US3906752A

US3906752A - Latch detector stop motion system for circular knitting machines

Info

Publication number: US3906752A
Application number: US449066A
Authority: US
Inventors: Peter C Eichhorst
Original assignee: Individual
Current assignee: Individual
Priority date: 1974-03-07
Filing date: 1974-03-07
Publication date: 1975-09-23
Anticipated expiration: 1992-09-23
Also published as: IT1011348B; BR7407416A; AU6955174A; NL7405544A; FR2263326A1; CH582263A5; GB1406598A; FR2263326B1; ES427393A1; JPS50118056A; DE2427079A1; CA995335A

Abstract

A latch detector stop motion system for circular knitting machines, including an electrically conductive contact probe connected to one input of one of a pair of NAND gates crossconnected as a bistable flip-flop which is set by application of supply voltage to the flip-flop to provide a high voltage state at the output and changes state responsive to contact of the probe with a closed needle latch to provide a low voltage state at the output which activates a gate and relay driver transistor to energize a stop motion relay.

Description

United States Patent Eichhorst 1 Sept. 23, 1975 15 LATCH DETECTOR STOP MOTION 3,659,437 5/1972 McArthur et a1 66/157 SYSTEM FOR CIRCULAR KNITTING 3,690,127 9/1972 Tellerman et a1 66/157 3,731.205 5/1973 Gardner 307/215 x MACHINES Peter C. Eichhorst, 302 Shady Dr., lnman, S. C. 29349 Filed: Mar. 7, 1974 Appl. No.: 449,066

Inventor:

References Cited UNITED STATES PATENTS Primary ExaminerWm. Carter Reynolds Attorney. Agent, or Firm-Mason, Fenwick & Lawrence [57] ABSTRACT A latch detector stop motion system for circular knitting machines, including an electrically conductive contact probe connected to one input of one of a pair of NAND gates cross-connected as a bistable flip-flop which is set by application of supply'voltage to the flip-flop to provide a high voltage state at the output and changes state responsive to contact of the probe with a closed needle latch to provide a low voltage state at the output which activates a gate and relay driver transistor to energize a stop motion relay.

13 Claims, 4 Drawing Figures US Patent Sept. 23,1975 Sheet 1 0f 2 US Patent Sept. 23,1975 Sheet 2 01 2 3,906,752

LATCH DETECTOR STOP MOTION SYSTEM FOR CIRCULAR KNITTING MACHINES BACKGROUND AND OBJECTS OF THE INVENTION The present invention relates in general to stop motion devices having latch detectors for circular knitting machines, and more particularly to devices for undesired closed needle latches on the needles of circular knitting machines during operation of the knitting machine with great speed and high reliability without requiring application of mechanical force to the latch engaging member for producing a signal indicating a closed latch.

During the operation of circular knitting machines, the cylinder needles are moved along a circular path by the rotating cylinder and are raised and lowered in accordance with the settings of cams on the knitting machine in the path of travel of the needle butts to bring the needles out at the feed position to receive the yarn in the needle hook, after which the needles are withdrawn back to their normal knitting positions for movement around the remainder of the circular path defined by the needle cylinder. During operation of the knitting machine, each individual needle latch is opened and closed in a prearranged order so as to form a new loop or stitch. Normally, in the highest position of the needle, where the yarn is caught by the needle hook, the latch is in open condition, and if for any reason the latch is closed or partly closed at this position instead of remaining open, an irregularity or fault is produced in the knitted fabric. Also, the fact that the latch is closed at the high position of the needle when it should normally be opened may be the result of yarn breakage, as well as other faulty conditions, any of which cause the fabric being knitted thereafter to be damaged or faulty.

