GB2171528A - Conversion to half frame camera - Google Patents

Abstract

Movement (to the left of Fig. 6) of an operating member 45 and supporting plate 40 causes (a) a half size viewing window 26 to move in front of a full size viewing window 24, (b) plate 33 carrying push rods 31 to retract (by interaction of stud 32 and inclined slot 41) whereby masking blades 121 are moved against a spring bias to reduce the exposure window by half, and (c) lowering of reciprocating plate 501 and associated locating hook 50 to block lower and upper positioning pins 61 and 62 and allow only half a rotation of film advance wheel 60 (lower pin 61 only being blocked in the upper position of plate 501 and hook 50 to allow a full rotation of wheel 60). Rotation of wheel 60 returns shutter striking plate 70 to its charged position. <IMAGE>

Description

SPECIFICATION Camera having means for regulating the exposure area of a frame of film This invention relates to a camera which can regulate the exposure area of a frame of film.

Nowadays, cameras can be divided into two types. One type is a "whole frame" camera and the other type is a "half frame" camera.

If we load a 36 exposure roll of film in a camera and we can take 36 pictures, it is a "whole frame" camera, but if we load a 36 exposure roll of film and we can take 72 pictures, it is a "half frame" camera. The reason is that when the shutter release button of a whole frame camera is pressed, a whole frame of film will be exposed to light. In a "half frame" camera, only "one half" of a frame of film will be exposed to light, which is why a "half frame" camera can take twice as many pictures as a "whole frame" camera.

Of course, a whole frame" camera can take wider and clearer pictures because its exposure area is a "whole frame". However, when an object to be photographed is small or far away, there are areas in the sides of the frame of film which are unnecessary and some parts of the film will be wasted. Under this situation, the most ideal and economic way is to take pictures with a "half frame" camera.

Moreover, when we are taking pictures, we invariably find that, when the roll of film is nearly used up, there are still several valuable pictures not yet taken but for which there is insufficient film. Under such situations it would be convenient if we could change a "whole frame" camera to a "half frame" camera in order to take the desired pictures.

It has previously been proposed to provide devices for adjusting the exposure area or to adjust photographing but such devices have tended to be complicated and inefficient.

One such device proposed in U.S. Patent Specification No. 2247104 adjusts the exposure area of a film by using a roll and a string to pull a screen to move toward the film horizontally so that the area of exposure can be appropriately shielded. This device is very complicated, cannot ensure the film length which has been wound, and is not easily operated.

Another device has been proposed in U.S.

Patent Specification No. 2295801 which uses a slide to adjust a mask plate to shield the dimensions of the viewfinder and adjust the winding length of the film simultaneously by means of a gear set. Another separate operation makes the opening rotate 90O to change the exposure area.

A further device has been proposed in U.S.

Patent Specification No. 2522387, in which the body of the camera can be moved from two end sides towards the centre to change the width of the camera body such that the exposure area and the viewfinder dimensions are adjusted.

All the devices described above possess a complicated structure and cannot be manufactured easily. Therefore, they cannot provide a device which can change dimensions quickly, be operated easily, not easily be broken with a simple body structure.

The present invention aims to provide a two-size camera which utilizes a slide to move one special device to actuate the view shield device to shield portions of the view area from two sides of the viewfinder such that the effective view width of the viewfinder is reduced to one half of the original size, to move two opaque blades to shield the sides of the exposure window such that the exposure width is reduced to one half of the original size, and, at the same time, to reduce the film length to be wound by the film advance wheel to one half of the normal length.

