US3683294A - Contactless synchronizer, particularly for sewing machines - Google Patents

Abstract

Synchronizer without contacts, particularly for sewing machines, utilizes a unitary assembly of rotating position indicators for reducing flux changes in a common field and a transistorized oscillating circuit for converting the flux changes into separate signals for different control functions.

Description

United States Patent Gaa Aug. 8, 1972 [54] CONTACTLESS SYNCHRONIZER, [56] References Cited PARTICULARLY FOR SEWING MACHINES UNITED STATES PATENTS [72] Inventor: Hans Gaa Hockenheim, Germany 3,311,824 3/1967 Pitt ..250/233 X 3,128,387 4/1964 Hughes et al. ..340/271 X Assigneer Firm" Frflnkl & Kirchner Fflbrik 2,154,287 4/1939 Schewe ..331/181 x Elekmmmmn Elektrische 3,502,955 3/1970 Minks ..331/181 x Apparate, Schweitzingen/Baden, Germany FOREIGN PATENTS OR APPLICATIONS [22] Filed: Feb. 13, 1970 1,047,560 11/1966 Great Britain ..112/219 A 9 [21] Appl NO 11,0 9 Primary Examiner-Roy Lake Assistant ExaminerSiegfried H. Grimm [30] Foreign Application Priority Data Am R b H J ob Feb. 18, 1969 Germany ..P 19 07 975.5

[57] ABSTRACT [52] CL -331/65v 112/219 A, 250/220 R, Synchronizer without contacts, particularly for sewing 250/233, 318/467, 331/66, 331/117 R, machines, utilizes a unitary assembly of rotating posi- 331/172, 340/271 340/282 tion indicators for reducing flux changes in a common [51] Int. Cl. ..D05b 69/00, H03b 5/12 field and a transistorized oscillating circuit for com [58] Field of Search ..112/219 A; 331/65, 66,172,

verting the flux changes into separate signals for different control functions.

6 Claims, 5 Drawing Figures PHENTEmus 8 I972 SHEU 2 BF 3 van for ///W5 44/: WW

75MB VARIAEL'E' PATENTEDAm; 81912 3.683.294 sum 3 or 3 In ven tor: fiA/Vf M BACKGROUND OF THE INVENTION The invention relates to a contactless synchronizer or position setter, especially for sewing machines. Position setters are intended to initiate certain control operations such as stopping of the machine, actuation of a thread cutter or of a presser foot on reaching or passing through predetermined operating positions of the controlled machine. For this purpose they include position indicators coupled with the moving part of the machine, which in the position for which they are set automatically initiate the desired control operation. Synchronizers operating with electrical contactors may include several contact cam disks intended for different control operations; synchronizers operating without contacts, on the other hand, require sources of rays such as light sources or magnetic field sources, for example permanent magnets or electromagnetic coils, that are provided in the vicinity of the rotating position indicator and which therefore must be installed directly in the synchronizing device. In this connection the accommodation and relative separation of separate ray or field sources in the device proper causes difficulties and necessitates an increase in the structural dimenslons.

SUMMARY OF THE INVENTION The invention is intended to eliminate the problems of the prior art. It is particularly concerned with a contactless synchronizer particularly for sewing machines having several rotating position indicators for different control operations, and it is characterized in that a common field or radiating source is provided for several control operations in the range of which at least two position indicators that act on the field are rotating as a unit.

These position indicators may be perforated shield disks known per se which are coupled with the machine that is being surveyed and which, depending on their position, interrupt or release the field or the ray. At the side remote from the source there are located receivers that respond to changes of the field or of the radiation, which emit corresponding impulses to the control devices which cause or initiate the desired control functions.

For example, a common light source is disposed between at least two rotating slotted shields or a magnetic coil between at least two magnetic shields which, depending on their position, alternately shield and open the light source or the magnetic field and thereby effect different control operations. The action of the control means to be influenced may, moreover, be the same as in a contact making or contact breaking action. These control means disposed externally of the synchronizer are not the subject of the invention and therefore need not be described in detail.

In lieu of the magnetically intercepting shields it is also possible to provide rotating magnetic bridges, which as they pass, direct magnetic fields into certain paths and thereby initiate the intended control operatrons.

In all cases the invention makes it possible to utilize one and the same source of rays or field source for several control operations whereby different sectors of the field of rays or of the magnetic field can be acted on by the position indicators cooperating with the same source.

