US2773142A - Clockwork controlled electric switch mechanism - Google Patents

Description

Dec. 4, 1956 'r. BOWEN 2,

CLOCKWORK CONTROLLED ELECTRIC SWITCH MECHANISM Filed April 19, 1954 4 Sheets-Sheet 1 Dec. 4, 1956 T. BOWEN 2,773,142

CLOCKWORK CONTROLLED ELECTRIC SWITCH MECHANISM Fild April 19, 1954 4 SheetsSheet 2 INJ NTORi ATFbQNEXS Dec. 4, 1956 T. BOWEN 2,773,142

CLOCXWORK CONTROLLED ELECTRIC SWITCH MECHANISM Filed April 19, 1954 4 Sheets-Sheet 5 F y ,5: l '35 63 U15 I I 6% 2" 30.

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ism Bode Dec. 4, 1956 BOWEN 2,773,142

CLOCKWORK CONTROLLED ELECTRIC SWITCH MECHANISM Filed April 19-, 1954 4 Sheets-Sheet 4 ATTORNEYS.

United States Patent CLOCKWORK CONTROLLED ELECTRIC SWITCH MECHANISM Tom Bowen, London, England Application April 19, 1954, Serial No. 424,189

7 Claims. (Cl. 20038) This invention relates to clockwork controlled electric switch mechanism and has for an object to provide an arrangement in which the clockwork mechanism may actuate the switch mechanism accurately at a preselected time after the clockwork has been set in motion.

According to this invention a clockwork controlled switch mechanism comprises a switch arranged for connection in circuit with the mechanism to be controlled and which switch is actuated through a transmission by an adjustable movable element of the clockwork which element in being adjusted to a pre-selected position closes the switch and from which position the element may be moved by the clockwork to return it to a datum position whereupon the switch is opened, a stop mechanism for the clockwork under the combined control of a yielding detent for holding the said stop mechanism in a position to arrest the clockwork, and of an operator actuated member and of said transmission whereby when the adjustable element of the clockwork has been pre-set to close the switch the detent holds the stop mechanism in a position to arrest the clockwork until such time as it may be released by the operator actuating member thereby causing the adjustable element to commence its movement to the datum position when the adjustable element opens the switch through said transmission, which latter actuates the stop mechanism to arrest the clockwork and also resets the detent.

The switch mechanism may be actuated by one or more snap over devices each comprising a length of resilient material which is initially bowed and has its ends arranged between and in contact with two spaced fixed abutments and is acted upon by a part of said transmission so as to apply a force transversely to the length of the material.

The aforesaid adjustable movable element of the clockwork and the associated transmission may comprise two discs or plates arranged face to face, the disc being adjustably fixed direct to an operating spindle driven by said clock-work mechanism, and the other disc having a limited rotational movement on the spindle, both of which discs are provided with cut away portions having edges extending inwardly towards the axis of rotation, one edge on the disc being substantially radial and one edge on the other disc being inclined to a radius, the arrangement being such that during the resetting operation the rotation of the disc with the inclined edge first causes a cam follower actuating the aforesaid transmission to be forced outwardly along the inclined edge and on to the periphery of that disc, the cam follower also engaging with the disc first through its radial edge and, after the follower has reached the periphery of the disc with its periphery thereby ensuring that the lost motion between the discs is taken up in the resetting direction, and, during the return motion, the engagement of the follower with the periphery of the disc ensures that the lost motion between the discs is taken up in the running direction, so that when the cam portion reaches the radial edge on that disc it will move quickly radially inwards.

Patented Dec. 4, 1956 The aforesaid stop mechanism may be arranged to operate upon the oscillating balance wheel of the clockwork mechanism.

The following is a more detailed description of two similar embodiments of the invention suitable for switching on and off a light source in a photographic enlarger so as to provide a predetermined exposure, reference'being made to the accompanying more detailed drawing in which:

Figures 1 to 4 are diagrammatic views of one form of mechanism showing the parts of the mechanism in the different positions they assume during the operation of the lever;

Figure 5 is a face view of the mechanism on the inner side of a mounting plate;

Figure 6 is a face view of the outer side of the plate;

Figure 7 is a side elevation looking from the right of Figure 6; and

Figure 8 is a rear view of a clock to which the mounting plate is to be secured.

Referring to Figures 1 to 4 the mechanism comprises two snap over switches the first switch being provided with a pair of contacts 12 and 13 and the second switch with a pair of contacts 10 and 11. For the purpose of simplicity the contact 10 is shown movable and anchored by an insulating connection to a spring blade 14 which is initially bowed and has its ends arranged between and abutting two spaced and fixed abutments, whilst another contact 11 is fixed. Similarly the contact 12 is shown connected by an insulating connection to a spring blade 15 arranged similarly to the blade 14, the contact 13 being fixed.

