JP2014048492A - Image capturing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image capturing device capable of superimposing an electronic view finder image on an optical finder image for simultaneous viewing and allowing a superimposed electronic view finder image to be viewed clearly without being buried in an object image in the optical finder even in bright outdoor light.SOLUTION: When object luminance acquired by photometric means is lower than a predefined object luminance level, luminance of an electronic view finder is increased as the object luminance increases and light reduction means is made fully transmissive. When object luminance acquired by photometric means is no less than the predefined object luminance level, luminance of the electronic view finder is kept at a predefined luminance level and transmittance of the light reduction means is reduced as the object luminance increases.

Description

  The present invention relates to a viewfinder of an image pickup apparatus, and more particularly to an image pickup apparatus such as a single-lens reflex camera capable of superimposing an image of an electronic viewfinder on an optical viewfinder image and simultaneously viewing both images.

  In recent years, even in a single-lens reflex camera type imaging apparatus, it is possible to shoot still images by so-called live view display that displays continuous captured images of an imaging element on an external display unit (display), and even movie recording. Yes. At that time, the main mirror that guides the subject light to the optical viewfinder of the single-lens reflex camera is retracted out of the shooting optical path, so that the photographer of the camera cannot see the optical viewfinder image, and instead the external viewfinder placed on the back of the camera. You will see the scene image on the display.

  However, it is troublesome for the optical viewfinder and the external display section to change the position of looking into the camera, and shooting with a single-lens reflex camera while looking at the external display section makes it difficult to close the arm holding the camera, causing camera shake. It is a disadvantage that it becomes an unstable posture that is easy to do. In particular, hand-held telephoto lens photography without using a tripod was impractical.

  In order to solve this problem, a camera that can switch between an optical viewfinder and an electronic viewfinder has been proposed. If the optical viewfinder and the electronic viewfinder can be switched in the same optical path, the posture of the photographer looking into the camera's viewfinder in the live view display shooting using the electronic viewfinder and the movie shooting Since it is not different from the state in which the viewfinder is used, the camera can be held in an ideal position and shooting can be performed.

  The most realistic means for allowing the camera photographer to observe both the optical viewfinder and the electronic viewfinder is a half mirror between the exit surface of the pentaprism, which is a member of the optical viewfinder, and the eyepiece. It is conceivable to arrange a half prism) and introduce the display optical path of the electronic viewfinder from the middle of the optical path of the optical viewfinder.

  Further, in Patent Document 1, a finder apparatus that superimposes and displays an electronic viewfinder image on a finder optical image has been proposed. Specifically, the amount of light in the optical subject image can be made variable by placing a liquid crystal filter in the viewfinder optical path, while the amount of light in the superimposed electronic image can be changed by changing the brightness of the display panel of the electronic viewfinder. Is possible.

  Also, an optical viewfinder mode that does not display an electronic image, a superimposed display mode that displays an electronic image superimposed on an optical image, and an image confirmation mode that displays only the electronic image that has been captured in the past (playback mode) ) Can be realized in accordance with various display state modes. Furthermore, a configuration example in which the present invention is applied to a single-lens reflex camera is also shown.

JP 2003-78785 A

As described above, Patent Document 1 discloses a viewfinder configuration example of a single-lens reflex camera that can superimpose an image of an electronic viewfinder on an optical viewfinder image and can visually recognize both images at the same time. In Patent Document 1,
1) In the optical finder mode In the optical finder mode in which no electronic image is displayed, the control circuit stops the image sensor and the signal processing circuit. As a result, the electronic image display function is completely deactivated. At this time, the liquid crystal filter as the light reducing means is set in a transmissive state (transmittance 100%).
2) In superimposed display mode In the superimposed display mode in which an electronic image is superimposed on an optical image, a moving image is displayed on a liquid crystal monitor by continuously operating an imaging device, a signal processing circuit, and the like. At this time, the liquid crystal filter is set in a semi-transmissive state (transmittance 50%). Furthermore, when the brightness of the subject is low, the optical image may not be visible.
On the other hand, there may be a case where a reduction of 50% is insufficient. Therefore, if the luminance of the subject is measured and the transmittance of the liquid crystal filter is changed in accordance with the value, a stable finder image can always be obtained. Further, the backlight light quantity may be adjusted to achieve a relative balance.
3) In playback mode In an image confirmation mode in which an electronic image captured in the past is read out and only that image is displayed, the image sensor is stopped and the signal processing circuit reads out the previous image taken from the image memory. Display a still image on the LCD monitor. At this time, the liquid crystal filter is set to a non-transmissive state (transmittance 0%).

  As described above, the optimal viewfinder display for the photographer is achieved by changing the transmittance of the light reduction means of the subject light consisting of the liquid crystal filter and changing the amount of backlight of the liquid crystal monitor according to the various finder display modes of the camera. Proposals have been made for such control.