Heretofore, various types of electric stop motions have been employed on knitting machines involving a latch detector or feeler which is operatively connected to an electrical switch or the like, wherein mechanical force is required to move the detector contact or feeler member to a position contacting a stationary conductive element for completing an electrical circuit therethrough for tripping a relay to stop the knitting machine. In such an arrangement, the detector member or feeler must be mechanically contacted and forced to an abnormal position by engagement with the closed needle latch to achieve closed latch detection; With this type of device involving mechanically forced displacement of the feeler device to an abnormal position by engagement with the closed latch, there is necessarily some delay in stopping the machine dueto the delay in translation of the feeler member from the normal to the abnormal position and transmitting the motion through the detector to the switch. Also there are problems of adjustment of the detector relative to the electrical switch and adjustment of the electrical switch itself. It is desirable to detect the faulty condition, indicated by the needle latch being in closed position, with the utmost speed and highest reliability, and to-achieve stopping of the knitting machine withminimum delay upon detection of the closed latch, in order to minimize the amount of faulty or damaged fabric which will be produced.

An object of the present invention is the provision of.

a reliable stop motion closed latch detector for circular knitting machines which does not require mechanical translatory movement of the contact probe or feeler by the closed latch to achieve closed latch detection and which provides electrical current to activate a stop motion relay which in turn interrupts the supply to the motor operating the knitting machine to stop rotation of the needle cylinder.

Another object of the present invention is the provision of the novel stop motion device for detecting closed needle latches in the needles of circular knitting machines which overcomes disadvantages of prior art stop motion devices requiring mechanical force to move the contact member and effect closure of an electrical circuit, the novel stop motion device being operative by merely establishing an electric current path to ground through the closed needle latch and knitting machine frame when the contact probe or feeler engages the closed latch, thereby avoiding variations in the speed of activation of a stop motion relay which may arise due to variation in mechanical force applied to latch engaging members of the prior art mechanical stop motion devices and avoiding unnecessary damage to the needle latches.

Another object of the present invention is the provisions of a stop motion device for detecting closed or partially closed latches of needles in circular knitting machines wherein a contact probe is electrically grounded through the knitting machine frame upon engagement with a closed needle latch and activate a pair of cross connected NAND gates forming a bistable flipflop circuit to produce an output signal for activating a stop motion relay in a most reliable and rapid manner, and which may be arranged in a highly compact physical unit readily capable of placement in limited spaces on circular knitting machines.

Another object of the present invention is the provision ofa stop motion device for detecting closed needle latches at the yarn feed stations of a circular knitting machine, which device relies on very low supply voltage and low current minimizing electrical shock hazzards to the knitting machine operator.

Other objects, advantages and capabilities of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawing illustrating a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE FIGURES FIG. I is a diagrammatic view illustrating a pair of latch detectors each adjacent a needle of an associated set of needles, such as cylinder and dial needles, of a circular knitting machine, and connected to a power supply and relay control unit;

FIG. 2 is a schematic diagram illustrating the electrical circuit of the needle latch detector shown adjacent a diagrammatically indicated needle of a knitting machine;

FIG. 3 is a top plan view of a needle detector embodying the present invention, showing the physical configuration thereof moved from the housing shell; and

FIG. 4 is a side elevation view of the latch detector, viewed from below FIG. 3.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT While the needle latch detector of the present invention can be used with knitting devices other than circular knitting machines, it will be described, by way of example, in association with a circular knitting machine having a rotating needle cylinder, not shown, provided with a plurality of vertically or axially extending channels or needle grooves in the outer surface of the cylinder. ln such a machine, the cylinder needles in the grooves are raised and lowered in accordance with the shape of a stationary cam track defined by the usual cams of the circular knitting machine, whereby the cam track received the needle butts and raises the needles by action of the cam surfaces on the butt of each cylinder needle. As the latch detector is designed to monitor the condition of the needle latches to be sure that the latch is opened when the needle reaches the highest position immediately prior to taking the new yarn into the hook of the needle, the latch detector is conventionally located at a test station near the yarn feed station where the cylinder needles are brought up or raised to the yarn feed position. It will be appreciated that the cams for the cylinder needles provide an upwardly inclining ramp surface along the cam track whereby the needles progressively rise from a lower knit position to a higher feed position where the yarn is introducted into the hook of each needle as the cylinder progressively rotates. The normal position for the cylinder needle latch detector of the present invention is such that the contact probe or conductor wire of the latch detector terminates immediately below the end of the hook of the needles just before they reach the top of the upwardly inclined approach to the yarn feed position. If the latches are in their proper open positions, shown in H6. 1,-as they approach and move through the test station, they move along what may be termed their normal path and do not engage the contact probe. If the latch of any of the needles is in closed position at the test station, the latch then moves along what may be called an abnormaLpath and momentarily engages the contact probeslf the cylinder needles are raised at several feed locations about the periphery of the cylinder, then latch detectorsmay be provided adjacenteach of the feed positions. Also, if the circular knitting machine is of the. type having dial needles as well as cylinder needles,-a latch detector or detectors are also provided im- -mediately in advance of the feed position where the dial needles take the yarn, so as to monitor the condition of the dial needle latches.

