IE48131B1 - A camera adapted for automatic and manual focusing - Google Patents

Abstract

A camera has an adjustable focus lens (12) and a mode selector switch (SA/M) for selecting manual or automatic focusing. A lens-position switch (Sp) is closed when the lens is in its normal focusing range and is open when the lens is moved to an at- rest position outside the normal focusing range, the at-rest position constituting the lens starting position for an automatic focusing operation. Closure of the mode selector switch and a further switch (S1F) initiates a sequence including acoustic automatic focusing and exposure, followed by automatic return of the lens to the at-rest position. When the mode-selector switch is opened and the camera is manually focused, closure of another switch (S1T) initiates an exposure; thereafter closure of the mode-selector switch will automatically return the lens to the at-rest position and open the lens switch (Sp) connected in series with the mode-selector switch.

Description

The present invention relates to a camera having an adjustable focus lens and including automatic focusing means.

A camera having a focus control system coupled to its lens for automatically focusing a remote object at the film plane of the camera in response to a range-finderderived signal representative of the distance between camera and object, is known, A camera having a focus control system that utilizes acoustical energy to determine the distance to an object is described in U.S. Patent No. 3,522,764.

A focus control system that can move the lens in either of two directions from any initial position within the normal focusing range of the lens, for focusing purposes, is also known. One example of such a system is described in the above-mentioned U.S. Patent.

Another kind of focus control system always focuses the lens in response to a rangefinder signal by moving it away from the same known reference. Focusing in response to the rangefinder signal is never performed during movement of the lens towards the reference point. A system of this kind is significantly less complex than a bidirectional focus control system because it is unnecessary continuously to monitor the movement of the lens moving towards the reference point.

In Patent No. 2563/78 a focus control system having manual and bidirectional automatic focussing modes 4813 - 3 is disclosed for use in a self-processing adjustable focus lens camera. In that system, the focus control mode is selected by switching means actuated by movement of the lens to a position lying outside of its range of movement in which subjects could be focussed. The manual focus control mode is selected by manually moving the lens to any position within its normal focusing range. The automatic focus control mode is selected by actuating the switch means by either manually moving the adjustable focus lens to the switch position or, in another embodiment thereof, by taking a picture when the lens is within its normal focusing range which will cause the automatic focus control system to position the lens to the said predetermined position after a picture has been taken and fully processed. With such a camera, the operator may fail to take note of the lens position and incorrectly assume that the camera is in its automatic focus control mode at the beginning of a picture taking sequence which may result in the taking of at least one out-of-focus picture.

A camera according to the present invention comprises an adjustable focus lens mounted for displacement over a given range of positions to focus at a given image plane subjects within a given range of distances and for displacement outside the said range of lens positions to an attest position; a lens-position switch which is in a first state when the lens is at the at-rest position and is in a second state when the lens is within the said given range of positions; distance measuring means for deriving a signal representing the subject distance and means for automatically displacing the lens in response to the said signal from the at-rest position to a position within the - 4 said range at which it focusses the subject at the image plane; a manually operable focus-mode selector actuable between a manual focusing mode and an automatic focusing mode; second manually operable means having first and second conditions; and control means responsive to the operation of the second manually operable means from its first to its second condition when the selector is in its automatic focusing mode to energise the distance-measuring means and to initiate automatic displacement of the lens from the at-rest position to the focused position and exposure of a light-sensitive medium to the focussed image and responsive to completion of exposure, return of the second manually operable means to its first condition and to the lens-position switch being in its second state to effect automatic return of the lens to its at-rest position, and responsive to the operation of the second manually operable means from its first condition to its second condition to initiate an exposure operation without automatic focusing when the selector is in its manual focusing mode and there20 after operative in response to the completion of exposure, the return of the second manually operable means to its first condition, the lens position switch being in its second state, and the restoration of the mode selector to its automatic focusing mode, to effect the automatic return of the lens to its at-rest position.

The provision of a focus-mode selector that does not rely on lens position removes the possibility that the operator will incorrectly assume that the camera is in an automatic focus control mode at the beginning of a picture sequence; once the mode selector has been placed in its automatic focusing mode, the lens automatically returns to its at-rest position. - 48131 - 5 In the preferred camera embodying the invention, the second manually operable means comprises two switches, one for initiating exposure following manual focusing and the other for initiating a sequence involving automatic focusing followed by exposure, the latter switch being effective only when the mode-selector is in its automatic focusing mode. Advantageously, the switch for initiating the sequence including automatic focusing and the lensposition switch are connected in parallel with each other and in series with a switch constituting the mode selector, in the supply lead from the battery. The mode selector switch is closed for automatic focusing and is open for manual focusing and the two switches constituting the second manually operable means are biased to an open position.

