A two-focus camera in which a short focal-distance lens system is constituted by only a main lens when the main lens is set at a first position on an optical axis and a converter lens is set at a second position out of the optical axis, and a longer focal-distance lens system is constituted by the main lens and the converter lens when the main lens is set at a third position in front of the first position on the optical axis and the converter lens system is set at a fourth position behind the main lens on the optical axis.

This invention relates to a multi-focus camera. 
Generally, in order to take photographs which satisfy various ideas, it is 
required to use corresponding lenses different in focal distance and 
optimal for photographing purposes. As a camera which satisfies such 
requirements, there is a lens-exchangeable single-lens reflex camera. 
Although such a single-lens reflex camera is capable of satisfying almost 
all photographing ideas, it is bulky and expensive. In order to use such a 
camera, one must obtain several expensive large-sized exchange lenses and 
carry them with him, therefore, everybody cannot easily use such camera. 
In taking a normal photograph, two lenses, namely, a wide-angle lens and a 
telephoto lens, would suffice almost all photographing desires. 
Recently, lens-shutter type multi-focus cameras are appearing one after 
another. A camera of this type generally includes a main lens and a 
converter lens in its casing, in which the main lens is always disposed 
movably along the optical axis and the converter lens is selectively 
inserted on the optical axis. 
A focal-distance switching mechanism in such a multi-focus camera is 
disclosed, for example, in Published Unexamined Japanese Patent 
Application No. 17540/1984. This conventional apparatus includes a main 
lens slidable between a first position and a second position using a 
support shaft as a guide provided in a lens barrel along the optical axis 
and a converter lens which can be inserted on the optical axis. The lens 
barrel fixing the converter lens therein is supported rotatable around a 
support provided out of the optical axis. 
Switching between a first focal distance (for example, in the wide-angle 
photographing) and a second focal distance (for example, in the telephoto 
photographing) is performed as follows. 
In order to set the multi-focus camera to a wide-angle photographing mode, 
the converter lens is put out of the optical axis and the main lens is 
moved backwardly along the optical axis. Thus the wide-angle mode is 
constituted only by the main lens. 
On the other hand, in order to set the camera to a telephoto photographing 
mode, the main lens is moved forwardly along optical axis and the 
converter lens is put back on the optical axis. Thus the telephoto mode is 
constituted by the main lens sand converter lens. 
In such conventional multi-focus camera, the alignment of the converter 
lens with the optical axis is relatively easy, but the lens barrel, is 
extremely large. 
It is also necessary to provide a space within the camera body for stowing 
the support for the main lens in wide-angle photographing mode, therefore 
the camera body is also bulky. 
In converter lens moving means which can avoid an increase of the size of 
the camera body, and movement of the converter lens is complicated, and 
the mechanism which aligns the axis of the converter lens with the optical 
axis is also complicated, therefore assembling is troublesome, which is a 
new problem. 
This invention is intended to eliminate the above problem of the 
conventional apparatus. 
It is a first object of this invention to provide a multi-focus camera 
which prevents an increase of the size of the lens barrel and prevents a 
decrease in the efficiency of utilizing the space of the camera body. 
It is a second object of this invention to provide a multi-focus camera 
which is compact in structure, easy to assemble and adjust, capable of 
reliable aligning the axis of the converter lens with the optical axis, 
and holding the converter lens at a correct position relative to the main 
lens. 
The first object of this invention is achieved by a two-focus camera in 
which a short focal-distance lens system is constituted by only a main 
lens when the main lens is set at a first position on an optical axis and 
a converter lens is set at a second position out of the optical axis, and 
a longer focal-distance lens system is constituted by the main lens and 
the converter lens when the main lens is set at a third position in front 
of the first position on the optical axis and the converter lens system is 
set at a fourth position behind the main lens on the optical axis, said 
two-focus camera comprising: 
a means for moving the main lens between the first and third positions; 
a lens frame for holding the converter lens; 
a support member for supporting the lens frame in order that the lens frame 
can move freely within a predetermined limit; 
a shaft fixed to one end of the support member and extending substantially 
orthogonal to an axis of the converter lens; 
a second means for moving the shaft in parallel with the optical axis in 
interlock with the first means; and 
a third means for swiveling the shaft around an axis perpendicular to the 
optical axis when the shaft is moving between a predetermined intermediate 
position and a foremost position. 
