JP3726630B2 - Digital still camera - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a single-lens reflex digital still camera.
[0002]
[Prior art]
In a single-lens reflex type digital still camera, an image sensor such as a CCD is attached to a film loading portion of a camera using a single-lens reflex type silver salt film (hereinafter abbreviated as a silver salt camera) to form a digital still camera. Many. In such a digital still camera, a phase difference autofocus (AF) system in which the light passing through the imaging lens is separated by a separator lens, and the amount of lens movement is obtained based on the distance between the images to perform focusing. Focusing.
[0003]
[Problems to be solved by the invention]
In recent years, the pixel pitch of an image sensor tends to decrease and the number of pixels tends to increase, but the required focus accuracy increases as the pixel pitch decreases. On the other hand, the phase difference AF method has a limit in focusing accuracy, and it is becoming impossible to perform auto-focusing with a focusing accuracy corresponding to the pixel pitch.
[0004]
By the way, in the AF method, in addition to the phase difference AF method, image signal auto-focusing is performed based on the contrast of image data obtained by the image sensor, and more specifically, focusing is performed based on the image contrast. There is a contrast AF method. The contrast AF method has better focus accuracy than the phase difference AF method. Therefore, a digital still camera that employs the contrast AF method in response to an increase in the number of pixels of the image sensor is desired. However, as described above, contrast AF cannot be performed with a single-lens reflex digital still camera.
[0005]
The present invention is intended to overcome the above-described problems in the prior art, and an object of the present invention is to provide a digital still camera that can perform auto focus on an image signal while being a single lens reflex type.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 is directed to an optical finder that makes it possible to visually recognize an imaging target by changing an optical path from an imaging optical system to an imaging device by a quick return mirror, and the quick return mirror to the imaging optical. A single-lens reflex digital still camera having a mirror driving means for driving between the system and outside the imaging optical system, a shutter button that can be half-pressed and fully pressed, and a phase difference that performs phase difference autofocus Focusing means, image signal focusing means for performing image signal autofocusing that is in-focus based on the image signal obtained by the image sensor, and phase difference auto when the shutter button is pressed halfway in the shooting mode by the optical viewfinder A half-press control means for controlling the phase difference focusing means to perform focusing, And a, a shooting focusing control means for controlling said image signal focusing unit to perform an image signal autofocus.
[0007]
Further, the invention of claim 2 is the digital still camera according to claim 1, and further includes a display means for displaying live-view candidate images and a live view display on the display means. And a focusing control unit for controlling the image signal focusing unit to control the mirror driving unit to retract the quick return mirror from the imaging optical system and to perform image signal autofocusing .
[0008]
Further, the invention of claim 3 is the digital still camera according to claim 2 , further comprising a live view operation member for instructing at least off of live view display , and the live view display by the live view operation member. View-off control means for turning off the live view display based on an off instruction, and when turning off the live view display, the quick return mirror is positioned in the imaging optical system so that the subject image can be visually recognized by the optical viewfinder. And a phase difference focus control means for controlling the phase difference focus means to perform phase difference autofocus .
[0009]
According to a fourth aspect of the present invention, in the digital still camera according to the third aspect, when the view-off control means turns off the live view display, the display means is turned off .
[0010]
The invention according to claim 5 is the digital still camera according to claim 1 , further comprising a focus instruction means for instructing switching between a phase difference autofocus method and an image signal autofocus method, and the focus. When the image signal autofocus method is instructed by the instruction means, the mirror drive means is controlled to retract the quick return mirror from the imaging optical system, and the phase difference autofocus method is instructed by the focus instruction means. Mirror control means for controlling the mirror driving means to position the quick return mirror in the imaging optical system .
[0011]
The invention according to claim 6 is the digital still camera according to claim 5 , further comprising a display means capable of displaying live view images for displaying images of photographing candidates, and the image signal auto by the focusing instruction means. Display control means for controlling the display means to turn on the live view display when a focus method is designated .
[0012]
The invention according to claim 7 is the digital still camera according to claim 6 , further comprising a display-off control means for turning off the display means, and the mirror driving means when the display means is turned off. And a focusing selection means for selecting the phase difference autofocus method corresponding to the quick return mirror in the imaging optical system .
[0013]
Further, the invention of claim 8 is the digital still camera according to claim 7, further, after the main shooting, at least the display by the display means is set to an on / off state of the live view display before the main shooting. Display return control means for returning is provided.
