JP2014115497A - Auxiliary light projector, flash device, and camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology for improving a robustness to the change of a focal-length of the pattern for automatic focus detection.SOLUTION: An auxiliary light projection part 32 (auxiliary light projection device) is mounted on a camera 10 (imaging device) provided with a focus detection part 16 (automatic focus detection device), and the focus detection device 16 projects an automatic focus detection pattern P as an auxiliary light for performing an automatic focus detection to a subject F. The automatic detection pattern P includes: a rough pattern region Pr; a middle pattern region Pm denser than the rough pattern region Pr; and a dense pattern region Pc denser than the middle pattern region Pm. In the automatic focus detection pattern P, the central coordinates of the rough pattern region Pr, the central coordinates pmc of the middle pattern region pmc, and the central coordinates pcc of the dense pattern region Pc are separated from one another by taking the parallaxes between an imaging lens 20 (imaging optical system) of the camera 10 and the projection system of the auxiliary light projection part 32 into consideration.

Description

  The present invention relates to an auxiliary light projection device, a flash device, and a camera.

  As this kind of technology, Patent Document 1 is mounted or built in a camera equipped with an automatic focus detection device, projects a focus detection pattern onto a subject as auxiliary light, and automatically outputs the focus detection pattern reflected by the subject. An auxiliary light projection device that is detected by a focus detection device is disclosed. This focus detection pattern is dense in the vicinity of the center of the shooting screen, and is coarse in other areas. Thereby, even when a wide-angle lens or a telephoto lens is used, the relationship between the distance measurement area and the focus detection pattern can be made appropriate, so that accurate automatic focus detection can always be performed.

JP 2010-8589 A

  By the way, since the auxiliary light projection device is disposed at a position away from the photographing lens, the distance measurement area moves in accordance with the focal length in the focus detection pattern. Therefore, when the focus detection pattern disclosed in Patent Document 1 is adopted, if the focal length is large, the center of the distance measurement area deviates from the dense area of the focus detection pattern, and as a result, automatic focus detection by auxiliary light projection is performed. In some cases, sufficient accuracy could not be secured.

  An object of the present invention is to provide a technique for improving the robustness of an automatic focus detection pattern against a change in focal length.

According to the first aspect of the present invention, an automatic focus detection pattern as auxiliary light that is attached to or built in an imaging device including an automatic focus detection device and that serves as an auxiliary light for the automatic focus detection device to perform automatic focus detection. The automatic focus detection pattern includes a rough pattern region and a dense pattern region denser than the rough pattern region, and in the automatic focus detection pattern, The center coordinates of the coarse pattern area and the center coordinates of the dense pattern area are separated in consideration of the parallax between the imaging optical system of the imaging apparatus and the projection system of the auxiliary light projection apparatus. An optical projection device is provided.
According to a second aspect of the present invention, an automatic focus detection pattern as auxiliary light that is attached to or built in an imaging device including an automatic focus detection device and that is used as an auxiliary light for the automatic focus detection device to perform automatic focus detection. The automatic focus detection pattern includes a rough pattern region, a medium pattern region denser than the rough pattern region, and a dense pattern region denser than the medium pattern region. In the automatic focus detection pattern, the center coordinates of the coarse pattern region, the center coordinates of the middle pattern region, and the center coordinates of the dense pattern region are the imaging optical system of the imaging device. There is provided an auxiliary light projector that is separated from each other in consideration of parallax with the projection system of the auxiliary light projector.
According to a third aspect of the present invention, there is provided a flash device that is mounted on the imaging device and emits flash light based on an operation instruction from the imaging device, and includes the auxiliary light projection device. Is done.
According to the 4th viewpoint of this invention, the imaging device carrying the said auxiliary light projector is provided.

  According to the present invention, the robustness of the automatic focus detection pattern with respect to a change in focal length is improved.

