only while shooting is performed.

  In FIG. 7, when the second microcomputer 24 detects that the third mode is set in step S102, the second microcomputer 24 proceeds to step S133 in FIG. 9 to open the shutter, and the CCD 3a. Then, image signal accumulation is started, and a finder image is displayed on the EVF 6.

  Next, the second microcomputer 24 monitors whether or not the release SW1 is turned on (step S134). When the release SW1 is turned on, the second microcomputer 24 performs autofocus (step S135) and exposure setting (step S136). Then, it is monitored whether or not the release SW2 is turned on (step S137).

  If the release SW2 is not turned on, the AF, AE, and release SW2 are continuously monitored. When the release SW2 is turned on, the second microcomputer 24 starts the shake correction operation to the first microcomputer 20 that controls the shake correction. Is instructed (step S138). Thereby, the shake correction operation is started. At this time, as a frequency characteristic for shake correction, a characteristic having a gain up to a relatively low frequency for photographing is selected.

  Next, the second microcomputer 24 resets the CCD 3a (step S139), and closes the shutter 2e at a timing that matches the exposure setting performed in advance (step S136) from the end of the reset (step S140).

  Thereafter, the second microcomputer 24 outputs a command signal to the video signal processing circuit 26, and transfers the image signal stored in the CCD 3a to the memory card 4 (step S141).

  When the transfer is completed, the second microcomputer 24 confirms whether the power is not turned off (step S118), and then returns to step S102 and repeats the operation.

Here, the operation with respect to the time of the third mode in the second embodiment will be described with reference to a timing chart shown in FIG.
When the power switch is turned on at time t0, the second microcomputer 24 opens the shutter and projects the image obtained by the CCD 3a on the EVF 6 as a finder image. A video signal is output from the first output terminal 13a.

When the mode is selected at time t1, the second microcomputer 24 recognizes that the third mode has been selected, and the shake correction operation is performed with the shake correction frequency having a characteristic expanded to the low frequency region side. Set characteristics.
Next, when release SW1 is turned on at time t2, AF and AE are performed.
Next, when the release SW 2 is pressed at time t3 and shooting is performed, the second microcomputer 24 instructs the first microcomputer 20 to start shake correction, and the shake correction operation starts. Further, the second microcomputer 24 resets the CCD 3a.

  After the reset of the CCD 3a, the second microcomputer 24 outputs a shutter close signal to the shutter control circuit 25 at time t4 when the exposure time previously calculated by the luminance signal output of the video signal processing circuit 26 has elapsed. While closing the shutter 2e, a shake correction stop command is issued to the first microcomputer 20 to stop the shake correction.

  At the same time, the second microcomputer 24 outputs a command signal for reading the image signal stored in the CCD 3a to the video processing circuit 26. The video processing circuit reads the image signal from the CCD 3a, and the image of one screen is displayed. The signal is output to the memory card 4 and the EVF 6 as a signal. The memory card 4 stores the input signal, and the EVF 6 displays it.

  Although the release SW2 is turned off at time t5, the second microcomputer 24 finishes reading the image signal from the CCD 3a at time t6, opens the shutter again, performs standby for the next shooting, and releases at time t7. When SW1 is turned off and the power supply SW is turned off at time t8, all operations are terminated.

  As described above, in the third shooting mode of the present embodiment, since the shake correction is activated only during shooting, battery consumption can be suppressed, and a variable apex angle prism serving as an optical focal length shake correction unit can be suppressed. However, there is an effect that the optical performance of the photographing lens can be fully utilized because the photographing can be performed at a position where the light beam is not substantially bent.

(Third embodiment)
Next, a third embodiment of the electronic still camera of the present invention will be described.
In an electronic still camera, a CCD is generally used as an image sensor. Therefore, even when the sensitivity of the CCD is relatively low, typically about ISO 75, the image signal can be amplified electrically only when a dark subject is photographed. Auto gain control (hereinafter referred to as AGC) that automatically performs this is also performed in today's electronic still cameras.

  By the way, when shooting with low illuminance of the subject, for example, when shooting a night view of a town, there is contrast even in darkness, and in dark places, it may be dark and when shooting indoors As described above, there is a subject that has a low contrast and wants to capture the entire image brightly.

