US3357637A

US3357637A - Process and apparatus for zero indexing op a number wheel on a calculator

Info

Publication number: US3357637A
Authority: US
Publication date: 1967-12-12
Anticipated expiration: 1984-12-12

Description

Dec. 12, 196? E. STAUTMEISTER 3,

PROCESS AND APPARATUS FOR ZERO INDBXING OF A NUMBEH WHEEL ON A CALCULATOR Filed Aug. 10, 1966 INVEN TOR ERICH STAUTMEISTER Aitorney g United States Patent M PROCESS AND APPARATIZTS FOR ZERO INDEXING 0F A NUMBER WHEEL ON A CALCULATOR Erich Stautmeister, Gottmadingen, Germany, assignor to Avo Apparatebau Vogt A.G., Kreuzlingen, Switzerland Filed Aug. 10, 1966, Ser. No. 571,491 Claims priority, application Germany, Aug. 13, 1965, A 49,995; Jan. 20, 1966, A 51,375 6 Claims. (Cl. 235144) ABSTRACT OF THE DISCLOSURE A zero resetting arrangement for number wheels wherein the resetting cam is gradually actuated by a zero index lever. The lever is not directly actuated by the resetting solenoid, but a motion transmitting means is interposed between the solenoid and index lever. The latter means comprise a ratchet mechanism, actuated by the solenoid and a yieldable spring means between the ratchet and index lever whereby the lever is given a gradual motion towards the cam. Movement of the reset solenoid is controlled by an interrupter which operation is controlled by a cam on the ratchet wheel.

The present invention relates to the apparatus for zero indexing or resetting of a number wheel of a calculator, especially an electromagnetic calculator, whereby each number wheel is mechanically connected with a heartshaped curved reset cam member which serves as the inner cam for actuation by a zero indexing lever.

In the prior art, the reset cams are actuated to zero position by lever means actuated directly by solenoids. Due to inertia forces and initial high current flow to the solenoids, the lever means forcefully and suddenly contact the cams and cause undue wear on the cam surfaces. Such sudden actuation also causes the number wheel to which the cams are connected to override or overrun their Zero position. Examples of such direct actuation of the cam levers by the solenoid means are shown in US. Patent No. 2,980,329 to Hoifman and in US. Patent No. 3,050,250 to Mann.

One object of this invention is to gradually reduce the impact contact between the cams and their zero index levers and thereby reduce the wear between these elements.

Another object is to reduce the forces with which the zero index levers actuate the resetting cams by controlling and varying the forces exerted by the solenoid means upon the index levers.

Another object is to introduce a ratchet and spring device between the solenoid means and the zero index lever means and to also introduce a switch control for the solenoid means whereby the zero indexing forces are reduced and the resetting cam motion takes place gradually without undue wear and without overrunning of their zero position.

Other and further objects of the invention will become apparent from a consideration of the drawings and the more detailed description which follows and which form a part of the present specification.

In the drawing, the new device of the present invention is shown in two different operational positions, as follows:

FIG. 1 shows the present device for zero indexing of the number wheel in the inoperative position and without any connection for movement with the number wheel;

FIG. 2 shows the device of FIG. 1 in the operating position at a stage during the stopping of the number wheel after its return to zero; and

3,357,537 Patented Dec. 12, 1967 FIG. 3 shows a schematic view of the self-interrupting electromagnetic switch device.

The number wheel 1 in the figures of the drawing is fitted with a heart-shaped curved cam member 2 and both are mounted rotatably on a single axis which is in the center of the wheel 1. At the bottom of the wheel 1 in FIG. 1 the zero index lever 4 which is biased by the spring 5 and which is rotatable around the zero index lever axis 12 in a direction which brings the head of the lever towards the heart-shaped member when elongating and tensioning the spring 5. The ratchet wheel 6 has two driver pins 7 as well as two cams 8 on its periphery and is mounted rotatably on the ratchet wheel shaft 9. On the zero index lever 4 and at a lower edge thereof there is provided a stop 10 which projects from the body of the lever and serves as a safety stop for the circular ratchet wheel spring 11 which is wrapped around the axis 12.

The pawl 14 moves the wheel 6 in clockwise direction step by step while the retaining spring 13 acts only as a detent to prevent counterclockwise rotation of the wheel. The counterclockwise rotation could occur under the influence of the

springs

5 and 11 when stop 7 contacts 11, especially when the wheel 6 has a position between the designed positions in FIG. 1 and FIG. 2.