FIG. 1 is a functional block diagram of a camera equipped with a flash device. FIG. 2 is a front view of a camera equipped with a flash device. FIG. 3 shows an automatic focus detection pattern. FIG. 4 is a plan view of the image zoomed to the wide angle side. FIG. 5 is a diagram illustrating how the subject appears from the projection system when zoomed to the wide-angle side. FIG. 6 is a plan view of an image of zooming to the telephoto side. FIG. 7 is a diagram illustrating how the subject appears from the projection system when zoomed to the telephoto side. FIG. 8 is a front view of a camera with a built-in auxiliary light projection unit.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  In FIG. 1, a camera 10 (imaging device) is, for example, a single-lens reflex camera configured such that a photographing lens 20 that is an imaging optical system is detachable. The camera 10 may be a compact digital camera instead of the single-lens reflex camera. The camera 10 includes a quick return mirror 11, a sub mirror 12, a shutter 13, an image sensor 14, a lens mount unit 15, a focus detection unit 16 (automatic focus detection device), a CPU 17 (Central Processing Unit), and a hot shoe 18. .

  The taking lens 20 can be attached to and detached from the camera 10 via the lens mount unit 15, and a telephoto lens having a long focal length, a wide-angle lens having a short focal length, a zoom lens having a variable focal length, or the like is attached. In the following description, the description of the wide-angle lens and the telephoto lens includes the wide-angle side and the telephoto side of the zoom lens.

  The lens mount portion 15 is provided with a contact portion 15a that can be electrically connected to a contact portion 20a provided on the photographing lens 20 side.

  The flash device 30 is an external flash device in the present embodiment, and is attached to the camera 10 via a hot shoe 18 that is a sync contact. The flash device 30 is sold in association with the camera 10. The flash device 30 is a dedicated product for the camera 10 or a shared product for a plurality of cameras including the camera 10. The flash device 30 includes a light emitting unit 31 that emits flash light for illuminating a subject at the time of photographing, and an auxiliary light projecting unit 32 (auxiliary light projection unit 32) that projects an automatic focus detection pattern P (see also FIG. 3) serving as auxiliary light. A light projection device) and a CPU 33.

  As shown in FIG. 2, in the present embodiment, the flash device 30 is mounted on the upper left of the photographing lens 20 when viewed from the front of the camera 10. Therefore, the auxiliary light projection unit 32 is located at the upper left of the photographing lens 20 when viewed from the front of the camera 10.

  With the above configuration, the light of the subject incident through the photographing lens 20 is divided into a finder system and a focus detection system (not shown) in the quick return mirror 11. Among these, the light to the finder system is guided to a finder section (not shown) that is photographed by the photographer through an optical system such as a finder screen, a pentaprism, and an eyepiece. On the other hand, the light to the focus detection system passes through the quick return mirror 11, is reflected by the sub mirror 12, and enters the focus detection unit 16.

  Then, when the photographer half-presses a release button (not shown) while viewing the subject image displayed on the viewfinder, the focus detection unit 16 applies the incident light to the incident object light in a distance measurement area (not shown) selected automatically or manually. Based on this focus detection information, the photographing lens 20 is driven via the contact portion 15a and the contact portion 20a to adjust the focus.

  Information on the brightness or contrast of the subject light incident on the focus detection unit 16, information on the ranging area selected automatically or manually, and the like are sent to the CPU 17.

  When the CPU 17 determines that the luminance or contrast of the subject is low, the CPU 17 transmits an operation instruction signal to the CPU 33 of the flash device 30 to project the automatic focus detection pattern P from the auxiliary light projection unit 32 toward the subject. . The focus detection unit 16 detects the automatic focus detection pattern P reflected from the subject, performs automatic focus detection in the same manner as described above, and drives the photographing lens 20 based on this focus detection information to adjust the focus. I do.

  Note that the CPU 33 on the flash device 30 side may determine whether the luminance or contrast of the subject is low.

