JP6083120B2 - Electronic camera - Google Patents

Description

  The present invention relates to an electronic camera.

  There are many needs for single-lens reflex cameras equipped with an optical viewfinder that can observe the movement of raw subjects. A typical single-lens reflex camera places a movable mirror between the lens and the image sensor, reflects incident light to the optical viewfinder when observing the subject, and mechanically flips the movable mirror during exposure. The structure is such that incident light is projected onto the image sensor (see, for example, Patent Document 1). On the other hand, a technique of forming a movable micromirror (DMD: Digital Micro-mirror Device) as a microelectromechanical element is known. Since DMD can change the reflection direction of light, a method of using it instead of a shutter of a photosensitive film camera is considered (for example, see Patent Document 2).

JP 2007-243561 A Japanese Patent Application Laid-Open No. 08-043939

  When an optical viewfinder is used with a conventional single-lens reflex camera, the mirror is flipped up at the time of exposure and incident light is projected onto the image sensor. Therefore, the field of view of the optical viewfinder is blacked out during the exposure period. Further, since the shutter operation start time is limited by the operation time of the mechanical movable mirror, there is a problem that the shutter time lag becomes large. Furthermore, the focal plane shutter used as a typical mechanical shutter has a problem that it is difficult to realize batch exposure (global shutter) because a time difference occurs between the start and end of the operation.

  An object of the present invention is to provide an electronic camera that can shorten the blackout period of an optical viewfinder and can cope with a global shutter, a rolling shutter, and the like.

In the present invention , a photographing lens that forms an image of light incident from a subject, and a plurality of movable micromirrors that are arranged on the optical axis of the photographing lens and that can control the light reflection direction are arranged two-dimensionally. The optical element, the imaging element arranged in the first reflection direction of the optical element, the optical viewfinder arranged in the second reflection direction of the optical element, and the reflection direction of the optical element as the first reflection direction or In an electronic camera including a control unit that switches to the second reflection direction, two shooting modes of a global shutter mode and a rolling shutter mode are provided, and the control unit sets all the minute mirrors in the second reflection direction except during shooting. Switching, when shooting in global shutter mode, switches all the micro mirrors to the first reflection direction, and when shooting in rolling shutter mode, images captured by the image sensor Switching only micromirrors in the position corresponding to the position on the first reflecting direction.

The control unit, when imaging in the rolling shutter mode is controlled at a different angle from the other micro mirror angle of a portion of the micro mirror of the plurality of micromirrors.
Moreover, a control part changes the timing which switches the angle of several micromirrors at random.

In addition , the position of the optical viewfinder and the position of the image sensor are at a conjugate focal position of the photographing lens.

In addition, the second image sensor is arranged at the position of the optical viewfinder .
Further, the control unit randomly changes the cycle for switching the angles of the plurality of micromirrors so that the light of the optical element is reflected by the imaging element or the optical viewfinder .
The photographing lens is composed of a bending optical system that changes the direction of incident light, and the optical element reflects light projected from the bending optical system in the incident direction of the bending optical system.

  The electronic camera according to the present invention can shorten the blackout period of the optical viewfinder and can cope with a global shutter, a rolling shutter, and the like.

It is a figure which shows the characteristic of the electronic camera 101 which concerns on 1st Embodiment. FIG. 4 is a diagram illustrating an arrangement example of an optical element 104. FIG. 3 is a diagram illustrating a structural example of a micromirror 201. It is a figure which shows an example of pixel arrangement | positioning and mirror arrangement | positioning. 1 is a diagram illustrating a configuration example of an electronic camera 101. FIG. It is a figure which shows the characteristic of the electronic camera 101a which concerns on the application example 1. FIG. It is a figure which shows the characteristic of the electronic camera 101b which concerns on the application example 2. FIG. It is a figure which shows the characteristic of the electronic camera 101c which concerns on the application example 3. FIG. 6 is a diagram illustrating an example of control of the optical element 104. FIG.