The second object of this invention is achieved by a two-focus camera in 
which a short focal-distance lens system is constituted by only a main 
lens when the main lens is set at a first position on an optical axis and 
a converter lens is set at a second position out of the optical axis, and 
a longer focal-distance lens system is constituted by the main lens and 
the converter lens when the main lens is set at a third position in front 
of the first position on the optical axis and the converter lens is set at 
a fourth position behind the main lens on the optical axis, said two-focus 
camera comprising: 
a lens frame holding the converter lens and having male threads on outer 
periphery thereof; 
an outer lens barrel threadedly engaged with the lens frame so that the 
lens frame can move along the optical axis; 
a support member supporting the outer lens barrel in order that the outer 
lens barrel can move within a predetermined limit and driven in parallel 
with the optical axis in the vicinity of the fourth position; 
a positioning plate disposed orthogonally to the optical axis for 
positioning the converter lens at the fourth position; 
a guide member provided on the positioning plate for guiding the outer lens 
barrel so that an axis of the converter lens aligns with the optical axis 
by abutting against an outer periphery of the outer lens barrel when the 
converter lens is set at the fourth position; and 
a spring member fixed to the support member at one end thereof and fixed to 
the outer lens barrel at the other end thereof for urging the outer lens 
barrel against the positioning plate.

DETAILED DESCRIPTION 
An embodiment of this invention will now be described in detail with 
reference to the accompanying drawings. 
Before a specific description, the basic structure of a converter lens in a 
two-focus camera according to this invention will be described with 
reference to FIGS. 2(A) and (B). 
As shown in FIG. 2(A), in wide-angle photographing or short focal-distance 
photographing, a main lens 10 is disposed before a film surface F, an iris 
also functioning as a shutter 30 is disposed immediately after the main 
lens 10 to form a short focal-distance optical system. 
At this time, the converter lens 20 supported inside a converter lens 
barrel 21 which in turn is supported pivotally around a shaft 22 is 
located outside the optical axis between the shutter 30 and the film 
surface F. 
As shown in FIGS. 2(B), in telephoto or longer focal-distance 
photographing, both the main lens 10 and the shutter 30 disposed before 
the film surface F are moved forwardly along the optical axis and the 
converter lens 20 is disposed behind the main lens 10. 
The converter lens 20 is moved in order that the shaft 22 moves forwardly 
by a predetermined distance along an axis parallel to the optical axis 
without being swiveled from its completely stowed position shown by a in 
FIG. 2(A) to an intermediate position shown by b in FIG. 2(B). If the 
shaft 22 is moved further forwardly, the converter lens barrel 21 is moved 
forwardly while swiveling counterclockwise around the shaft 22. As a 
result, as shown by reference characters b, c and d in FIG. 2(B), the 
shaft 22 is moved forwardly along the axis parallel to the optical axis 
while the converter lens barrel 21 is swiveled counterclockwise around the 
shaft 22 and the barrel 21 moves to a position shown by a reference 
character e. 
As a result, the main lens 10 and the converter lens 20 constitute a longer 
focal-distance lens system. 
A specific embodiment of the driving mechanism and stabilizing mechanism 
for the converter lens of a two-focus camera according to this invention 
will now be described with reference to FIGS. 1 and 3-8. 
A main lens barrel 11 in which the main lens 10 comprising four lenses are 
disposed on the optical axis of the camera body 100. The main lens barrel 
11 is fixed to a cylindrical movable barrel 12 behind which is formed a 
flange 12a which is fitted slidably into a guide 13 formed on the camera 
body 100. 
Formed in the middle portion of the movable barrel 12 is a shutter base 
plate 12b acting as a positioning plate having a circular hole through 
which the flux of light passes. The shutter base plate 12b has a shutter 
30 also acting as an iris. As shown in FIGS. 4 and 6, the flange 12a has 
right and left portions, each of which is provided with a pin 14 connected 
to one end of an arm 15 rotatably, the other end of which has a hole into 
which is fitted a pin 17 which in turn is fitted into an arcuate guide 
slot 16 formed in the camera body 100. 
The pins 17 are adapted to move within the guide slots 16 with the aid of 
sectoral driving plates 19 supported rotatably by support shafts 18 fixed 
to the camera body 100. 
Therefore, when the torque of a motor (not shown) is transmitted via a 
reduction gear mechanism to gears 19a, the driving plates 19 having a 
sectoral gear meshing with the gears 19a are rotated. The pins 17 on the 
driving plates 19 are then moved along the guide slots 16. This causes the 
arms 15 and hence the pins 14 to move, so that the movable barrel 12 
guided by the guides 13 can move to a reference position shown in FIGS. 3 
and 4 and to a telephoto position shown in FIGS. 5 and 6. 