The system of needle latch detectors embodying the present invention is diagrammatically illustrated in FIG. 1, wherein latch detectors indicated generally at and 11 have probes l2 and 13 in the paths of closed latches of the cylinder needles l4 and dial needles 15 respectively. The probes are disposed at locations where the probes will not engage any open latches moving along their normal paths but will momentarily engage any closed latch moving along the aforementioned abnormal path. It will be understood that a single latch detector may be used, if the circular knitting machine has only cylinder needles, brought up at a single feed position and no dial needles, or that plural latch detectors of like construction corresponding to the number of yarn feed positions present will be used if there is more than one feed position for the cylinder needles or if both cylinder needles and dial needles are present. The latch detectors l0 and 11 diagrammatically shown in FIG. 1 include a housing shell 16 which in the illustrated embodiment has a tapered conical capacitor C-l, a current limiting resistor R-3, a driver nose at one end thereof from which the

probe

12 or 13 projects, and has an indicator lamp 17 at the opposite end thereof to be illuminated and provide a visual indication when a closed latch has been detected. Conductor wires, indicated at 18, from the latch detector or detectors 10, 11 are connected to a power supply, which in the preferred embodiment is a conventional 5 volt regulated power supply, indicated by the reference character 19, and other electrical conductor leads 20 connect the latch detector or detectors l0, 11 to a relay control unit 21 indicated in block diagram form in FIG. 1.

The physical construction of a preferred embodiment of the latch detector is illustrated in FIGS. 3 and 4, wherein the latch detector is indicated generally by the reference character 10, and comprises a printed circuit board or panel of thin rectangular configuration, indicated by the reference character 25, formed in the usual manner of an insulating substrate and photo etched patterns of conductive layer or coating material thereon, on which is mounted the contact probe which has the form of a conductor wire 26 which in the preferred embodiment has a coil spring configuration indicated at 26a on the inner neck portion adjacent the mounting head formation 26!; by which it is secured to the printed circuit board 25. The outer free end or tip 26c of the probe is to be positioned relative to the cylinder needle or dial needle immediately below or inwardly of the tip of the hook on the needle at the location normally occupied by the needle latch as it moves .in closed position along the abnormal path, in the region of the needle path about the circular knitting machine cylinder where the needle is immediately approaching the feed position where the hook takes the yarn. Also mounted on the rigid printed circuit board v25 is a small rectangular integrated circuit module or member 27 forming a pair of NAND gates, to be later described, which is preferably a Texas Instruments SN- 7400 TTL, as well as a pair of resistors R-1 and R-2, a

transistor 0-1, and an indicator lamp 17. It will be noted that all of the electronic components of the latch detector unit are conveniently and compactly sup ported and arranged on the printed circuit board 25 providing a detector assembly of such small size as to be readily mountable in the limited space available adjacent the needle path on circular knitting machines.

Referring now to FIG. 2 showing the schematic diagram of the latch detector circuit, the latch detector may generally be described as basically a bounceless switch", which automatically sets itself into the off state after the power has been applied, and when a closed latch of the needles being monitored touches the contact probe 26, the output from the units switches from 0 or low state to the l or high state, providing an output signal to be processed to energize the stop motion relay. The power supply must be interrupted in order to reset the bounceless switch" of the circuit once it has been set by contact with a closed latch.