  Hereinafter, embodiments of an electronic camera according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram illustrating features of the electronic camera 101 according to the first embodiment. In FIG. 1, an electronic camera 101 is a single-lens reflex camera, and includes a camera body 102 and a detachable photographing lens 103. The electronic camera 101 can change the direction of reflecting the light incident from the subject to a negative direction or a positive direction by the optical element 104 disposed on the optical axis of the light incident from the photographing lens 103. For example, in the case of FIG. 1, the image can be projected onto the imaging device 105 in the negative (−) direction (first reflection direction) or the finder screen 106 in the positive (+) direction (second reflection direction). The image sensor 105 performs exposure to shoot an image, and the subject image formed on the finder screen 106 can be observed by an optical view finder including a pentaprism 107 and a finder optical system 108.

  Here, the optical element 104 will be described. The optical element 104 is manufactured using a semiconductor manufacturing process, has a high degree of area and a high reflectance, and is arranged in a two-dimensional manner capable of controlling the light reflection direction, as shown in FIG. And a plurality of movable micromirrors 201. For example, as shown in FIGS. 3 (a) to 3 (c), the structure of each micromirror 201 is such that the hinges 202 and 203 are arranged at diagonal positions, as shown in FIG. 3 (b). It can be rotated to an angle in the negative direction as shown in FIG. 3A and an angle in the positive direction as shown in FIG. The rotation angle is electrically controlled by a voltage applied to an electrode (not shown) or the like, and can be controlled to an arbitrary angle within a range of ± 10 degrees, for example. Such an optical element 104 is known as DMD (Digital Micro-mirror Device), and is a well-known technique, and thus detailed description thereof is omitted.

  The electronic camera 101 according to the present embodiment can form an image of light incident from the photographing lens 103 on the image sensor 105 or the finder screen 106 illustrated in FIG. 1 by using the optical element 104 such as DMD. In particular, in conventional single-lens reflex cameras, the optical viewfinder side and the image sensor side are moved by mechanical flip-up movable mirrors, but since they are mechanical, high precision is required when manufacturing working mirrors. Because of its large size, high-speed operation is difficult, and there is a problem that the blackout time of the optical viewfinder at the time of exposure becomes long. In contrast, the DMD 104 is capable of high-speed operation on the order of microseconds and has a high durability. Therefore, the DMD 104 can be used in place of the shutter, and the blackout period can be greatly shortened. For example, by using DMD, the operation time can be shortened to about 10 μsec (= 1 / 100,000 sec).

  In addition, with a conventional mechanical shutter (for example, a focal plane type), there is a time difference between the start and end of the shutter operation, and simultaneous batch exposure (global shutter) was very difficult. A global shutter that eliminates the time difference from the start to the end of the operation can be realized.

  Further, a focal plane operation (rolling shutter) is also possible by operating the micromirrors 201 arranged in a matrix of the DMD 104 in a line-sequential manner for each row or column. In this case, as shown in FIG. 2C, only the row or column that is being exposed is controlled to a position that reflects to the image sensor 105 side, and the micromirrors 201 of other rows or columns are reflected to the viewfinder screen 106 side. By setting the position to the position, the field of view in the optical viewfinder is not completely blacked out.

Note that the position of each pixel of the image sensor 105 and the position of the micromirror 201 of the DMD 104 may correspond one to one, or one micromirror 201 may correspond to a plurality of pixels. For example, FIG. 4A is a diagram showing a pixel array of the image sensor 105, and the image sensor 105 has 256 pixels from the pixel p (1,1) to the pixel p (16,16). FIG. 4B is a diagram illustrating the arrangement of the micromirrors 201 of the DMD 104, and corresponds to the imaging region of the imaging element 105 in FIG. For example, four pixels from pixel p (1,1) to pixel p (1,4), four pixels from pixel p (2,1) to pixel p (2,4), and pixel p (3,1 ) To pixel p (3,4) and four pixels from pixel p (4,1) to pixel p (4,4), for a total of 16 pixels, one micromirror 201 (mirror m ( 1, 1)).
[Electronic camera 101]
Next, a configuration example of the electronic camera 101 will be described with reference to FIG. In FIG. 5, an electronic camera 101 is a single-lens reflex camera having a camera body 102 and a detachable photographing lens 103 as described with reference to FIG. The camera body 102 includes a DMD 104, an image sensor 105, a finder screen 106, a pentaprism 107, a finder optical system 108, an image buffer 109, an image processing unit 110, a control unit 111, a display unit 112, The memory card IF 113, the operation unit 114, the memory 115, and the DMD driving unit 116 are included. The blocks having the same reference numerals as those in FIG. 1 are the same. Further, a well-known DMD is used as the optical element 104 in FIG. 1, and is denoted as DMD 104 in FIG.