The two pairs of contacts are shown connected in series with two conductors 16 and 17 which in their turn are connected with the enlarger lamp and source of supply. The spring blade of the second switch 14 is arranged to extend through a fork 18 on a first lever arm 19 which may be moved by a manipulating knob 20. The blade 15 of the first switch is arranged to extend through a fork 21 on a second lever arm 22 which is a wire arm of a bell crank lever the other arm 23 of which is provided with a pin or roller 24 at its extremity which in turn engages a cam disc mechanism 25 driven by a clockwork mechanism controlled by a balance wheel 26. The cam disc mechanism comprises two discs or plates 25, arranged face to face, the disc 25 being adjustably fixed direct to an operating spindle 27 driven by said clockwork mechanism, and the other disc 70 having a limited rotational movement on the spindle 27. The discs 25, 70 are both provided with cut away portions having edges extending inwardly towards the axis of rotation, one edge 71 on the disc 70 being substantially radial and one edge 72 on the other disc 25 being inclined to a radius. The arrangement is such that during the resetting operation the rotation of the disc 25 with the inclined edge 72 first causes a cam follower 24 actuating the aforesaid transmission to be forced outwardly along the inclined edge and on to the periphery of that disc. The cam follower also engages with the disc 70 first through its radial edge 71 and, after the follower has reached the periphery of the disc 25 engages with its periphery thereby ensuring that the lost motion between the discs is taken up in the resetting direction. During the return motion, the engagement of the roller 24 with the periphery of the disc 70 ensures that the lost motion between the discs is taken up in the running direction, so that when the cam portion reaches the radial edge on that disc it will move quickly radially inwards. The cam disc is settable in different angular positions on its driving spindle 27, and the pin or roller 24 at the end of the arm 23 is moved inwardly by a spring 29 engaging the other arm 22 of the bell crank lever. This latter arm of essence the bell crank lever is provided with a projection 30, which is disposed beneath one end of a third lever arm 33. which end also overlies an end of the first lever arm 19 carrying the fork 18. In practice the lever arms 19 and 31 are arranged to pivot about the same axis, one of them being provided with a lateral projection overlying the end of the other lever arm. When the pin or roller 24 is lying within the depression 28 (as shown in Figure 4), the projection 30 on the bell crank lever holds the third lever arm 31 in such a position that a wiper 32 at the other end thereof engages the balance wheel 26 and prevents the clockwork mechanism operating. The third lever arm 31 having been moved into that position is held by a spring detent 33 engaging a projection 34 thereon until such time as the third lever arm can be moved in an anti-clockwise direction by a manually operated plunger 35. 7

At the end of a cycle, as will be seen from Figure 4 the contacts it) and 11 are closed while the contacts 1'2 and 13 are opened.

in resetting the mechanism the cam disc mechanism 25 is rotated by hand anti-clockwise to an extent determined by the length of exposure required, thus bringing the pin 24 at the end of the arms 23 of the second lever into engagement with the periphery of the cam, and swinging the second lever arm clockwise causing the spring blade 15 to snap over from an upwardly disposed position to a downwardly disposed position to close the contacts 12 and 33 as shown in Figure l. The light in the enlarger will then be switched on. Assuming how ever that it is not desired to switch on the light in the enlarger by the resetting of the cam device then the operator control lever 19 would have previously been moved into a position to open the contacts 1%) and 11 and the parts of the mechanism would then assume the positions shown in Figure 2.

The lever 22 in closing the contacts 12 and 13 has the effect of withdrawing the projection from the under side of the lever arm 31 which is held in its initial position by the detent 34. The mechanism is now set ready for use.

When it is required to set the clockwork mechanism into operation the plunger is depressed as shown in Figure 3, thereby rotating the first lever arm 19 clockwise (should it have been moved into the position of Figure 2) and closing the contacts 10 and lit, the spring blade 14 snapping over from an upwardly disposed po sition. At the same time the lever arm 31 is rotated anti-clockwise thereby drawing the wiper 32 over and then away from the balance wheel 26, causing the clockwork mechanism to start. The cam disc mechanism 25 then commences to rotate clockwise and when the rolicr or pin 24 reaches the depression 28, it will be drawn into that depression by spring 29 causing the bell crank lever 22 to swing clockwise, whereupon the projection 30 engages the under side of the extremity of the third lever arm 31 causing to be moved clockwise and to bring the wiper 32 again into engagement with the balance wheel 26 at the same time the movement of the bell crank lever 22 will cause the spring blade 15 to snap over from a downwardly disposed position to an upwardly disposed position opening the contacts 12 and 13 and interrupting the circuit controlling the enlargers light source. The nature of the cam disc mechanism and of the snap over switches enables a very rapid and accurate opening of the contacts to be obtained.