[0014]
The invention according to claim 9 is the digital still camera according to claim 1 , and further controls the mirror driving means to position the quick return mirror in the imaging optical system when half-pressed. In addition, a half-press focusing control unit that controls the phase difference focusing unit so as to perform phase difference autofocus, and, when the shutter button is fully pressed, controls the mirror driving unit to retract the quick return mirror from the imaging optical system. And full-press focusing control means for controlling the image signal focusing means to perform image signal auto-focusing .
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0018]
<1. Device configuration>
FIG. 1 is a schematic configuration diagram of a main mechanism portion in a digital still camera according to an embodiment of the present invention, and FIG. 2 is an operation state diagram of the main mechanism portion at the time of photographing.
[0019]
The digital still camera 1 has a camera body 2 configured using a silver salt single-lens reflex camera. A photographing lens 3 is attached to the front surface of the camera body 2, and the photographing lens 3 includes a photographing lens unit 4. And a diaphragm 5 and the like.
[0020]
A quick return mirror M1 pivotally supported by a pivot 6 at the rear upper part in the camera body 2 is disposed behind the photographing lens unit 4 in the optical path direction. Further, the optical path direction of the quick return mirror M1 A focal plane shutter 7 is disposed behind, and an image sensor 8 is disposed behind the focal plane shutter 7.
[0021]
Although the focal plane shutter 7 is also left in the camera body 2, the focal plane shutter 7 may be removed depending on the type of the image sensor 8.
[0022]
An optical low-pass filter 18 for preventing the influence of aliasing noise during sampling of the analog image signal from the image sensor 8 is disposed on the front surface of the image sensor 8. The optical low-pass filter 18, the focal plane shutter 7 and the imaging sensor 8 constitute an imaging unit 19.
[0023]
The imaging unit 19 can be moved in the front-rear direction along the optical axis by the moving mechanism 30. Then, the imaging unit 19 moves in the optical axis direction forward until the imaging position, that is, the light receiving surface of the imaging sensor 8 reaches the position of the lens back, in conjunction with the quick return mirror M1 rotating upward during imaging. After the photographing, the quick return mirror M1 is moved backward in the optical axis direction to the retracted position that does not cause mechanical interference with the quick return mirror M1 in conjunction with the rotation return of the downward.
[0024]
As the moving mechanism 30, a mechanism having a known configuration may be employed. For example, a mechanism that converts the rotation of a bolt that is rotationally driven by a motor into a linear motion in the axial direction of the bolt may be used. Good.
[0025]
Above the quick return mirror M1, the camera body 2 is formed with a finder equivalent part 9 of the silver salt camera, and a pentagonal prism 11 is disposed in the finder equivalent part 9 via a focusing screen 10. Has been. Further, a predetermined relay lens 12 is disposed behind the prism 11, an eyepiece 13 is disposed behind the relay lens 12, and a photometric sensor 14 is disposed above the relay lens 12. ing. In FIG. 2, the relay lens is omitted. Further, the range from the photographing lens 3 to the optical low-pass filter 18 of the imaging unit 19 corresponds to the imaging optical system in the present invention. Furthermore, the quick return mirror M1, the prism 11, the relay lens 12, and the eyepiece 13 form an optical viewfinder.
[0026]
The quick return mirror M1 is in a steady position inclined at an angle of 45 degrees with respect to the optical axis as shown in FIGS. 1 and 2A until the shutter button 24a shown in FIG. 3 is fully pressed. The optical path L from the photographing lens unit 4 is directed to the focusing screen 10. When the shutter button is fully pressed, as shown in FIGS. 2B to 2D, the optical path L from the photographic lens unit 4 is rotated by being displaced upward to a substantially horizontal position with the pivotal support 6 as the center. Open.
[0027]
M2 is a mirror integrated with the quick return mirror M1, and an optical image transmitted through a half mirror portion partially provided on the quick return mirror M1 is measured by the mirror M2 and the fixed mirror M3 below. It is directed to the sensor 15. The distance measuring sensor 15 receives the optical image, detects the distance to the subject, and automatically focuses the photographing lens unit 4.
[0028]
The prism 11 plays the role of reversing and reducing the optical image formed on the focusing screen 10 and directing it toward the photometric sensor 14 and the eyepiece 13. Further, based on the light amount data obtained by the camera control CPU 20 based on the image data obtained by the photometric sensor 14 or the image sensor 8, the aperture value and shutter speed control values are set. The amount is set.
[0029]
A focus motor 36 for driving a focus lens included in the photographing lens unit 4 in the optical axis direction is provided in the camera body 2.
