JP2005292544A - Focusing mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a very simply constituted focusing mechanism used in common for long and close photographing. <P>SOLUTION: A focusing plate 3 constituted of one optical material where a prescribed tilt angle is formed by an incident surface 3a and an exit surface 3b and the thickness is varied from a thin part 31 to a thick part 32 is arranged between a lens 2 and an imaging device 5, and photographing light transmitted through the thin part 31 of the plate 3 is made incident on the imaging device 5 so as to function as long-photographing light, on the other hand, photographing light transmitted through the thick part 32 of the plate 3 is made incident on the imaging device 5 so as to function as close-photographing light. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a far and near focus adjustment mechanism incorporated in a lens group of a digital camera, for example.

  There is a technique for correcting the focus by so-called tilt correction when a digital camera or the like is used to image a person close to the lower half of the screen and an image of a distant landscape as a background in the upper half. When tilt correction is performed by a camera back equipped with an imaging device, conventionally, a tilt mechanism is usually provided at the connecting portion between the camera body and the camera back.

However, in such a configuration, since the camera is increased in size, a proposal has been disclosed in which a tilt mechanism is provided in the camera back (see, for example, Patent Document 1). In this case, an image pickup apparatus having an image pickup device mounted in a camera back that is detachable from the camera body is provided, and the image pickup surface of the image pickup device is used as the optical axis in a state where the center of the image pickup device coincides with the image pickup optical axis. It is equipped with a tilt mechanism that includes a tilt mechanism that tilts around an orthogonal axis.
JP-A-9-331476

  By the way, recently, with the diversification of needs, there has been a demand for a novel idea that can be corrected with a simpler configuration. That is, it has been desired that such tilt correction can be realized even with an integrated digital camera having an image sensor in the camera body. However, since the space is limited in such a digital camera, the above-described conventional tilt mechanism cannot be applied as it is.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a far and near focus adjustment mechanism having a very simple configuration.

  In the focus adjustment mechanism according to the present invention, a focus adjustment plate made of a single optical material having at least an inclined portion in which an incident surface and an output surface form a predetermined inclination angle is disposed between a lens and an image sensor. In the inclined portion of the focus adjustment plate, the imaging light transmitted through the thin portion is incident on the imaging device as short-distance imaging light, while the imaging light transmitted through the thick portion is input to the imaging device as long-distance imaging light. It is made to enter.

  According to such a configuration, the photographing light transmitted through the thin portion of the focus adjustment plate disposed between the lens and the imaging device is incident on the imaging device as the short-distance photographing light, and the photographing light transmitted through the thick portion. Is incident on the image sensor as long-distance shooting light, so the upper half of the imaging screen can clearly shoot far-field scenery such as the background, and the lower half can shoot nearby people clearly, Focus correction (tilt correction) becomes possible.

  Preferably, the focus adjustment plate further includes a parallel portion in which the incident surface and the emission surface are formed in parallel, and either the inclined portion or the parallel portion is moved by moving the focus adjustment plate. Alternatively, the photographing light may be transmitted.

  According to such a configuration, by allowing the photographing light to pass through the inclined portion of the focus adjustment plate, it is possible to correct the tilt as described above, and by allowing the photographing light to pass through the parallel portion of the focus adjustment plate, It can also be used for shooting without tilt correction.

  The focus adjustment mechanism according to the present invention includes a lens and an image of a focus adjustment plate made of a single optical material in which the incident surface and the output surface have a predetermined inclination angle and the thickness changes from the thin portion to the thick portion. The photographic light that is disposed between the sensor and the light passing through the thin part of the focus adjustment plate is incident on the image sensor as short-distance photography light, while the photographic light that is transmitted through the thick part of the focus adjustment plate is used as the long-distance photography light Therefore, the upper half of the imaging screen can clearly capture a distant view, and the lower half can clearly capture a nearby person.