BRIEF DESCRIPTION OF THE DRAWINGS One embodiment of a synchronizer or position setter in accordance with the invention is described in the drawings, where a magnetic coil is arranged between at least two magnetic shields. Here this magnetic coil is a component of a feedback coupled transistor oscillating circuit, and magnetic shields with passage areas that are displaced with respect to one another rotate in the magnetic field of the feedback coil.

FIG. 1 shows the synchronizing device in a longitudinal section,

FIG. 2 shows another section similar to FIG. 1 to an enlarged scale, illustrating particularly the circuit components,

FIG. 3 is a bottom view of the components illustrated in FIG. 2,

FIG. 4 is a circuit diagram of the feedback oscillating transistor circuit, and

FIG. 5 shows a synchronizer in accordance with FIG.

2 using a ray emitting light source between two rotating slotted disks.

DESCRIPTION OF THE INVENTION In accordance with FIG. 1 the synchronizer is in the form of a structural unit enclosed in a removable housing 1 adapted to be coupled to the end of the arm shaft of a sewing machine. It includes a base plate 2 in which a shaft 3 is journalled in the ball bearing 6. This shaft carries at one end a connecting socket 3a that can be connected to the end of the arm shaft of the sewing machine. The shaft 3 has secured thereto shield disks 4 and 5 which serve as position indicators and rotate with the shaft and which are suitably angularly adjustable.

The stationary part of the synchronizer is supported by a frame 7 that can be seated on the base plate 2 and which upon mounting of the circuit components may be filled with a resinous substance. The components are protected by the resin filling 8 and held in their respective positions.

The synchronizer frame 7 in accordance with FIG. 5 has a common light source 9 disposed between the rotating slotted disks 4 and 5. The rays emitted by the light source 9 are bunched in the lenses 12, 13 and are received by photocells 10, 11 as determined by the movement of shields 4, 5.

The feedback transistor circuit in accordance with FIG. 4 comprises three magnet coils L1, L2 and L3, between which project the shield disks 4 and 5. These shield disks which are provided with radial slots constitute magnetic shields which upon rotation establish and interrupt the passage of magnetic flux therethrough, or which in other words interrupt or open the magnetic fields that extend between the coils L1 and L3, respectively L2 and L3, depending on whether the closed portions of the disks or the slots provided therein are at the time disposed between the coils.

The circuit in accordance with FIG. 4 includes, besides the back coupled transistor T and the coils L1, L2 and L3, five ohmic resistors R2, R3, R36, R37, R39, two adjustable temperature responsive resistors or hot conductors R1 and R38 serving for temperature compensation, as well as three capacitors C8, C9 and C11. The resistor R36 and the combination of the resistors R37, R38 and R39 form together a potential divider at the juncture point of which the base of the transistor T15 is connected. The emitter-base potential of the transistor is adjusted by means of the potential divider to its bias value. The resonance frequency of the oscillating circuit is determined by the inductance and'the capacitance of the oscillating circuit defined by the coil L3 and the condenser C9. The condenser C8 serves for bridging the high frequency of the resistor network R37, R38, R39. This circuit branch contains the resistors R1, R2. The capacitor C11 forms a supplemental feedback coupling. The oscillator circuit is connected by means of the terminal A3 to the negative pole and, depending on the control operation to which it is adjusted, either with the terminal Al or A2 by means of a switch sw to the positive pole of a direct current source B of, for example, 7 volts. In series with the terminal A3 there is connected a resistor R40 of, for example, 1,000 ohms at which the initial signal is picked up. This is then fed, if need be upon further amplification, to the control devices of the sewing machine that are to be operated.

The oscillating circuit operates as follows:

It is assumed that coil L1 is in circuit by way of the terminal A1. As long as the closed part of the shielding disk 4 is between the coils L1 and L3, there exists no feedback. Depending on the values of the resistors R36, R37, R38 and R39, the transistor T15 carries a small collector current determined by the emitter-base potential. If the slot of the shield disk 4 passes between the coils L1 and L3, there develops a rectified altemating current between the emitter and the baseas a result of the feedback arising between them. As a con-' sequence the bias of the base and thereby the-collector current increases. As a result the internal resistance of the circuit between the terminals A1 and A3 decreases and the initial current increases producing a voltage drop across the aforementioned 1,000 ohms resistor R40 preceding the terminal A3. This voltage drop can be utilized as the signal-for the passage of the slot of the shield and for the instant operating position of the sewing machine in the same manner as with a contact synchronizer. In operation, a small emitter current flows through coil L1 when terminal A1 is connected to the source of direct current. When the slot of the shield disk 4 appears between coils L1- and L3, the flux from coil Ll induces a voltage in coil L3 which causes resonance circuit L3 C9 to oscillate, thereby producing an oscillator signal between the emitter and the base of transistor T15. This causes amplified oscillations in the emitter-collector circuit, so that the oscillations rapidly build up due to the positive feedback from coil L1 to coil L3. When the shielding disk 4 again blocks coupling between coils L1 and L3, the circuit stops oscillating. Coils L1 and L2 are, therefore, the flux producing means, and coil L3 is the sensing means. However, only one of the coils L1 and L2 and the corresponding shielding disks 4 and 5 are operative at one time, depending on the connection of terminals A1 and 'th the d. .s cc. ril same oger ti ons take place when the coil L2 is connected by way of terminal A2 to the positive pole of the direct current source and the shield disk 5 passes with its slot between the coils L2 and L3.