[0030]
On the back surface of the camera body 2, a display unit 16 including a liquid crystal display (LCD) that displays an image obtained based on the output of the imaging sensor 8 is provided.
[0031]
FIG. 3 is a block diagram showing a control system of the digital still camera 1.
[0032]
In FIG. 3, 3 is a photographic lens, 4 is a photographic lens unit, 5 is a diaphragm, M1 is a quick return mirror, 7 is a focal plane shutter, 8 is an image sensor, 11 is a prism, 13 is an eyepiece, and 16 is a display unit. These are the same as those shown in FIGS.
[0033]
Reference numeral 20 denotes a camera control CPU. The camera control CPU 20 controls each part of the camera body 2. Specifically, the diaphragm 5 is controlled via a diaphragm driver 21, and the image sensor 8 is controlled via a timing generator (sensor drive) 22. In addition, the actuator 17 of the quick return mirror M1 and the moving mechanism 30 of the imaging unit 19 are controlled via the mirror / imaging unit drive circuit 23, and the focal plane shutter 7 is controlled via the shutter driver 25. Further, the focus motor 36 is controlled via the motor driver 26.
[0034]
A camera operation switch 24 is connected to the camera control CPU 20. The camera operation switch 24 includes a shutter button 24a, a power switch, and the like.
[0035]
In this embodiment, the image sensor 8 is formed of a charge coupled device (CCD). The imaging sensor 8 is an area sensor in which primary color transmission filters of R (red), G (green), and B (blue) are stretched in a checkered pattern in units of pixels. , G, and B color component image signals (signals composed of a signal sequence of pixel signals received by each pixel) are photoelectrically converted and output.
[0036]
The timing generator 22 generates and outputs a drive control signal for the image sensor 8 based on a reference clock transmitted from the camera control CPU 20. The timing generator 22 generates, for example, a clock signal such as a timing signal for integration start / end (exposure start / end), a light reception signal read control signal (horizontal synchronization signal, vertical synchronization signal, transfer signal, etc.) of each pixel, It outputs to the image sensor 8 via a driver.
[0037]
The output of the image sensor 8 is signal-processed by a CDS (correlated double sampling) circuit 81, an AGC (auto gain control) circuit 82, and an A / D converter 83, respectively. The CDS circuit 81 reduces the noise of the image signal, and the AGC circuit 82 adjusts the level of the image signal by adjusting the gain. The A / D converter 83 converts the analog signal normalized by the AGC circuit 82 into a 10-bit digital signal.
[0038]
An image processing unit 40 forms an image file by performing image processing on the output of the A / D converter, and is controlled by an image processing CPU.
[0039]
At the time of shooting, image data from the image sensor 8 is taken into the image processing unit 40 and various processes are performed.
[0040]
The signal from the A / D converter 83 taken into the image processing unit 40 is written in the image memory 61 in synchronization with the reading from the image sensor 8, and thereafter, the data in the image memory 61 is accessed to access each block. Processing is to be performed.
[0041]
In the image processing unit 40, the pixel interpolation block 41 is a block that performs pixel interpolation with a predetermined interpolation pattern. In this embodiment, the R, G, and B pixels are masked with their respective filter patterns, and then up to a high band. For G having pixels, a median (intermediate value) filter is used to substitute the average value using the intermediate two values of the surrounding four pixels, and R and B are average-interpolated to obtain respective outputs.
[0042]
The color balance control block 42 performs R, G, and B color correction by independently performing gain correction on the R, G, and B outputs subjected to pixel interpolation by the pixel interpolation block 41. Regarding the color balance, R / G and B / G are calculated by the camera control CPU 20 with respect to the average values of the R, G, and B outputs, and are used as R and B correction gains.
[0043]
The gamma correction block 43 performs non-linear conversion on R, G, and B outputs with normalized color balance, and gradation conversion suitable for the display unit 16 is performed. The gamma-corrected image data is stored in the image memory 61.
[0044]
The video encoder 44 calls up the data stored in the image memory 61, encodes it into NTSC / PAL, and displays it on the display unit 16.
[0045]
The image compression block 45 performs a compression process on the captured image obtained from the image sensor 8 by calling image data from the image memory 61 and compresses the captured image to the memory card 62 via the memory card driver 46 after compression. To be recorded.
[0046]
The memory card 62 is detachably attached to a predetermined part of the camera body 2.
[0047]
FIG. 4 is a view showing a state of the back surface of the digital still camera.
