JPH0234012B2 - KAMERAYOADAPUTA - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a camera adapter that is attached to a camera or lens equipped with an automatic focus adjustment device and that allows the photographic lens to be set in a predetermined focus state regardless of the subject distance.

In (AF) cameras equipped with an automatic focus adjustment device, a method is used in which the photographic lens is moved in the optical axis direction in conjunction with the release operation, etc., and then stopped at the in-focus position. Distance setting is performed by obtaining distance information to the subject using various autofocus mechanisms and automatically achieving a focused state.

When attempting to manually adjust the distance of the photographing lens in such an AF camera, the linkage between the focus detection section of the autofocus device and the lens extension or retraction mechanism must be cut off in some way, and the distance adjustment member of the lens must be You will have to adjust it manually.

However, the distance adjustment mechanism in AF cameras is generally integrated with the camera's autofocus device, and a complicated mechanism is required to shut it off for manual operations that are not used very often, and to enable manual operation. Providing a manual distance adjustment mechanism leads to disadvantages such as a decrease in reliability due to the complexity of the mechanism and an increase in cost.Therefore, in many general AF cameras, the manual distance adjustment mechanism is omitted.

The present invention has been made in view of the above circumstances, and
A camera equipped with a distance measuring device that projects a signal light from a light projecting means, receives the reflected light by a light receiving means, and measures the distance to a subject based on the angle formed by the direction in which the signal light is projected and the direction in which the light is received. The adapter is mounted, and includes a first reflecting means for reflecting the signal light projected from the light projecting means, and a first reflecting means for guiding the signal light reflected by the first reflecting means to the light receiving means. and a second reflecting means for causing the distance measuring device to detect a predetermined distance, so that the photographing lens can be set at a predetermined focus position without affecting the automatic focus adjustment mechanism of the camera or the lens. Therefore, it is an object of the present invention to provide a camera adapter that can enhance the applicability and expandability to fields such as close-up photography.

Embodiments of the present invention will be described below with reference to the drawings.

First, the principle of the distance measuring method using infrared light according to the present invention will be explained with reference to FIG. In the figure,
1 is a light emitting element such as an infrared light emitting diode as a light projecting means, and 2 is a silicon photocell or the like as a light receiving means for measuring the amount of infrared light emitted by 1 as a signal light reflected from a subject. , 3 is a light projecting lens that forms a beam, and 4 is a light receiving lens that images the spot on the object produced by the light projecting device 1 onto the light receiving device 2 . The light projecting element 1 is capable of rotational movement between positions 1 and 1'' in the figure.
When the object 5 is located at a distance R from the principal point of the light emitting/receiving lens, the optical axis of the reflected light incident on the light receiving element 2 is the optical axis 9 since the surface of the object is usually a diffuse reflection surface. Therefore, the amount of light incident on the light-receiving element 2 becomes maximum when the projection optical axis and the reflection optical axis 9 coincide with each other above the subject 5. The angle θ _R formed by both optical axes at this time is determined as the angle formed by optical axes 6 and 7. The distance R can be determined from this angle _θR as R=L/tanθR, where L is the distance between the light emitting lens and the light receiving lens, that is, the base line length.

Also, instead of replacing the light emitting element 1 and the light receiving element 2 with the above configuration and moving the light receiving element 2,
The distance can be measured in the same way by dividing the beam into multiple sections and measuring the distribution of light incident on them.