According to the invention, there is provided a camera which can regulate the exposure area of a frame of film comprising a body; a film advance wheel for turning the film take-up spool around and for returning a shutter striking plate to its original position; a regulating plate; a view shield device arranged to be actuated by the regulating plate and movable between a first position in which it is substantially clear of the viewfinder and a second position in which it is effective to shield the viewfinder to reduce the viewing area to approximately half the total width thereof; means for guiding movement of the regulating plate; at least two opaque movable blades arranged to be driven by the regulating plate to shield an exposure window of the camera from the sides of the window such that the width of the exposure window is reduced to approximately one half of the total width; a clutch device actuable by the regulating plate to control the film advance wheel to rotate through one cycle or one half cycle on each operation of the shutter mechanism of the camera; and an operating member accessible from outside the camera, said operating member being arranged to move the regulating member between two positions and the regulating member being arranged, when being moved from a first to a second position, to move the view shield device to the second position, to move the opaque movable blades to shield half of the width of the exposure window and to move control means for the film advance wheel so that said wheel can rotate through only one half cycle after each shutter operation such that the length of the film advanced is reduced to one half of the normal length advanced; and, when being moved from the second position back to the first position, to move the view shield device to the first position, to move the opaque movable blades to a position in which they no longer obstruct the exposure window and to move said control means for the film advance wheel so that said wheel can rotate through one full cycle after each shutter operation so that the length of film advanced corresponds to a full frame of the exposure window.

According to one embodiment of the invention, the view shield device comprises a viewfinder eyepiece cover whose width is one half of the width of the viewfinder and which is movable with the regulating plate to overlap the viewfinder when the said regulating plate is moved to its second position.

In another embodiment of the invention, the view shield device comprises a pair of indicating pointers which are actuable by the regulating plate and can be moved from the sides of the viewfinder to cover the side areas of the viewfinder when the regulating plate is moved to its second position.

As a further alternative, the view shield device may comprise an indicating device which is actuable by the regulating plate and is pivotally movable to cover the side areas of the viewfinder when the regulating plate is moved to its second position.

The clutch device may comprise at least one inclined plate on the regulating plate which is engageable with means for regulating the elevation of a locating hook and the film advance wheel may be provided with two projections of differing height, the locating hook being effective to block only one of the projections in the first position of the regulating plate to permit one complete revolution of the film advance wheel and to block both of the projections in the second position of the regulating plate to permit only half a revolution of said film advance wheel.

Alternatively, the clutch device may comprise two overlapping clutch plates mounted on a shutter striking plate and the film advance wheel may be provided with two projections of differing height, said clutch plates being movable by the regulating plate so that in one position only one of the projections is blocked by the clutch plates so as to permit one complete revolution of the film advance wheel and in the other position both of the projections are blocked by the clutch plates so as to permit only half a revolution of the said film advance wheel.

Preferably, the projections on the film advance wheel comprise pins of differing height spaced apart by 1800 from each other and located at substantially the same radial distance from the axis of the wheel.

According to another embodiment of the invention, the clutch device comprises an auxiliary drive wheel which is engageable with the film advance wheel and which is coaxially arranged with respect thereto, the regulating plate having an inclined face which is engageable with the auxiliary drive wheel to raise or lower said wheel and the auxiliary drive wheel having a projection which in the lower position of said wheel is engageable with blocking means to restrict rotation of the film advance wheel. The projection on the auxiliary drive wheel may comprise an auxiliary drive rod which extends through a bore in the film advance wheel and the film advance wheel may be provided with a main drive rod spaced from the auxiliary drive rod by 1800, the rods being located at substantially the same radial distance from the axis of said film advance wheel.Alternatively, the projection on the auxiliary drive wheel may comprise a drive cam.

According to a further embodiment of the invention, the clutch device comprises a cam having two cam lobes mounted on the film advance wheel, one cam lobe being engageable with a projection in both positions of the regulating plate and the other cam lobe being engageable with a projection in only the second position of the regulating plate. The regulating plate may be provided with an inclined face which is engageable with a lever and which is effective, when the regulating lever is moved to its second position, to move said lever into a position in which it is engageable with both of said cam lobes.According to yet another embodiment of the invention, the clutch device comprises a brake plate engageable by a drive cam mounted on the film advance wheel, one end of the brake plate being engageable by the drive cam and the other end being engageable in an opening in a press plate, the brake plate being movable, in response to movement of the regulating plate, between a first position in which it permits one complete revolution of the film advance wheel for full frame photography and a second position in which it permits only one half revolution of the film advance wheel for half frame photography.