[0048]
In addition to the display unit 16 described above, a quadruple switch 35 is provided on the right side of the camera body 2 and selection items corresponding to the display on the display unit 16 with buttons U, D, L, and R. Various operations such as selection are possible.
[0049]
An LCD button 31, a confirm button 32, a cancel button 33, and a menu button 34 are provided below the quadruple switch 35 on the back of the camera body 2. Among these, the LCD button 31 is a button for turning on and off the display of the display unit 16, and the on / off of the display unit 16 is switched every time the LCD button 31 is pressed. The confirm button 32 and the cancel button 33 are switches for inputting an instruction to confirm or cancel the selection when selecting an item for various settings, and the menu button 34 switches and displays various setting screens such as a menu selection screen described later. It is a switch for.
[0050]
<2. State transition and operation>
Next, state transition and operation of the digital still camera 1 will be described. The digital still camera 1 is mainly provided with two modes of “photographing mode” and “reproduction mode”. Among these modes, the shooting mode is a mode for performing processing related to shooting. In the shooting standby state, the display unit 16 performs live view display in some cases as described later, and displays a shot image immediately after shooting. The reproduction mode is a mode for performing processing relating to a photographed image such as reproducing and displaying a photographed image recorded on the memory card 62 on the display unit 16.
[0051]
The shooting mode and the playback mode can be switched as follows. That is, the mode selection screen is displayed on the display unit 16 by operating the menu button 34 or the like, and the shooting mode and the playback mode are switched by operating the quad switch 35, the confirmation button 32, and the cancel button 33 on the screen. It is possible to do.
[0052]
FIG. 5 is a state transition diagram in the shooting mode of the digital still camera 1. Hereinafter, state transition in the photographing mode will be described. Unless otherwise specified, the operation control of each unit is performed by the camera control CPU 20.
[0053]
When the power is turned on, the camera enters the photographing mode by the optical viewfinder, and the quick return mirror M1 is brought into the state shown in FIG. 2A, and the display unit 16 is turned off. Thus, the digital still camera 1 is activated (state S1). In this state, AF processing is not performed. Therefore, the subject image obtained by the optical viewfinder has a slight blur, but in this state, rough framing can be performed by the optical viewfinder.
[0054]
Further, when the photographer presses the menu button 34 in the state S1 or the state S6 described later, the menu setting screen is displayed, and the photographer performs menu setting (state S2).
[0055]
FIG. 4 described above shows a state where the menu setting screen is displayed on the screen of the display unit 16. As shown in FIG. 4, the menu setting screen selectively designates the AF method to be performed when the shutter button is half-pressed. By pressing either the button U or the button D of the quadruple switch 35, it is possible to select whether the AF method when half-pressed is the contrast AF method or the phase difference AF method. Yes.
[0056]
When the phase difference AF is selected in the state S2, the process proceeds to the state S1, and when the contrast AF is selected in the state S2, the process proceeds to the state S6. At this time, when the state S2 is shifted to the state S1, the display unit 16 is turned off (live view display is turned off), and when the state S2 is shifted to the state S6, the display unit 16 is kept on and the live display is performed. View display is turned on.
[0057]
When the shutter button 24a is half-pressed in the state S1, the phase difference AF and the exposure amount adjustment are performed while the quick return mirror M1 is in the down state and the live view display off state (state S3). Hereinafter, the operation of the state S3 will be described in detail.
[0058]
When the shutter button 24a is half-pressed, as shown in FIG. 2 (A), the light incident through the photographing lens unit 4 and the diaphragm 5 moves up the optical path L by the quick return mirror M1 in the camera body 2. After being focused on the focusing screen 10, it is inverted and reduced by the pentagonal prism 11 and enters the photometric sensor 14. The photometric sensor 14 measures the amount of light, and the camera control CPU 20 calculates exposure control data based on the light amount data. Then, based on the calculated exposure control data, the diaphragm 5 is controlled via the diaphragm driver 21 so that the exposure amount to the image sensor 8 becomes an appropriate value, and a drive control signal is supplied to the image sensor 8. The timing generator 22 is controlled.
[0059]
At this time, the imaging unit 19 is in the rearward retracted position in order to avoid mechanical interference with the quick return mirror M1, and the light receiving surface of the imaging sensor 8 is positioned rearward of the lens back position.