As stated above, the retaining spring 13 engages the outer periphery of the ratchet wheel and the spring tine fits into the ratchet to prevent it from being turned backwards. The advance of the ratchet wheel is accomplished by the driving pawl 14 pushing the wheel forward or clockwise, the anchor lever 18 being directly connected to the driving pawl 14 and being tiltable forwards and backwards about the anchor pivot 19. The anchor lever 18 is moved to the left by the electromagnetic solenoid 17, the tension of the spring 16 increasing thereby. Consequently pawl 14 will drop behind the next tooth. Through the self-interrupter, shown in FIG. 3 and described subsequently, the electromagnetic solenoid 17 is interrupted and the spring 16 can move the anchor lever 18 with the pawl 14 to the right. The wheel 6 turns for a section of a tooth in direction of the arrow. This sequence is being repeated to provide a stepwise movement until one of the cams 8 cuts off the switching contact 15 of the self-interrupter. The movement of the zero index lever 4 between the position shown in FIG. 1 and the position shown in FIG. 2 is accomplished through the transient connection of the driver pin 7 to the spring 11. The zero index lever 4 is moved by the spring 11 in the direction of the arrow because the projecting driver pin engages the upper surface of spring 11 during the clockwise movement of the ratchet wheel and the lever 4 tilts in the counterclockwise direction about its axis 12 and as shown by the arrow applied to lever 4 in FIG. 2. This movement of the lever engages cam member 2 and moves it in the direction which brings about the zero position of the number wheel. It is possible to vary the forces acting to move index lever 4 in accordance with the energy supply by varying the number of teeth of the ratchet wheel, through one or several driver pins 7, as well as through the adaptation of the number of switching cams 8. In the figures, two driver pins 7 and two switching cams 8 are shown but more may be used. The ratchet wheel 6 continues to run after completion of the zero indexing process, until the electromagnet 17 is cut off via the switching contact 15 which is shown schematically in FIGS. 1 and 2.

The number wheels 1 move slowly from a dead stop because of the inertia of their mass and because of the initial resting condition. A rigid connection of the electromagnet with the zero index would not help in achieving an accurate zero setting from a dead stop. When the number wheel is in position to permit the zero index lever to touch the heart-shaped curve member in the vicinity of the axis, the energy impinging upon the heart-shaped curve member rises quadratically with the distance of the anchor lever from the electromagnet. The striking energy is least whenever the zero index lever engages the point of the heart-shaped curve member most remote from the axis 3 of the number wheel and the energy is highest when it engages the heart-shaped curve member at a point close to the axis 3, e.g. at the short cusp.

Thus, an important feature of the present invention is that the striking energy is at a minimal value of the energy range when the zero index lever engages the heart-shaped curve member at a point remote from the axis, based upon the electromagnetic interrupter mean which permits slower zero indexing with greater accuracy. The new function of this improved electrical interrupter means shown in FIG. 3 will become more apparent from the more detailed description which follows.

The self-interrupter, shown in FIG. 3, comprises the electric conductor 21 which is intermittently connected to the locally fixed contact element 2.2 by means of the contact element 23. The contact element 23 projects from the interrupter member 25 which is pivotally movable about its axis 24. The movement of interrupter member 25 is limited between magnet 26 and fixed contact element 22. The permanent magnet 26 serves as a stop and as a limitation of the angle of horizontal swing of the interrupter member 25. FIG. 3 also shows the connection f conductor 21 to the electromagnet 27 and of the latter to the negative terminal of the battery.

The anchor lever 29 of the interrupter is swivelable about the axis 28 located at the bottom of the anchor lever. The pawl 30 is pivotally connected to anchor lever 29 and includes a U-shaped end 31 which encloses the free end of the interrupter member 25 at the U-shaped end 31.

The mode of operation of the self-interrupter, shown in its closed state is as follows: when a current flows in the conductor 21 the anchor lever 29 is attracted by the electromagnet 2 7, which imparts a swinging movement to the interrupter 25 via the rearward movement of the pawl 3t), e. g., to the left, as shown in FIG. 3, and up to the stop on the permanent magnet 26. Simultaneously, however, the

contact

22, 23 is interrupted, and the magnetic effect of the electromagnet 27 on the anchor lever 29 is eliminated. The anchor lever 29 is then again pulled toward the right, in FIG. 3, under the influence of the spring 32 which urges the interrupter member 25 into closed position with contact 23. Since the interrupter 25 consists of magnetic metal for example, a steel sheet, this interrupter remains attracted to the permanent magnet 26 until the end 31 of the pawl brings it again into the contact position. Depending on the width of the opening of the U-shaped part, a larger or smaller predetermined delay is provided.

If the interrupter 2.5 were prevented from adhering to the permanent magnet 26 or if there were no play in the connection between the pawl 33 and the interrupter 25, then the interrupter 25 would move simultaneously with the anchor lever 29, a rapid flickering would occur in the interrupter contact, e.g the

contacts

23, 22 would open and close in rapid sequence. This flickering is an undesirable disadvantage. A more sluggish reconnection of the opened contact is preferred. The desired predetermined delay which is achieved depends on the width of the U-shaped opening of the end 31 of the pawl and makes the process of zero indexing more accurate while eliminating wear.