As will be apparent from inspection of FIG. 2, illustrating the latch detector assembly 10 adjacent the feed position of the cylinder needles 14, the contact probe 12 which is engaged by the needle latch if the latch moves along the abnormal path in closed position is electrically connected to the pin 1 of the NAND gate 1 section G-l, forming part of the SN-7400 TTL integrated circuit unit 27, and the probe and pin 1 of NAND gate G-l are also connected through resistor R-l to the +5 volt supply terminal of power supply 19. The NAND gate G2 associated with

pins

4, 5 and 6 of the SN7400 TTL integrated circuit unit 27 has its pin 5 connected through the K ohm resistor R-2 to the +5 volt supply and through the capacitor C'l to ground. The two outputs and inputs of the NAND gates G-1 and G-2 are cross connected, in the manner illustrated in FIG. 2, in such a way that the resulting circuit acts as a bistable or RS flip-flop.

Each of the NAND gates G-1 and 6-2 form a separate circuit which requires a voltage in the order of 3.0 volts or higher on its two inputs in order to change its output state from a high voltage to a low logic voltage state of less than 0.8 volts. If any of the inputs to either NAND gate, for example the inputs at

pins

1 or 2 of NAND gate G-] or the inputs at pins 4 or 5 of NAND gate G-2, changes to a low logic voltage state (less than 0.8 volts), this causes the particular output to change its state to a high voltage. The logic condition of the outputs of this bistable or RS flip-flop is determined both by the instantaneous and the prior condition of its inputs. 1n the particular application here disclosed provided by the cross connected NAND gates, the bistable flip-flop has been modified in such a way that the output at pin 3 of the NAND gate 6-1 will change to the low state shortly after supply voltage is being applied to the latch detector circuit. This is accomplished by capacitor C-l, resistor R-2 and NAND gate G-2. Upon initial power supply turn-on, capacitor C-l becomes charged at a rate determined by the resistor R-2 and the input current from NAND gate G-2. During the charge time (determined by the value of capacitor C-1 and resistor R-2) the logic state of input 5 of NAND gate 6-2 will relatively slowly change from the low logic state to the high state. The very action of holding the input at pin 5 of NAND gate G-2 low for a short period of time causes the output at pin 6 of NAND gate G-2 to change to the high state. The output at pin 6 of NAND gate 6-2 is connnected with the input pin 2 of NAND gate 6-1. At the very moment the change of the output at pin 6 from the low to the high state takes place, the output at pin 3 of NAND gate G4 is changing to the low state because high voltage was present on both inputs at

pins

1 and 2 of NAND gate G-l.

The input at pin 1 of NAND gate (5-1 is held high at all times by the resistor R-l except when the contact probe 12 touches a closed latch, which forces the voltage level at input pin 1 of gate G-l immediately to ground during the moment of contact.

The ground connection of all the latch detectors associated with the knitting machine and the ground connection of the power supply are connected to the knitting machine frame. When the

contact probe

12 or 13 momentarily touches a closed latch of a needle in the group of needles being monitored, the input at the pin 1 of NAND gate 6-1 is momentarily held down to ground level, so that the bistable flip-flop formed by the cross connected NAND gates G-1 and G-2 changes state, causing the output at pin 3 of NAND gate 6-1 to go high, thus causing the transistor Q-l, which may be a 2N 1613 transistor, to conduct, as the base of the transistor is connected through the resistor R-3 to the pin 3 of gate G-l. Conduction through the transistor Q-l applies the supply voltage from the 5 volt power supply through the indicator lamp 17 connected to the collector of transistor Q-l, producing a visual indication that a closed latch has been detected. At the same time, the output from the pin 6 of the gate G-2 changes to the low state because of the change at pin 3 of gate G-l to the high state upon closed latch detection, and this change to the low state of the output pin 6 of gate (3-2 is coupled to one of the inputs of NAND gate G-3, as indicated in the drawings, causing the output of the gate 6-3 to go high. This change to the high state of the output of NAND gate G-3 caused by one of its inputs becoming low, is coupled through resistor R-4 to the transistor Q2, causing this transistor to conduct, this applying current through the coil 28 of motor relay RE-l to energize the relay and open the supply to the knitting machine motor so as to stop the knitting machine. The other inputs-to the NAND gate G-3 are connected to the pin 6 output of the NAND gate G-2 of each additional latch detector in the system, monitoring the needles at the remaining points where they are brought out to feed yarn to them, so that detection of a closed latch at any of the monitoring stations will cause the output of the NAND gate G-3 to go high and cause transistor Q-2 to conduct and activate the motor relay RE-l.

