JP5665506B2 - Imaging device - Google Patents

Description

  The present invention relates to an imaging apparatus having a superimpose (SI) display function for displaying a plurality of focus detection areas in a finder field so as to overlap a subject image.

  Patent Document 1 illuminates a plurality of display units corresponding to a plurality of focus detection areas formed on a focusing screen, guides reflected light from each display unit to an eyepiece, and realizes an SI display function. The light that illuminates the display unit is reflected by the reflecting surface of the prism. In Patent Document 2, a light source and a light guide member that totally reflects a light beam twice are arranged on a hollow pentagon and guided to a focusing screen. There exists patent document 3 as another prior art.

JP 2005-338661 A Japanese Patent Laid-Open No. 7-244317 JP 2007-264029 A

  However, since the reflecting surface of the prism of Patent Document 1 is formed by depositing a reflecting film, it causes a cost increase. Further, as in Patent Document 2, if a light source and a light guide member are provided on a hollow pentagon, it interferes with the flash device, and the height of the camera is increased to prevent downsizing.

  Accordingly, an object of the present invention is to provide a small and inexpensive finder device and imaging device.

The finder apparatus of the present invention is a finder apparatus that superimposes and displays a plurality of focus detection areas in a finder field, and a focusing screen having a surface on which a display unit corresponding to the plurality of focus detection areas is formed, A pentamirror that reflects the reflected light from the display unit to the eyepiece, a light source that is disposed closer to the eyepiece than the pentamirror and emits light that illuminates the display, and the eyepiece side of the pentamirror A light guide means having two reflective surfaces that reflect light from the light source twice and guide it to the display unit, and each reflective surface is not provided with a reflective film , The two reflecting surfaces are composed of a first reflecting surface and a second reflecting surface, and light from the light source is reflected in the order of the first reflecting surface and the second reflecting surface, and the focusing disc. A first illumination area is formed on the surface of the screen; light from the light source is reflected in the order of the second reflective surface and the first reflective surface; An illumination area is formed, and an angle formed by the two reflecting surfaces is set to be smaller than 90 degrees so that the first illumination area and the second illumination area have an overlapping portion. .

  According to the present invention, a small and inexpensive finder device and imaging device can be provided.

It is a perspective view of the finder apparatus of a present Example. It is a perspective view of the imaging device (single-lens reflex digital camera) of a present Example. It is sectional drawing of the imaging device shown in FIG. It is the perspective view and sectional drawing of a finder apparatus shown in FIG. It is a figure for demonstrating reflection of the illumination light for superimpose (SI). It is a figure of SI lens of the finder apparatus shown in FIG. 1, and the conventional SI lens. It is a graph which shows the relationship of the incident angle in the case where it has and the case where an SI lens does not have a roof surface. It is a viewfinder visual field figure of a present Example.

  FIG. 2 is a perspective view of the image pickup apparatus (single-lens reflex digital camera) 1. The imaging device may be a single lens reflex silver salt camera. In FIG. 2, reference numeral 2 denotes a lens unit that is replaceably mounted on the housing 3 of the main body of the imaging apparatus 1 and houses a photographing optical system that forms an optical image of a subject. 4 denotes an optical axis of the photographing optical system housed in the lens unit 2, 15 denotes a release button, and 16 denotes an operation button. Although the imaging device 1 has many operation buttons, the operation button 16 is a typical operation button. The release button 15 is a two-stage button. Hereinafter, the half-press operation of the release button 15 is referred to as S1, and the full-press operation is referred to as S2.

  FIG. 3 is a cross-sectional view of the imaging apparatus 1 and shows a so-called mirror-down state. In FIG. 3, 5 is a photographing optical system, 6 is an image pickup device that photoelectrically converts an optical image formed by the photographing optical system 5, 7 is an optical viewfinder (finder device) provided in the image pickup apparatus 1, and 8 is an electronic viewfinder. Reference numeral 9 denotes an AF sensor, 10 denotes a main mirror, and 11 denotes a sub mirror. The AF sensor 9 has a plurality of focus detection areas.