  However, when the electronic image is superimposed on the optical image, the camera is controlled so that the electronic image with limited brightness can be clearly seen with respect to the subject optical image in the optical viewfinder under bright external light. There was no disclosure about what to do.

  Accordingly, an object of the present invention is to visually recognize a superimposed display without being buried in an optical subject image in an imaging apparatus such as a single-lens reflex camera capable of superimposing an electronic viewfinder image on an optical viewfinder image and simultaneously viewing both images. An object of the present invention is to provide an imaging device that can be used.

In order to achieve the above object, in the present invention, an optical viewfinder for observing a subject image, an electronic viewfinder capable of displaying an image captured by an image sensor and photographing information, a photometric means for measuring subject brightness, A dimming means for dimming subject light toward the optical viewfinder, and an imaging device capable of visually recognizing the display of the electronic viewfinder superimposed on the subject image of the optical viewfinder,
When the subject brightness obtained by the photometry means is lower than a predetermined subject brightness, the brightness of the electronic viewfinder is increased as the subject brightness increases, and the dimming means is set in a transmissive state.
When the subject brightness obtained by the photometry means is equal to or higher than the predetermined subject brightness, the brightness of the electronic viewfinder is maintained at a predetermined brightness, and the transmittance of the dimming means is decreased as the subject brightness increases. It was set as the characteristic characterized by this.

Also, an optical viewfinder for observing a subject image, an electronic viewfinder capable of displaying an image captured by an image sensor and photographing information, a dimming means for dimming subject light toward the optical viewfinder, and the optical viewfinder An imaging device capable of visually recognizing the display of the electronic viewfinder superimposed on a subject image of the optical viewfinder and a mirror for guiding subject light;
In the display mode in which the mirror blocks the optical path of the subject light toward the optical viewfinder, the dimming means is set in a dimming state.

  According to the present invention, in an imaging apparatus capable of superimposing an image of an electronic viewfinder on an optical viewfinder image and viewing both at the same time, the electronic viewfinder is not buried in the subject image of the optical viewfinder even under bright external light. It is possible to provide an imaging apparatus capable of clearly viewing the superimposed display of images.

It is explanatory drawing of the display sequence of a finder image. It is the schematic of the structure of a camera. It is explanatory drawing of the example 1 of PNLCD arrangement | positioning. It is explanatory drawing of the example 2 of PNLCD arrangement | positioning. It is an electrical block diagram of an imaging device. It is explanatory drawing of TFT backlight control. It is explanatory drawing of PNLCD control. It is explanatory drawing of a finder image. It is explanatory drawing of the operation member of live view and video recording. It is explanatory drawing of the optical path which returns to a photographer's eye as ghost light. It is explanatory drawing of the optical path which returns to a photographer's eye as ghost light.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS.
In FIG. 1 to FIG. 11, the same component parts are given the same numbers.

  FIG. 2 is a diagram showing a schematic configuration of a digital single-lens reflex camera as an imaging apparatus to which the present invention is applied.

In FIG. 2, reference numeral 101 denotes a CPU (central processing unit), and the operation of the camera is controlled by the CPU 101. Reference numeral 105 denotes a photographic lens as a photographic optical system, which forms an image of subject light on the image sensor 106.
Note that the photographing lens 105 shown in FIG. 2 is expressed by a single lens 105a for the sake of convenience, but actually includes a plurality of lenses.

  Reference numeral 120 denotes a focus detection plate (hereinafter referred to as a focus plate) placed on an image formation surface (primary image formation surface) equivalent to the image formation surface of the imaging element 106 of the photographing lens 105, and the subject image is reflected by the main mirror 123. The primary image is formed on the focus plate 120. The photographer has a so-called TTL type optical viewfinder configuration in which the subject image can be viewed through a pentaprism 128 as a viewfinder optical path conversion means and further through an eyepiece lens 121.

  On the other hand, the main mirror 123 is a semi-transmissive mirror, and a part of the light beam that has passed through the main mirror 123 is guided to the focus detection unit 119 that is a focus detection unit through the sub mirror 122, and the focus detection by the well-known phase difference detection method. Perform the action. The focus detection means can detect the focus for a plurality of areas on the shooting screen.

  Reference numeral 130 denotes a photometric sensor as a photometric means comprising 15 × 23 pixels in the vertical and horizontal directions, and can detect each luminance obtained by dividing the subject image formed on the focusing plate 120 by the photometric lens 129 into a plurality of regions.