[0060]
On the other hand, a part of the light incident from the photographing lens unit 4 and the diaphragm 5 passes through a half mirror part provided at the center of the quick return mirror M1, and then passes through the mirror M2 and the fixed mirror M3, and the distance measuring sensor. Head to 15. The distance measuring sensor 15 receives this and detects the distance to the subject, and based on this, the focus lens in the photographing lens unit 4 is driven to perform automatic focusing.
[0061]
Simultaneously with the photometry and distance measurement operations as described above, the optical image whose optical path L is converted by the quick return mirror M1 is reduced by the prism 11 and the relay lens 12, and then reaches the eyepiece 13. Therefore, the photographer can visually recognize the subject through the eyepiece unit 13 while being in focus. Although not shown, when the half-pressed state of the shutter button 24a is released in the state S3, the state returns to the state S1 and the framing can be performed again, and the accurate framing can be performed.
[0062]
When the shutter button 24a is further pushed in by the photographer and is fully pressed, a three-frame continuous shooting is executed for a predetermined AF area, and the focus lens position that is in the best focus is selected from the obtained three partial images. (State S4). Hereinafter, the operation of the state S4 will be described in detail.
[0063]
FIG. 6 is a diagram for explaining the focus lens position in the three-frame continuous shooting. In the three-frame continuous shooting, the position when the focus lens is fully pressed (the position focused by the phase difference AF), and the position moved by the deviation amount d obtained from the focal depth before and after the position. In each of the following (hereinafter referred to as “front focus position” and “rear focus position” respectively), partial image data of only the AF area, which is a partial rectangular area at the center of the image, is obtained by the imaging sensor 8. That is, a partial image for three frames is taken. Here, the depth of focus is obtained from the position of the focus lens and the aperture value at the time of full depression, and further obtained for each depth of focus in advance and stored in a ROM (not shown) in the camera control CPU 20. Is used to obtain and use the deviation amount d corresponding to the depth of focus.
[0064]
Then, AF evaluation values (contrast) of the obtained three partial image data are obtained and compared. Then, the partial image with the maximum AF evaluation value is regarded as the partial image with the best focus, and the focus lens position is selected.
[0065]
Hereinafter, an internal operation when the shutter button 24a is fully pressed in the state S4 will be described. When the shutter button 24a is fully pressed, the focus lens is kept at the position driven by the phase difference AF performed when the shutter button 24 is half-pressed, and the diaphragm 5 is narrowed by a predetermined amount. At the same time, the white arrow in FIG. As shown by, the quick return mirror M1 starts to be pivoted upward via the pivot 6. In conjunction with this, the imaging unit 19 moves forward in the optical axis direction of the photographic lens unit 4 via the moving mechanism 30. In FIG. 2, the actuator 17 that drives the quick return mirror M1 and the moving mechanism 30 that moves the imaging unit 19 are omitted.
[0066]
When the quick return mirror M1 reaches the lower part of the focusing screen 10 and the mirror up operation is completed as shown in FIG. 2C, the forward movement of the imaging unit 19 is also stopped, and the light receiving surface of the imaging sensor 8 is moved to the lens back position. Set to Then, as shown in FIG. 2D, the focal plane shutter 7 opens and closes at a predetermined speed, and an optical image that has passed through the photographing lens unit 4 and the diaphragm 5 is formed as it is on the image sensor 8, where photoelectric conversion is performed. Is done. Then, by the timing control of the camera control CPU 20, only the partial image signal in the AF area is output via the buffer among the signals photoelectrically converted.
[0067]
Next, as described above, the depth of focus when fully pressed is calculated, and the deviation amount d of the focus lens corresponding to the depth of focus is calculated. Then, based on this, the focus lens is moved to the front focus position and the rear focus position, and partial images are taken in the same manner as described above. Then, as described above, the focus lens position corresponding to the partial image with the best focus is selected, and the focus lens is actually moved to the focus lens position.
[0068]
Next, a photographing operation is performed at the set focus lens position (state S5). Specifically, as shown in FIG. 2D, the focal plane shutter 7 opens and closes at a predetermined speed, and an optical image that passes through the photographing lens unit 4 and the diaphragm 5 is directly formed on the image sensor 8. Is photoelectrically converted. Then, the photoelectrically converted signal is output through the buffer.
[0069]
The image data output from the image sensor 8 is subjected to predetermined signal processing by the CDS circuit 81, the AGC circuit 82, and the A / D converter 83, and then taken into the image processing unit 40 for reading by the image sensor 8. Synchronously written in the image memory 61.