The essential portion of this invention will next be described. The 
converter lens 20 constituted by four lenses is fixed to an inner barrel 
23 as a lens frame as shown in detail in FIGS. 7 and 8. The inner barrel 
23 having male threads 23a formed on an outer periphery thereof is 
threadedly engaged with female threads 24a formed at forward portion of an 
outer barrel 24 having a larger diameter than that of the inner barrel 23. 
Therefore, by rotating the inner barrel 23, the position of the inner 
barrel 23 with respect to the optical axis relative to the outer barrel 24 
can be finely adjusted. 
Shafts 24b and 24c project in opposite direction orthogonally to the 
optical axis from the outer periphery of the outer barrel 24. 
The shafts 24b and 24c are supported elastically by a support member 21 so 
as to be movable in a predetermined range. The support member 21 has a 
receiving portion with a substantially semicircular cross section. The 
shafts 24b and 24c are fitted in guide holes 21c and 21d provided on 
either side of the support member 21 which has on either side pins 21e and 
21f around which are wound torsion springs 25a and 25b at their middle 
portions. The torsion springs 25a and 25b urge at one end thereof the 
shafts 24b and 24c toward the shutter base plate 12b and are engaged at 
the other end thereof with spring hooks 21g and 21h on the support member 
21. 
The support member 21 is pivotted on a lower part of a frame 50 fixed to 
the back of a shutter base plate 12b. A central shaft 53 of a lever 52 
having a gear 51 meshing with the gear 21b is pivotted on the frame 50. 
As shown in FIG. 1, a torsion spring 54 is wound several times around the 
central shaft 53 of the lever 52. One end of the torsion spring 54 is 
fixed to a spring hook 55 provided on the lever 52 and the other end is 
engaged with a pin 56 provided on the side of the frame 50. The position 
of an end of the lever 52 is restricted by a pin 57 fixed to the camera 
body 100. 
Therefore, the torsion spring 54 applies a counterclockwise turning force 
to the lever 52 around the central axis 53 (in FIGS. 3 and 5). 
In FIG. 5, finder lenses 60 constitute a telephoto finder optical systems 
in telephoto photographing. In FIG. 3, auxiliary lenses 61 are inserted by 
a finder switching mechanism (not shown), and the auxiliary lenses 61 and 
finder lenses 60 constitute a standard finder optical system in standard 
photographing. 
Lugs 70 are provided around the exposure opening in the shutter plate 12 to 
guide the forward portion of the outer barrel 24 into the exact position 
defined by the slant portions of the lugs 70 to thereby align the axis of 
the converter lens 20 with the optical axis. 
The operation of the two-focus camera having such structure will now be 
described. 
In standard photographing, when pin 17 is driven to its aftermost position 
by the gear 19a which in turn is driven by the motor via the reduction 
gear mechanism as shown in FIG. 4, the movable barrel 12 is retracted to 
its aftermost position inside the camera body 100, as shown in FIGS. 3 and 
4. 
At this time, the frame 50 moves together with movable barrel 12 to situate 
at their backward position. Therefore, the lever 52 supported on the frame 
50 by the shaft 53 also moved backward to be released from the pin 57, so 
that the lever 52 is turned by the action of the spring 54 (FIG. 1) to 
thereby rotate the shaft 22 via the gears 51 and 21b. Thus the converter 
lens 20 is moved to its backward stowing position in the lower part of the 
camera body 100. Under this condition, the light shielding lug 21a (FIGS. 
1 and 2) formed on the support member 21 eliminaes unnecessary light flux. 
When torque of the motor (not shown) is applied to the gears 19a to shift 
the lenses from such standard photographing state to the telephoto 
photographing state, the torque is transmitted from the gears 19a to the 
sectoral gears to rotate the driving plates 19 around the shafts 18. As a 
result, the pins 17 move forwardly along the guide slots 16 and the 
movable barrel 12 is moved forwardly via the arms 15 and pins 14. 
The frame 50 is also moved forwardly together with the movable barrel 12, 
therefore, the shaft 22 and the central shaft 53 move in parallel with the 
optical axis. The support member 21 moves forwardly in parrel with the 
optical axis without rotating until it reaches an intermediate position 
where the lever 52 hits against the pin 57. 