  When the main mirror 10 is in the mirror-down position, the subject light that has passed through the photographic optical system 5 is reflected by the main mirror 10 and the upper surface of the focusing screen (focus plate) 33 that is disposed on the planned imaging plane of the photographic optical system. The subject image is projected onto the mat surface. The lower surface of the focusing screen 33 is a Fresnel lens surface that collects subject light.

  The subject image projected on the focusing screen 33 is observed by a photographer through a hollow pentamirror (hereinafter referred to as “hollow penta”) 31 and an eyepiece group 43 that are changed into a focused erect image.

  In the still image shooting operation, the photographer operates the operation buttons 16 to make settings for shooting, and then determines the composition using the optical viewfinder 7 or the electronic viewfinder 8 (aiming operation). When the optical viewfinder 7 is used, the photographer observes the subject through the optical viewfinder 7 as shown in FIG. On the other hand, when the electronic viewfinder 8 is used, the main mirror 10 and the sub mirror 11 are raised to guide the light flux to the image sensor 6, and the image obtained by the image sensor 6 is displayed on the electronic viewfinder 8 to display the subject. Observe (Live View shooting).

  After the aiming operation, when the release button 15 is pressed halfway, the imaging apparatus 1 captures information necessary for photographing such as photometry and focus detection, and the imaging apparatus 1 determines that the main subject is present and performs focus adjustment. . Superimpose (SI) has been proposed as means for notifying a photographer of a focus detection area whose focus has been adjusted within the viewfinder field.

  FIG. 4A is a perspective view of the optical viewfinder 7, and FIG. 4B is a cross-sectional view of the optical viewfinder 7. In FIG. 4, 32 is a reflecting mirror which is one surface of the hollow penta 31, 34 is an SI lens, 35 is a light source for SI, 41 is a finder holding member to which an eyepiece lens group 43 is attached, and 42 is an SI holding member. The optical path of SI is indicated by a broken line in FIG.

  The SI light source 35 emits light for illuminating the display unit, and the light flux from the SI light source 35 is projected from the SI lens 34 onto the focusing screen 33 through the opening 31 a of the hollow penta 31 and provided on the focusing screen 33. Reflected by the display. Thereafter, the reflected light from the display unit is reflected on the eyepiece lens group 43 by the hollow penta 31 directly above the focusing screen 33 and is observed by the photographer.

  The SI lens 34 and the SI light source 35 are attached to an SI holding member 42, and the SI holding member 42 is disposed at the back of the eyepiece lens group 43 side of the hollow penta 31 as shown in FIG. For this reason, both the SI lens 34 and the SI light source 35 are provided on the eyepiece side of the hollow penta 31. Since the SI lens 34 and the SI light source 35 are not provided on the hollow penta 31, the interference with the flash means and the height of the finder device or the imaging device are prevented from increasing.

  Further, the SI lens 34 and the SI light source 35 camera are arranged in the horizontal direction when viewed from the front. A photometric lens, photometric sensor, etc. (not shown) are arranged on the eyepiece lens group 43. If the SI lens 34 and the SI light source 35 camera are arranged in a direction parallel to the optical axis, these members may interfere with each other. Because there is.

  FIG. 1 is a perspective view of an optical finder (finder device) 7 that superimposes and displays a plurality of focus detection areas in the finder field. For the sake of clarity, the hollow penta 31 is cut at the center and only half of it is shown. In FIG. 1, reference numerals 33a, 33b, 33c, and 33d respectively indicate a center, a longitudinal end, a short direction end (downward view of the photographer's field of view), and a short direction end (upward direction of the photographer's view). Part. Reference numerals 35a, 35b, and 35c denote light-emitting elements that illuminate the display units 33a, 33b, and 33c, respectively. Reference numerals 36a, 36b, and 36c denote light beams directed from the light sources 35a, 35b, and 35c to the display units 33a, 33b, and 33c, respectively. Reference numeral 37a denotes a light beam reflected by the display unit 33a.