The invention will now be further described, by way of example, with reference to the drawings, in which: Fig. 1 is a sectional view of one example of a camera according to the invention taken on the line 1-1 in Fig. 2 and showing the changing device for the exposure window width; Fig. 2 is a front view of the camera shown in Fig. 1 showing part in section on the section line 2-2 in Fig. 1; Fig. 3 is a rear view of the camera shown in Figs. 1 and 2 to show the position of the regulating plate; Fig. 4 is a view taken on the line 4-4 in Fig.

3; Fig. 5 is a view taken on the line 5-5 in Fig.

3 to show the length control of wound film; Fig. 6 is a perspective view showing the main components and corresponding positions of the same of the example shown in Figs. 1 to 5; Fig. 7 is an exploded perspective view of components of a camera according to a second example of the invention; Fig. 8 is a plan view of some of the com ponents shown in Fig. 7, the components being shown assembled to illustrate the operating relationship between the regulating plate and the opaque movable blades; Fig. 9 is a front view of some of the components shown in Fig. 7, the components being shown assembled to illustrate the view shielding device for shielding the viewfinder; Fig. 10 is a plan view of the second example shown in Fig. 7; the components being shown assembled to illustrate the operating relationship between the regulating plate and the film advance wheel; Fig. 11 is a section taken on the line 11-11 in Fig. 10; Fig. 12 is a section through a third example to show how the regulating plate controls the film advance wheel; Fig. 13 is a section corresponding to Fig.

12 but showing the components in a different position; Fig. 14 is a further section corresponding to Fig. 13 but showing additional components; Fig. 15 is a section showing a fourth example illustrating how the regulating plate controls the film advance wheel; Fig. 16 is a section taken at right angles to the section shown in Fig. 15; Fig. 17 is a side view of a fifth example to show how the regulating plate controls the film advance wheel; Fig. 18 is a section taken on the line 18-18 in Fig. 17; Fig. 19 is a section taken on the line 19-19 in Fig. 17; and Fig. 20 is a perspective view of a sixth example. In the drawings, like parts are denoted by like reference numerals.

Referring to the drawings, the camera has a chamber for accommodating a film cartridge 101 from which a film 10 can be pulled to pass an exposure window 12 of an exposure chamber 11 and be wound up by a film advance wheel 13. Between the exposure window 12 and the lens 21 of the camera, there are two opaque pivotally movable blades 121 which are acted upon by respective springs 122 and open toward the lens 21. The movable blades 121 are engaged by respective push rods 31 which, when moved towards the back cover 22 of the camera, push the opaque movable blades 121 to cover the two sides of the exposure window 12 (as indicated by the chain-dotted lines in Figs. 1 and 2) so that the exposure width of the frame of the film 10 will be less than one half of the original exposure width.The push rods 31 are mounted on a plate 33 a first portion of which extends perpendiculariy to the axes of the push rods 31 and then is bent to extend at 90" to said first portion and is connected to a rod 32. The rod 32 is located in an elongate slot 41 provided in a regulating plate 40. This regulating plate 40 can be moved towards the left or the right and its rear edge has a positioning projection 42 which is engageable in either one of a pair of matching notches 141 provided in a positioning plate 14, whereby the engagement of the projection 142 in the notches 141 is effective to position the regulating plate 40 at either of two fixed locations.

As shown in Figs. 3, 4 and 6, an operating member 45 is mounted on the regulating plate 40 and extends to the outside of the camera body 20 such that the regulating plate 40 can be controlled by the operating member 45 from outside the camera body to move the regulating plate to the right or left for positioning of the same. A pair of plates each having an inclined face project from the left end of the regulating plate 40 and engage with a reciprocating plate 501. Each end of the reciprocating plate 501 carries a rod 502 which passes through a plate 23 and a respective coil spring 503 is mounted on each of the rods 502 to urge the plate 501 against the plates 44. A locating hook 50 is mounted on one of the rods 502 so that the locating hook 50 can move with the reciprocating plate 501.

The free end 5 4 of the locating hook 50 has an opening that is used for blocking a lower positioning pin 61 or an upper positioning pin 62. These two positioning pins, 61 and 62, spaced apart by 1800 with the same radius are fixed on a film advance wheel 60 and are engageable with a striking plate 70 to move the latter to a position to prepare striking. The striking plate 70 has a pair of elongate slots 701 in which respective guide pins 22 are located to limit the extent of movement of the striking plate 70.