  In FIG. 5, the photographing lens 103 forms an image of light incident from a subject on the light receiving surface of the image sensor 105 or the finder screen 106. Here, the light receiving surface of the image sensor 105 and the finder screen 106 are disposed at a conjugate focal position of the photographing lens 103. The subject image formed on the finder screen 106 can be optically observed by the photographer via the pentaprism 107 and the finder optical system 108 as described with reference to FIG. 5 is a block diagram, the positions of the finder screen 106 and the image sensor 105 are not accurately drawn. As described with reference to FIG. 1, the finder screen 106 and the image are captured in the light reflection direction controllable by the DMD 104. An element 105 is arranged. Further, the light reflection direction of the DMD 104 can be changed by varying the control voltage applied to each micro mirror 201 of the DMD 104 according to a command given from the control unit 111 to the DMD drive unit 116. . For example, the light reflection direction of the DMD 104 in the state of FIG. 2A described above corresponds to the finder screen 106, and the light reflection direction of the DMD 104 in the state of FIG. 2B corresponds to the image sensor 105. Can be controlled.

  The subject image formed on the light receiving surface of the image sensor 105 is converted into an electrical signal corresponding to the amount of light by a photoelectric conversion element of a pixel arranged two-dimensionally, and further a digital image obtained by A / D converting the electrical signal. Data is taken into the image buffer 109. The image data captured in the image buffer 109 is subjected to white balance processing, color interpolation processing, gradation processing, contour enhancement processing, and the like by the image processing unit 110. Then, the control unit 111 reads out the image data processed by the image processing unit 110 and displays the image data on the display unit 112 or saves it as a photographed image in the memory card 113 a mounted via the memory card IF 113.

  The operation unit 114 includes operation buttons such as a power button, a release button, and a shooting mode selection dial. Operation information on these buttons is output to the control unit 111. The control unit 111 controls the operation of each unit in accordance with operation information input from the operation unit 114. For example, when the release button of the operation unit 114 is pressed, an image is captured by the image sensor 105, and when still image shooting, continuous shooting, movie shooting, or the like is selected by the shooting mode selection dial, it is selected. Perform processing according to the shooting mode. In particular, the electronic camera 101 according to the present embodiment selects a global shutter mode in which light from a subject incident on the image sensor 105 is exposed at the same timing and a rolling shutter mode in which exposure is performed while scanning in a row order, for example. It can be done.

  The memory 115 stores parameters necessary for the operation of the electronic camera 101 and holds, for example, exposure data according to the resolution of the captured image and the shooting mode. In particular, in the electronic camera 101 according to the present embodiment, parameters such as the control position, reflection angle, or control voltage of the DMD 104 corresponding to the shooting mode are stored in advance.

  Here, control of the micro mirror 201 of the DMD 104 by the control unit 111 in the global shutter and the rolling shutter will be described. When the position of the micro mirror 201 of the DMD 104 is in the state shown in FIG. 2A (horizontal position of 0 degrees) described above, the incident light of the photographing lens 103 is reflected to the viewfinder screen 106 side, and FIG. In the state (b) (negative angle), incident light from the photographing lens 103 is reflected to the image sensor 105 side.

  When the global shutter shooting mode is selected by the shooting mode selection dial, when the release button of the operation unit 114 is pressed, the control unit 111 changes the angle of the minute mirror 201 of the DMD 104 from the state of FIG. After switching to the state of FIG. 2B and the necessary exposure time has elapsed, the state of FIG. 2A is restored. Thereby, batch exposure by the image sensor 105 can be performed.