If the frame 50 proceeds further, the central shaft 53 is moved further 
forwardly, so that the lever 52 abuts against the pin 57 planted on the 
camera body 100 whereupon the lever 52 is turned clockwise (FIG. 3) 
against the action of the spring 54 (FIG. 1). The torque of the lever 52 
is transmitted via the gears 51 and 21b to the shaft 22 to rotate the 
entire support member 21 counterclockwise (FIG. 3) around the shaft 22. 
Such rotation of the support member 21 continues until the forward end of 
the outer barrel 24 supported loosely by the support member 21 is guided 
by the lugs 70 for optical axis alignment and abuts against the shutter 
base plate 12b as shown in FIGS. 7 and 8. 
Such positioning, is ensured since the shafts 24b and 24c are pushed 
forwardly, somewhat diagonally and downwardly by the ends of the torsion 
springs 25a and 25b fixed to the support member 21. 
During the setting for the telephoto photographing is proceeding, the 
auxiliary finder lenses 61 are put out of the optical axis as shown in 
FIG. 5 by a finder switching mechanism (not shown) so that only the finder 
lenses 60 constitute the telephoto finder optical system. 
To shift the lenses from the telephoto photographing state to the standard 
photographing state, the movable barrel 12 is moved back by an operation 
reverse to the operation above described and the converter lens 20 is 
completely put out of the optical axis. 
Therefore, according to this specific embodiment, the optical axis 
alignment and the positioning relative to the main lens 10 for the 
converter lens 20 can be performed accurately and easily using a simple 
structure without increasing the size of the camera body and the movable 
barrel. Namely, since the optical axis alignment is performed by abutting 
the forward end of the outer barrel 24 against the shutter base plate, the 
total error involved in assembling the inner barrel 23, outer barrel 24 
and support member 21 can be eliminated. In addition, the outer barrel 24 
is fitted loosely into the support member 21, so that the high assembling 
accuracy is not required and hence the assembling operation is simplified, 
fine focusing is performed by adjusting the threaded engagement between 
the inner and outer barrels 23 and 24. Therefore, the adjusting operation 
is simplified and the manufacturing cost is reduced. 
This invention is not limited to the above embodiment. Various changes and 
modifications could be made by those skilled in the art without departing 
from the spirit and gist of this invention. 
For example, the lugs 70 are not limited to the discrete ones shown in FIG. 
1 and may be replaced by an annular body into which the forward end of the 
outer barrel 24 can fit. 
The springs 25a and 25b are not restricted to the substantially U-like 
torsion ones shown in FIG. 1 and may be coil-like springs if the 
installing space permits. 
For example, the support member 21 and outer barrel 24 are not limited to 
those having the structure shown in FIG. 1 and may have structures shown 
in FIGS. 9-11. 
In FIG. 9, assume an orthogonal coordinates in which the Z-axis extends 
forwardly along the optical axis, the Y-axis extends upwardly and the 
X-axis extends right-wardly. 
Plate-like stops 80a and 80b protruding in the X-axis direction from either 
side of the upper portion of the outer barrel 24 are provided to restrict 
the movement of the outer barrel 24 in the Z-axis direction to a 
predetermined limit, and leg-like stops 81a and 81b extending in the 
optical axis direction and also protruding downwardly in FIG. 9 are 
provided on either side of the lower portion of the outer barrel 24 to 
restrict the rotational movement around each of the X-, Y- and Z-axis to a 
predetermined limit. 
The support member 21 has at its bottom a pair of grooves 83a and 83b 
extending along the optical axis of the converter lens 20 and loosely 
receiving the stops 81a and 81b. It also has, at its bottom rear and front 
ends, upwardly extending stop receivers 83c and 83d (83d is not shown) 
which prevent the stops 81a and 81b from protruding outwardly from both 
the rear and front ends. The support member 21 has horizontally protruding 
steps 84a and 84b on either upper end of its semicircular cross section 
receiver. Guide slots 85a and 85b extending substantially in the optical 
axis direction are provided in the substantially central portions of the 
steps 84a and 84b so that they receive upper ends of springs 25a and 25b, 
respectively. Stop receivers 87a-87d are provided in opposing relationship 
at the front and rear ends of the steps 84a and 84d for engaging the stops 
80a and 80b, respectively. Slant surfaces 70a, 70b of the lugs 70 
cooperate to position the outer barrel radially. A member in FIG. 9 
similar to that in FIGS. 1-8 is given the same number as in FIGS. 1-8 and 
further description is omitted. 
FIG. 10 is an elevational cross-section view of the modification of FIG. 9 
viewed from the shutter base plate 12b. 