  A fine prism is formed on the focusing screen 33 and deflects the SI light flux. For example, the display unit 33a deflects the light beam 36a into the light beam 37a. The display unit is provided corresponding to each focus detection area of the AF sensor 9 shown in FIG. In FIG. 1, there are seven focus detection areas and a display unit corresponding to them. As described above, an area determined to be a main subject is presented to the photographer by illuminating the focus detection area used for focus adjustment.

  The plurality of light emitting elements 35a, 35b, and 35c are constituted by, for example, LEDs, and each light emitting element is arranged to illuminate a corresponding display unit.

  The SI lens 34 has a role as a lens for condensing the light of the light emitting element of the SI light source 35 on the display unit, and a role as a prism for turning back the SI light flux. The SI lens 34 also functions as a light guiding means for guiding light from the SI light source 35 to the display unit.

  As shown in FIG. 1, the light beam that is folded by the SI lens 34 and travels toward the SI light source 35 is folded diagonally downward so as not to increase the height of the imaging device 1. Here, “downward” means the direction opposite to the vector 37a in FIG. 1A, and for this purpose, it is necessary to reduce the incident angle. This will be schematically described with reference to FIG.

  FIG. 5 is a schematic diagram showing a folded state of a light beam (SI illumination light) emitted from the light source of the SI light source 35. FIG. 5 shows a planar relationship including the light beams 36a and 36b in FIG. FIGS. 5A, 5B, and 5C are diagrams showing the light flux 36a that irradiates the display unit 33a and its folded state. FIGS. 5D, 5E, and 5F show the display unit 33b. It is a figure which shows the light beam 36b irradiated and the return state. In FIG. 5, reference numeral 34 a denotes the reflecting surface of the SI lens 34. θ is an incident angle when the SI illumination light is turned back by the reflecting surface 34a.

  As can be seen from FIGS. 5A, 5 </ b> B, and 5 </ b> C, the position of the SI light source 35 shown in FIG. Although it is necessary to change to the position shown in (c), the incident angle θ is reduced by doing so. Further, when FIGS. 5A to 5C are compared with FIGS. 5D to 5F, the incident angle θ of the light beam 36b toward the display unit 33b is particularly small.

5A and 5D, the SI light source 35 and the SI lens 34 are arranged so that the light emission position of the SI light source 35 is higher than the incident position of the reflection surface 34a of the SI lens 34. Yes.
5B and 5E, the SI light source 35 and the SI lens 34 are arranged so that the light emission position of the SI light source 35 is the same as the incident position of the reflection surface 34a of the SI lens 34. Yes.
5C and 5F, the SI light source 35 and the SI lens 34 are arranged so that the light emission position of the SI light source 35 is lower than the incident position of the reflecting surface 34a of the SI lens 34. Yes.

  In order to form the reflecting surface 34a at a low cost without depositing a reflecting film on the reflecting surface of the SI lens 34 as in the prior art, it is effective to use total reflection. The total reflection condition can be expressed as in Equation 1 with a critical angle of θm.

However, n _A is the refractive index of medium A (medium A is a medium outside the reflecting surface 34a in FIG. 5 and air in the example of FIG. 5), and n _B is the refractive index of medium B (what is medium B? In FIG. 5, the medium is inside the reflecting surface 34a, and in the example of FIG. 5, the material of the SI lens 34). Solving Equation 1 with an air refractive index of 1 and an SI lens 34 made of acrylic resin (refractive index of about 1.49171), θm> 42.1 degrees, and if the incident angle is larger than 42.1 degrees, all reflect.

  The refractive index of acrylic resin is a representative example of a material that is smaller than the refractive index of other glass materials and is difficult to totally reflect. Other glass materials such as polycarbonate (refractive index of about 1.585) can be totally reflected at an incident angle lower than 42.1 degrees.

  In FIG. 5, if it is attempted to satisfy the total reflection condition for the light fluxes directed to all the display units, the SI light source 35 must be disposed at a higher position than those shown in FIGS. 5 (a) and 5 (d). The height of the housing 3 of the device 1 is increased. In order to prevent an increase in the size of the image pickup apparatus 1, conventionally, the reflection surface 34a does not use total reflection, but a reflection surface is obtained by depositing an appropriate reflection film, which leads to an increase in cost.