  When the photographer presses a release button (not shown), the CPU 17 retracts the quick return mirror 11 and the sub mirror 12 from the photographing optical path and opens the shutter 13. As a result, the subject image formed by the photographing lens 20 is picked up by the image pickup device 14 formed of, for example, a CCD or a CMOS, and an image is acquired.

  Next, the automatic focus detection pattern P of this embodiment will be described in detail with reference to FIG.

  As shown in FIG. 3, the automatic focus detection pattern P includes a rough pattern region Pr, a middle pattern region Pm, and a dense pattern region Pc. The middle pattern area Pm is a pattern for automatic focus detection that is denser than the coarse pattern area Pr. The dense pattern region Pc is a pattern for automatic focus detection that is denser than the middle pattern region Pm. The middle pattern region Pm is arranged so as to be nested inside the coarse pattern region Pr. The dense pattern region Pc is arranged so as to be nested inside the middle pattern region Pm.

  In FIG. 3, the outline pr of the rough pattern region Pr is an imaginary line drawn for convenience of explanation so that the outline of the rough pattern region Pr can be easily grasped. Similarly, the outline line pm of the middle pattern area Pm is an imaginary line drawn for convenience of explanation so that the outline of the middle pattern area Pm can be easily grasped. Similarly, the outline line pc of the dense pattern region Pc is an imaginary line drawn for convenience of explanation so that the outline of the dense pattern region Pc can be easily grasped.

  Here, the center coordinate prc of the rough pattern region Pr is the center coordinate of the rough pattern region Pr that is uniquely determined based on the outline pr of the rough pattern region Pr. In the present embodiment, since the outline pr of the rough pattern region Pr is a square, its center coordinate prc is uniquely determined as the intersection coordinate of two diagonal lines of the square.

  Similarly, the center coordinate pmc of the middle pattern region Pm is the center coordinate of the middle pattern region Pm that is uniquely determined based on the outline pm of the middle pattern region Pm. In the present embodiment, since the outline pm of the middle pattern region Pm is a parallelogram, the center coordinate pmc thereof is uniquely determined as the intersection coordinate of two diagonal lines of the parallelogram.

  Similarly, the center coordinate pcc of the dense pattern region Pc is the center coordinate of the dense pattern region Pc that is uniquely determined based on the outline pc of the dense pattern region Pc. In the present embodiment, since the contour line pc of the dense pattern region Pc is a parallelogram, its center coordinate pcc is uniquely determined as the intersection coordinate of two diagonal lines of the parallelogram.

  FIG. 3 shows an epipolar line E that is uniquely determined based on the parallax between the photographing lens 20 (imaging optical system) of the camera 10 and the projection system of the auxiliary light projection unit 32. The epipolar line E is a line corresponding to the optical axis of the photographing lens 20 of the camera 10 in the automatic focus detection pattern P.

  In the present embodiment, in the automatic focus detection pattern P, the center coordinate prc of the coarse pattern region Pr, the center coordinate pmc of the middle pattern region Pm, and the center coordinate pcc of the dense pattern region Pc are Considering the parallax between the photographing lens 20 (imaging optical system) and the projection system of the auxiliary light projection unit 32, they are separated from each other. In the automatic focus detection pattern P, the middle pattern region Pm and the dense pattern region Pc are elongated along the epipolar line E. In the automatic focus detection pattern P, the center coordinate pmc of the middle pattern region Pm and the center coordinate pcc of the dense pattern region Pc are located in the vicinity of the epipolar line E. Specifically, in the automatic focus detection pattern P, the center coordinate pmc of the middle pattern region Pm and the center coordinate pcc of the dense pattern region Pc are located on the epipolar line E. The center coordinate prc of the coarse pattern region Pr, the center coordinate pmc of the middle pattern region Pm, and the center coordinate pcc of the dense pattern region Pc are arranged in this order on the epipolar line E toward the upper right of the automatic focus detection pattern P. Are lined up.