  When the photographer presses release SW 114 (FIG. 3), main mirror 126 is retracted out of the optical path of photographing lens 105. On the other hand, the light of the subject focused by the photographing lens 105 is controlled by the focal plane shutter 133, and after the photoelectric conversion processing is displayed as a subject image by the image sensor 106, it is recorded on a recording medium as a photographed image. In addition, the captured image is displayed on the external display unit 113 of the TFT display.

  This is the basic operation of normal still image shooting, but the camera can also perform live view shooting and movie shooting.

  In a general single-lens reflex camera equipped with an optical viewfinder, as described above, when the main mirror 123 is retracted out of the optical path of the photographing lens 105 at the time of photographing, the optical viewfinder is in a light-shielding state and the photographed subject cannot be seen.

  On the other hand, in the camera of the present embodiment, an electronic viewfinder including the finder internal display unit 124 which is a small XGA (1024 × 768 pixel) size TFT display panel is arranged in the middle of the optical finder optical path. Even when the mirror 123 is retracted out of the photographing optical path, the subject image displayed on the finder internal display unit 124 can be confirmed.

  That is, the subject can be observed with an electronic image in the same finder optical system as that for observing the optical finder, which enables so-called live view shooting.

  In the live view shooting, the main mirror 123 is retracted from the shooting optical path, the image pickup device 106 continuously takes an image of the shooting subject with the shutter 133 opened, and the image is an external display which is a TFT monitor on the back of the camera. The subject image is continuously displayed in either the unit 113 or the viewfinder internal display unit 124 of the electronic viewfinder, and the photographer performs still image shooting at an arbitrary timing while observing this display.

  The electronic viewfinder 124 can display an image captured by the image sensor and shooting information.

  Furthermore, moving image shooting is performed by converting the live view shooting state into a moving image format and recording at an arbitrary timing.

  FIG. 9 shows a live view switch 140 and a moving image shooting switch 141 arranged on the exterior of the camera. The live view switch 140 is a rotary switch. When the protrusion of the switch is at the position of the icon 142 in the shooting mode, the live view switch 140 is a normal still image shooting mode using the optical viewfinder, and the protrusion is at the position of the icon 143. When is moved, the shooting mode of the camera is set to the live view shooting mode.

  When the moving image start / stop switch 141 is pressed in the live view shooting mode, moving image shooting / recording is started, and the moving image shooting is stopped again by pressing the button again.

  Next, specific configurations regarding the optical viewfinder and the electronic viewfinder will be described in detail below.

  FIG. 3 is a detailed enlarged view of the optical viewfinder portion in FIG. In FIG. 3, reference numeral 126 denotes an optical path synthesis prism as an optical path synthesis means for synthesizing the image of the finder internal display unit (electronic viewfinder) 124 and the optical finder image.

  The optical path combining prism 126 is formed by bonding two triangular prisms, and a joint surface 126a of one triangular prism is a half mirror.

  The image displayed on the finder internal display unit 124 is partially reflected by the half mirror 126a and enters the photographer's eyes. At the time of live view shooting or moving image shooting, the main mirror 123 retracts out of the shooting optical path, so that the subject light from the shooting lens 105 does not reach the photographer's eyes.

  That is, the photographer can observe only the subject image displayed on the finder internal display unit 124. Further, a part of the amount of light from the photographic subject is attenuated by the half mirror 126a, but much of the light reaches the eyes of the photographer.

  Here, in order to reduce the amount of light of the optical viewfinder subject image without any practical problem, a vapor deposition film on the half mirror surface 126a is formed so that the transmittance is 70% and the light of the internal display unit 124 is 30% reflected (70% attenuation). The amount of light attenuation of the electronic viewfinder is set, and the light intensity balance of the optical viewfinder subject light and the electronic viewfinder is balanced by increasing the brightness of the backlight LED 124a of the finder internal display unit 124.

The optical viewfinder looks at the subject image projected on the focus plate 120 by the photographing lens 105 with the eyepiece 121 enlarged, but the eyepiece 121 is also shared in the electronic viewfinder, The EVF lens 125 and the EVF mirror 127 for bending the optical path are arranged so that the diopter of the finder internal display unit 124 at different positions of the optical path is the same.
The eyepiece 121 is usually composed of a plurality of lenses in order to suppress various optical aberrations, but here, a single lens is substituted for convenience.

  With the above configuration, the photographer of this camera observes the subject with the normal optical viewfinder during normal still image shooting, but the same posture that was looking into the optical viewfinder during live view shooting or movie shooting The display by the finder internal display unit 124, that is, subject observation using a so-called electronic view finder can be performed.

  In addition, the camera automatically selects whether images continuously captured by the image sensor 106 are displayed on the finder internal display unit 124 or the external display unit 113. . An eyepiece detection sensor 160 for detecting whether the photographer is observing the optical viewfinder of the camera is provided in the vicinity of the eyepiece lens 121, and it is determined that the photographer is looking into the viewfinder of the camera according to the output. Then, the photographed image is displayed on the finder internal display unit 124, and when it is determined that the photographer is not looking into the finder of the camera, the image is displayed on the external display unit 113.