The latch detector circuit will remain in this activated state with the transistor Q-2 conducting and the motor relay energized to break the supply circuit to the knitting machine motor until either the knitting machine is manually turned off or the operator starts up the knitting machine again, which will remove the supply voltage from the circuit whereupon the charge developed across the capacitor C-l leaks'off and input 5 on NAND gate G-2 returns to ground potential. Releasing of the start button for the machine will again apply supply voltage as previously described, resetting all of the latch detectors without any specific action by the operator. I v

What is claimed is: v

1. A stop motion device for detecting closed needle latches of needles moving through a test station near a yard feed station in a circular knitting machine wherein the needles and their latches conductively communicate with electrical ground and the latches in the region of said test station move along a normal path when in open position and move along an abnormal path when in undesired closed position, comprising a normallyungrounded electrically conductive contact probe disposed adjacent said test station at a location along said abnormal path to conductively contact any closed latch and momentarily establish an electrical grounding path from the probe through the closed latch, a bistable flipflop circuit having first and second input terminals, the first input terminal being connected to said probe to be momentarily connected directly to ground through the probe and closed latch when the probe contacts a closed latch, said flip-flop circuit having connection means including means connecting supply voltage to the first input terminal to set the flip-flop circuit upon application of supply voltage thereto to a ready first state wherein a normal first voltage state is provided at an output thereof and wherein the flip-flop is conditioned to respond to momentary connection of its first input terminal to ground to shift the flip-flop to.a second state causing said output to instantaneously change to a second voltage state, and a 'relay control circuit including a relay for stopping the knitting machine and circuit connections to said flipflop output responsive to occurrence of said second voltage state to activate the relay to stop the knitting machine.

2. A stop motion device for detecting closed needle latches as defined in claim 1, including a normally nonconducting lamp controlling transistor connected to an indicator lamp to regulate current flow therethrough and connected to a second output of said flip-flop circuit to energize said indicator lamp when said probe contacts a closed latch.

3. A stop motion device for detecting closed needle latches as defined in claim 1, including a DC supply voltage source, said flip-flop circuit having said second input terminal connected through a resistor to said supply voltage source and through a capacitor to ground, and said first input terminal being maintained at a predetermined positive DC voltage level when said probe is not in contact with an electrically grounding conductor to coact with the voltage condition on said second input terminal to maintain said flip'flop circuit in said first state.

4. A stop motion device for detecting closed needle latches as defined in claim 1, wherein said bistable flipflop circuit comprises a pair of NAND gates each having a pair of inputs and an output, one input of a first one of said NAND gates forming said first input termi nal and being connected to said probe and through a resistor to a supply voltage source and an input ofa second one of said NAND gates forming said second input terminal and being connected through a resistor to said supply voltage source and through a capacitor to ground and the remaining inputs of said NAND gates being cross-connected to the output of the other NAND gates, and said output of said flipflop being the output of the second of said NAND gates.

5. A stop motion device for detecting closed needle latches as defined in claim 3, wherein said bistable flipflop circuit comprises a pair of NAND gates each having a pair of inputs and an output, one input of a first one of said NAND gates forming said first input terminal and being connected to said probe and through a resistor to said supply voltage source and an input of a second one of said NAND gates forming said second input terminal and being connected through said first mentioned resistor to said supply voltage source and through said capacitor to ground and the remaining inputs of said NAND gates being cross-connected to the output of the other NAND gates, and said output of said flip-flop being the output of the second of said NAND gates.