Should the light be required to be extinguished before the termination of the preselected time the first said lever in may be rocked in an anti-clockwise position, thereby opening the contacts 1i) and i1 and bringing the wiper blade 32 into engagement with the balance wheel without disturbing the setting of the cam disc mechanism. Tl e clockwise mechanism then may be brought into operation again.

A preferred and simpler form of construction is now described with reference to Figures 5 to 8. It operates on the same general principle to that last described and differs mainly in replacing the two pairs of contacts 10, 11 and 12, 13 by a single pair of contacts 38, 39, the movable contact 38 being controlled jointly by the spring blades 14 and 15 as hereinafter described.

The control mechanism is mounted as a unit on a plate 41 having three drilled bosses 42, 43, 44 on one side thereof (see Figure 5) through which securing screws may extend and engage threaded holes 45, 46, 47 (see Figure 8) on the back plate 38 of a clock. The back plate is so shaped as to expose a part of the balance wheel 36 and mounted on the outside of the back plate is the aforesaid cam disc 27 which is provided with the recess 28.

As in the previous construction a first lever arm 19 is provided with a forked portion 18 which engages a spring blade 14 and ends of the spring blade engage notches in two abutments on the aforesaid plate 41 one of which abutments 49 only can be seen. The outer end of the first lever arm 19 is forked and slidably mounted in said fork is a manipulating member 20 (see Figure 6). The upper end of the lever arm 19 is also provided with a lug 50 the path of movement of which intersects a nose piece 62 on a lever arm 3'1 corresponding to the third lever arm in the first construction. The lever arm 31 is formed with a laterally extending lug 63 which is engageable by the manually operated spring plunger 35. A comparatively short push bar 36 is mounted in slideways on the plate 41 and is arranged to engage the underside of the spring blade 14 and the upper side of the extremity of a contact blade 38, which contact blade may move into engagement with a contact block 39 which is secured on the opposite side of the plate 41. The second lever arm 22 is pivoted at 52 on the plate 41 and carries a roller 24 which, when the plate 4-1 is attached to the back plate 48 of the clock, engages the periphery of the cam disc 27. The end of the second lever arm remote from the pivot axis 52 is connected by a tension spring 29 to a fixed anchorage pin 53. The second lever arm is provided with a lug 34), which overlies a projection 40 on a third lever arm 31. The third lever arm is pivoted at 54 on the plate 41 and secured to the outer end of the third lever arm is a balanee-wheel-control-wire 32 which is bent to provide two depressions 55, 56 which engage with the boss 42. The control wire passes through an eye 57 and is then bent so as to extend to the opposite side of the plate 41 and its extremity 58 (best seen in Figure 7), may be brought into and out of engagement with the balance wheei 26. The second lever arm 22 is provided with a fork 21, which engages the second spring blade 15 the ends of which are confined notched abutments (not shown). A second and longer push bar 37 is disposed between the under side of the second spring blade 15 and a part of the contact blade 33. The contact blade 38 is fixed to a terminal block 5 and this block and the block 39 are provided with terminal screws 60, 61.

The operation of the mechanism is as follows: At the end of a cycle the roller 24 on the lever arm 22 will be in the recess in the cam disc 23 and the lever arm 22 will therefore have been swung downwardly under the action of the spring 29 anti-clockwise and the spring blade 15 will have been snapped downwardly so as to move the spring contact blade 38 away from the contact block 39 through the pusher bar 37. In resetting the mechanism the cam disc mechanism 25' is rotated by hand anticlockwise to an extent determined by the length of exposure r quired, thus bringing the pin 24 into engagement with the periphery of the cam, swinging the arm 22 clockwise causing the spring blade 15 to snap over into its upper position and the springiness in the contact blade 38 will move the push bar 37 upwardly and the spring contact blade 38 will come into contact with the block 39', thus closing the circuit and switching on the light in the enlarger. The upward movement of the arm 22 will have brought the lug 30 clear of the projection 4% on the 31. The lever arm 31 will be held in its initial position by reason of the fact that one of the depressions in the balancewhetl-control-wire 32 is engaged by the pillar 42 and the balance wheel will be prevented from movement. Assuming however, it is not desired to switch on the light in the enlarger by the resetting of the cam disc 25, then the operator control lever 19 will have previously been moved clockwise thus causing the spring blade 1-4- to snap over into the lowermost position, depressing the push bar 36 and deflecting the contact blade 3-8 so that it is maintained away from the contact block 39.