As shown in Fig. 3, the re9ulating plate 40 can be pushed by the operating member 45 to be moved to the right. Under this condition, the whole device is set for whole frame use. The active viewfinder eyepiece cover 46 is moved to uncover the viewfinder 24 so that the viewfinder 24 can be used for whole frame photography. The inclined plates 44 on the regulating plate 40 push the reciprocating plate 501 to cause the locating hook 50 to rise such that the free end 504 of the locating hook 50 can block the upper positioning pin 62 but cannot block the lower positioning pin 61 because the lower positioning pin 61 can pass under the locating hook 50.Furthermore, the elongate slot 41 in the regulating plate 40 does not push the rod 32 at this time so that the push rods 31, which are connected to the rod 32 via the plate 33, will not shut the opaque movable blades 121 so that the exposure window 12 is fully open. The film advance wheel 60 can rotate one cycle on each winding. During the rotation, the striking plate 70 is pushed to the preparing position for shutter striking. The film advance wheel 60 can rotate once as the shutter is struck once and the film advance wheel 60 will wind the film to the length required for whole frame photography.

If it is desired to change the camera to perform half frame photography, the operatir member 45 is moved to the left as shove the drawings to push the regulating plate along the positioning plate 14 until the pe tioning projection 42 engages in the left notch 141 of the positioning plate 14. In this position, the viewfinder eyepiece cover 46 will be located over the viewfinder 24. Since the width of the viewfinder cover 46 is one half of the width of the viewfinder 24, an object viewed through the viewfinder 24 is reduced to one half of the whole frame use.The inclined faces of the plates 44 allow the reciprocating plate 501 to move towards the regulating plate 40, under the action of the springs 503, whereby the free end 504 of the locating hook 50 is moved to a position in which it is effective to block both the upper positioning pin 62 and the lower positioning pin 61. At the same time, the elongate slot 41 pushes the rod 32 to move the plate 33 towards the rear of the camera in a direction which is perpendicualr to the pulling direction of the film 10. The push rods 31 are thus effective to push the associated opaque movable blades 121 towards one another to shield the sides of the exposure window 12 so that the width of the exposure window 12 is reduced to one half of the original width of the whole frame use.Since the locating hook 50 can block both the upper positioning pin 62 and the lower positioning pin 61, the shutter striking plate 70 moves to prepare the shutter strike position as the film take-up spool 13 rotates one half cycle, and cannot continue winding the film 10. Therefore, the length of the film 10 to be wound is only half of the length for whole frame use. As described previously, the width of the partly shielded viewfinder 24 is reduced to one half of the width for whole frame use and the same is true for the exposure window 12. Thus, the camera has become a half frame camera completely and can photograph twice as many pictures as when the camera is used as a whole frame camera.

The present invention therefore provides a camera which can be used for whole frame photographing or half frame photographing functions. Whenever the half frame camera is wanted, using the operating member 45 outside the camera body 20 to push the regulating plate 40 inside the camera body 20, it makes the viewfinder eyepiece cover 46 superpose the viewfinder 24, and also makes the opaque movable blades 121 move to cover the sides of the exposure window 12 located between the lens 21 and the film 10 to shield the exposure window 12 so that the width of the exposure window 12 is reduced to one half. At the same time, the locating hook 50 is moved to a position in which it is effective to block the upper positioning pin 61 such that the film advance wheel 60 only can wind one half length of the whole frame film as the striking plate 70 has been prepared for shutter striking.Thus, the viewfinder 24, the exposure window 12, and the wound film length are reduced to one half of the whole frame camera use at the same time to serve half frame photography.