6. A stop motion device as defined in claim 1 including gate means having a plurality of inputs and an output, means connecting one of said inputs to the output of said flip-flop circuit and the other inputs of said gate means being adapted to be connected to the similar output of similar flip-flop circuits of additional like closed latch detectors, and said relay control circuit including a normally non-conducting relay driver transistor controlling current flow through the winding of said relay and connected to the input of said gate means to conduct and activate said relay upon application of said second voltage state to any of the inputs of said gate means.

7. A stop motion device as defined in claim 5 including gate means having a plurality of inputs and an output, means connecting one of said gate inputs to the output of said flip-flop circuit and the other inputs of said gate means being adapted to be connected to the similar output of similar flip-flop circuits of additional like closed latch detectors, and said relay control circuit including a normally non-conducting relay driver transistor controlling current flow through the winding of said relay and connected to the input of said gate means to conduct and activate said relay upon application of said second voltage state to any of the inputs of said gate means.

8. A stop motion device for detecting closed needle latches of needles moving through a test station near a yarn feed station in a circular knitting machine wherein the needles and their latches conductivcly communicate with electrical ground and the latches in the region of said test station move along a normal path when in open position and move along an abnormal path when in undesired closed position, comprising a normally ungrounded electrically conductive contact probe disposed adjacent said test station at a location along said abnormal path to conductivcly contact any closed latches and momentarily establish an electricaly grounding path from the probe through the closed latch, a bistable flip-flop circuit formed of a pair of cross-connected NAND gates each having a pair of inputs and an output, one input of a first one of said NAND gates forming a first input terminal for the flipflop circuit connected to said probe to be momentarily connected directly to ground through the probe and closed latch when the probe contacts a closed latch, connecting means including connections between said NAND gates and including means connecting supply voltage to said first input terminal to initially set the flip-flop circuit to a ready first state wherein a normal first voltage state is provided at the output of said second NAND gate and wherein the flip-flop is conditioned to respond to momentary connection of said first input terminal to ground by probe engagement with a closed latch to shift the flip-flop to a second state causing said output of the second NAND gate to instantaneously change to a second voltage state, and a relay control circuit including a relay for stopping the knitting machine and circuit connections to the output of said second NAND gate responsive to occurrence of said second voltage state to activate the relay to stop the knitting machine.

9. A stop motion device for detecting closed needle latches as defined in claim 8, wherein each of said NAND gates respond to predetermined low and higher input voltage levels to determine the output voltage states thereof, and said connecting means includes a resistor connected between said first input of said first NAND gate and said supply voltage to immediately apply a higher input voltage level to said first input upon initial application of supply voltage to the flipflop circuit, and the connecting means further including means for momentarily applying a low input voltage level to the second input of the second NAND gate causing its output to apply a higher input voltage level to the first NAND gate to cause the flip-flop to be set and maintained in said ready first state until the probe is electrically grounded by engagement with a closed latch.

10. A stop motion device as defined in claim 8, including gate means having a plurality of inputs and an output, means connecting one of said inputs to the output of the second one of said NAND gates and the other inputs of said gate means being adapted to be connected to the similar output of similar flip-flop circuits of additional like closed latch detectors, and said relay control circuit including a normally nonconducting relay driver transistor controlling current flow through the winding of said relay and connected to the output of said gate means to conduct and activate said relay upon application of said higher voltage state to any of the inputs of said gate means.

11. A stop motion device as defined in claim 9, including gate means having a plurality of inputs and an output, means connecting one of said inputs to the output of the second one of said NAND gates and the other inputs of said gate means being adapted to be connected to the similar output of similar flip-flop circuits of additional like closed latch detectors, and said relay control circuit including a normally nonconducting relay driver transistor controlling current flow through the winding of said relay and connected to the output of said gate means to conduct and activate said relay upon application of said higher voltage state to any of the inputs of said gate means.

12. A stop motion device as defined in claim 10, including a normally non-conducting lamp controlling transistor connected to an indicator lamp to regulate current flow therethrough and connected to the output of the first one of said NAND gates to energize said indicator lamp when said probe contacts a closed latch.