  According to the above-described automatic focus detection pattern P, the robustness of the automatic focus detection pattern P with respect to changes in focal length is improved. The reason will be described in detail below with reference to FIGS.

  4 and 6 show the subject F. FIG. As shown in FIG. 4, when the subject F is imaged on the wide-angle side, as shown in FIG. 5, in the autofocus detection pattern P, the range Q (in the distance measurement area) that functions effectively for autofocus detection. Is equivalent to substantially the entire autofocus detection pattern P, and the center of the range Q is substantially equal to the center of the autofocus detection pattern P.

  On the other hand, as shown in FIG. 6, when the subject F is imaged on the telephoto side, as shown in FIG. 7, the range Q that functions effectively for automatic focus detection in the automatic focus detection pattern P is as follows. This is a narrow area in the upper right of the automatic focus detection pattern P.

  Thus, the range Q that functions effectively for automatic focus detection in the automatic focus detection pattern P moves without stopping in accordance with the change in the focal length of the photographing lens 20. That is, the appropriate pattern resolution and pattern position (position Q in the range Q) as the automatic focus detection pattern P change according to the focal length of the photographing lens 20.

  Speaking of the movement direction of the range Q that functions effectively for automatic focus detection in the automatic focus detection pattern P, the auxiliary light projection unit 32 is arranged at the upper left of the photographing lens 20 in the front view shown in FIG. In this case, the range Q moves to the upper right of the automatic focus detection pattern P as (a) telephoto, and (b) moves toward the lower left of the automatic focus detection pattern P as the wide angle is reached. Therefore, in this case, as shown in FIG. 3, the automatic focus detection pattern P has a higher resolution toward the upper right side of the automatic focus detection pattern P, and the automatic focus detection pattern P is automatically moved toward the lower left side. It is preferable that the focus detection pattern P has a low resolution.

  If the auxiliary light projection unit 32 is arranged on the upper right side of the photographing lens 20 in the front view shown in FIG. 2, the range Q is (a) toward the upper left of the automatic focus detection pattern P as the distance increases. (B) Move toward the lower right of the automatic focus detection pattern P as the angle becomes wider. Therefore, in this case, the autofocus detection pattern P becomes higher in resolution toward the upper left of the autofocus detection pattern P, and the autofocus detection pattern P is moved toward the lower right of the autofocus detection pattern P. It is preferable to have a low resolution.

  Then, considering that the above range Q (ranging area) at the time of automatic focus detection moves on the epipolar line E according to the focal length, the dense pattern region Pc and the middle pattern region Pm are changed to the epipolar line E in FIG. Or, more specifically, the central coordinate pcc of the dense pattern region Pc and the central coordinate pmc of the middle pattern region Pm are arranged near the epipolar line E, preferably on the epipolar line E, and zoomed to the telephoto side. In some cases, the portion to be enlarged can be pinpointed to a high resolution. As a result, the robustness of the automatic focus detection pattern P with respect to the change in focal length is improved.

  As mentioned above, although preferred embodiment of this invention was described, the said embodiment has the following characteristics.

(1, 4) The auxiliary light projection unit 32 (auxiliary light projection device) is attached to the camera 10 (imaging device) including the focus detection unit 16 (automatic focus detection device), and the focus detection unit 16 performs automatic focus detection. An automatic focus detection pattern P as auxiliary light to be performed is projected onto the subject F. The automatic focus detection pattern P includes a rough pattern region Pr, a middle pattern region Pm that is denser than the rough pattern region Pr, and a dense pattern region Pc that is denser than the middle pattern region Pm. In the automatic focus detection pattern P, the center coordinate prc of the coarse pattern region Pr, the center coordinate pmc of the middle pattern region Pm, and the center coordinate pcc of the dense pattern region Pc are determined by the taking lens 20 (imaging optical system) of the camera 10. ) And the projection system of the auxiliary light projection unit 32 are separated from each other in consideration of parallax. According to the above configuration, the automatic focus detection pattern P is realized based on the movement of the distance measurement area accompanying the change in the focal length of the photographic lens 20. As a result, the robustness of the automatic focus detection pattern P with respect to changes in the focal length is improved.