Such an arrangement minimises the possibility of a drain on the camera battery when the camera is not in use. In the camera disclosed in our above-mentioned application, leakage currents could be drawn by the automatic focus control system when the manual focus control system had been selected and although these currents were relatively small they could be enough to exhaust the camera battery if the camera were left in its manual focus control mode for an extended period.

In order that the invention may be better understood, an example of apparatus embodying the invention will now be described with reference to the accompanying drawings, in which sFig. 1 is a schematic diagram of an automatic and manual focus control system in accordance with a preferred embodiment of the invention; - 6 Fig. 2 is a logic diagram of the operation of the manual and automatic focus control system depicted in Fig. 1.

Fig. 1 shows a schematic diagram of a manual and 5 automatic focus control system 10 for an adjustable focus lens 12, of a self-processing camera 14. In order to automatically focus the adjustable focus lens 12, both a mode select switch S. ,.. and a switch S,„ must be closed. If A/M IF switches S ... and S,„ are closed, power from the battery A/M IF (not shown) connected to terminal 16 is applied to a rangefinger 18 through a c ontrol logic unit 20. When so activated, the rangefinder 18 acoustically determines the distance to a subject 22. When the distance to subject 22 has been determined, the rangefinder 18 causes the automatic focus control 24 to move the lens 12 to focus the subject 22 at a film plane 26. A shutter mechanism 28 is then actuated by a signal from automatic focus control 24 through path 30. Since the camera 14 is of the self-processing kind, once the exposure is completed a film processing and transport means 32 initiates film processing and movement of the film out of the camera 14. When switch S,„ is IF opened after a signal 34 indicative of the completion of the film processing and transport cycle is transmitted to automatic focus control 24, the automatic focus control 24 will cause the lens 12 to be driven to the point where switch Sp is actuated to its open position by mechanical linkage 36.

In order to take a manually focused picture of an object with the camera 14, mode select switch must be opened. With mode select switch open switches S^^ and Sp are disabled. Once switch is open, adjustable focus - 7 lens 12 is moved by manually moving focus wheel 38 until the subject is in focus. Then, shutter mechanism 28 is manually actuated ty switch S·^ which causes a shutter-actuating signal to be sent to shutter mechanism 28 through path 40.

When the shutter mechanism 28 has completed its operation, film processing and transport is automatically initiated in the same manner as in the automatic focus control mode.

When switch S opens by manual release, if the lens switch Sp was left in a closed position by the manual movement of lens 12, automatic focus control 24 will sense the closed position of switch Sp through path 42 upon return of the mode select switch S, .,, to its closed position, and will A/M cause movement of lens 12 until switch Sp is opened by means of the connection 36. Switch Sp is opened when the lens 12 moves a predetermined distance outside of its normal focusing range. This predetermined distance corresponds to the reference position from which all automatic focusing is initiated. A logic diagram of automatic and manual focus control system 10 for adjustable focus lens 12 is depicted in Fig. 2.

In control system 10, electrical power from a battery (not shown) in camera 14 (Fig. 1) is applied to one terminal of the mode select switch S, .,, and to one terminal of the A/M manual spring-biased, single-pole switch S^. When mode select switch Sft/M is closed, power is supplied to one terminal of lens-movement actuated single-pole switch S P and to one terminal of manual spring-biased, single-pole switch S, Switches and are mechanically interIF* locked such that switch S^p closes before switch S^T· Signal Sp appears at the output of switch Sp when switches SA/M and SP are 1301:11 closed- Signal S^p appears at the 4-8131 - 8 output of switch SlF when both switches and are closed. Signal S^F appears at the output of the switch S^F when either of switches and S^F is open. Signal S^T appears at the output of switch Sj^when switch S^ is closed and signal S1T appears at the output of switch S^T when switch S.^ is open. When signal Sp, s-j_p, or S^T is generated power is supplied to loads other than those depicted in Fig. through OR gate 43. The loads depicted in Fig. 2 receive their power in accordance with the control system of Fig. 2.

