GB2074741A - Motorised camera - Google Patents

Abstract

A motorised camera (after shutter release) operates the film take- up spool and charges the shutter whether or not a film is present. As shown, on actuation of a shutter release 28, lever 27 is rotated against a spring bins closing a switch 38 to actuate a film wind motor 31 (operating take-up spool 10), and freeing a disc 24 having a cut-out 24a. During film advance, rotation of a film sprocket 34 is transmitted through a one-way clutch 14a to disc 24 which, during rotation, rotates lever 26 against a spring bias to effect shutter charging. On one complete rotation of disc 24, lever 27 returns to its original position, stopping motor 31. In the absence of film, the forward film drive is transmitted from spool gear 9 through a one way clutch 14b to disc 24 for operation as before. In depressing a button 37, motor 31 is connected to rewind fork 35 instead of spool 10. <IMAGE>

Description

SPECIFICATION A camera film transportation device This invention relates to a film transportation device for a camera, in which the film is transported by driving a film take-up spool.

In general, film transportation in a small format still camera is carried out by driving a sprocket engaged in perforations in the film; such a mechanism is known as sprocket drive.

In a sprocket drive camera, the sprocket shaft is driven to turn through a certain angle to advance the film one frame at the same time as the shutter is charged. Therefore, in such a camera, regardless of whether or not a film is loaded, the operation of the wind-up lever or the like also drives the shutter charging mechanism. For this reason, even when there is no film in the camera, the camera shutter can be released, so enabling the operator to check the functions of the camera with considerable ease, as the camera structure is suited for this purpose.

However, a sprocket drive mechanism requires upper and lower sprockets for engaging the aligned rows of perforations in the film to assure smooth movement of the film, the two sprockets being connected to each other by a spocket shaft. The bulk and size of the sprocket assembly as a whole is, therefore, very large. Moreover, as the sprocket arrangement has to be dictated by the film to be employed, the degree of freedom of the design is very limited. Further, the winding-up force is applied by the sprockets directly on the perforations, so that even a slight catch of the film often results in breakage of the perforations and in tearing of the film.

To overcome this drawback, it is known to provide a camera having a spool drive, in which the film is transported by driving the Laft of the take-up spool. Since the winding force is applied by the spool across the entire width of the film strip, the perforations are protected from damage and the possibility of tearing of the film can be much reduced.

However, in a spool drive camera, as the film is taken up on the spool the effective diameter thereof is increased, and the amount of film taken up by the spool on one turn thereof gradually increases. Because of this, to ensure a constant length of the film is taken on each cycle of operation, the spool must be stopped at a different position each time.

Since this is very difficult to achieve, use is made of a sprocket gear arranged to engage one of the rows of perforations, and rotation of the sprocket through a certain angle is used to control advancement of the film through one frame, the operation of the film footage counter, and the shutter charging mechanism.

With such spool drive cameras, therefore, when no film has been loaded, the shutter cannot be charged by operating the wind-up lever, and the operator cannot check whether or not the camera is functioning properly until a film is loaded.

Since the sprocket used in a spool drive camera does not necessarily have to engage both the upper and lower perforations but may engage only one row, the sprocket may be positioned at a desired location, for example in the vicinity of one of the longitudinal margins of the exposure aperture, thus contributing to the compactness of the camera.

Another advantage is that when a motor drive unit is associated therewith, as the driving torque acts across the entire area of the film, there is no possibility of the occurrence of perforation breaking. Accordingly, recently developed automated cameras tend to employ this drive mechanism.

Despite this, since the checking of the camera functions without a film loaded is inconvenient, a measure making this possible must be provided. The conventional arrangement is for there to be a changeover mechanism of complicated structure operating in such a manner that when the film is present, the shutter is charged by the sprocket being moved as the film is transported, but when the film is absent, the changeover mechanism is switched to transmit the driving torque to the sprocket by which the shutter is charged.

However, the use of a complicated changeover mechanism increases the production cost, and at the same time necessitates the provision of a device for actuating the mechanism in response to detecting whether or not the film is present. The means for detecting the presence of the film is rather easy if it may take the form of detecting the presence of a film container. But, since the shape of film containers differ to some extent, depending upon the kind of film or the like, this must be taken into account when designing the detecting device.

An object of the present invention is, therefore, to eliminate the above-described drawbacks of the known mechanisms, so as to provide a wind-up mechanism for a camera which allows charging of the shutter whether or not a film is present.