The operation of this modification having such structure will now be 
described with reference to FIGS. 11(a), (b) and (c). In FIG. 11(a), the 
shaft 24b (24c) is urged by the spring 25a (25b) against the front end of 
the guide slot 21c. The support member 21 is rotated clockwise around the 
shaft 22 toward the lugs 70 so that as shown in FIG. 11(b) the outer 
barrel 24 abuts at its forward end against the slant surfaces 70a of the 
lugs 70, the shaft 24b is retreated against the force of the spring 25a to 
abut against the upper end of the guide slot 21c. Under such condition, 
the outer barrel 24 is guided by the slant surfaces 70b to approach the 
shutter base plate 12b. As shown further in FIG. 11(c), the outer barrel 
24 abuts at its front end 82 against the rear end of the shutter plate 
12b, the shaft 24b is further retreated, thereby obtaining positioning in 
the optical axis direction and the positioning in the radial direction for 
the outer barrel 24 by the horizontal surfaces 70b to establish an optical 
axis alignment. 
As described earlier in the above embodiment, since the shaft 24b is 
received loosely in the guide slot 21c, as shown in FIG. 11(b), during the 
outer barrel 24 is guided toward the optical axis, the outer barrel 24 and 
the receiver of the support member 21 may abut against each other at any 
position to apply an excessive force to the outer barrel 24. In order to 
avoid this, the rotational movement of the loosely received outer barrel 
24 around the X-, Y- and Z-axes is restricted to the predetermined limit 
by the stops 80a and 80b, and the stops 81a and 81b to thereby restrict 
the movement of the outer barrel 24 to only linear movements in the X-, Y- 
and Z-axis directions. Namely, in the state of FIG. 11(b), the outer 
barrel 24 receives from the slant surfaces 70a forces to rotate the outer 
barrel 24 counterclockwise around the shafts 24b and 24c, or around the 
X-axis, but the semicircular ends of the stops 81a and 81b abut against 
the semicircular bottoms of the grooves 83a and 83b to convert the 
rotational movement of the outer barrel 24 to a substantially linear 
movement in the Y-axis direction. 
In order to position the converter lens 20, for example, the arrangement 
shown in FIG. 12 may be used instead of the lugs 70 on the shutter base 
plate 12b as shown in FIG. 1. 
Namely, the shutter base plate 12b has a V-shaped receiver 12' which 
receives the lower portion of the inner barrel 23 to which the converter 
lens 20 is fixed and has an opening 12" in which the inner barrel 23 can 
move freely. An outer barrel 24 threadedly engaged with the inner barrel 
23 has shafts 24b and 24c (24b is not shown) which are supported by guide 
slots 21c and 21d provided, as in the previous embodiment, in the support 
member 21 which in turn has a shaft 21e, a spring receiver 21g and springs 
25a and 25b (25a is not shown) as in the above embodiment. Therefore, 
forces urging the converter lens 20 against the shutter base plate 12b are 
applied to the shafts 24b and 24c via the springs 25a and 25b. 
The bottom of the receiver 12' has a groove 12' a into which a rotation 
stopping pin 24' is fitted extending in parallel with the axis from an end 
face of the outer barrel 24 having a diameter larger than that of the 
inner barrel 23. 
Therefore, the outer barrel 24 can be positioned relative to the shutter 
base plate 12a. At the same time, the inner barrel 23 is pressed at its 
bottom against the receivers 12', so that the converter lens 20 is aligned 
with the optical axis. 
In the above embodiment the main lens 10 has been described as the standard 
lens, but it may be a wideangle lens. This invention may be applicable to 
any camera which has a mechanism for switching the lens system between a 
long focal-distance mode and a shorter focal-distance mode. 
As seen from the above detailed description, according to this invention, 
the converter lens not only swivels around the fixed shaft as in the above 
conventional device, but also moves in parallel with the optical axis from 
the aftermost stowing position to the intermediate position as the main 
lens moves forwardly, and thereafter, swivels toward the optical axis as 
the main lens further moves forwardly. Therefore, the converter lens can 
be transferred by a small space, so that the entire space of the camera 
body is effectively utilized. In addition, the converter lens can be 
stowed outside the barrel of the main lens, so that this camera is greatly 
miniaturized as a camera of this type. 
Although this camera is of the type in which the converter lens aligns with 
the optical axis after moving in parallel with the optical axis, 
positioning of the converter lens relative to the main lens is quite 
accurate and stable.