The operation is as follows: When the number wheel must be returned to zero the switch is first closed by hand. The interrupter is in the closed position shown in FIG. 3 and the device is in the position of FIG. 1. Current flows through the electromagnetic solenoids 17 and 27 (which may be the same). The anchor lever 18 and the anchor spring 16 are so built that the lever 18 is in its left position before the interrupter opens the

contacts

22 and 23. When

contacts

22 and 23 are open no current flows in the

electromagnetic solenoids

17 and 27. The pawl 14 moved by spring '16 switches the wheel 6, and the

contacts

22 and 23 will reclose by spring 32 so that current can again fiow through the

electromagnetic solenoids

17 and 27. This sequence is repeated until one Of the cams 8 cuts oif the switching contact 15 and thereby current to solenoids 17 and g7.

As can be seen from FIGS, 1 and 2, the zero index lever 4 ends in the driver spring 11. This spring 11 is the point of application for movement by the driver pin 7 under the clockwise movement of the ratchet wheel 6. This driver spring 11 is a leaf spring with inherent flexibility in-the leaf end which cancels out the rigid connection and adapts itself admirably to the requirements of energy absorption during the zero indexing process. The leaf spring makes the impact of hitting the heart sha-ped curve member less dependent on the relative position of the heart-shaped curve member and the electromagnet 17 stores suflicient energy for the zero indexing steps. The balance of the energy from the electromagnet is against the energy of the spring 16 which returns the anchor lever 18 toward the right to move pawl 14 to rotate wheel 6.

From the foregoing, it is seen that the switching step of the ratchet wheel 6 is accomplished tensionally by the spring 16 together with the energizing movement of the electromagnet. This 'spring tension and electromagnetic energizing movement permits the impact of th zero indexing lever upon the heart-shaped curve member to be come independent of the distance of the anchor lever. When using two driver pins 7 and only one switching camj8, it will be possible to carry out two zero indexing processes, one after the other. Both indexing processes run their course before switching off of the electromagnet via the switching cam 8, as shown by the lifting of the upper contact of switch 15 by cam 8 in PEG. 1.

. slaim 1.- Apparatus o ero in exi the nu b r Wheel f an el c omagnetic c sulatg comp isin a rth p 3 11 membe oper t ely c nnec ed t e um Wheel, a p o ed zer inde lev r ha n one e f g ng a d moving d am member and its ass c a Wheel to zero position, a spring device carried by the other end of aid in e lever, a ratche Whee engag ng means ri d y th ratchet hee o C II BCI a d p i device and there y more the i d x lev a sol no d m an a pawl means to actuate step-by-step said ratchet wheel, means onn ct ng a solenoid n p wl m ans, an ne u'p er c nt o ing the e s zation of s id l noid means n epeated in ervals o impart a radual movement to said engaging means and thereby gradually and yielda ly mo e the sp ing device a d index l ver tow and ga ns th am mem er for a zero res ing ope ation.

2- The pparatus e fo th in cla m 1, whe th 1 e ting means comprises an arm tur le er drawn by th olenoid t move he paw me ns n s e k and spring means biasing the armature lever towards the working stroke- 3. The apparatus set forth in claim 1, wherein the interrupter comprises two contacts, one of which is of magnetic material, interrupter solenoid meanscontrolled by the contacts, lost-motion means connecting said interup e olenoid means and h m gnet c ta to m ve it alternately to open and closed positions, and a permanent magnet to act as a stop for said contact in its opening direction,

4 The apparatus set forth in claim 1, wherein a plurality of spaced engaging means are carried by the ratchet wheel to permit a series of zero indexing operations.

5. The apparatus set forth in claim 1, wherein means 5 for terminating the operation of said interrupter means means is operatively connected With the ratchet Wheel to terminate the interrupter operation at a predetermined point of the wheels movement.

6. The apparatus set forth in claim 3, further comprising a cam carried by the ratchet Wheel and a switch means in series With the interrupter means, said cam means opening said switch means to terminate the operation of the interrupter means.

References Cited UNITED STATES PATENTS Loosii 235144 Hoffman 235144 Mann 235-444 Hartkorn 235144

Claims

1. APPARATUS FOR ZERO INDEXING THE NUMBER WHEEL OF AN ELECTROMAGNETIC CALCULATOR COMPRISING: A HEART-SHAPED CAM MEMBER OPERATIVELY CONNECTED TO THE NUMBER WHEEL, A PIVOTED ZERO INDEX LEVER HAVING ONE END FOR ENGAGING AND MOVING SAID CAM MEMBER AND ITS ASSOCIATED WHEEL TO ZERO POSITION, A SPRING DEVICE CARRIED BY THE OTHER END OF SAID INDEX LEVER, A RATCHET WHEEL, ENGAGING MEANS CARRIED BY THE RATCHET WHEEL TO CONTACT SAID SPRING DEVICE AND THEREBY MOVE THE INDEX LEVER, A SOLENOID MEANS, A PAWL MEANS TO ACTUATE STEP-BY-STEP SAID RATCHET WHEEL,