  Even when the main mirror 123 is located in the photographing optical path, that is, when the optical viewfinder is enabled in the still image photographing state, the focus detection area and the remaining battery level are displayed on the viewfinder internal display unit 124. If shooting information such as ISO sensitivity value is displayed as a character or a number, it is possible to superimpose the superimposed image on the optical image of the shooting subject.

  However, the finder internal display unit 124 generally has a TFT transmittance as low as about 20%, the backlight is diffused illumination of LEDs, and further, the half mirror 126a is used to reduce the amount of light emitted by the finder internal display unit 124 to 30%. Since only% will reach the photographer's eyes, there is a limit to increasing the brightness of the superimpose display. Therefore, when shooting a high-luminance subject such as outdoors in fine weather, the viewfinder internal display 124 superimposed on the optical viewfinder image of the subject is buried in a bright subject image, resulting in poor visibility. There's a problem.

  In other words, in high-brightness subject shooting with a camera, if only the subject light of the optical viewfinder can be reduced, the viewfinder internal display unit 124 can be relatively clearly viewed.

  Therefore, as shown in FIG. 3, a PNLCD (light scattering liquid crystal) panel 150, which is a type of liquid crystal panel, is used in the vicinity of the focus plate 120, which is the primary imaging plane of the photographic subject, to reduce the subject light of the optical viewfinder. The PNLCD 150 performs voltage reduction to reduce the brightness of the subject image.

  The configuration of this camera is similar to that of Patent Document 1. The PNLCD 150 has an advantage that the original brightness of the subject light of the optical finder is hardly impaired because the transmittance in the non-scattering state in which an antireflection coating is applied to the front and back surfaces of the panel and a driving voltage of 5 V is applied exceeds 90%. is there.

  On the other hand, the transmittance is about 3% in the scattering state with no drive voltage, and the light intensity can be controlled by about 5 steps by reducing the subject brightness value (BV value) by 1/30 of the light from the transmitting state. It becomes.

  However, as described above, in a general single-lens reflex camera, for optimal exposure control, the subject image primarily formed on the focusing screen 120 is secondarily formed on the photometric sensor 130 via the photometric lens 129, Thus, luminance detection of the subject, so-called photometry is performed, and when the transmittance of the liquid crystal panel 153 changes, the output of the photometry sensor 130 changes.

  For example, when the transmittance of the liquid crystal panel 153 is 50%, the output of the photometric sensor is reduced by one step (light quantity 1/2) as an exposure value (EV value) when considered simply. Means that the optimum value is controlled by one step. This problem can be dealt with by performing control to correct the exposure amount in accordance with the decrease in the transmittance of the liquid crystal panel. Actually, the amount of light incident on the photometric sensor 130 varies in a complicated manner due to the relationship between the diffusion characteristics of the liquid crystal of the panel, which is a dimming means, and the optical characteristics of the photographing lens mounted on the camera.

  Therefore, the number of photometric correction parameters that the camera has at the time of normal total transmission is prepared in a number corresponding to the step of changing the transmittance of the PNLCD 150, or a correction value corresponding to the transmittance is obtained in the form of a function. In this case, the correct photometric value can be obtained even if the PNLCD 150 has an arbitrary light reduction amount or the photographic lens attached to the camera is changed.

  Next, another arrangement example of the PNLCD 150 which is a dimming means is shown in FIG. The PNLCD 150 is disposed between the optical path combining prism 126 (that is, the half mirror 126a) and the pentaprism 128 which is a finder optical path converting means.

  Here, the PNLCD 150 includes all of the finder light beams f0 (field center), f1 (field upper limit), and f2 (field lower limit), and the light metering light beams e0 (metering field center), e1 (light metering field upper limit), and e2 (light metering field upper limit). The arrangement has the advantage that there is no need to perform complicated photometric correction because the PNLCD 150 does not affect the photometric output even if the subject light directed to the optical viewfinder is dimmed. It has become.

  FIG. 8 shows an example in which the subject image of the optical viewfinder and the image of the viewfinder internal display unit 124 composed of the TFT panel are displayed in a superimposed manner. The finder internal display unit 124 displays a focus detection area and a shutter speed at which the photographing lens 105 is brought into focus, an aperture value of the photographing lens 105, and a sensitivity setting value of the image sensor 106.

  Here, the finder internal display unit 124 sets the effective range of display up to the out-of-field region including the optical finder image range and the photographing information display range below it.