13. A stop motion device for detecting closed needle latches moving through a test station near a yarn feed station in a circular knitting machine wherein the needles and their latches conductively communicate with electrical ground and the latches in the region of said test station move along a normal path when in open position and move along an abnormal path when in undesired closed position, comprising a normally ungrounded electrically conductive contact probe disposed adjacent said test station at a location along said abnormal path to conductively contact any closed latch and momentarily establish an electrical grounding path from the probe through the closed latch, a bistable flipflop circuit comprising a pair of NAND gates each having a pair of inputs and an output, one input of the first one of said NAND gates being connected to said probe and through a resistor to a supply voltage source and an input of a second one of said NAND gates being connected through a resistor to the supply voltage source and through a capacitor to ground and the remaining inputs of said NAND gates being crossconnected to the output of the other NAND gate whereby the flip-flop circuit is automatically set to a first state upon application of supply voltage to the flipflop circuit providing a normal first voltage state at the output of the second NAND gate which first state is maintained until the probe contacts a closed latch and the cross-connections of the NAND gates causing the flip-flop circuit to shift to a second state providing a second voltage state at the output of said second NAND gate upon momentary grounding of the probe by contact with the closed latch, and a relay control circuit including a relay for stopping the knitting machine and circuit connections to the output of said second NAND gate responsive to occurrence of said second voltage state to activate the relay to stop the knitting machine.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 1 3,906,752

DATED September 23, 1975 lN\/ ENTOR( Peter c. Eichhorst It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 5, line 7, "two outputs and inputs of the" should read outputs and inputs of the two-.

Column 5, line 14, "high voltage" should read high logic voltage state.

Column 5, line 42, before "from" there should be inserted of NAND gates G2-.

Signed and Scaled this Twentieth Day of July 1976 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner ufParents and Trademarks

Claims

1. A stop motion device for detecting closed needle latches of needles moving through a test station near a yard feed station in a circular knitting machine wherein the needles and their latches conductively communicate with electrical ground and the latches in the region of said test station move along a normal path when in open position and move along an abnormal path when in undesired closed position, comprising a normally ungrounded electrically conductive contact probe disposed adjacent said test station at a location along said abnormal path to conductively contact any closed latch and momentarily establish an electrical grounding path from the probe through the closed latch, a bistable flip-flop circuit having first and second input terminals, the first input terminal being connected to said probe to be momentarily connected directly to ground through the probe and closed latch when the probe contacts a closed latch, said flip-flop circuit having connection means including means connecting supply voltage to the first input terminal to set the flip-flop circuit upon application of supply voltage thereto to a ready first state wherein a normal first voltage state is provided at an output thereof and wherein the flip-flop is conditioned to respond to momentary connection of its first input terminal to ground to shift the flip-flop to a second state causing said output to instantaneously change to a second voltage state, and a relay control circuit including a relay for stopping the knitting machine and circuit connections to said flip-flop output responsive to occurrence of said second voltage state to activate the relay to stop the knitting machine.

2. A stop motion device for detecting closed needle latches as defined in claim 1, including a normally non-conducting lamp controlling transistor connected to an indicator lamp to regulate current flow therethrough and connected to a second output of said flip-flop circuit to energize said indicator lamp when said probe contacts a closed latch.

3. A stop motion device for detecting closed needle latches as defined in claim 1, including a DC supply voltage source, said flip-flop circuit having said second input terminal connected through a resistor to said supply voltage source and through a capacitor to ground, and said first input terminal being maintained at a predetermined positive DC voltage level when said probe is not in contact with an electrically grounding conductor to coact with the voltage condition on said second input terminal to maintain said flip-flop circuit in said first state.

4. A stop motion device for detecting closed needle latches as defined in claim 1, wherein said bistable flip-flop circuit comprises a pair of NAND gates each having a pair of inputs and an output, one input of a first one of said NAND gates forming said first input terminal and being connected to said probe and through a resistor to a supply voltage source and an input of a second one of said NAND gates forming said second input terminal and being connected through a resistor to said supply voltage source and through a capacitor to ground and the remaining inputs of said NAND gates being cross-connected to the output of the other NAND gates, and said output of said flip-flop being the output of the second of said NAND gates.