When it is required to set the clockwork mechanism in motion spring plunger 35 will be depressed which coming into contact with the lug 63 on the arm 31 will depress the balance-wheel-control-Wire 32 which causes the balance wheel to short, also should the control lever have previously been moved clockwise to maintain the contact blade away from the contact 9 the downward and anti-clockwise movement of the arm 3-1 will cause the projection 62 to move the lug 59 on the arm 19 to the left and the resulting anti-clockwise movement of the arm 19 will snap the spring blade upwards and the short push bar 36 releases the contact blade 37 thus establishing the circuit or the light. The cam disc mechanism 25 commences to rotate and when the roller or pin 24 reaches its depression 28 it Will again be drawn into that depression by the spring 2 causing the spring blade 15 again to snap over into its lowermost position pressing the contact 38 away from the contact block 39. The lug 30 on the lever arm 31 will again engage the projection 39 swinging the lever arm 31 clockwise and bringing the balance-wheel-control-wire 32 into engagement with the balance wheel and stopping the movement.

I claim:

1. A clock controlled switch mechanism comprising a clock mechanism, first, second and third pivoted lever arms, a first snap-over spring connected to the said first lever arm, a first switch operating member moving with said first snap-over spring, a cam rotatably adjustable on a driven shaft of the said clock mechanism and engaged by a part of the said second lever arm, spring means maintaining said part in engagement with said cam, a second snap-over spring connected to the said second lever arm, a second switch operating member moving with said second snap-over spring, a stop device connected to the said third lever arm and adapted to control the clock mechanism, a yielding detent for holding said stop device in its limiting positions, said third lever arm being formed with parts which are arranged in the path of movement of parts of the said first and second lever arms, and a manually controlled member adapted to engage said third lever arm.

2. A clock controlled switch mechanism comprising a clock, first, second and third pivoted lever arms, first, second and third snap action restraining means associated respectively with said first, second and third lever arms to restrain each arm stably in either a first or a second position, a first switch member moving with said first lever arm, a cam manually settable from a datum position and adapted to be returned to said datum position by the said clock and engaged by a part of the said second lever arm, spring means to maintain said part in engagement with said cam whereby said second lever arm moves between its first and second positions under the control of said cam and said spring means and said second lever arm retains its first position when the said cam is in its datum position, a second switch member moving with said second lever arm, a stop device connected to the third lever arm and adapted to stop the clock when the said third arm is in its first position, first manually operable means to move the first lever arm between its first and second positions, second manually operable means to move the third lever arm from its first position to its second position, and first interengaging means on the first and third lever arms to move the said third lever arm to its first position upon movement of the said first lever arm to its first position, and to move said first lever arm to its second position upon the movement of the said second lever arm to its second position, the said first and second switch members being operative to complete an electric circuit only when the said first and second lever arms are both in their second positions.

3. A clock controlled switch mechanism according to claim 2 wherein second interengaging means are provided on the said second and third lever arms adapted to move the said third lever arm to its first position upon movement of the second lever arm to its first position.

4. A clock controlled switch mechanism according to claim 2 wherein said first and second snap action restraining means each comprise a length of resilient material which is initially bowed and has its ends between and in contact with two spaced fixed abutments, said lever arms being mounted so as to apply movements to the said resilient members in directions transverse to their lengths.

5. A clock controlled switch mechanism according to claim 2 wherein said rotatably adjustable cam comprises two discs arranged face-to-face, one of said discs being adjustably fixed direct to an operating spindle driven by said clockwork mechanism, and the other of said discs having a limited rotational movement on the said spindle, both of said discs being provided with cutaway portions having edges extending inwardly towards the axis of rotation, one edge on one of said discs being substantially radial and one edge on the other of said discs being inclined to a radius, the arrangement being such that during the resetting operation the rotation of the disc with the inclined edge first causes a cam follower on said second lever arm to be forced outwardly along the said inclined edge and onto the periphery of that disc, the cam follower also engaging with the disc first through its radial edge and, after the follower has reached the periphery of the disc, with its periphery thereby ensuring that the lost motion between the discs is taken up in the resetting direction, and, during the return motion, the engagement of the follower with the periphery of the disc ensures that the lost motion between the discs is taken up in the running direction, so that when the cam portion reaches the radial edge on that disc it will move quickly radially inwards.

6. A clock controlled switch according to claim 1 wherein the two operating members moving with the snap-over springs associated with the said first and second pivoted lever arms are both arranged to operate the same contact blade of a switch.

7. A clock controlled switch according to claim 1 wherein the two operating members moving with the snapover springs associated with the first and second lever arms are arranged to control respectively two switches in series with the device to be controlled.

References Cited in the file of this patent UNITED STATES PATENTS 1,073,707 Phelps Sept. 23, 1913

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