[0070]
After shooting, the quick return mirror M1 returns to its original position, the optical path L again moves toward the focusing screen 10 and enters a shooting standby state. In conjunction with the rotation return operation of the quick return mirror M1, the imaging unit 19 moves to the retracted position in the rear in the optical axis direction to avoid interference with the quick return mirror M1 returning to the rotation.
[0071]
Next, the selected image data is recorded on the memory card 62. Specifically, the image data written in the image memory 61 is subjected to the above-described pixel interpolation processing, color balance control, and gamma correction processing in the image processing unit 40, and is stored in the image memory 61 again. Then, it is read from the image memory 61 and displayed on the display unit 16 as a captured image. At the same time, the image is compressed by the image compression block 45 and then recorded on the memory card 62 via the memory card driver 46.
[0072]
When the photographing operation ends, the process returns to the state S1.
[0073]
In addition, when the LCD button 31 is pressed in the state S1, the display unit 16 is turned on and the mode is changed to the shooting mode with live view display, and the quick return mirror M1 is raised as shown in FIG. When the display unit 16 is turned on, live view display is started and contrast AF is performed (state S6).
[0074]
In state S6, the quick return mirror M1 is raised, so that the light from the photographing lens unit 4 reaches the imaging sensor 8. As a result, the image data output from the image sensor 8 every predetermined time (for example, every 1/30 seconds) is temporarily stored in the image memory 61 via the image processing unit 40. Then, the image data is read out to the image processing unit 40, where the above-described image processing is performed and stored again in the image memory 61. Then, the video encoder 44 calls the data stored in the image memory 61, encodes the data to NTSC / PAL, and displays the data on the display unit 16, thereby performing live view display.
[0075]
The camera control CPU 20 also performs contrast AF during live view display. The contrast AF method performed here reads the image data stored in the image memory 61, obtains the AF evaluation value (contrast) of the image, and drives the focus motor 36 so that the AF evaluation value is maximized. This is an autofocus method in which the focus lens is moved to perform focusing. At this time, a known technique such as a hill-climbing method can be used as a control method for maximizing the contrast.
[0076]
Next, when the shutter button 24a is half-pressed, the state is almost the same as in the state S6, but exposure amount adjustment and more precise contrast AF are performed (state S7). The exposure amount adjustment here is performed by adjusting the aperture by the aperture driver 21 and the exposure amount of the CCD 303, that is, the charge accumulation time of the image sensor 8 corresponding to the shutter speed. Further, with respect to contrast AF, the focus lens moving step is made finer in the state S6, thereby performing more precise focusing. Thereby, more accurate framing can be performed.
[0077]
Subsequently, when the shutter button 24a is fully pressed, a photographing operation is executed under the contrast AF (state S8). As a photographing operation, the focal plane shutter 7 opens and closes at a predetermined speed as described above, and an optical image from the photographing lens unit 4 is formed as it is on the image sensor 8, and the output image data is stored in the image memory 61. Is done. The image data is taken out by the image processing unit 40, subjected to the above-described image processing, and then stored in the image memory 61 again. Further, the image data is also recorded on the memory card 62.
[0078]
When the photographing operation is completed, the process returns to the state S6 again, and the next photographing is possible.
[0079]
Note that when the LCD button 31 is pressed in the state S6, the display unit 16 is turned off, and thus the live view display is turned off, and the photographing mode using the optical viewfinder in the state S1 described above is entered.
[0080]
The above is the state transition and operation of the digital still camera 1.
[0081]
As described above, according to this embodiment, in a single-lens reflex digital still camera, when performing live view display, the quick return mirror M1 is an imaging optical system including the imaging lens unit 4, the diaphragm 5, and the imaging unit 19. Since it is retracted from the system and contrast AF is performed, contrast AF can be performed according to live view display. In addition, contrast AF is performed during live view display, and accurate framing can be performed.
[0082]
Further, when the live view display is turned off, the quick return mirror M1 is positioned in the imaging optical system so that the subject image can be visually recognized by the optical viewfinder and the phase difference AF is performed. Auto-focusing is also possible when switching from display to optical viewfinder and framing with optical viewfinder.
[0083]
Further, since the display unit 16 is turned off when the live view display is turned off, power consumption can be suppressed.
[0084]
In addition, since the phase difference AF is performed when the shutter button 24a is half-pressed (state S3) in the photographing mode by the optical viewfinder, the processing time of autofocus when the shutter button 24a is half-pressed can be shortened, and there is no time lag for autofocus. .