5. A stop motion device for detecting closed needle latches as defined in claim 3, wherein said bistable flip-flop circuit comprises a pair of NAND gates eacH having a pair of inputs and an output, one input of a first one of said NAND gates forming said first input terminal and being connected to said probe and through a resistor to said supply voltage source and an input of a second one of said NAND gates forming said second input terminal and being connected through said first mentioned resistor to said supply voltage source and through said capacitor to ground and the remaining inputs of said NAND gates being cross-connected to the output of the other NAND gates, and said output of said flip-flop being the output of the second of said NAND gates.

8. A stop motion device for detecting closed needle latches of needles moving through a test station near a yarn feed station in a circular knitting machine wherein the needles and their latches conductively communicate with electrical ground and the latches in the region of said test station move along a normal path when in open position and move along an abnormal path when in undesired closed position, comprising a normally ungrounded electrically conductive contact probe disposed adjacent said test station at a location along said abnormal path to conductively contact any closed latches and momentarily establish an electricaly grounding path from the probe through the closed latch, a bistable flip-flop circuit formed of a pair of cross-connected NAND gates each having a pair of inputs and an output, one input of a first one of said NAND gates forming a first input terminal for the flip-flop circuit connected to said probe to be momentarily connected directly to ground through the probe and closed latch when the probe contacts a closed latch, connecting means including connections between said NAND gates and including means connecting supply voltage to said first input terminal to initially set the flip-flop circuit to a ready first state wherein a normal first voltage state is provided at the output of said second NAND gate and wherein the flip-flop is conditioned to respond to momentary connection of said first input terminal to ground by probe engagement with a closed latch to shift the flip-flop to a second state causing said output of the second NAND gate to instantaneously change to a second voltage state, and a relay control circuit including a relay for stopping the knitting machine and circuit connections to the output of said second NAND gate responsive to occurrence of said second voltage state to activate the relay to stop the knitting machine.

9. A stop motion device for detecting closed needle latches as defined in claim 8, wherein each of said NAND gates respond to predetermined low and higher input voltaGe levels to determine the output voltage states thereof, and said connecting means includes a resistor connected between said first input of said first NAND gate and said supply voltage to immediately apply a higher input voltage level to said first input upon initial application of supply voltage to the flip-flop circuit, and the connecting means further including means for momentarily applying a low input voltage level to the second input of the second NAND gate causing its output to apply a higher input voltage level to the first NAND gate to cause the flip-flop to be set and maintained in said ready first state until the probe is electrically grounded by engagement with a closed latch.

13. A stop motion device for detecting closed needle latches moving through a test station near a yarn feed station in a circular knitting machine wherein the needles and their latches conductively communicate with electrical ground and the latches in the region of said test station move along a normal path when in open position and move along an abnormal path when in undesired closed position, comprising a normally ungrounded electrically conductive contact probe disposed adjacent said test station at a location along said abnormal path to conductively contact any closed latch and momentarily establish an electrical grounding path from the probe through the closed latch, a bistable flip-flop circuit comprising a pair of NAND gates each having a pair of inputs and an output, one input of the first one of said NAND gates being connected to said probe and through a resistor to a supply voltage source and an input of a second one of said NAND gates being connected through a resistor to the supply voltage source and through a capacitor to ground and the remaining inputs of said NAND gates being cross-connected to the output of the other NAND gate whereby the flip-flop circuit is automatically set to a first state upon application of supply voltage to the flip-flop circuit providing a normal first voltage state at the output of the second NAND gate which first state is maintained until the probe contacts a closed latch and the cross-connections of the NAND gates causing the flip-flop circuit to shift to a second state providing a second voltage state at the output of said second NAND gate upon momentarY grounding of the probe by contact with the closed latch, and a relay control circuit including a relay for stopping the knitting machine and circuit connections to the output of said second NAND gate responsive to occurrence of said second voltage state to activate the relay to stop the knitting machine.