  The TFT panel of the viewfinder internal display 124 is a panel having an aspect ratio of 4: 3. If the field of view of the optical finder and the effective imaging range of the image sensor are 3: 2, the TFT panel has a region corresponding to the entire field of view of the optical finder. Shooting information such as a shutter speed using the finder internal display unit 124 below the optical finder image range, an aperture value of the photographic lens 105, and a sensitivity (so-called ISO value) setting value is displayed while displaying a captured image or a focus detection area. It is possible to display.

  In the above, the arrangement of the optical system and the dimming means in which the optical viewfinder and the electronic view finder are compatible has been described. However, the position of the PNLCD 150 as the dimming means in any of the above two examples depends on the space. This may be determined according to the above problem, ROM capacity problem, and the like.

  Next, the control operation of the entire camera, the optical viewfinder, the electronic viewfinder, and the PNLCD 150, which is a dimming means, will be described using the flowchart of FIG.

  In step S300 of FIG. 1, the camera shooting mode is selected. If it is determined in step S301 that the selected shooting mode is the live view shooting mode (no determination), the camera sequence performs an operation of shifting from mirror-down to mirror-up, and a shutter opening operation. In step S306, the PNLCD 150 When the power is turned off, the imaging device 106 starts a continuous photographing operation.

  The captured images are sequentially displayed on the finder internal display unit 124 turned on in step S307, and the photographer can observe the subject with the electronic viewfinder. In step S300 of FIG. 1, the camera shooting mode is selected.

(Backlight control 1)
If it is determined in step S301 that the selected shooting mode is the live view shooting mode (no determination), the camera sequence performs an operation of shifting from mirror-down to mirror-up, and a shutter opening operation. In step S306, the PNLCD 150 When the power is turned off, the light is in the opaque state, which is the maximum dimming state, and the image sensor 106 starts a continuous photographing operation.

  The captured images are sequentially displayed on the finder internal display unit 124 turned on in step S307, and the photographer can observe the subject with the electronic viewfinder. At this time, the current value of the backlight LED 124a of the finder internal display unit 124 is controlled according to the backlight control 1 of FIG. 6 corresponding to the brightness (luminance) of the subject (step S308).

  Here, the camera is in a state where the main mirror 123 is lifted and retracted out of the photographing optical path (mirror up state), and the photometric sensor 130 cannot measure the subject brightness (BV value) primarily imaged on the focusing screen 120. The brightness of external light is measured using the output of the eyepiece detection sensor 160 provided in the vicinity of the eyepiece lens 121.

  Originally, in the live view shooting mode, the main mirror 123 is retracted out of the optical path of the taking lens, and although the subject light cannot be observed with the optical viewfinder, the focus plate 120 and the pentaprism 128 are intentionally moved in step 306. The PNLCD 150 disposed between them is in a non-transmitting / diffusing state which is the maximum dimming state.

  This is because the external light component that enters from the eyepiece lens 121 or the light of the in-viewfinder display unit 124 passes through the half mirror 126a and becomes stray light, and is almost perpendicular to the finder optical axis and facing the photographer's eye. This is to prevent the photographer from seeing it as ghost light reflected by the main mirror 123.

  In FIG. 10, the display light of the finder internal display unit 124 passes through the half mirror 126a, is reflected on the bottom surface of the optical path combining prism 126, is reflected again on the subject side by the half mirror 126a, passes through the pentaprism 128, The optical path is reflected by the main mirror 123 retracted from the optical path of the photographing lens 105 and returned to the photographer's eyes as ghost light.

  However, if the applied voltage of the PNLCD 150 disposed between the focus plate 120 and the pentaprism 128 is turned off, the minimum transmittance and the maximum light-shielding state can be obtained, so that the intensity of the ghost light is greatly suppressed. It becomes possible.

  On the other hand, FIG. 11 shows the case where the display light of the finder internal display unit 124 is emitted obliquely (that is, the display light of the peripheral part) rather than on the optical axis. The optical path is reflected in the prism 128 and returned to the photographer's eyes as ghost light.

  In this case, even if the PNLCD 150 is disposed between the focus plate 120 and the pentaprism 128, it cannot be prevented, but between the optical path combining prism 126 (that is, the half mirror 126a) and the pentaprism 128 that is the finder optical path conversion means. It can be seen that if the PNLCD 150 is arranged to have the lowest transmittance and the maximum light-shielding state, this ghost and the ghost can be effective countermeasures.

  As described above, in the backlight control 1, in the display mode in which the main mirror 123 blocks the optical path of the subject light toward the optical viewfinder, the dimming unit is set to the maximum light shielding state.