  Therefore, in this embodiment, the SI lens 34 is provided with two reflecting surfaces that reflect the light from the SI light source 35 twice and guide it to the display unit, and no reflecting film is provided on each reflecting surface. The two reflecting surfaces may be roof surfaces having an angle between them of 90 degrees.

  Hereinafter, the SI lens 34 of this embodiment and the conventional SI lens 100 will be compared and described with reference to FIG.

  FIG. 6B is a perspective view of a conventional SI lens 100. 6B, the SI lens 100 has an incident surface 110, a reflective surface 120 on which a reflective film is deposited, and an exit surface 130. The reflective surface 120 has a portion disposed on the upper surface of the exit surface 130. FIG. 6B shows a light beam from an SI light source (not shown in FIG. 6B), L21 shows a light beam after the light beam L21 is reflected by the reflecting surface 120, and L22 shows a light beam transmitted through the reflecting surface 110.

  In the conventional SI lens 100, since the reflecting surface 120 is composed of one surface, it is difficult to satisfy the total reflection condition as it is, and the viewfinder device is enlarged to satisfy the total reflection condition. In a state where no reflective film is deposited on the reflection surface 120, the light beam is transmitted like the light beam L22, and the light beam cannot be guided to a display unit (not shown). When a reflective film is deposited on the reflective surface 120, the light beam L20 is reflected by the reflective surface 120 and the display unit can be irradiated as the light beam L21. The reflection surface 120 extends 45 degrees obliquely upward from the upper surface 140 parallel to the bottom surface of the SI lens 100 provided with the emission surface 130, but the angle of the reflection surface 120 is not limited to this.

  FIG. 6A is a perspective view of the SI lens 34 of the present embodiment. The SI lens 34 has an incident surface 50, two reflecting surfaces 51 and 52 on which no reflecting film is deposited, and an exit surface 53. L10 indicates a light beam from the SI light source 35, and L11 indicates a light beam after the light beam L10 is reflected on the reflecting surfaces 51 and 52 in this order. The reflection surfaces 51 and 52 are adjacent to each other and both have a portion disposed on the emission surface 53.

  In FIG. 6A, the angle p formed by the reflecting surfaces 51 and 52 is 90 degrees, which constitutes a roof surface (two planes forming 90 degrees with each other), but is not limited thereto. In this embodiment, the angle formed by the vertical surface provided with the incident surface 50 and the bottom surface provided with the exit surface 53 is 90 degrees. In FIG. 6A, the reflection surface 120 of the conventional SI lens 100 is virtually shown by a broken line.

  A straight line (ridge line) 54 where the reflecting surfaces 51 and 52 which are two planes intersect each other is on the virtually shown reflecting surface 120, and the straight line 54 is parallel to the bottom surface of the SI lens 34 on which the exit surface 53 is formed. The upper surface 55 extends obliquely upward by 45 degrees. However, the angle of the straight line 54 is not limited to this. The two reflection surfaces 51 and 52 can easily satisfy the total reflection condition, and the reflection surface 120 only needs to satisfy the total reflection condition.

  In FIG. 6A, the reflecting surfaces 51 and 52 form roof surfaces, and a large incident angle to each reflecting surface can be ensured, making it easy to satisfy the total reflection condition. As a result, the light beam L10 can be totally reflected by the two roof surfaces and guided as the light beam L11 to irradiate the display unit.

  FIG. 6C is a diagram showing the relationship between the reflective surface by the roof surface of the SI lens 34 and the conventional reflective surface, and the portion of the SI lens 34 viewed from the U direction parallel to the reflective surface 120 of FIG. It is a top view. FIG. 6C shows the roof surface portion with emphasis. In FIG. 6C, 51n, 52n, and 120n are surface normals of the reflecting surfaces 51, 52, and 120, respectively. The surface normals 51n and 52n are both 45 degrees with respect to the surface normal 120n.