FIG. 2 is a diagram showing the optical system configuration and operating principle of the camera adapter according to the present invention. 1 to 4 in the diagram
1 shows a camera or lens distance measuring device having the same components as in FIG. In the figure, reference numeral 12 denotes a movable mirror as a first reflecting means that can rotate around an axis 13, and 14 denotes a fixed half mirror as a first reflecting means having an angle of 45 degrees with respect to the reflection optical axis 9. Reference numeral 15 denotes a diffuse transmission plate 1 that forms a spot of the projected light beam from the light projecting element 1 that is reflected by the movable mirror 12 and focused by the condensing lens 16.
Reference numeral 7 denotes a lens for forming an image of a spot on the diffuser-transmitting plate onto the light-receiving element 2 via the fixed half mirror 14. FIG. 2A shows the state where the distance is set to infinity, and FIG. 2B shows the state where the distance is set to short distance. In either case, the distance measuring device detects the focused state when the beam from the light projecting element 1 passes through the diffuser transmitting plate 1.
5, when the lens is located on the intersection a of the optical axes of the lenses 16 and 17. This point corresponds to the in-focus point detection state in FIG. That is, in this adapter, instead of the actual subject, a diffuse transmitting plate 15 is arranged on the extension of the light receiving optical axis, and this diffuse transmitting plate 1
5, when the light emitting axis and the receiving optical axis coincide, the amount of light received by the light receiving element 2 becomes maximum, and the distance measuring device determines that the subject is at a certain distance from the swing angle of the light emitting element 1 at that time. By using this judgment and associating the position of the movable mirror 12 with the swing angle of the light projecting element 1, the distance desired by the user is given. In this embodiment, the lens 16 is fixed and the movable mirror 12 is rotated and translated simultaneously to achieve this objective. Next, the movement of the movable mirror 12 will be explained with reference to FIG. In the figure,
The origin 0 of the xy coordinate system is the principal point of the light emitting lens, the y axis is the optical axis of the light emitted to the object at infinity (i.e. parallel to the receiving optical axis),
θ is the swing angle of the light projecting element 1. 21 is a projection optical axis; 22 is an optical axis of lenses 16 and 17 (not shown) to align the projection optical axes bent by a movable mirror;
23 is a movable mirror surface corresponding to infinity, 24 is
It is a movable mirror surface corresponding to the deflection angle θ. At this time, when the movable mirror 12 is at an infinite position, it is sufficient to hold its rotation center at the point (-x ₁ , 0) and rotate it θ' while moving it to the point (X, Y). At this time,
^By geometric ^calculation _, x ₁ = y ₁ θ' = ¹ /2θ 1} Y=y ₁ [1tanθ ¹・tan(90°−θ ^1/2 )/tan(90
°−θ ¹ /2)−1] Amount of change in X=amount of change in Y. This results in
For example, if y ₁ = 50 mm, in the range of θ < 5 degrees, θ' should change by 0.5 degrees for a 1 degree change in θ, and X and Y should change by about 0.43 mm uniformly. Appropriate. At this time, errors caused by regarding changes in X and Y as constant are corrected using a distance scale.

Now, a mechanism for causing the movable mirror to perform such a movement will be explained with reference to FIGS. 4, 5, and 6. As explained above, this mechanism is
The mirror is rotated by a certain angle, and the axis of rotation is moved in a straight line by a certain distance. In the figure, 1 is a light projecting element, and 2 is a light projecting lens. 12 is a movable mirror, and 31 is a movable mirror lever. The movable mirror lever 31 is integrated with a gear 31a at one end, and supports the mirror 12 at the other end 31b. The straight lever 32, on which the lever 31 is pivotally supported, is slidably fitted to the shaft 33 of the main body through an elongated hole 32a, and is provided with a rack 32b. In addition, 32
The direction of movement is 45° with respect to the projection optical axis 6. 3
4 is a fixed rack that meshes with the gear 31a, 35 is interlocked with a distance knob 36 via a deceleration mechanism (not shown),
The rack 32b and the meshing gear 37 are tensioning coil springs to prevent rattling due to backlash of each meshing portion. FIG. 4 shows a state in which the distance is set to infinity, and FIG. 5 shows a state in which the distance is set to short distance. The transition from the state shown in FIG. 4 to the state shown in FIG. 5 is performed as follows. Distance knob 36
When the gear 35 is rotated counterclockwise, the gear 35 rotates clockwise by the rotation angle according to the reduction ratio during this time.
The lever 32 moves straight by a predetermined amount by the rack 32b.
Move to the front right.