(Backlight control 2)
Here, returning to step S301 again, if it is determined that the camera is set to a mode other than the live view mode (YES determination), the process proceeds to step S302. In step S302, when it is detected that the camera is set in an image playback mode for confirming playback of a captured image or a menu mode for setting camera shooting conditions (YES determination), in step S303, the optical viewfinder is set. By turning off the voltage of the PNLCD 150 that controls the object light amount, the object light amount of the optical finder is set to the maximum opaque state (actually, the light is reduced by 1/30).
Subsequently, in step S304, the finder internal display unit 124 is turned on, and the LED control of the backlight 124a in step S305 is performed according to the backlight control 2 in FIG.

(Backlight control 3)
On the other hand, if it is determined in step S302 that a mode other than the image playback mode or menu mode, that is, the camera is set to a still image shooting standby state (still image shooting mode) such as a shutter speed priority mode or an aperture priority mode, In S309, as shown in FIG. 7, the transmittance of the PNLCD 150 is variably controlled in accordance with the subject brightness (PNLCD control).
Subsequently, in step S310, the finder internal display unit 124 is turned on, and the LED control of the backlight 124a in step S311 is performed according to the backlight control 3 in FIG.

  Here, the LED control of the backlight 124a and the dimming control of the PNLCD 150 will be described in detail.

  In the backlight control 3 in step S311 of FIG. 6, the brightness of display marks such as a focus detection area displayed by the finder internal display unit 124 in the still image shooting mode is sufficiently visible with respect to the background optical finder subject light. The LED current of the backlight 124a is controlled so that

  That is, as can be seen from the control graph showing the relationship between the subject brightness and the LED energization current in FIG. 6, the control is performed to increase the current to the LED as the subject brightness increases. The backlight control 3 is a control that causes a larger current to flow even if the subject brightness is lower than the other controls.

  However, since the maximum rating of the current that can be applied to the LED is normally limited to about 20 mA, the display mark is displayed on a bright background of the optical viewfinder subject image even if the maximum current is applied when the subject brightness exceeds BV = 7. There is a high possibility that it will be buried and disappear.

  Therefore, in the PNLCD control in step S309 of FIG. 1, when the subject brightness exceeds BV = 7 as shown in the control graph showing the relationship between the subject brightness and the PNLCD drive voltage control shown in FIG. The maximum non-transmission state (maximum dimming state) is obtained at BV = 12.

  In other words, even if the outside light becomes bright, the brightness of the subject image of the optical viewfinder is kept approximately constant. On the other hand, since the brightness of the LED of the backlight 124a is maintained at MAX (maximum brightness), the brightness relationship between the display mark displayed by the finder internal display unit 124 and the subject image is relatively unchanged. Even when the luminance is high, the photographer can clearly see the display mark.

  In the backlight control 3, when the subject brightness obtained by the light metering means 130 is lower than the predetermined subject brightness BV = 7, the brightness of the electronic viewfinder 124 is increased as the subject brightness increases and the light reducing means 150 is transmitted. When the subject brightness obtained by the photometry means 130 is equal to or higher than the predetermined subject brightness, the brightness of the electronic viewfinder 124 is maintained at the maximum brightness, and the transmittance of the dimming means 150 decreases as the subject brightness BV increases. I am letting.

  From the subject brightness BV = 7 to BV = 9, the transmittance slope (first derivative) of the light reducing means 150 increases, and from BV = 9 to BV = 12, the slope of the light transmittance of the light reducing means 150 (primary differential). The derivative) is decreasing.

  On the other hand, in the backlight control 2 in step S305 in FIG. 1, the PNLCD 150 is in the maximum opaque state in step S303 regardless of the subject brightness, and the subject light is always greatly dimmed. The visibility of the finder internal display unit 124 is sufficiently good until the subject light reaches BV = 12. Incidentally, BV = 12 is a brightness higher than that of a clear sky and can be regarded as the maximum brightness in most shooting scenes in practice.

  Note that the subject luminance here is measured by the photometric sensor 130, but since the PNLCD 150 is maximally opaque, the amount of light of the subject facing the eye of the photographer actually observing the optical viewfinder is as described above. In addition, the difference is about 5 steps lower from the difference between the total transmission and maximum non-transmission transmittance of the PNLCD 150. Therefore, the backlight is controlled by uniformly adding an offset value of five steps to the output of the photometric sensor 130.

  Further, in the backlight control 1 in step S308 of FIG. 1, since the light from the subject is completely blocked by the retraction of the main mirror 123 with the live view operation to the outside of the optical path, luminance detection by the photometric sensor 130 is detected. Is impossible. Therefore, since it is considered that the external light component around the eyepiece of the camera affects the observation of the finder internal display unit 124, the backlight is used as in the backlight control 1 of FIG. 6 using the output of the eyepiece detection sensor 160. The LED current control of 124a is performed.

  Here, except for the gaze target finder internal display unit 124, the state is almost dark, and it is only necessary to deal with the luminance change around the face looking into the optical finder, so current control is not performed over a wide range. In other words, in the backlight control 1, even if the current value is constant, there is almost no problem in practical use.