A second example of a camera according to the invention is illustrated in Figs. 7 to 11 of the drawings in which the upper and lower walls of both sides of an exposure chamber 11 has a pair of bores 110 to accommodate pivot pins of respective opaque pivotally movable blades 121. Moreover, the upper wall of the exposure chamber 11 carries a guide pin 111, a regulating plate 40, and an operating member 45, the latter extending to the outside of the camera body. The plate 40 and operating member 45 are formed integrally and the plate 40 is provided at each side with a horizontal slot 401 and a rod 402. Each rod 42 is connected to a respective eccentric pin 123 provided on the upper portion of an associated plate 121 by a respective tension spring 142.Furthermore, a projection 403 is provided at the right hand side of the regulating plate 40 and an elongate slot 404 is provided at the left hand side of the plate for the reception of the guide pin 111 so that the slot 404 can guide the regulating plate 40 in moving back and forth when the latter is mounted on the exposure chamber 11. A slider 405 is connected behind the left hand side of the regulating plate 40, the portion of the slider that is close to the regulating plate 40 having a contracted neck 406 which is symmetrical with the same slope.

A plate 47 is located over the regulating plate 40, the centre of the plate 47 having an opening 471 whose side has a support plate 473 to support the slide wall at the lower end of the control member 45. The plate 47 further has two raised projections 472 which are engageable in respective slots 701 provided in a striking plate 70. Therefore, when the striking plate 70 is mounted on the plate 47 it can slide horizontally with respect to the plate 47 within the limits imposed by the engagement of the projections 472 in the slots 701. The left side of the far end of the plate 47 has a pair of lugs 474, each lug having a bore 475 for pivotally receiving a respective view shielding stick 48. The lower end 482 of each view shielding stick is pulled towards the other view shielding stick to clasp the neck 406 of the regulating plate 40. The upper end of each view shielding stick has an indicating pointer 481, or other appropriate equivalent indicating device, and as shown in Fig. 9, the pointers are usually located at the sides of the viewfinder 24. Inside the viewfinder 24, there is a wider whole frame area boundary line 241 for photograph viewing and a half frame area boundary line 242, inside the whole frame boundary line, whose width is one half ofthe whole frame area.If the regulating plate 40 is moved towards the rear of the camera, the lower ends 482 of the view shielding sticks will clasp the wide portion of two sides of the slider 405 such that the two indicating pointers 481 will be pivoted towards each other and enter the position between the half frame boundary line 242 and the whole frame boundary line 241 to let the user understand that the camera is set for half frame photography and that only the view inside the half frame boundary line 242 can be photographed. The right side of the striking plate 70 has two guide rods 702 and a spring rod 703, and a clutch plate 71 provided with two parallel elongate slots 711 is located over the plate 70 with the guide rods 702 extending through the slots 711 in the clutch plate 71.

A spring 704 is mounted on the spring rod 703 and on a similar rod mounted on the clutch plate 71 to urge the clutch plate to the position shown in Fig. 7 of the drawings in which an inclined side edge of the clutch plate 71 is held against the spring rod 703. The clutch plate 71 is engageable by the projection 403 on the regulating plate 40 and can be moved by said projection relative to the striking plate 70 against the action of the spring 704. The lower edge of the film advance wheel 60 has a long rod 64 and a short rod 63 spaced apart by 1800 at the same radial distance from the axis of the wheel 60 although the rods can be substituted by cams or other equivalent components which must possess the effective motion with specific cyclic property.When the clutch plate 71, as shown in Fig. 11, is pushed by the projection 403 on the regulating plate 40 and is moved in the direction towards the position for half frame photography, the long rod 64 and the short rod 63 of the film advance wheel 60 can push the striking plate 70 to shift, and the positioning arm 50 moves to the blocking position after the striking plate 70 moves away. After taking a picture, the striking plate 70 comes back to the original position and the positioning arm 50 is therefore pushed away so that the film advance wheel 60 can rotate. Thus, the film advance wheel 60 can only rotate by one half cycle after each photograph.However, if the regulating plate 40 is moved by the operating member 45 back to the original position, only the long rod 64 can push the striking plate 70 to move, therefore, the film advance wheel 60 can rotate by one cycle after each photograph.

According to the above description, as the regulating plate 40 is moved towards the rear of the camera on the axial line parallel to the lens 21, the pointers 481 of the view shield ing sticks, designed for view shielding, can shield the sides of the viewfinder 24 and the opaque movable blades 21 also shield the sides of the exposure window 12 so that the exposure window 12 has only a half width.