  By disposing the reflecting surfaces 51 and 52 in this way, the light beam is inverted in the direction orthogonal to the straight line 54 in the plane 120, but the other portions have substantially the same reflection. As a result, in the present embodiment, as shown in FIG. 1, the light flux that has been guided to the display unit 33c is changed to be guided to the display unit 33d, but the light beam directed to the display units 33a and 33b is spotted. Although it is reversed, it is not affected by the irradiation range. Further, as described above, in the present embodiment, the display in the vertical direction of the display unit is inverted, but this may be done by changing the light source to be turned on in correspondence with the focus detection area by software.

  FIG. 7 is a graph showing changes in the incident angle θ due to the provision of the two reflecting surfaces 51 and 52 on the SI lens 34 when the incident angle θ shown in FIG. 5 is considered. In FIG. 7, the horizontal axis represents the incident angle when there is no roof surface, and corresponds to the incident angle θ in FIG. The vertical axis represents the angle of incidence on each surface when the roof surface is attached. The incident angle without a roof surface increases with the roof surface. Furthermore, the total reflection conditions in the case where the medium shown by using Equation 1 in FIG. 7 is acrylic and air are shown by broken lines.

  According to FIG. 7, when only the light beam existing in the plane shown in FIG. 5 is considered, the total reflection condition is satisfied at any incident angle θ. For example, even in the arrangement as shown in FIGS. 5C and 5F, the light beam can be guided to the display unit by total reflection by using the roof surface.

  Actually, in FIG. 5, there is also a light beam having a component in a direction perpendicular to the paper surface. Therefore, as shown in FIG. 7, the total reflection condition cannot be satisfied in all cases regardless of the incident angle. The presence of the surface makes it easy to satisfy the total reflection condition. In an actual design, the maximum value of the angle of the effective light beam taken into the SI lens 34 in the direction perpendicular to the paper surface in FIG. 5 is estimated, and that amount may be set with a margin with respect to the total reflection condition in FIG.

  For example, when taking a luminous flux having a spread of 8 degrees (a luminous flux that forms 8 degrees in each direction from a light source) as an effective luminous flux, the total reflection angle of acrylic resin is 42.1 degrees, What is necessary is just to set so that an angle | corner of about 50 degree | times may be made, seeing a margin of 8 degree | times. In other words, the vertical axis should be higher than 50.1 degrees.

  At this time, as shown in FIG. 7, the incident angle when there is only one reflecting surface is 25 degrees or more corresponding to 50.1 degrees on the vertical axis for the strictest incident angle in FIG. For this reason, when there is only one reflecting surface, the total reflection condition cannot be satisfied.

  Next, with reference to FIG. 8, a preferred dimension setting of the two reflecting surfaces 51 and 52 of the SI lens 34 will be described.

  FIG. 8A is a schematic plan view showing a state in which the SI light beam is projected onto the surface on which the display unit of the focusing screen 33 is formed. In FIG. 8A, the central display portion 33a functions as a reflection portion in the central circular portion or the square outer contour portion of the display portion 33a. Reference numeral 61 denotes a circular spot (illumination region) on the focusing screen of the SI light beam that irradiates the display unit 33a.

  In FIG. 8A, the spot 61 is formed so as to include the display portion 33a. The size of the spot 61 is set to a size that illuminates the display unit 33a and does not illuminate another adjacent display unit even when there is an error in the position of an SI light source or SI lens 34 (not shown). Has been.

  FIG. 8B is a partially enlarged view around the display unit 33a in FIG. In FIG. 8A and FIG. 8B, the angle p formed by the two reflecting surfaces 51 and 52 is 90 degrees, and the two reflecting surfaces 51 and 52 constitute a roof surface.

  The spot 61 is composed of spots 61a and 61b. The spot 61 a is a semicircular spot (second illumination area) formed by a light beam reflected in the order of the reflecting surface (second reflecting surface) 52 and the reflecting surface (first reflecting surface) 51 of the SI lens 34. is there. The spot 61 b is a semicircular spot (first illumination region) formed by a light beam reflected in the order of the reflective surface (first reflective surface) 51 and the reflective surface (second reflective surface) 52 of the SI lens 34. is there. The shape of the spots 61, 61a, 61b is not limited to the shape shown in FIG.