Accordingly, this invention provides a film winding device for a camera, which device comprises a take-up spool having means for driving the spool in a film winding direction, a sprocket arranged to be rotated by a film on winding thereof on to the spool, and single frame advancement control means arranged to be driven by either the sprocket or the spool driving means, there being a first one-way clutch for transmitting motion of the sprocket to the control means when the film is advanced in the winding direction and a second one-way clutch for transmitting motion of the driving means when operated in the winding direction, whereby when a film is loaded in the camera, the single-frame advancement control means is operated through the first one-way clutch, but when no film is loaded, the control means is operated through the second one-way clutch.

In order to ensure the sprocket drives the control means when a film is loaded, it is preferred for there to be a speed reduction gear between the spool driving means and the second one-way clutch, so that on winding a film the sprocket runs sufficiently fast to permit motion to be transmitted to the singleframe advancement control means through the first one-way clutch.

Preferably the film winding device is provided with film rewinding means and changeover means to allow the motion of the driving means to be transmitted selectively to the take-up spool or to the rewinding means.

The device of this invention particularly lends itself to use in an automated camera, including an electric motor for driving the spool and also the rewinding means.

This invention extends to a camera whenever fitted with a film winding device of this invention as described above.

By way of example only, one specific embodiment of this invention will now be described in detail, reference being made to the accompanying drawings, in which: Figure 1 is a perspective view of a film transportation mechanism for a camera, according to the present invention; Figure 2 is a plan view showing the details of the one-way clutch used in the embodiment of Fig. 1; and Figure 3 is a perspective view of another example of one-way clutch, suitable for use in the embodiment of Fig. 1.

Fig. 1 shows a camera film transportation mechanism of this invention, in the wound-up position. A pinion 1 is fixed on an output shaft 32 of an electric motor 31 to be described more fully later; gears 2 to 6 comprise a speed reduction train meshing with the pinion 1; and a wind-up gear 7 is provided on the same shaft as carries the gear 6. A rewind gear 8 also is provided on the same shaft as the gears 6 and 7. A gear 9 is formed in unison with a take-up spool 10, the spool having a holiow core in which the motor 31 is positioned. In the illustrated position where a film 33 is being or has just been wound-up, the gear 8 is separated from a gear 1 8 constituting part of a rewind gear train, while the gear 7 is meshing with the gear 9.

A gear 1 2 is coupled through gears 11 a and 11 b with the gear 9, to drive a gear 13, gears 13, 14 and 1 5 together constituting two'one-way clutches. The first one-way clutch is arranged between the gears 1 3 and 14 and comprises a clutch member 14b, balls 36 and springs 37, and the second one-way clutch is arranged between the gears 14 and 1 5 and likewise comprises a clutch member 14a, balls 36 and springs 37. The gear 13 meshes with the gear 12, and the gear 1 5 meshes with a gear 1 6 secured to the same shaft as a film sprocket 34, the film being shown at 33.A gear 1 7 meshes with the gear 14 and is coupled co-axially with a single frame advancement control disc 24 and a charge control cam 25. The shutter charge control cam 25 co-operates with a lever 26 when charging the shutter (not shown), the lever 26 being urged to abut on the camming surface of the cam 25. A winding stop lever 27 has a pawl 27a arranged to enter a cut-out 24a in the periphery of the disc 24, an actuator 28 being provided for the lever 27 which is urged by a spring 29 in the direction of arrow A. When the shutter is closed, the actuator 28 moves in the direction indicated by the arrow until the actuator strikes the tail 27b of the lever 27 to lift the pawl 27a out of the cut-out 24a.

A rewinding fork 35 for a film cassette is connected to a gear 23, for driving by the gear train 18-22. A switch 38 is arranged to control the current supply to the motor 31, so that when the switch is closed the motor 31 is energised but when open, current is not supplied to the motor 31.

Fig. 2 shows in more detail the one-way clutches of Fig. 1. Gear 1 3 has an annular rim within which is fitted the clutch member 14b. In each recess of the clutch member, there is a ball 36 urged by a spring 37 to a position where the ball tends to become wedged between the clutch member and annular rim. When the gear 1 3 rotates in the direction indicated by the arrow, the wedging action of the balls 36 between the inner circumferential surface b of the annular rim of the gear 1 3 and the surface a of the clutch member recess serves to cause the gear 1 3 and the member 14b to rotate in unison.

Conversely, when the gear 1 3 rotates in the reverse direction to that indicated by the arrow, the balls 36 are caused to move toward positions where the balls are free in the respective recesses, against the force of the springs 37. Thus, there is no wedging action between the surfaces a and b so that though the gear 1 3 rotates, the clutch member 1 4b does not rotate. Therefore, the illustrated mechanism functions as a one-way clutch.