  In the above description, the subject brightness at which the backlight 124aLED of the backlight control 3 reaches the maximum brightness is set to BV = 7, and the maximum brightness at which the PNLCD 150 serving as the light shielding means starts the dimming operation is also set to the same threshold as BV = 7. However, if the subject needs to be more visible until high brightness, the threshold brightness for the start of dimming operation of the PNLCD 150 is changed to a higher brightness side, or the PNLCD control curve is made more gradual than the current one. A certain amount of response is possible by changing.

  With the above-described LED control of the backlight 124a and dimming control of the PNLCD 150, it is possible to display the finder internal display unit 124 in an easy-to-see manner regardless of the shooting mode set in the camera and without being affected by the luminance of the subject. It becomes.

  FIG. 5 is an electric block diagram showing a schematic configuration of a digital camera as an imaging apparatus of the present invention. In FIG. 5, reference numeral 101 denotes the CPU (central processing unit) described above, and an EEPROM 101a which is a nonvolatile memory is configured therein. Further, the CPU 101 is supplied with a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, a data storage means 104, an image processing unit 108, a display control unit 111, a release SW 114, and a power source that store a control program. DC / DC converter 117 is connected to each other, and image sensor control unit 107 and image sensor 106 are connected to image processing unit 108.

  The image sensor 106 has approximately 10 million effective pixels (3888 × 2592 pixels).

  An external display unit 113 and a finder internal display unit 124 provided in the camera exterior back surface and in the viewfinder, respectively, are TFT color liquid crystals capable of displaying an image obtained by thinning the image captured by the image sensor 106 vertically and horizontally. It is.

  The display control unit 111 drives display of still images and moving images captured by the image sensor 106 on the external display unit 113 and the finder internal display unit 124. The motor control unit 125 starts mirror driving in response to an instruction from the CPU 101 and controls a plurality of motors inside the camera. The DC / DC converter 117 is supplied with power from the battery 116.

  The CPU 101 performs various controls based on a control program in the ROM 102.

  Among these controls, a process of reading a captured image signal output from the image processing unit 108 and transferring it to the RAM 103, a process of transferring data from the RAM 103 to the display control unit 111, and a process for transferring image data to JPEG There is a process of compressing and storing the data in the data storage means 104 in a file format. In the case of moving image data, the same processing is performed to compress it into a MOV format file and store it in the data storage means 104.

  Furthermore, the CPU 101 instructs the image sensor 106, the image sensor control unit 107, the image processing unit 108, the display control unit 111, and the like to change the number of data fetching pixels and digital image processing.

  Reference numeral 119 denotes a focus detection control unit including the above-described pair of line CCD sensors for focus detection. The voltage obtained from the line sensor is A / D converted and sent to the CPU. Further, under the instruction of the CPU 101, the focus detection control unit 119 also controls the accumulation time of the line sensor and AGC (auto gain control).

  Various processing such as an instruction of a photographing operation accompanying the operation of the release SW 114 and output of a control signal for controlling power supply to each element to the DC / DC converter 117 are also based on the control of the CPU 101. Has been done.

  The RAM 103 includes an image development area 103a, a work area 103b, a VRAM 103c, and a temporary save area 103d. The image development area 103a is a temporary buffer for temporarily storing a captured image (YUV digital signal) sent from the image processing unit 108 or JPEG compressed image data read from the data storage unit 104, or an image. Used as an image-dedicated work area for compression processing and decompression processing.

  The work area 103b is a work area for various programs. The VRAM 103 c is used as a VRAM that stores display data to be displayed on the display unit 113. The temporary save area 103d is an area for temporarily saving various data.

  The data storage unit 104 is a flash memory for storing captured image data or MOV format moving image data compressed by JPEG by the CPU 101 in a file format. The image sensor 106 can output thinned pixel data in the horizontal direction and the vertical direction in accordance with a resolution conversion instruction from the CPU 101.

  The image sensor control unit 107 is a timing generator for supplying a transfer clock signal and a shutter signal to the image sensor 106, a circuit for performing noise removal and gain processing of the CCD output signal, and further converting the analog signal into a 10-bit digital signal. An A / D conversion circuit for conversion is provided. Further, in order to perform live view display and moving image shooting on the external display unit 113 and the finder internal display unit 124, pixel thinning is performed in accordance with a resolution conversion instruction from the CPU 101. A circuit for processing is included.

  Further, the image processing unit 108 performs image processing such as gamma conversion, color space conversion, white balance, and flash correction on the 10-bit digital signal output from the image sensor control unit 107, and performs YUV (4: 2: 2). ) Format 8-bit digital signal output. The display control unit 111 receives the YUV digital image data transferred from the image processing unit 108 or the YUV digital image data obtained by performing JPEG decompression on the image file in the data storage unit 104, and converts it into an RGB digital signal. , Processing to output to the external display unit 113 or the finder internal display unit 124 is performed.