Having now described the invention, what I desire to protect by Letters Patent of the United States is set forth in the appended claims.

I claim:

1. In a synchronizer having two rotatable position indicators for different control functions, the combination of an rotary shaft supporting said indicators coaxi ally in laterally spaced and rotatably adjustable relation to each other, energy flux producing means fixedly positioned at the axially outer sides, respectively of said position indicators, said indicators being operable upon rotation thereof to control passage of said energy flux therethrough, sensing means fixedly positioned intermediate, said indicators and responsive to said passage of said energy flux through said indicators; and an electrical circuit controlled by said sensing means to produce signal outputs in response to rotation of said position indicators, said energy flux producing means being magnetic coils and said position indicators being magnetic shield disks having radial slots, respectively, for the passage of magnetic flux from said coils through said disks to said sensing means.

2. A synchronizer in accordance with claim 1, where said magnetic coils are components of an oscillator circuit having a feedback field in which said magnetic shield disks rotate.

3. A synchronizer in accordance with claim 2, where said slots are displaced relative to one another.

4. Synchronizer in accordance with claim 3, where said oscillator circuit includes a transistor.

5. Synchronizer in accordance with claim 4, where said oscillator circuit includes a potential divider provided with a first hot conductor constituting a temperature compensator.

6. Synchronizer in accordance with claim 5, including a capacitive circuit branch serving as a high frequency bridge for a plurality of potential dividers and including a second hot conductor for temperature compensation.

' UNITED STATES PATENT OFFICE QETIMCATE OF CORREQHQN Patent No.j,685,294 I I Dated AUg'LlSt 8, 1972 Inventor 3) H8118 G88.

' It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Signed and sealed this 19th day of December 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,IJR. Attesting Officer ROBERT GOTTSCHALK Commissioner of Patents USCOMM-DC 60376-P69 h us. GOVERNMENT FFHNYING OFFICE: I969 o-aes-gsa FORM PO-105O (10-69) UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIQN Paterit No. Dated Aug-rust 8, 1/72 Inventor( s HElYlS 08.8.

It is celftified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Signed and sealed 'this 19th day of December 1972.

(SEAL) Attest:

EDWARD M.FLETCHER, JR. Attesting Officer ROBERT GOTISCHALK Commissioner of Patents 7 v USCOMMDC 60376-1 69 U.S. GOVERNMENT PRINTING OFFICE 1 I969 O-366-33fl FORM PO-105O (10-69)

Claims (6)

1. In a synchronizer having two rotatable position indicators for different control functions, the combination of a rotary shaft supporting said indicators coaxially in laterally spaced and rotatably adjustable relation to each other, energy flux producing means fixedly positioned at the axially outer sides, respectively of said position indicators, said indicators being operable upon rotation thereof to control passage of said energy flux therethrough, sensing means fixedly positioned intermediate, said indicators and responsive to said passage of said energy flux through said indicators; and an electrical circuit controlled by said sensing means to produce signal outputs in response to rotation of said position indicators, said energy flux producing means being magnetic coils and said position indicators being magnetic shield disks having radial slots, respectively, for the passage of magnetic flux from said coils through said disks to said sensing means.

2. A synchronizer in accordance with claim 1, where said magnetic coils are components of an oscillator circuit having a feedback field in which said magnetic shield disks rotate.

3. A synchronizer in accordance with claim 2, where said slots are displaced relative to one another.

4. Synchronizer in accordance with claim 3, where said oscillator circuit includes a transistor.

5. Synchronizer in accordance with claim 4, where said oscillator circuit includes a potential divider provided with a first hot conductor constituting a temperature compensator.

6. Synchronizer in accordance with claim 5, including a capacitive circuit branch serving as a high frequency bridge for a plurality of potential dividers and including a second hot conductor for temperature compensation.

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