GB2236387A

GB2236387A - Opto-electronic width measurement

Info

Publication number: GB2236387A
Application number: GB8920202A
Authority: GB
Inventors: Anton Craig Nielsen
Original assignee: LONRHO TEXTILES Ltd
Current assignee: LONRHO TEXTILES Ltd
Priority date: 1989-09-07
Filing date: 1989-09-07
Publication date: 1991-04-03
Also published as: GB8920202D0

Abstract

The device serves for measuring and particularly for checking, the width of a web of material as it passes through a processing machine and comprises a linear array of spaced sensors 13, each sensor being adapted to indicate the absence or presence of a respective part of a web 10 when the array is held adjacent and transverse the web; and electronic means 19 associated with the sensors arranged to determine the number of sensors which indicate the presence of the web thus to determine the width of the web. Preferably said electronic means is arranged to indicate whether said number is lower than a lower acceptable limit, or higher than a higher acceptable limit. The sensors are preferably infra-red sensitive devices and a respective sensor array is provided for each edge of the web. The arrays may be adjustable in a direction transverse to the web, preferably against a measuring scale to determine the position of the arrays. <IMAGE>

Description

IMPROVEMENTS IN OR RELATING TO WIDTH MEASURING DEVICES This invention relates to a device for measuring and particularly for checking, the width of a web of material as it passes through a processing machine.

While the present invention is described particularly with regard to the measuring and checking the width of a textile fabric web, the invention also finds application in the measurement of other webs such as paper, plastics materials, or even sheet metal material. The invention is also applicable to a hand held device for performing a similar measuring or checking function.

It is an object of the present invention to provide a simple means of monitoring the width of material passing through a processing machine and giving an indication when that width is in or out of a given tolerance range.

Accordingly the present invention provides a device for measuring the width-of a web of material including a linear array of spaced sensors, each sensor being adapted to indicate the absence or presence of a respective part of a web when the array is held adjacent and transverse the web; and electronic means associated with the sensors arranged to determine the number of sensors which indicate the presence of the web thus to determine the width of the web.

Preferably said electronic means is arranged to indicate whether said number is lower than a lower acceptable limit, cr higher than a higher acceptable limit.

Preferably such array is divided into two separate portions each being associated with a respective edge of the web to be measured.

Preferably when the device is associated with a machine handling the web to be measured, each such portion is mounted on the machine to be adjustable in a direction transverse to the web, preferably against a measuring scale, to determine the position of that portion of the array.

Preferably each such portion is individually so adjustable.

Preferably the sensors are infrared sensitive devices and means is provided to illuminate them with infrared radiation in such manner that the edges of the web cast respective shadows on the array of sensors or the respective portion of the array.

Preferably the said electronic means comprises a microprocessor with a suitable program to effect such determination.

In order to promote a fuller understanding of the above and other aspects of the present invention an embodiment will now be described, by way of example only, with reference to the accompanying drawing which shows in schematic perspective view an embodiment of the invention.

The drawing shows an embodiment of the invention arranged to measure and/or check the width of a web 10 passing through a machine handling the web part of the frame of which is indicated at 11. The drawing shows one half of the measuring device and it should be understood that the second half is generally similar to that shown.

A portion 12 of a linear array of spaced sensors 13 is mounted on a beam 14 of the machine to be adjustable in a direction transverse to the web 10 by means of a lead screw 15. The portion of the array 12 includes a pointer 16 which moves over a scale 17 to indicate the position of the portion 12.

The sensors 13 are preferably infrared responsive sensors and means, not shown, are provided for illuminating the sensors so that edge of the web 10 indicated at 18 casts a shadow on the portion 12 of the array. The sensors 13 are arranged to give an electrical indication of whether they are in shadow or not and thus to indicate the presence or absence of a respective part of the edge of the web.

As mentioned the opposite side of the device is exactly similar, having a second portion of the linear array of sensors exactly similar to that shown in the drawing and mounted for similar adjustment with respect to the opposite edge of the web 10.

Thus it can be seen that by counting the number of the sensors 13 which are in shadow the width of the web can be determined in terms of the spacing of the sensors 13 as the unit of measurement. With the arrangement shown adjustment of the lead screw 15 will position the portions of the array with the aid of the scale 17 and the pointer 16 to a position suitable for the nominal width and the overall transverse position of the web 10 on the machine.

In some arrangements, the linear array of sensors 13 can be continuous across the width of the web so that the portions are in effect joined, in which case it would still be desirable to have adjustment by means of a single lead screw 15 to position the array relative to the general position of the web transverse to the machine.

The outputs of the sensors 13 are connected to an electronic device indicated at 19 which is arranged to determine electronically the number of sensors which are in shadow thus indicating the width of the web, and preferably to determine whether that number is less than a chosen minimum or greater than a chosen maximum to indicate whether the width of the web is inside or outside a chosen tolerance.

The electronic device 19 may include a microprocessor with a suitable program to cause it to make such a determination.

The electronic device 19 may include output means responsive to the width determination to stop or otherwise control the operation of the machine in the event that the width of the web falls outside a chosen tolerance range. The electronic device 19 may comprise a programmable logic device.

Claims

CLAIMS:

1. A device for measuring the width of a web of material including a linear array of spaced sensors, each sensor being adapted to indicate the absence or presence of a respective part of a web when the array is held adjacent and transverse the web; and electronic means associated with the sensors arranged to determine the number of sensors which indicate the presence of the web thus to determine the width of the web.

2. A device as claimed in claim 1, wherein said electronic means is arranged to indicate whether said number is lower than a lower acceptable limit, or higher than a higher acceptable limit.

3. A device as claimed in claim 1 or 2, wherein such array is divided into two separate portions each being associated with a respective edge of the web to be measured.

4. A device as claimed in claim 3, wherein when the device is associated with a machine handling the web to be measured, each such portion is mounted on the machine to be adjustable in a direction transverse to the web, preferably against a measuring scale, to determine the position of that portion of the array.

5. A device as claimed in claim 4, wherein each such portion is individually so adjustable.

6. A device as claimed in any one of claims 1 to 5, wherein the sensors are infrared sensitive devices and means are provided to illuminate them with infrared radiation in such manner that the edges of the web cast respective shadows on the array of sensors or the respective portion of the array.

7. A device as claimed in any one of claims 1 to 6, wherein the said electronic means comprises a microprocessor with a suitable program to effect such determination.

8. A device for measuring the width of a web of material substantially as described with reference to the accompanying drawing.