8A and 8B, the spots 61a and 61b are in contact with each other at a semicircular straight portion (string portion) to form a circular spot 61 as a whole. 8 (a) and 8 (b), since the spot 61 covers the entire display portion 33a, the reflection portion of the display portion 33a is located at the central portion 33a ₂ even if the reflection portion is at the contour portion 33a _1. Can also illuminate it, and the photographer can easily recognize it.

  FIG. 8C shows the spots 61a and 61b when the angle p formed by the two reflecting surfaces 51 and 52 is smaller than 90 degrees. At this time, the angle p formed by the reflecting surfaces 51 and 52 is set so that the spots 61a and 61b have overlapping portions. When the angle p formed by the two reflecting surfaces 51 and 52 is further reduced, the spot 61a moves further downward in FIG. 8C and the spot 61b further moves upward in FIG. 8C. Come away.

In FIG. 8 (c), the spot 61a, since the overlapping portions of 61b covers the entire display section 33a, also the reflection portion of the display portion 33a is in the contour portion 33a ₁ even in the central portion 33a ₂ This can be illuminated. In addition, since the illuminance is high in the overlapping portion, the photographer can more easily recognize this. For example, if the distance from the reflective surface in the SI lens to the display unit is 30 mm and the spot radius is 1.0 mm, the spot 61a and 61b will pass each other when moved about 1 degree, so the angle p is about 89 degrees to 90 degrees. Should be set.

  FIG. 8D is a diagram showing spots 61a and 61b when the angle p formed by the two reflecting surfaces 51 and 52 is larger than 90 degrees. At this time, a gap is formed between the spots 61a and 61b, and the gap becomes larger as the angle p formed by the two reflecting surfaces 51 and 52 becomes larger.

  In FIG. 8C, when the spots 61a and 61b are removed from each other and the spots 61a and 61b are close to the display unit 33a even when the state shown in FIG. Can be recognized.

  As described above, according to the present embodiment, a small and inexpensive finder device can be provided.

  As mentioned above, although the preferable Example of this invention was described, this invention is not limited to these Examples, A various deformation | transformation and change are possible within the range of the summary.

  The viewfinder device can be applied to an imaging device. The imaging device can be applied to use for imaging a subject.

1 Imaging device 7 Optical viewfinder (finder device)
33 Focusing screen 33a, 33b, 33c, 33d Display unit 34 SI lens (light guiding means)
35 SI light source 51, 52 Reflection surface

Claims (3)

A finder device that superimposes a plurality of focus detection areas in a finder field,
A focusing screen having a surface on which a display unit corresponding to the plurality of focus detection areas is formed;
A pentamirror that reflects reflected light from the display unit to an eyepiece;
A light source that is disposed closer to the eyepiece than the pentamirror and emits light that illuminates the display unit;
A light guide unit disposed on the eyepiece side of the pentamirror and having two reflecting surfaces that reflect light from the light source twice and guide the light to the display unit;
Have
Each reflective surface is not provided with a reflective film ,
The two reflecting surfaces are composed of a first reflecting surface and a second reflecting surface,
The light from the light source is reflected in the order of the first reflecting surface and the second reflecting surface to form a first illumination area on the surface of the focusing screen, and the light from the light source is the second reflecting surface. A second illumination area is formed on the surface of the focusing screen by being reflected in the order of the reflective surface of the first reflective surface,
The finder apparatus characterized in that an angle formed by the two reflecting surfaces is smaller than 90 degrees and the first illumination area and the second illumination area have an overlapping portion . The light source and the light guide unit are arranged so that an emission position of the light of the light source is lower than an incident position of one of the two reflecting surfaces of the light guide unit. The finder device according to Item 1 . The imaging device provided with the finder apparatus of Claim 1 or 2 .