The gear 1 5 has an annular rim defining an inner circumferential surface co-operative with recesses in the clutch member 14a in which balls and springs are positioned, in a similar manner to those of Fig. 2. This second oneway clutch thus operates in a similar manner.

The operation of the mechanism described above is as follows.

(1) The case where a film has been loaded in the camera.

When the camera is released by operating a shutter button (not shown), the actuator 28 is moved in the direction of the arrow as the shutter is closed, causing the lever 27 to turn in the opposite sense to arrow A until the pawl 27a is disengaged from the cut-out 24a in the case 24. At the same time, the switch 38 is closed by an arm of the lever 27, to supply the motor 31 with current from a drive circuit (not shown). As the motor shaft 32 rotates, the motion of the pinion 1 is transmitted through the gear train 2 to 6 to the gear 7 and by means of gear 9 the spool 10 also is rotated. In this way, the film 33 is wound up on the spool 10.

As the film 33 is advanced, the sprocket 34 in engagement with the perforations in the film is driven to rotate in the direction indicated by the arrow. Motion of the sprocket 34 is transmitted through the sprocket gear 16 to the gear 1 5. The direction of rotation of the gear 1 5 causes the second one-way clutch to become engaged, thereby driving the clutch gear 1 4 which in turn rotates the gear 1 7 in the direction indicated by the arrow, along with the disc 24 and cam 25. Such rotative movement of the cam 25 causes the control lever 26 to turn against the force of the spring 30, thus charging the shutter mechanism (not shown).It is to be noted here that as soon as the cut-out 24a has moved away from the pawl 27a, the actuator 28 is retracted by means (not shown), but the pawl 27a remains riding on the periphery of the disc 24 so that the power supply control switch 38 also remains closed.

Then, when the disc 24 has completed one revolution, the cut-out 24 becomes aligned with the pawl 27a again, allowing the lever 27 to turn in the direction A under the action of spring 29, thus stopping the above-described gear system from further rotation, and permitting the switch 38 to open, so as to deenergise the motor 31. Since the velocity ratio of the above-described disc 24 and the sprocket 34 is arranged to be 1:1, the foregoing action results in the sprocket 34 turning through one revolution, thus advancing the volume through the length of one frame.

It is to be noted in this connection that motion of the motor 31 is also transmitted through the spool gear 9 and the gear train 11 and 1 2 to the gear 1 3 and first one-way clutch. However, since the gear 1 3 runs slower than the gear 1 5 rotated by the sprocket 34, motion of the gear 1 3 is not transmitted by the clutch member 1 4b to the gear 14, and this thus has no effect on the disc 24. As a result, rotation of the disc 24 is performed only by the movement of the film 33. Therefore, the advancement of the film through the length of one frame completes one revolution of the sprocket 34 and also one cycle of the winding operation.

(2) The case where the camera lacks the film.

When the shutter release has been actuated and the shutter is closed, the lever 27 is turned by actuator 28 to lift the pawl 27a out of the cut-out 24a and to energise the motor 31, as in the former case (1). Though motion of the motor 31 is transmitted through the gear train 2 to 6 and the wind-up gear 7 to the spool gear 9, rotating the spool 10, because of the absence of a film, the sprocket 34 remains stationary and the gears 1 6 and 1 5 are therefore not rotated. Motion of the spool gear 9 is transmitted through the gears 11 and 12 to the gear 13. As the gear 13 rotates in the direction indicated by the arrows, this motion is transmitted through the first one-way clutch to the gear 14.Since, as has been mentiond above, the sprocket 34 and gear 1 5 are stationary, motion of the clutch gear 14 is not transmitted to the gear 15, but does cause gear 1 7 to rotate the disc 24 and cam 25 as in the case (1). One revolution of the disc charges the shutter, and turns off the switch 38, thus completing one cycle of the shutter charging operation.

(3) The case where the film is to be rewound.