At the same time, the clutch plate 71 is moved to the position at which the short rod 63 can push, and the positioning arm 50 can swing toward the left to enter the position for blocking the long rod 64 and the short rod 63 only after the striking plate 70 has shifted to the left. Therefore, the film advance wheel 60 can rotate only one half cycle after each photograph so that each film length to be wound is one half of the film length to be wound for whole frame photography.

A third example of a camera according to the invention which employs a regulating plate 40 to control the film advance wheel 60 is shown in Figs. 12 and 13 of the drawings.

In this example, there is a flange 601 above the film advance wheel 60, and a main drive rod 602 is installed below the flange 601. A bore 603 is provided in the flange 601 at the opposite side spaced from the rod 602 by 1800. The upper end of the film advance wheel 60 passes through an elongate slot 441 which is located between the inclined plates 44 on the regulating plate 40. An auxiliary drive wheel 65 is mounted on the film advance wheel 60 and carries an auxiliary drive rod 651 which engages in the bore 603 of the film advance wheel 60 and which extends from the flange 601 by substantially the same distance as the main drive rod 602. The upper portion of the auxiliary drive wheel 65 is acted on by a coil spring 66.When the regulating plate 40 is moved to the right as viewed in Figs. 12 and 13, the auxiliary drive wheel 65 is raised by the inclined faces of the plates 44 so that only the main drive rod 602 can push the striking plate 70 to move to the left at this moment (there is no clutch plate 71 overlapped on the striking plate 70 in this example) the positioning arm 50 driven by the striking plate 70 only can block the main drive rod 602 each time so that the film advance wheel 60 can rotate one cycle for each photograph. However, if the regulating plate 40 is moved to the left, the auxiliary drive rod 651 descends with the auxiliary drive wheel 65 to the position where it can push the striking plate 70, and the positioning arm 50 can block both the main drive rod 62 and the auxiliary drive rod 651.Therefore, the film advance wheel 60 only can rotate through one half cycle after each photograph. In this case, the regulating plate 40, similar to the first example of this invention, has one elongate slot 41. When the plate 40 shifts horizontally, it can drive the regulating plate 80 (identical with the regulating plate 40 of the second example) back and forth by the aid of the rod 32 to control the opaque movable blade 121 to swing to the shield exposure window. In this case, the indicating device of the viewfinder 24 can apply either the shielding method of the first example or the pointer method of the second example.

In the fourth example of a camera according to the invention shown in Figs. 15 and 16, the regulating plate 40 is similar to the second example, and the film advance wheel 60 and the auxiliary drive wheel 65 are similar to the third example, but the spring 66 is installed between the auxiliary drive wheel 65 and film advance wheel 60. The upper portion of the auxiliary drive wheel 65 contacts a pivoting lever 67, and a sloping face 671 is below the left side of the lever 67. The lever 67 has a bore substantially at its centre for the reception of a pivot pin 673 and the other end of the lever has a rod 672.A push lever 407 projecting from the regulating plate 40 moves with the regulating plate to the near end to push the rod 672 and to make the lever 67 pivot so that the sloping face 671 acts on the auxiliary drive wheel 65 to depress the latter, against the action of the spring 66, so that the auxiliary drive rod 651 is moved to the position in which it can push the striking plate 70. The film advance wheel 60 can then only rotate one half cycle for each photograph to achieve the purpose that the film length to be wound is one half of the original length. The working procedure is similar to the third example.

A fifth example of a camera according to the invention is shown in Figs. 17 to 19 of the drawings. The regulating plate 40 of this example is similar to the second example but the side below the operating member 45 is connected to a plate 451 which has a sloping face and two different elevated faces. The right side of the striking plate 70 has a pair of lugs 705 on which a lever 706 is pivotally mounted, the lever 706 being urged upwardly to contact the plate 451. A cam 68 is mounted above the film advance wheel 60, the cam 68 having two cam lobes and one of them having an opening 681. The characteristics of the cam 68 are demonstrated clearly in Figs. 18 and 19.

