Monitor for knitting machines

A portable monitor unit for knitting machines and particularly suitable for circular knitting machines including a yarn speed sensor pulsing a numeral display counter via a gate, a needle detector controlling the gate via a settable counter, a frequency meter, and a switch for selectively engaging the signals of the yarn sensor, needle detector and frequency meter to display yarn length per needle stitch, yarn length per unit time, and rpm of the knitting machine.

BACKGROUND OF THE INVENTION 
The present invention relates to the monitoring of knitting units and is 
concerned, more particularly, with the sensing and comparison of multiple 
parameters in circular knitting units. 
BRIEF DESCRIPTION OF THE PRIOR ART 
Various procedures have been employed in the monitoring of knitting units 
to an indication of the nature of the actual knit with regard to a desired 
norm. 
For example, a given knitting operation will consume a predetermined length 
of yarn in a preselected number of stitches per unit length of the knitted 
product. Deviations from these norms or parameters produce variations in 
the quality of the knit and, therefore, provide sensible or measurable 
bases for monitoring the quality of the knit. 
This sensing or measuring has been accomplished in several ways which, 
however, have been complex and typically have required permanent 
association of the sensors with the knitting unit. Therefore, prior units 
have greatly increased the cost of multiple-unit knitting installation and 
have added undesirable complexity and volume or bulk in such 
installations. These problms are particularlly evident in 
circular-knitting installations. 
The prior monitoring procedures have involved a variety of measuring steps 
for determining the yarn input and the stitch count. Tachometers have been 
used to indicate the speed of the knitter for auging the stitch rate. 
Stroboscopes have been conveniently employed for circular knitters. 
The yarn rate has been sensed by tachometers or by measured and marked 
lengths of yarn. One system employs electrostatic marking of the yarn, at 
spaced points along its length. 
The quality of the knit may then be determined in terms of the length of 
yark consumed in forming a predetermined number of stitches and in 
comparison with the desired norms. 
French Pat. No. 2,038,483 discloses a yarn-monitoring system including a 
yarn feeder having a rotating disc with alternating dark and light 
sections, and a reader for transforming the resultant light pulses into 
electrical pulses. A microcontact in engagement with a rotating element of 
the machine delivers a simple pulse per revolution, which pulses are 
accumulated in a counter serving a function selector. The feeder signals 
are amplified and formed and delivered via an integrating meter to an 
intermediate unit connectable with the counter. A control circuit is 
provided in parallel with the intermediate element to control the cycling 
of pulses from the feeder. 
This yarn-measuring system has proven effective, with an accuracy involving 
only a 1% margin of error. However, such systems involve a great deal of 
elaboration of the intallation since elements functional to the sensor 
system must be incorporated in each unit. Also, additional sensing means 
are necessary to achieve complete monitoring of the operation. 
Therefore, prior knitting monitors have not been found to be entirely 
satisfactory, particularly for circular knitting installations. 
SUMMARY OF THE INVENTION 
In general, the preferred form of the present invention comprises a 
portable monitoring unit including a yarn sensor for delivering a fixed 
number of yarn pulses per unit of yarn length, a gate for receiving the 
yarn pulses for delivery to a numeral display, a needle detector for 
delivering needle pulses to a counter, and switch means for connecting the 
yarn sensor and the needle detector to the gate. Preferably, the 
monitoring unit includes a frequency meter and the switch means includes 
means for selectively delivering the yarn pulses and the needle pulses 
through the gate for an interval set by the frequency meter. 
OBJECTS OF THE INVENTION 
It is an object of the present invention to provide a portable monitor unit 
for knitting machines. 
It is another object of the present invention to provide a portable monitor 
unit for circular knitting machines which is capable of use with a 
plurality of machines without requiring complication of the structure of 
the individual machines. 
It is a further object of the present invention to provide a portable 
monitor unit for circular knitting machines which is capable of indicating 
the relationship between the number of knit stitches and the length of 
yarn consumed in the stitches. 
It is another object of the present invention to provide a portable monitor 
unit for circular knitting machines which is capable of indicating the 
rate of yarn consumption of the machine. 
It is another object of the present invention to provide a portable monitor 
unit for circular knitting machines which is capable of indicating the 
rotational speed of the machine. 
Another object of the present invention is the provisions of a portable 
monitor unit for circular knitting machines which is capable of 
indicating, selectivley, the linear yarn consumption for a selected number 
of stitches, the linear speed of the yarn, and the rpm of the knitting 
machine.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
As shown in the drawing, the preferred form of monitor unit includes a 
yarn-sensor circuit Y, a needle-detector circuit N, a timer circuit T, a 
selector switch S, and a display D. The several components are mounted in 
any suitable casing for transport between knitting machines. 