In the (2, 5) automatic focus detection pattern P, the middle pattern region Pm and the dense pattern region Pc are elongated along the epipolar line E that is uniquely determined based on the parallax. According to the above configuration, the automatic focus detection pattern P reflecting the movement of the distance measurement area accompanying the change in the focal length of the photographic lens 20 is realized.

(3, 6) In the automatic focus detection pattern P, the center coordinate pmc of the middle pattern region Pm and the center coordinate pcc of the dense pattern region Pc are located in the vicinity of the epipolar line E that is uniquely determined based on the parallax. According to the above configuration, the automatic focus detection pattern P that strongly reflects the movement of the distance measurement area accompanying the change in the focal length of the photographic lens 20 is realized.

  Although the preferred embodiment of the present invention has been described above, the auxiliary light projection unit 32 may be built in the camera 10 as shown in FIG.

10 Camera 20 Shooting lens 32 Auxiliary light projection unit
P Automatic focus detection pattern
Pr Coarse pattern area
Pm Middle pattern area
Pc dense pattern area
prc center coordinates
pmc center coordinates
pcc center coordinates
E Epipolar line
Q range
F Subject

Claims (8)

An auxiliary light projection device that is mounted on or incorporated in an imaging device having an automatic focus detection device and projects an automatic focus detection pattern on a subject as auxiliary light for the automatic focus detection device to perform automatic focus detection. And
The automatic focus detection pattern includes a rough pattern region and a dense pattern region denser than the rough pattern region,
In the automatic focus detection pattern, the center coordinates of the coarse pattern area and the center coordinates of the dense pattern area are the parallaxes between the imaging optical system of the imaging apparatus and the projection system of the auxiliary light projection apparatus. Are taking into account,
Auxiliary light projector. The auxiliary light projector according to claim 1,
In the automatic focus detection pattern, the dense pattern region is elongated along an epipolar line that is uniquely determined based on the parallax.
Auxiliary light projector. The auxiliary light projection device according to claim 1 or 2,
In the automatic focus detection pattern, the center coordinates of the dense pattern region are located in the vicinity of an epipolar line that is uniquely determined based on the parallax.
Auxiliary light projector. An auxiliary light projection device that is mounted on or incorporated in an imaging device having an automatic focus detection device and projects an automatic focus detection pattern on a subject as auxiliary light for the automatic focus detection device to perform automatic focus detection. And
The automatic focus detection pattern includes a coarse pattern region, a medium pattern region denser than the coarse pattern region, and a dense pattern region denser than the medium pattern region,
In the automatic focus detection pattern, the center coordinates of the coarse pattern area, the center coordinates of the middle pattern area, and the center coordinates of the dense pattern area are the imaging optical system of the imaging apparatus and the auxiliary light projection. Considering the parallax between the projection system of the device and being separated from each other,
Auxiliary light projector. The auxiliary light projection device according to claim 4,
In the automatic focus detection pattern, the middle pattern area and the dense pattern area are elongated along an epipolar line that is uniquely determined based on the parallax.
Auxiliary light projector. The auxiliary light projection device according to claim 4 or 5,
In the automatic focus detection pattern, the center coordinates of the middle pattern area and the center coordinates of the dense pattern area are located in the vicinity of an epipolar line that is uniquely determined based on the parallax.
Auxiliary light projector. A flash device that is attached to the imaging device and flashes based on an operation instruction from the imaging device,
The auxiliary light projection device according to claim 1 is mounted.
Flash device. An imaging apparatus equipped with the auxiliary light projection apparatus according to claim 1.

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