When the operating member is moved to the near end, the plate 451 compresses the lever 706 down to the line 19-19 of Fig. 17 such that both lobes of the cam 68 can push the lever 706 to make the striking plate 70 move to the left and to make the positioning arm 50 enter the blocking position to hold against the rod 682 below the cam 68.

Therefore, the film advance wheel 60 can rotate only one half cycle for each photograph.

However, if the operating member 45 is moved to the far end, the lever 70 is moved upwardly due to the spring force to the elevation of the opening 681 in the cam 68 so that it can block only the cam lobe which does not have an opening. Therefore, the film advance wheel 60 rotates one complete cycle for each photograph.

All the examples described above use the film advance wheel 60 to push the striking plate 70 to the preparing position for shutter striking. However, in the sixth example shown in Fig. 20 of the drawings, the drive structure installed at the film advance wheel 60 is either a rod or a cam that causes pulling of the striking plate 70 instead of pushing. As shown in Fig. 20, there is a main drive cam 604 on the film advance wheel 60, whose function is equivalent to the main drive rod of the previous example. An auxiliary drive cam 691 is connected with an elevating ring 692, which can lift or descend freely on the film advance wheel 60 when the auxiliary drive cam 691 is pushed by the sloping face of the regulating plate 40.

A brake plate 81, having a raised portion 811 at one end, is located within the radius of the action range of the drive cam 604. An elongate slot 812 is provided at the centre of the brake plate by means of which the brake plate is pivotally mounted on a pin 82 such that the brake plate 81 can rotate and can swing back and forth within a fixed travel length. The other end of the brake plate 81 is bifurcated into a blocking foot 813 and a support foot 814, the support foot 814 being subjected to the force of a spring 83 and bearing against the base of an opening 852 in a press plate 85. The press plate 85 is so arranged that, when it is pressed, its lower end can push the shutter shield plate to act so that the film is exposed.One side face of the press plate 85 has a bulging portion 851 which is arranged to push the brake plate 81 to make it shift forward slightly so that the raised portion 811 can no longer block the cams 604 and 691 and the film advance wheel can rotate counterclockwisse due to external force. At this moment, the brake plate 81 is pulled by the spring 83 to draw back and to swing slightly toward the right to let the blocking foot 813 enter the opening 852 of the press plate 85. The press plate 85 cannot then be pressed further until one of the cams 604 and 691 can touch the edge of the brake plate 81 and pull it forward to make the blocking foot 813 move away from the opening 852 of the press plate 85. Since the cams 604 and 691 are spaced apart from each other by 1800, photographing can proceed as the film advance wheel is controlled by the regulating plate 40 to rotate one complete cycle or one half cycle.

In all the examples described above, when the striking plate 70 is pushed each time to the preparing position for shutter striking, whether the film advance wheel rotates through a full cycle or a half cycle, and the clutch device for the interaction between the striking plate 70 and the film advance wheel, whatever it applies, rod, cam, or other equivalent devices, always possesses an equivalent function motion with a specific cyclic property, they are regarded to be the characteristics of this invention.

Based on all the examples, it can be understood that the regulating plate 40 of this invention actuates the view shield device, shields the portion of the view area from the sides of the viewfinder, drives the opaque movable blades to swing to shield the exposure window from the sides, and actuates a clutch device to control the rotation range of the film advance wheel such that those devices compose this invention for providing a camera which has two operations for whole frame and half frame photographing and the options can be quickly switched.

Claims (14)

1. A camera which can regulate the exposure area of a frame of film comprising a body; a film advance wheel for turning the film take-up spool around and for returning a shutter striking plate to its original position; a regulating plate; a view shield device arranged to be actuated by the regulating plate and movable between a first position in which it is substantially clear of the viewfinder and a second position in which it is effective to shield the viewfinder to reduce the viewing area to approximately half the total width thereof; means for guiding movement of the regulating plate; at least two opaque movable blades arranged to be driven by the regulating plate to shield an exposure window of the camera from the sides of the window such that the width of the exposure window is reduced to approximately one half of the total width; a clutch device actuable by the regulating plate to control the film advance wheel to rotate through one cycle or one half cycle on each operation of the shutter mechanism of the camera; and an operating member accessible from outside the camera, said operating member being arranged to move the regulating member between two positions and the regulating member being arranged, when being moved from a first to a second position, to move the view shield device to the second position, to move the opaque movable blades to shield half of the width of the exposure window and to move control means for the film advance wheel so that said wheel can rotate through only one half cycle after each shutter operation such that the length of the film advanced is reduced to one half of the normal length advanced; and, when being moved from the second position back to the first position, to move the view shield device to the first position, to move the opaque movable blades to a position in which they no longer obstruct the exposure window and to move said control means for the film advance wheel so that said wheel can rotate through one full cycle after each shutter operation so that the length of film advanced corresponds to a full frame of the exposure window.