  Hereinafter, a focus adjustment mechanism according to the best embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a configuration of a focus adjustment mechanism, where reference numeral 1 is an aperture, 2 is a lens, 3 is a focus adjustment plate, 4 is an infrared cut filter, and 5 is an image sensor such as a CCD or CMOS. The focus adjusting plate 3 is made of one optical material in which the incident surface 3a and the exit surface 3b form a predetermined inclination angle R1, and either the entrance surface 3a or the exit surface 3b (in the illustrated example, the exit surface 3b). 3b) is substantially orthogonal to the optical axis direction, and the focus adjusting plate 3 is disposed between the lens 2 and the image sensor 5. The image sensor 5 is erected so as to be orthogonal to the optical axis direction. ing.

  According to such a configuration, the photographing light transmitted through the thin portion 31 of the focus adjusting plate 3 disposed between the lens 2 and the image pickup device 5 is incident on the image pickup device 5 as the short-distance photographing light 6 and is thick. Since the photographic light transmitted through the unit 32 is incident on the image sensor 5 as the long-distance photographic light 7, for example, as shown in FIG. A nearby person can be clearly photographed, and both focal points can be adjusted.

  As described above, since a single focus adjustment plate 3 is disposed between the lens 2 and the image sensor 5, both near and near focus correction (tilt correction) is possible. It can be formed compactly and can be provided at low cost.

  In addition, this invention can be variously changed within the range of the technical matter described in the claim, without being limited to the said embodiment.

  For example, although not shown, in the focus adjustment plate 3 as described above, a portion where the entrance surface 3a and the exit surface 3b are parallel is further provided, and the photographing light is transmitted through the parallel portion, as described above. It is also possible to handle shooting without correction.

  The focus adjusting plate 3 may have any shape as long as the incident surface 3a and the exit surface 3b form a predetermined inclination angle R1, and the entrance surface 3a or the exit surface 3b It does not need to be substantially orthogonal to 6c and may be arranged at any angle.

  The focus adjustment mechanism according to the present invention includes a lens and an image pickup element, each of which includes a focus adjustment plate made of a single optical material in which the incident surface and the output surface have a predetermined inclination angle and the thickness changes from the thin portion to the thick portion. The photographic light transmitted through the thin part of the focus adjustment plate is incident on the image sensor as short-distance photographic light, and the photographic light transmitted through the thick part is incident on the image sensor as long-distance photographic light. By doing so, both focal points are corrected (tilt correction), so that the optical system can be made very compact, and is particularly useful for digital cameras and the like.

  The focus adjustment mechanism according to the present invention includes a lens and an image pickup element, each of which includes a focus adjustment plate made of a single optical material in which the incident surface and the output surface have a predetermined inclination angle and the thickness changes from the thin portion to the thick portion. The photographic light transmitted through the thin part of the focus adjustment plate is incident on the image sensor as short-distance photographic light, and the photographic light transmitted through the thick part is incident on the image sensor as long-distance photographic light. By doing so, both near and far focus corrections (tilt correction) are performed, and therefore, the present invention can be widely applied to technical fields such as small cameras that require an extremely compact optical system.

Structure explanatory drawing of the focus adjustment mechanism which concerns on one Embodiment of this invention Explanatory drawing of the imaging screen for the same perspective

Explanation of symbols

2 Lens 3 Focus adjustment plate 3a Incident surface 3b Outgoing surface 31 Thin portion 32 Thick portion 5 Image sensor 6 Short-distance photographing light 7 Long-distance photographing light

Claims (2)

  A focus adjusting plate made of a single optical material having at least an inclined portion in which the incident surface and the exit surface form a predetermined inclination angle is disposed between the lens and the image sensor, and the inclined portion of the focus adjusting plate In this case, the focus adjustment is characterized in that the imaging light transmitted through the thin portion is incident on the imaging device as short-distance imaging light, and the imaging light transmitted through the thick portion is incident on the imaging device as long-distance imaging light. mechanism. The focus adjustment plate further includes a parallel portion in which the incident surface and the exit surface are formed in parallel, and the photographing light is transmitted to either the inclined portion or the parallel portion by moving the focus adjustment plate. The focus adjusting mechanism according to claim 1, wherein:

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