When a rewind button 37 is pushed upward in the direction indicated by an arrow (Fig. 1), the gears 6, 7 and 8 on the shaft 37 are moved so that gear 7 comes out of mesh with the spool gear 9, but instead the gear 8 is brought into meshing engagement with the gear 1 8 with which the rewind gear train begins. The other gear 6 is maintained meshed with the pinion of gear 5, which is axially elongate. In response to the movement of the shaft 37, the lever 27 is caused to turn in the reverse direction to that indicated by arrow A through an intermediary (not shown), so as to close the switch 38. Then, motion of the motor shaft 32 is transmitted through the gear train 1 to 6 to the gear 8 and therefrom through the rewind gear train 18 to 23 to rotate the co-axial fork 35 of the gear 23.The fork 35 is drivingly coupled to a supply spool (not shown) for film, so that the film is rewound thereon. The backward movement of the film 33 rotates the sprocket 34 in the reverse direction to that when the film 33 is advanced, but the direction of rotation of the gear 1 5 as driven by the sprocket 34 is permitted by free-wheeling of the second oneway clutch, without transmitting movement to the gear 1 4. Therefore, the shutter charging mechanism including the disc 24 is not affected by this motion.As the clutch gear 14 is at a standstill, so also is the gear train 1 3 to 11 and therefore the reversed driving force is not applied to the spool 1 0. It is to be noted that when no film is loaded, switching to the rewind mode by upward movement of the rewind button 37 is followed by a similar procedure to that described above, with the result that motion of the motor shaft 32 is transmitted only to the fork 35.

Fig. 3 shows another example of one-way clutch construction, usable in the mechanism of Fig. 1. A shaft 50 fixedly carries a gear 14' and also a pair of gears 15' and 13', there being respective one-way clutches 15'b and 13'a between the gears 15' and 13' and the shaft 50. The action of these clutches is similar to that of the clutches shown in Fig. 2.

As has been described in detail, the embodiment of mechanism according to the present invention uses one-way clutches to make it possible for a spool drive to be established when a film is loaded in the camera (as in the prior art), but even when the film is absent, a camera release followed by shutter charging can be obtained without the need to recourse to opening and closing the back cover of the camera. Such action is however necessary in the conventional spool drive type of camera.

Thus, a camera incorporating a device of this invention can be handled in a similar fashion to that in which a conventional sprocket drive mechanism is provided. Another advantage of the invention is that when the film is to be rewound, the operator does not have to pay particular attention to a special device which disengages a sprocket from the shutter charging mechanism, and therefore the film transporting mechanism can be constructed in a simple manner. This gives the additional advantage that the compactness of the camera (which is characteristic of spool drive cameras) can be further improved.

Claims (9)

1. A film winding device for a camera, which device comprises a take-up spool having means for driving the spool in a film winding direction, a sprocket arranged to be rotated by a film on winding thereof on to the spool, and single frame advancement control means arranged to be driven by either the sprocket or the spool driving means, there being a first one way clutch for transmitting motion of the sprocket to the control means when the film is advanced in the winding direction and a second one-way clutch for transmitting motion of the driving means when operated in the winding direction, whereby when a film is loaded in the camera, the single-frame advancement control means is operated through the first one-way clutch, but when no film is loaded, the control means is operated through the second one-way clutch.

2. A film winding device according to claim 1, wherein there is provided a speed reduction gear between the spool driving means and the second one-way clutch, so that on winding a film the sprocket runs sufficiently fast to permit motion to be transmitted to the single-frame advancement control means through the first one-way clutch.

3. A film winding device according to claim 2, wherein the take-up spool has a spool gear and the motion of the driving means is transmitted from the spool gear through the speed reduction gear to the second one-way clutch.

4. A film winding device according to any of the preceding claims, wherein the first and second one-way clutches are arranged in a coaxial relation to each other.

5. A film winding device according to any of the preceding claims, wherein there is provided film rewinding means and changeover means to allow the motion of the driving means to be transmitted selectively to the take-up spool or to the rewinding means.

6. A film winding device according to any of the preceding claims, wherein the driving means for the take-up spool is provided with an electric motor.

7. A film winding device according to any of the preceding claims, wherein at least one of the one-way clutches includes a clutch member fitted co-axially within a driving ring, the clutch member defining in conjunction with the ring at least one recess of tapering width in which is positioned a ball springurged to a position where the ball may provide a wedging action between the ring and the clutch member.

8. A film winding device for a camera, comprising a take-up spool having means for driving the spool in a film-winding direction, a sprocket arranged to be rotated by a film on winding thereof by the spool, and singleframe advancement control means arranged to be driven by transmission means for transmitting either the driving force of the sprocket or the winding force of the driving means, the transmission means having detecting means for detecting whether or not the sprocket is driven in the film winding direction, so that when rotation of the sprocket is detected by the detecting means, the rotation of the sprocket is transmitted to the single-frame advancement control means, but when the detecting means detects the sprocket is stationary despite operation of the driving means, the motion of the driving means is transmitted to the single-frame advancement control means.

9. A film winding device for a camera, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

1 0. A camera whenever fitted with a film winding device according to any of the preceding claims.