For automatic focusing of the lens 12 on a subject to be photographed, automatic/manual mode-select switch must be closed. If lens switch Sp is closed at the time that switch SA^M is closed, control system 10 causes the lens 12 to be driven until switch Sp opens, i.e. until the lens is in its at-rest position. With mode-select switch SA/M cl°se<^' an automatically focused picture will be taken by camera 14 (Fig. 1) by closing switch S . When switches IF s. /., and S.„ are both closed, signal S._ appears at the outA/M. IF IF put of switch S^F and at the input of rangefinder 18. The rangefinder 18 then determines the distance to a subject to be photographed. Signal also appears at the input of a latching OR gate 44 to render it conductive. The gate 44 remains conductive once it has an output because the output is fed back into the input of the gate 44. The output of gate 44 is removed only when the gate is reset by a pulse generated by a one-shot multivibrator 45 when the switch S,„ is initially closed while switch S. . is also closed.

IF A/M The output of latching OR gate 44 is fed to an AND gate 46. The AND gate 46 remains nonconductive until the focusing means 24 has positioned the lens 12 to the position at which subject is in focus. - 9 After the distance to the subject has been determined by rangefinder 18, a range-complete signal is applied at one input of a latching OR gate 50. The output of the gate 50 is transmitted to focus control means 24 to initiate focusing of lens 12. Latching OR gate 50 maintains focusing means 24 in operation even if switch is open before focusing is complete. Focus control means 24 sends a drive forward signal 48 to drive motor 52 to drive the lens mount 54 with lens 12 to the focus position. The focus position is sensed by means described in detail in the above-cited application. Once focusing is complete, focusing-complete signal 56 renders AND gate 46 conductive. Ihe. output of AND gate 46 renders an OR gate 58 conductive. The output of OR gate 58 actuates a mechanism which exposes and subsequently processes a selfprocessing film unit, for instance.

The output of OR gate 58 should of course, serve merely to trigger a conventional shutter mechanism. Once processing is complete, (or in the case of a non self-processing camera, once the shutter mechanism has been full actuated,) a signal 60 indicating completion of shutter actuation or film processing is sent to an AND gate 62. If switch Slp has been released by the camera operator, signal S, is presented at * ™ the input of AND gate 64. Signal S^ is already present at the AND gate 64 because when there is an output from switch SlF' conttol system 10 inhibits the subsequent output from switch S1T· The output of the gate 64 is present at one input of AND gate 62. Signal Sp is already present at another input of AND gate 62 because switch was closed when the lens 12 moved towards its normal focusing range.

When AND gate 62 is rendered conductive a reverse drive signal is applied at drive motor 52 through OR gate 66 to - 10 drive the lens mount 54 until lens-actuated switch Sp is opened. When the switch S is opened, signal S disappears and gate 62 is rendered nonconductive, thereby shutting off the reverse drive signal to drive motor 52. At this point, adjustable focus lens 12 is positioned outside of its normal focusing range. This lens position is the reference point from which all automatic focusing is initiated. Control system 10 is now ready again to focus the lens 12, if switch is again closed.

To focus manually, the focus control mode switch is opened. The adjustable lens 12 is then manually positioned to the correct focus position by focus wheel 67. Switch is closed to initiate a picture-taking sequence. Even though the mechanically interlocked switch S is closed before switch Slm is closed, the fact that the switch S„ IT A/M is open prevents the signal S from being generated at the IF output of switch S^p. With switch S^T closed signal S^T appears at the input of AND gate 68. There would be no output from latching OR gate 44 and, therefore, AND gate 68 is rendered conductive by the signal at its input. An output from AND gate 68 renders latching OR gate 70 conductive, said OR gate 70 remaining in its conductive state until reset by signal S^. An output from gate 70 renders OR gate 58 conductive to initiate a film exposure and proces25 sing cycle in the ease of a self-processing camera or merely actuates a shutter mechanism in the case of a non-selfprocessing camera.

Upon completion of film exposure, or of film exposure and processing, as the case may be, the lens 12 is not driven to the point where switch opens because of a lack - 11 is subsequently released and opened and with mode lo of a reverse drive output signal from AND gate 62. AND gate 62 is nonconductive because there is no Sp signal, mode selection switch S^/M being open. When the switch .ease select switch S„ also being open, camera 14 (Fig. 1) A/M can then be stored for an extended period of time without draining the battery. If switch Sp is left in its closed position and mode select switch is subsequently closed lens 12 is driven to the point where the switch Sp is opened. Lens 12 is driven to open switch Sp when switch SA/M °^ose<^ because AND gate 72 is rendered conductive when signal Sp appears at its input. An output from AND gate 74 is present at the input of gate 72 because switches and S1T are biased to their open positions and an exposure initiate signal is not present at the output of OR gate 58 and at the output of AND gate 76. AND gate 72 also responds via AND gate 76 to signal 60, on completion of processing, to cause the lens to be driven to the point where switch Sp is opened. This secondary function is the same as the function performed by AND gate 64; this duplication is useful but not essential.