Since the movable mirror lever 31 is pivotally supported on the straight lever 32, it still moves to the right. However, at this time, the gear 31a is engaged with the fixed rack 3, so the movable mirror lever 31 is moved counterclockwise by a predetermined amount. Rotate. The feed amount of the straight lever and the rotation angle of the movable mirror lever are determined by the pitch circle diameter of gear 35 being P.
CD1.If the pitch circle diameter of the gear 31a is PCD2.The rotation angle of the knob 36 is θ ₀ , and the reduction ratio from the distance knob 36 is n, then the feed amount of the straight lever = 1/2P.CD1×θ ₀ /n Movable mirror Lever rotation angle = PCD1/PCD2×θ ₀ /n.

The transition from the state shown in FIG. 5 to the state shown in FIG. 4 is performed in exactly the reverse manner. The spring 37 prevents backlash caused by the backlash of the gears. The displacement of the spring 37 due to the tensile force may be prevented by a friction, or a worm gear may be used in the speed reduction mechanism between 35 and 36.

Figure 6 shows the state when autofocus is activated by utilizing the distance measuring device.The distance knob is rotated further clockwise beyond the infinity position, and the AUTO focus is activated.
When aligned with the index, the movable mirror 12 moves out of the light projection path and the light is projected through the light projection window 38. The reflected light returns to the SPC through the light receiving window and fixed half mirror. Furthermore, if the fixed mirror also escapes from the optical path 9 when the distance knob is set to the AUTO index, there is no need to make it a half mirror.

The distance manual setting described above is set in advance by operating the distance dial before releasing the lens, and it is necessary to actually move the lens to this set position.
Perform the same action as AF, for example by pressing the shutter button.

Note that by reversing the arrangement of the fixed and movable mirrors relative to the light emitting and receiving system, it can also be applied to AF with a fixed light emitting side and multiple light receiving elements on the light receiving side.

Further, this camera adapter is configured to be detachably attached to the camera.

As described above, the present invention provides a camera adapter that allows a photographic lens to be set at a predetermined focus position without significantly affecting the mechanical and structural aspects of manual adjustment of the automatic focus mechanism. Moreover, by using it as a detachable adapter, it can be combined with a close-up lens, and by adding correction to the distance index, it can be used as a variable magnification close-up device, making it a highly versatile device. Therefore, the effect is extremely high.

[Brief explanation of drawings]

Fig. 1 is a principle diagram of the infrared light irradiation type distance measuring method according to the present invention, and Fig. 2 is a principle optical diagram showing the configuration and operation of the camera adapter according to the present invention.
FIG. 2A shows an infinite distance setting state, and FIG. 2B shows a (very) short distance setting state. Figure 3 is an explanatory diagram showing the movement of the movable mirror in the adapter shown in Figure 2, Figures 4 and 5 are perspective views of examples of the mechanism of the adapter shown in Figure 2, and Figure 4 shows the distance set to infinity. FIG. 5 shows a state in which the distance is set close.
FIG. 6 is a perspective view showing the adapter shown in FIGS. 4 and 5 set in an autofocus state. 1... Light emitting element, 2... Light receiving element, 3... Light emitting lens, 4... Light receiving lens, 12... Movable mirror, 14... Fixed mirror, 15... Diffusion transmission plate,
16, 17... Lens, 31... Movable mirror lever, 32... Straight lever, 34... Fixed rack,
35...Gear, 36...Distance setting knob, 37...
...Coil spring.

Claims (1)

[Claims] 1 A camera equipped with a distance measuring device that projects a signal light from a light projector and receives the reflected light by a light receiver to measure the distance to a subject based on the angle formed by the direction in which the signal light is projected and the direction in which the light is received. The adapter includes a first reflecting means for reflecting the signal light projected from the light projecting means, and a first reflecting means for guiding the signal light reflected by the first reflecting means to the light receiving means. A camera adapter comprising one reflecting means and a second reflecting means for causing the distance measuring device to detect a predetermined distance.