[0085]
When contrast AF is designated on the menu setting screen, the quick return mirror M1 is retracted from the imaging optical system (state S6), and when phase difference autofocus is designated on the menu setting screen, the quick return mirror is saved. Since M1 is positioned in the imaging optical system (state S1), when high focus accuracy is required, contrast AF can be performed accordingly, and phase difference AF is performed when high-speed autofocus is desired. It can be carried out. That is, the optimum autofocus method can be selected according to the judgment of the photographer.
[0086]
Further, since the live view display is turned on when the contrast AF method is designated on the menu setting screen, accurate framing can be performed based on the live view image subjected to contrast AF.
[0087]
Further, when the display unit 16 is turned off, the quick return mirror M1 is positioned in the imaging optical system, and the phase difference AF method is selected correspondingly, so that framing can be performed even when the live view display is turned off. it can.
[0088]
In addition, since at least the display on the display unit 16 is returned to the on / off state of the live view display before the main shooting after the main shooting, the operability is improved.
[0089]
In addition, since contrast AF is performed at the time of actual photographing (full press), it is possible to perform focusing with high accuracy at the time of actual photographing.
[0090]
Furthermore, in the photographing mode using the optical viewfinder, phase difference AF is performed when half-pressed, and contrast AF is performed when fully pressed, so that contrast AF can be performed when autofocus with high accuracy at the time of full-press is to be performed.
[0091]
<3. Modification>
Although an example of a digital still camera has been described in the above embodiment, the present invention is not limited to this.
[0092]
For example, in the above-described embodiment, when the shutter button is fully pressed in the shooting mode using the optical viewfinder, three frames are continuously shot. Of these, shooting is performed in the best focus state. It is possible to perform normal one-frame shooting under the contrast AF method.
[0093]
【The invention's effect】
As described above, according to the invention of claims 1 to 9, in the shooting mode according to the optical viewfinder, performs high-speed phase difference autofocus during half-pressing the shutter button, good during the shooting accuracy image Since signal autofocus is performed, an appropriate autofocus method can be automatically used according to circumstances, and operability is good.
Further, according to the invention of claim 2 to claim 4 , in the single-lens reflex type digital still camera, when the live view display is performed on the display means, the mirror drive means is controlled to control the quick return mirror from the imaging optical system. Since the image signal autofocus, which is the focus based on the image signal, is performed while being saved, the image signal autofocus can be performed during live view display. In addition, autofocus is performed during live view display, and accurate framing can be performed.
[0094]
In particular, according to the invention of claim 3 , when the live view display is turned off, the quick return mirror is positioned in the imaging optical system so that the subject image can be visually recognized by the optical viewfinder, and the phase difference autofocus is performed. Therefore, auto-focusing is possible even when framing is performed using the optical viewfinder by switching from the live view display to the optical viewfinder according to the photographer's intention.
[0095]
In particular, according to the invention of claim 4 , when the live view display is turned off, the display means is turned off, so that power consumption can be suppressed.
[0097]
In particular, according to the inventions of claims 5 to 8 , when the image signal autofocus is designated, the quick return mirror is retracted from the imaging optical system, and when the phase difference autofocus is designated. Since the quick return mirror is positioned in the imaging optical system by controlling the mirror driving means, the image signal autofocus can be performed when the image signal autofocus is designated. Further, when high focus accuracy is required, image signal autofocus can be designated, and phase difference autofocus can be designated when high-speed autofocus is desired. That is, the optimum autofocus method can be selected according to the judgment of the photographer.
[0098]
According to the invention of claim 6 in particular, since the live view display is turned on when the image signal autofocus method is designated by the focusing instruction means, it is accurate based on the live view image subjected to the image signal autofocus. Framing can be performed.
[0099]
In particular, according to the invention of claim 7 , when the display means is turned off, the mirror driving means is controlled so that the quick return mirror is positioned in the imaging optical system, and the phase difference autofocus system is correspondingly provided. Therefore, framing can be performed even when the live view display is off.
[0100]
In particular, according to the eighth aspect of the invention, after the actual photographing, at least the display by the display means is returned to the on / off state of the live view display before the actual photographing, so that the operability is improved.
[0103]
In particular, according to the ninth aspect of the invention, the phase difference autofocus is performed when half-pressed, and the image signal autofocus is performed when fully pressed. Auto focus can be performed.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a main mechanism portion in a digital still camera according to an embodiment of the present invention.
FIG. 2 is an operation state diagram of a main mechanism portion at the time of photographing.