Since lens-actuated switch Sp is opened when modeselect switch is closed the battery of camera 14 (Fig. 1) will not be drained by control system 10 even if the camera 14 is stored for an extended period of time while the mode-select switch S, remains closed.

A/M Switches Slp and are mechanically interlocked and collectively form a two-stage switch. Alternatively, the outputs from switches S^p and S^ could be electrically interlocked. Switch stage S^p is closed before switch stage S1T can be fully closed. If switch SA/M is closed 8131 - 12 when switch stage SgF is closed, a subsequent output from switch stage SgT will not result in shutter actuation.

Once there is an output from switch SgF» the control system 10 inhibits the subsequent output from the switch stage Sg^,.

However, an output from switch stage SgT, and no output from switch stage SgF, results in actuation of the shutter mechanism 28 and in the processing and transport of an exposed film unit.

It will be understood that the term lens” in this specification is intended to include multi-element lens assemblies and that references in the specification and claims to adjusting or displacing an adjustable focus lens to focus a subject at an image plane are intended to include displacing an adjustable part of a multi-element adjustable focus lens, for example a single element thereof.

Claims (8)

1. CLAIMS:1. A camera comprising: an adjustable focus lens mounted for displacement over a given range of positions to focus at a given image plane subjects within a given range of distances and for displacement outside the said range of lens positions to an at-rest position; a lens-position switch which is in a first state when the lens is at the atrest position and is in a second state when the lens is within the said given range of positions; distance measuring means for deriving a signal representing the subject distance and means for automatically displacing the lens in response to the said signal from the at-rest position to a position within the said range at which it focusses the subject at the image plane; a manually operable focus-mode selector actuable between a manual focusing mode and an automatic focusing mode; second manually operable means having first and second conditions; and control means responsive to the operation of the second manually operable means from its first to its second condition when the selector is in its automatic focusing mode to energize the distance-measuring means and to initiate automatic displacement of the lens from the at-rest position to the focused position and exposure of a light-sensitive medium to the focused image and responsive to completion of exposure, return of the second manually operable means to its first condition and to the lens-position switch being in its second state to effect automatic return of the lens to its at-rest position, and responsive to the operation of the second manually operable means from its first condition to its second condition to initiate an exposure operation without automatic focusing when the selector is in its manual focusing mode and thereafter operative in response - 14 to the completion of exposure, the return of the second, manually operable means to its first condition, the lens position switch being in its second state, and the restoration of the mode selector to its automatic focusing mode, 5 to effect the automatic return of the lens to its at-rest position.

2. A camera in accordance with Claim 1, in which the focus-mode selector is an electric switch in series with the lens-position switch in a voltage supply line connected 10 to the battery, the mode selector switch being closed for automatic focusing and open for manual focusing and the lens-position switch being open in its at-rest position and closed when the lens is within the said range of lens positions, whereby if the lens is not in its at-rest posi15 tion when the mode selector switch is closed, the control means operates to drive the lens to its at-rest position.

3. A camera in accordance with Claim 1 or 2, in which the second manually operable means comprises two switches, one for initiating exposure following manual focusing and 20 the other for initiating a sequence involving automatic focusing followed by exposure, the latter switch being effective only when the mode selector switch is in its automatic focusing mode.

4. A camera in accordance with Claims 2 and 3, wherein 25 the lens position switch and the automatic focusing switch of the second manually operable means are electrically connected in parallel with each other and in series with the switch constituting the focusing mode selector, the said automatic focusing switch being normally biased to an 30 open position. - 15 5. A camera in accordance with Claim 4, in which the switch for initiating exposure following manual focusing is connected directly to the said battery supply line and is normally biased to an open position.

5

6. A camera in accordance with Claim 3, 4 or 5, in which the two switches of the second manually operable means form a single two-stage switching means, the switch for initiating the sequence including automatic focusing closing before the switch for initiating exposure following 10 manual focusing when the second manually operable means is operated.

7. A camera in accordance with Claim 6, wherein an output signal from the switch which initiates the automatic focusing sequence precludes response of the control circuit 15 to the closure of the switch for initiating exposure following manual focusing.

8. A camera, substantially as herein described with reference to the accompanying drawings.