  Further, the CPU 101 controls the eyepiece detection sensor 160 that detects whether or not the photographer is looking through the viewfinder of the camera, the current control of the LED that is the backlight 124a that determines the display brightness of the viewfinder internal display unit 124, and the light quantity of the optical viewfinder subject light. Voltage control is performed to change the transmittance of the PNLCD 150, which is a dimming means for controlling the brightness.

  The release SW 114 is for instructing the start of the photographing operation. This release SW 114 has a two-stage switch position by the pressing pressure of a release button, which is a camera operation member (not shown). Camera settings such as white balance and photometry are detected by detecting the first position (SW1 ON). When the second position (SW2 ON) is detected, the subject image signal capturing operation is performed.

  The photometry control unit 132 drives and controls the photometry sensor 130 composed of 15 × 23 divided pixels in accordance with an instruction from the CPU 101, takes in a subject luminance signal, and sends data to the CPU 101.

  As a basic photometric operation, the luminance signals generated in the pixels on the light receiving surface of the photometric sensor 130 are each A / D converted by the CPU 101 to become 8-bit digital signals. Fno. Indicating the brightness of the photographing lens. (Effective Fno.) Value correction, sensor output signal variation correction (level / gain adjustment), and photometric correction from the information sent from the lens 105, etc., and finally the field luminance signal A value can be obtained.

  Based on these pieces of information, an optimal exposure calculation of the camera is performed, and an optimal exposure can be obtained by optimally controlling the shutter speed of the camera and the aperture of the photographing lens. Reference numeral 116 denotes a rechargeable secondary battery or a dry battery. A DC / DC converter 117 receives a power supply from the battery 116 and generates a plurality of power supplies by boosting and regulating the power supply to each element including the CPU 101. The power supply of the necessary voltage is supplied. The DC / DC converter 117 can control the start and stop of each voltage supply by a control signal from the CPU 101.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to these embodiments. For example, in the description of the finder configuration so far, two bonded triangular prisms are used in order to make both the optical finder and the electronic viewfinder compatible. However, a configuration in which one half mirror is simply arranged may be used. The internal display unit may be an organic EL display panel that does not require a backlight LED instead of a TFT display panel. Further, the dimming means is not a liquid crystal panel, but uses two polarizing filters to change the relative rotation angle of both to control the dimming amount of the subject light. Are possible, and various modifications and changes can be made within the scope of the gist.

101 CPU
105 Shooting Lens 106 Image Sensor 120 Focus Plate (Focusing Screen)
121 Eyepiece 124 Finder internal display (TFT display panel)
124a TFT backlight (LED)
125 Magnifying lens 126 Optical path combining prism 126a Half mirror surface 127 EVF mirror 128 Penta prism 130 Photometric sensor 150 PNLCD (light scattering liquid crystal)

Claims (4)

An optical viewfinder for observing a subject image, an electronic viewfinder capable of displaying an image taken by an image sensor and photographing information, a photometric means for measuring subject brightness, and a dimming for dimming subject light toward the optical viewfinder And an imaging device capable of visually recognizing the display of the electronic viewfinder superimposed on the subject image of the optical viewfinder,
When the subject brightness obtained by the photometry means is lower than a predetermined subject brightness, the brightness of the electronic viewfinder is increased as the subject brightness increases, and the dimming means is set in a transmissive state.
When the subject brightness obtained by the photometry means is equal to or higher than the predetermined subject brightness, the brightness of the electronic viewfinder is maintained at a predetermined brightness, and the transmittance of the dimming means is decreased as the subject brightness increases. An imaging apparatus characterized by that.   When the subject brightness obtained by the photometry means is equal to or higher than the predetermined subject brightness, the brightness of the electronic viewfinder is maintained at the maximum brightness, and the transmittance of the dimming means is decreased as the subject brightness increases. The imaging device according to claim 1. An optical viewfinder for observing a subject image, an electronic viewfinder capable of displaying an image captured by an image sensor and photographing information, a dimming means for dimming subject light toward the optical viewfinder, and subject light to the optical viewfinder An imaging device capable of visually recognizing the display of the electronic viewfinder superimposed on a subject image of the optical viewfinder,
An image pickup apparatus characterized in that the dimming means is in a dimming state in a display mode in which the mirror blocks an optical path of subject light toward the optical viewfinder.   The imaging apparatus according to claim 3, wherein in the display mode in which the mirror blocks an optical path of subject light toward the optical viewfinder, the dimming unit is set to a maximum dimming state.

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