FIG. 3 is a block diagram showing a control system of the digital still camera.
FIG. 4 is a diagram showing a state of a back surface of the digital still camera.
FIG. 5 is a state transition diagram in a shooting mode of the digital still camera.
FIG. 6 is a diagram for explaining a focus lens position in three-frame continuous shooting.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Digital still camera 8 Image sensor (Image signal focusing means with image sensor 20 and 36)
9 Viewfinder equivalent part 10 Focusing screen 11 Penta-shaped prism 12 Relay lens 13 Eyepiece 15 Distance sensor (phase difference focusing means 20 and 36)
16 Display unit 17 Actuator (mirror drive means)
19 imaging unit 20 camera control CPU (focus control means, view-off control means, phase difference focus control means, half-press control means, mirror control means, display control means, display return control means, shooting focus control means, Half-press focus control means, full-press focus control means)
21 Aperture Driver 23 Mirror / Imaging Unit Drive Circuit 24a Shutter Button 31 LCD Button (Live View Operation Member)
34 Menu button (Focus instruction means with 16)
36 Focus motor M1 Quick return mirror M2 Mirror M3 Fixed mirror

Claims (9)

An optical finder that changes the optical path from the imaging optical system to the imaging device by a quick return mirror so that an imaging target can be visually recognized, and the quick return mirror is driven between the imaging optical system and the outside of the imaging optical system. A single-lens reflex digital still camera equipped with a mirror driving means,
With a shutter button that can be pressed halfway and fully,
Phase difference focusing means for performing phase difference autofocus;
Image signal focusing means for performing image signal auto-focusing, which is focusing based on the image signal obtained by the image sensor;
In the shooting mode by the optical viewfinder, when the shutter button is half-pressed, the half-press control means for controlling the phase difference focusing means to perform phase difference autofocus,
In-focus control means for controlling the image signal focusing means to perform auto focus on the image signal at the time of actual shooting,
A digital still camera comprising: The digital still camera according to claim 1, further comprising:
A display means capable of displaying a live view that displays images of photographing candidates;
When performing live view display on the display means, the mirror drive means is controlled to retract the quick return mirror from the imaging optical system, and the image signal focusing means is controlled to perform image signal autofocus. Focus control means,
Digital still camera comprising: a. The digital still camera according to claim 2 , further comprising:
A live view operation member for instructing at least off of the live view display;
A view-off control means for turning off the live view display based on the off instruction of the live view display by the live view operation member;
When turning off the live view display, the quick return mirror is positioned in the imaging optical system so that the subject image can be visually recognized by the optical viewfinder, and the phase difference focusing means is configured to perform phase difference autofocus. Phase difference focusing control means for controlling;
A digital still camera comprising: The digital still camera according to claim 3,
The digital still camera characterized in that the view-off control means turns off the display means when turning off the live view display . The digital still camera according to claim 1 , further comprising:
Focusing instruction means for instructing switching between the phase difference autofocus method and the image signal autofocus method;
When the image signal autofocus method is instructed by the focus instruction means, the mirror drive means is controlled to retract the quick return mirror from the imaging optical system, and the phase difference is detected by the focus instruction means. Mirror control means for controlling the mirror driving means to position the quick return mirror in the imaging optical system when an autofocus method is designated;
Digital still camera comprising: a. The digital still camera according to claim 5 , further comprising:
A display means capable of displaying a live view that displays images of photographing candidates;
Display control means for controlling the display means to turn on the live view display when the image signal autofocus method is designated by the focusing instruction means;
A digital still camera comprising: The digital still camera according to claim 6 , further comprising:
Display off control means for turning off the display means;
A focusing selection unit that controls the mirror driving unit to position the quick return mirror in the imaging optical system when the display unit is turned off, and selects a phase-difference autofocus method correspondingly; ,
A digital still camera comprising: The digital still camera according to claim 7, further comprising:
A digital still camera comprising display return control means for returning at least the display by the display means to the on / off state of the live view display before the main photographing after the main photographing . The digital still camera according to claim 1 , further comprising:
At the time of half-pressing, the mirror driving means is controlled to position the quick return mirror in the imaging optical system, and the half-press focusing control means for controlling the phase difference focusing means to perform phase difference autofocus When,
A full-press focusing control unit that controls the mirror driving unit to retract the quick return mirror from the imaging optical system and controls the image signal focusing unit to perform image signal auto-focusing at the time of the full-pressing; ,
A digital still camera comprising:

Images