  On the other hand, when the shooting mode of the rolling shutter is selected by the shooting mode selection dial, when the release button of the operation unit 114 is pressed, the control unit 111 sets the angle of the minute mirror 201 of the DMD 104 in FIG. The state is switched to the state shown in FIG. 2C, and exposure for one screen is performed while sequentially switching the micromirrors 201 of the DMD 104 for each row, and then the state is returned to the state shown in FIG. When a plurality of rows of pixels of the image sensor 105 are included in one row of the micromirrors 201, exposure control may be performed for each row of the pixels of the plurality of rows, or batch exposure may be performed. In either case, as shown in FIG. 2C or FIG. 2D, only the micromirrors 201 in the row corresponding to the pixel position being exposed are controlled to a position that reflects to the image sensor 105 side, Since the minute mirrors 201 in the row are set at positions where they are reflected toward the viewfinder screen 106, it is possible to prevent the visual field in the optical viewfinder from being completely blacked out.

(Application 1)
Next, an application example 1 of the electronic camera 101 according to the first embodiment will be described. Since the DMD 104 has a short optical path switching time as described above and can be switched at an arbitrary timing, the optical path switching can be performed randomly so that it is difficult to be detected by human eyes. By using this feature, the electronic camera 101 according to the application example 1 can reduce flicker that occurs during a moving image that captures periodic images that are temporally continuous or during continuous shooting.

  For example, when performing moving images or continuous shooting, the DMD 104 periodically switches the optical path. Therefore, when shooting is performed under illumination such as a fluorescent lamp whose light amount changes periodically, the output image of the image sensor 105 periodically flickers. (Flicker) may occur. In this case, the control unit 111 periodically switches the micro mirror 201 of the DMD 104 to the image sensor 105 side in order to capture images continuously in time. Therefore, in the electronic camera 101 according to this application example, the flicker is dispersed by changing the period for switching the DMD 104 to the image sensor 105 side at random so as not to have periodicity, thereby making it difficult for human eyes to perceive. be able to.

  In particular, like the electronic camera 101a in FIG. 6, when the second image pickup device 105a for the electronic viewfinder is used instead of the finder screen 106 and the pentaprism 107 constituting the optical viewfinder in FIG. If the optical path switching by the DMD 104 is periodically performed during shooting, flicker occurs on the screen of the electronic viewfinder and the screen of the display unit 112. However, in the electronic camera 101 according to this application example, flickering of the screen shot by the image sensor 105 or the image sensor 105a is not periodic by randomizing the cycle for switching the DMD 104 to the image sensor 105 or the image sensor 105a. , Not noticeable.

(Application example 2)
In the electronic camera 101 of FIG. 1 and the electronic camera 101a of FIG. 6, the DMD 104 is arranged on the conventional flip-up movable mirror portion of a general single-lens reflex camera, but as shown in FIG. In addition, the electronic camera 101b according to the second application example is a camera in which the photographing lens 103 includes a bending optical system 251 that changes the direction of incident light. In this case, the DMD 104 is disposed in a part of the bending optical system 251 and is reflected by the imaging element 105 or the imaging element 105 a disposed in the incident direction of the bending optical system 251. Alternatively, as shown in FIG. 7B, the reflection direction of the DMD 104 may be reflected in a direction orthogonal to the incident direction of the subject light (longitudinal direction (horizontal width direction) of the casing of the electronic camera 101b).

  Thus, by combining the bending optical system 251 and the DMD 104, the degree of freedom of arrangement of the lens of the electronic camera 101, the image sensor 105, and the like is increased, and the size of the housing can be reduced.