The third embodiment of the present invention makes it possible to capture a beautiful image in accordance with the situation by combining such AGC and shake correction.
Hereinafter, a third embodiment of the present invention will be described with reference to FIGS.
FIG. 13 is a block diagram for explaining the configuration of the electronic still camera according to the third embodiment of the present invention, and FIGS. 14 and 15 illustrate the shake correction operation of the electronic still camera according to the third embodiment. It is a flowchart for doing.

In the following description, the same reference numerals are given to the same components as those in the first embodiment and the second embodiment described above, and detailed description thereof is omitted.
In FIG. 13, reference numeral 12 denotes a shooting mode setting switch, which is provided on the surface of the case 1 of the electronic still camera shown in FIG. 1, and the second microcomputer 24 sets the shooting mode when repeatedly pressed. It is like that.
Reference numeral 30 denotes an amplification circuit that amplifies the image signal stored in the CCD 3a with a predetermined gain and outputs the amplified image signal to the video signal processing circuit 26.

When the second microcomputer 24 shoots a dark subject in accordance with the shooting mode set by the shooting mode setting switch 12,
(1) Take a picture by correcting shake and extending the accumulation time.
(2) Amplifying and recording an image signal obtained with a predetermined relatively short accumulation time using AGC.
(3) The image signal immediately before photographing is scanned for one screen by pre-exposure, the contrast value is detected, and the image is photographed by automatically performing shake correction to extend the accumulation time.
(4) Amplifying and recording an image signal obtained with a predetermined relatively short accumulation time using AGC is selected.

  Then, the second microcomputer 24 outputs a command signal to the amplifier circuit 30 and the video signal processing circuit 26 according to the selected setting contents, and controls its operation.

Next, the operation of the electronic still camera of the third embodiment will be described with reference to FIGS.
In the third embodiment of the present invention, in the first photographing mode, the image signal immediately before photographing is scanned for one screen by pre-exposure, and the contrast value is detected. This is a mode for selecting whether to automatically perform shake correction to increase the accumulation time for shooting, or to use AGC to amplify and record an image signal obtained with a predetermined relatively short accumulation time. .

  The second mode is a mode in which only AGC is performed to perform imaging, and the third mode is an imaging in which only shake correction is performed, and AGC is a mode in which AGC is fixed to a predetermined value.

  As shown in FIGS. 14 and 15, when the power switch is turned on (step S200), the second microcomputer 24 first detects whether or not the photographing mode is the first mode (step S201).

  When the first mode is detected, the shutter is opened (step S202), the display brightness is set to a predetermined value by AGC, and the EVF 6 display is started (step S203).

  Next, the second microcomputer 24 detects the state of the release SW1 (step S204). When the release SW1 is turned on, the image signal for one screen is read from the video signal processing circuit 26 (step S205). A contrast value in the screen is detected based on the luminance of the pixel (step S206).

  Next, the second microcomputer 24 determines whether the contrast value in the screen is large or small (step S207). If the result of this determination is that the contrast value is greater than or equal to a predetermined value, the gain of the amplifier circuit 30 is set to a predetermined value (step S208), and a shake correction operation is started (step S209).

  Next, the second microcomputer 24 detects the state of the release SW2 (step S210). When the release SW2 is turned on, exposure is performed at a shutter speed calculated with a predetermined sensitivity (step S211), and once. Is finished (step S212).

  If the result of determination in step S207 is that the contrast value on the screen is less than or equal to a predetermined amount, the second microcomputer 24 turns on AGC (step S213). Next, the state of the release SW2 is detected (step S214). When the release SW2 is turned on, exposure is performed at a shutter speed set to a predetermined sensitivity by the AGC (step S215), and then the process proceeds to step S212. One shooting is completed.

  If the first mode is not detected in step S201, the process proceeds to step S216 to detect whether or not the second mode is selected. When the second mode is selected, the second microcomputer 24 turns on the AGC (step S217) and performs shooting in the AGC mode (step S218).

  If the second mode is not detected by the mode detection in step S216, the second microcomputer 24 turns on shake correction (step S217) since it is the third mode in this case. The image is taken with (step S218).

  As described above, in the electronic still camera according to the present invention, it is possible to select whether to give priority to shake correction or AGC depending on the situation of the subject. Highly beautiful image data can be obtained.