The yarn-sensor circuit Y includes a suitable yarn-engaging unit 10 which 
emits a fixed number of pulses per unit length of the travelling yarn it 
engages. The yarn-engaging unit 10 may be of any of several types, as may 
be desired. Most conveniently, the unit 10 includes a pulley 11, which is 
simply presented against the running yarn. The pulley has a reflective 
face carrying two diametrically-opposed, non-reflective black marks. Light 
from a bulb and reflected toward a photodiode (not shown) thus provides 
two pulses for each revolution of the pulley. The pulses from the unit 10 
are supplied, via a suitable amplifier 14, to a divider 15. 
Ideally, the pulley circumference engaging the yarn is 33.333 mm, so that 
three revolutions of the pulley (over a 100 mm length of the yarn) will 
provide 6 pulses per meter of yarn. This pulse rate per unit of yarn 
length is especially advantageous, as will be discussed hereinafter 
regarding operation of the monitor unit. 
The divider 15 is connected to a contract y1 in the switch assembly S. A 
branch line 16 bypasses the divider 15 and is connected to a contact y2 in 
the switch. 
The needle-detector circuit N includes a detector 17 which emits pulses, 
via a suitable amplifier 18, to a selective counter 19. Preferably, the 
detector 17 is a tunable stroboscope or a suitable optoelectronic unit 
employing fiber optics and avoiding contact with the needles. 
The counter 19 is connected to two contacts n1 and n3 in the switch 
assembly S. Preferably, the counter is set for 100, with one pulse being 
emitted for each needle, or a duration of 100 needles if the pulse rate is 
other than one per needle. 
The timer circuit T includes a time signal generator 20, preferably of the 
quartz crystal type, and a divider 21 to provide a signal duration of one 
second at contacts t2 and t3 in the switch assembly S. 
The switch assembly S includes a moveable arm 22 carrying a pair of 
contacts 23 and 24 in communication with a gate 25. The output of the gate 
25 is supplied to the numerical display unit D. 
OPERATION OF THE PREFERRED EMBODIMENT 
When it is desired to compare the yarn length consumed to the selected 
number of stitches, the switch is positioned as shown in the drawing with 
contact 23 closing on contact y 1 and gate-control contact 24 closing on 
contact n1. The monitor is then presented to the machine to be monitored, 
with the pulley 11 in driving contact with the yarn and the needle 
detector 17 associated with the needle bank. Yarn pulses are then 
delivered via the amplifier 14, divider 15 and the gate 25 for the 
duration of 100 stitches, as gauged by the passage of 100 needles. 
The needle pulses are delivered via the amplifier to the counter, which is 
set to hold the gate 25 open for that count. Upon closing of the gate 25, 
the total displayed on the display unit may be read directly as 
millimeters per 100 stitches, in view of the 33.333 mm pulley, the two 
pulses per rpm and the "6" divider 15. Other ratios may be provided, 
however, if it is desired. 
However, the preferred relationship is of advantage when it is desired to 
monitor the linear yarn speed alone. The switch is then moved to engage 
contacts y2 and t2, to provide yarn pulses through the gate under control 
of the signal of the frequency meter and divider via contacts t2 and 24. 
Since the pulley makes three revolutions per meter of yarn, a yarn speed of 
100 meters/mm will provide 6000 pulses per minute to the branch line 16 
and the contact y2 and 23 to he gate and counter display D. With the 
frequency meter circuit set for a duration of one second, the yarn speed 
is then directly displayed in meters/min. 
When it is desired to determine the rotary speed of the knitting machine, 
the switch is moved to close with contacts n3 and t3. With the stroboscope 
tuned to the rate of passage of the needles and the frequency meter 
duration remaining at one second, the rpm of the machine may be calculated 
with the formula: 
##EQU1## 
The duration of the count, as governed by the frequency meter, may be 
selected for a period other than 1 second. The formula would then require 
a corresonding adjustment. 
Therefore, it is apparent that the present invention provides a 
particularly advantageous monitor unit which is both portable and 
versatile and which will provide a full operating check of several 
machines in succession. This is accomplished without the need for 
complication of each of the several knitting machines with components 
useful only for the monitoring procedure. 
Various changes may be made in the details of the invention, as disclosed, 
without sacrificing the advantages thereof or departing from the scope of 
the appended claims.