2. A camera according to claim 1, wherein said view shield device comprises a viewfinder eyepiece cover whose width is one half of the width of the viewfinder and which is movable with the regulating plate to overlap the viewfinder when the said regulating plate is moved to its second position.

3. A camera according to claim 1, wherein said view shield device comprises a pair of indicating pointers which are actuable by the regulating plate and can be moved from the sides of the viewfinder to cover the side areas of the viewfinder when the regulating plate is moved to its second position.

4. A camera according to claim 1, wherein said view shield device comprises an indicating device which is actuable by the regulating plate and is pivotally movable to cover the side areas of the viewfinder when the regulating plate is moved to its second position.

5. A camera according to any preceding claim, wherein said clutch device comprises at least one inclined plate on the regulating plate which is engageable with means for regulating the elevation of a locating hook and wherein the film advance wheel is provided with two projections of differing height, the locating hook being effective to block only one of the projections in the first position of the regulating plate to permit one complete revolution of the film advance wheel and to block both of the projections in the second position of the regulating plate to permit only half a revolution of said film advance wheel.

6. A camera according to any one of claims 1 to 4, wherein said clutch device comprises two overlapping clutch plates mounted on a shutter striking plate and wherein the film advance wheel is provided with two projections of differing height, said clutch plates being movable by the regulating plate so that in one position only one of the projections is blocked by the clutch plates so as to permit one complete revolution of the film advance wheel and in the other position both of the projections are blocked by the clutch plates so as to permit only half a revolution of the said film advance wheel.

7. A camera according to claim 5 or claim 6, wherein the projections on the film advance wheel comprise pins of differing height spaced apart by 180 from each other and located at substantially the same radial distance from the axis of the wheel.

8. A camera according to any one of claims 1 to 4, wherein said clutch device comprises an auxiliary drive wheel which is engageable with the film advance wheel and which is coaxially arranged with respect thereto, the regulating plate having an inclined face which is engageable with the auxiliary drive wheel to raise or lower said wheel and the auxiliary drive wheel having a projection which in the lower position of said wheel is engageable with blocking means to restrict rotation of the film advance wheel.

9. A camera according to claim 8, wherein the projection on the auxiliary drive wheel comprises an auxiliary drive rod which extends through a bore in the film advance wheel and wherein the film advance wheel is provided with a main drive rod spaced from the auxiliary drive rod by 1800, the rods being located at substantially the same radial distance from the axis of said film advance wheel.

10. A camera according to claim 8, wherein the projection on the auxiliary drive wheel comprises a drive cam.

11. A camera according to any one of clai ms 1 to 4, wherein said clutch device comprises a cam having two cam lobes mounted on the film advance wheel, one cam lobe being engageable with a projection in both positions of the regulating plate and the other cam lobe being engageable with a projection in only the second position of the regulating plate.

12. A camera according to claim 11, wherein the regulating plate is provided with an inclined face which is engageable with a lever and which is effective, when the regulating plate is moved to its second position, to move said lever into a position in which it is engageable with both of said cam lobes.

13. A camera according to any one of claims 1 to 4, wherein said clutch device comprises a brake plate engageable by a drive cam mounted on the film advance wheel, one end of the brake plate being engageable by the drive cam and the other end being engageable in an opening in a press plate, the brake plate being movable, in response to movement of the regulating Plate, between a first position in which it permits one complete revolution of the film advance wheel for full frame photography and a second position in which it permits only one half revolution of the film advance wheel for half frame photography.

14. A camera substantially as described herein with reference to the drawings.