It is the perspective view which showed the 1st Embodiment of this invention and saw through the electronic still camera. 1 is a block diagram illustrating a configuration of an electronic still camera according to a first embodiment of this invention. FIG. FIG. 1 is an exploded perspective view of a lens barrel portion of an electronic still camera, showing a first embodiment of the present invention. 1 is a rear view of a lens barrel portion of an electronic still camera, showing a first embodiment of the present invention. FIG. 3 is a timing chart illustrating the operation of the electronic still camera according to the first embodiment of this invention. It is a block diagram which shows the 2nd Embodiment of this invention and demonstrates the structure of an electronic still camera. 10 is a flowchart illustrating a shake correction operation of the electronic still camera in the first mode according to the second embodiment of this invention. FIG. 10 is a flowchart illustrating a shake correction operation of the electronic still camera in the second mode according to the second embodiment of this invention. 10 is a flowchart illustrating a shake correction operation of the electronic still camera in the third mode according to the second embodiment of this invention. It is a timing chart for demonstrating operation | movement of a 1st mode. It is a timing chart for explaining operation of the 2nd mode. It is a timing chart for explaining operation of the 3rd mode. It is a block diagram which shows the 3rd Embodiment of this invention and demonstrates the structure of an electronic still camera. 12 is a flowchart illustrating a shake correction operation of an electronic still camera according to the third embodiment of this invention. 12 is a flowchart illustrating a shake correction operation of an electronic still camera according to the third embodiment of this invention.

Explanation of symbols

1 Electronic Still Camera Case 2 Shooting Lens 3 CCD Base 3a CCD
4 Memory Card 6 Electronic View Finder 8 Vibration Gyro 9 Vibration Gyro 11 Vibration Correction Mode Setting Switch 12 Shooting Mode Setting Switch 20 First Microcomputer 24 Second Microcomputer 26 Video Signal Processing Circuit

Claims (7)

In an electronic still camera,
A photographic lens, an image sensor that receives a subject image via the photographic lens and accumulates electric charge, a recording unit that records an output from the image sensor as an image signal, a release switch for starting photographing, A shake correction unit that optically corrects a shake based on a detection result of the shake detection unit, and a display unit that continuously displays an image based on an output from the image sensor,
The shake correcting means when the image is continuously displayed by the display means without taking the image recorded by the recording means and when the image recorded by the recording means is taken. An electronic still camera characterized by switching the frequency characteristic of shake correction by the camera. When continuously displaying images by the display means without taking an image recorded by the recording means, the frequency characteristics of shake correction by the shake correction means is a frequency characteristic without gain for low frequency,
When taking an image recorded by the recording unit, the frequency characteristic of shake correction by the shake correction unit is set to a frequency characteristic having a gain for a low frequency so as to follow the low frequency shake. The electronic still camera according to claim 1. In an electronic still camera,
A photographing lens; an imaging device that receives a subject image through the photographing lens and accumulates electric charge; a recording unit that records an output from the imaging device as an image signal; a two-stage release switch; Shake correction means for optically correcting shake based on the detection result of the means,
Regardless of the state of the release switch, the shake correction by the shake correction means is always started, and when the release switch is pushed to the first stage, the shake correction by the shake correction means is started. An electronic still camera, wherein a second mode and a third mode for starting shake correction by the shake correction means when the release switch is pushed to the second stage can be selected.   The electronic still camera according to claim 3, further comprising display means for continuously displaying images based on an output from the image sensor. In an electronic still camera,
A photographic lens, an image sensor that receives a subject image via the photographic lens and accumulates charge; an auto gain control unit; a recording unit that records an output from the image sensor as an image signal; A release switch for starting, and shake correction means for optically correcting shake based on the detection result of the shake detection means,
On the premise that the image signal is amplified by the auto gain control means, an auto gain control priority mode for performing photographing, and a shake correction priority mode for performing photographing on the premise that the shake correction by the shake correcting means is operated. An electronic still camera, characterized in that it can be selected.   6. The electronic still camera according to claim 5, wherein, in the shake correction priority mode, a restriction is provided on an amplification factor of the auto gain control means.   Prior to photographing, preliminary photographing is performed, contrast detection is performed using the image signal obtained by the preliminary photographing, and the automatic gain control priority mode and the shake correction priority mode are automatically switched based on the detection result. The electronic still camera according to claim 5 or 6.

Images