(Application 3)
In the electronic camera 101 of FIG. 1 and the electronic camera 101a of FIG. 6 described above, the DMD 104 reflects incident light in two directions, but the electronic camera 101c according to the application example 3 has a configuration as shown in FIG. By reflecting in three directions, it is possible to realize a three-plate electronic camera 101b including an R imaging element 105b, a G imaging element 105c, and a B imaging element 105d. In addition to the image sensor and the optical viewfinder, a plurality of light receiving elements such as a photometric element and an AF (autofocus) element may be arranged at a conjugate focal position of the photographing lens 103 and switched by the DMD 104. . Further, the DMD 104 may partially reflect the plurality of micromirrors 201 in different directions. For example, FIG. 9 shows a state of the DMD 104 when reflecting in three directions at the same time. The first row (+ θ degree), the second and third rows (0 degree), and the fourth row (− The light can be reflected in different directions (+ θ degrees, 0 degrees, −θ degrees). As an application in this case, for example, the first line reflects light toward the image sensor, the second and third lines reflect light toward the optical viewfinder, and the fourth line corresponds to the photometric element (or AF element) side. The light can be incident on the image pickup device, the optical viewfinder, and the photometric device partially at the same time. Then, the micromirror 201 of the DMD 104 is switched at high speed, the + θ degree row is switched to the second row, the 0 degree row is switched to the third and fourth rows, and the −θ degree row is switched to the first row. . Further, the + θ degree line is switched to the third line, the 0 degree line is switched to the fourth and first lines, and the −θ degree line is switched to the second line. Similarly, by sequentially switching the reflection direction of the micromirrors 201 in each row of the DMD 104 at high speed, the entire imaging screen can be scanned at the same time timing, and the deviation of image information obtained from the imaging element and the photometric element can be corrected. Can be reduced. In this case, since light is always projected onto the optical viewfinder, complete blackout can be avoided and the movement of the subject is not lost. In particular, when the resolution of the micromirror 201 is high, for example, when there is a resolution of about XGA (1024 × 764) rows, even if about 10% of the 764 rows are directed to the image sensor or photometric device side, about 700 rows. If the resolution is sufficient, the subject can be confirmed with the optical viewfinder without any problem.

  As described above, as described in each embodiment, the electronic camera according to the present invention can provide an electronic camera that can shorten the blackout period of the optical viewfinder and can cope with a global shutter, a rolling shutter, and the like.

  The electronic camera according to the present invention has been described by way of example in each embodiment, but can be implemented in various other forms without departing from the spirit or main features thereof. Therefore, the above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. The present invention is defined by the claims, and the present invention is not limited to the text of the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

101, 101a, 101b, 101c ... electronic camera 102 ... camera body 103 ... taking lens 104 ... optical element (DMD)
105 ... Image sensor 106 ... Viewfinder screen 107 ... Penta prism 108 ... Viewfinder optical system 109 ... Image buffer 110 ... Image processing unit 111 ... Control unit 112 ... Display unit 113 ... Memory card IF
113a ... Memory card 114 ... Operation unit 115 ... Memory 116 ... DMD drive unit 201 ... Micro mirrors 202, 203 ... Hinge

Claims (7)

  A photographic lens for imaging light incident from the subject;
  An optical element that is arranged on the optical axis of the photographing lens and in which a plurality of movable micromirrors that can control the reflection direction of light are arranged two-dimensionally;
  An image sensor disposed in a first reflection direction of the optical element;
  An optical viewfinder disposed in a second reflection direction of the optical element;
  A controller that switches the reflection direction of the optical element to the first reflection direction or the second reflection direction;
  In an electronic camera comprising:
  There are two shooting modes, global shutter mode and rolling shutter mode.
  The control unit switches all the micromirrors to the second reflection direction except during shooting, and switches all the micromirrors to the first reflection direction during shooting in the global shutter mode. An electronic camera that switches only the minute mirror at a position corresponding to a pixel position to be imaged by the image sensor in the first reflection direction when photographing in the shutter mode. The electronic camera according to claim 1,
Wherein, the case of imaging in a rolling shutter mode, the electronic camera to control the angle different from the plurality of other of said micromirrors an angle of the micro mirrors of some of the micromirrors. The electronic camera according to any one of claims 1 and 2 ,
The said control part is an electronic camera which changes the timing which switches the angle of several said micromirrors at random. The electronic camera according to any one of claims 1 to 3 ,
An electronic camera in which the position of the optical viewfinder and the position of the image sensor are at a conjugate focal position of the photographing lens. The electronic camera according to claim 4,
An electronic camera in which a second image sensor is disposed at a position of the optical viewfinder . The electronic camera according to claim 4 or 5 ,
The control unit is an electronic camera that randomly changes a cycle for switching angles of the plurality of micromirrors so that light of the optical element is reflected by the imaging element or the optical viewfinder . The electronic camera according to any one of claims 1 to 6 ,
The photographing lens is composed of a bending optical system that changes the direction of incident light,
The optical element is an electronic camera that reflects light projected from the bending optical system in an incident direction of the bending optical system.

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