DE3932376A1 - Hair face measuring arrangement for non-circular cross=sections - has rotatable holder for laser light source and light sensitive element arrangement - Google Patents

Abstract

An arrangement for measuring non-circular fibre cross-sections contains a laser light source (1), an arrangement (2) of light sensitive elements in the source's light path, a rotatable light source and light sensitive element mounting (5) and an evaluation device connected to the light sensitive elements. The light source and light sensitive elements are arranged so that if a fibre object is present on the axis of rotation an image of the object is produced on the arrangement of elements. USE/ADVANTAGE - Miniaturised arrangement enables automated measurement, esp. of cross-sections of hair fibres.

Description

The invention relates to a device for measuring not circular moderate fiber cross sections, in particular of hair fiber cross sections.

Tension-strain measurements are ideally suited to the pest to recognize the degree of hair fiber. With existing train deh The three para meters of maximum elongation, tensile force at 15% elongation and maximum tension force (tear strength) determined.

The measured sizes are strictly correct with the fiber cross section liert. To hair fibers of different thickness in their viskoela to be able to compare technical properties with one another generally the modulus of elasticity is given (Young's modulus), the is a quotient of effective force and cross-sectional area.

In contrast to synthetic fibers with mostly circular cross cuts have hair fibers more or less elliptical cross cuts by specifying the large and small semiaxes be characterized.  

All previous devices for thickness measurement have at least One of the following disadvantages: They are too bulky to be at their best existing tension-stretching devices can be integrated.

You are too slow to determine hair thickness in time the automated tension-stretching device for the tensile strength measurement solution needed. They are circular only for measuring Cross sections suitable. There is no automatic way Evaluation.

A known measuring system (brochure from the company Mikro-Epsilon Meß technology) determines the thickness by the shadow cast by the fiber in a laser beam and is not suitable for fibers with thickness, that are smaller than 200 microns. Another well-known measuring device (brochure of the company KJM) records the fiber thickness by means of Diffraction of a laser beam. Both measuring devices are however out finally suitable for capturing circular cross sections.

For this reason, a miniaturized and automated Fiber thickness measuring apparatus required in the known tensile strength equipment can be included. This should also ge be guaranteed that the hair cross section of each in the Tensile elongation of the hair to be measured was determined immediately beforehand and is transmitted without further intervention in the process computer. in the The Young's module can thus be connected to the tensile strength measurement can be calculated directly.

According to the invention, this object is achieved by a light source, an arrangement of photosensitive elements in the beam direction Light source, one by one between the light source and the arrangement located and perpendicular to the beam direction of the light source standing axis rotatable holder for the light source and the on  order and one connected to the photosensitive elements Evaluation device, the light source and the light sensitive union elements are arranged such that in the presence of a thread-like object in the axis of rotation on a diffraction pattern the arrangement arises.

In particular, it is proposed that the light source be used as a laser is trained.

Furthermore, one is arranged between the axis and the arrangement and suggested mounting lens attached to the bracket to a sharp bright and perfect according to the laws of optics to get it diffraction pattern.

So that the distance between the hair fiber and the surface of the Arrangement is reproducibly observed, there will also be two Guide plates with notches that can be moved perpendicular to the axis proposed for picking up and centering the fiber in the axis.

It is advantageous to determine the elliptical fiber cross section liable if the measurements are made at an angular distance of 45 ° the. Therefore, locking positions of the rotatable bracket at Win Distance between 1 ° and 60 °, preferably with angular distances of 45 ° suggested.

Hair fiber measurements often have to be at different relative Humidity can be carried out. It becomes such an interpretation the arrangement of the components of the device proposed that the Use of the device even at high relative air humidity up to 100% in the vicinity of the fiber.

The following is an embodiment with reference to the drawings explained in more detail. Show it

FIG. 1 is a diagram of the measuring device according to the invention,

Fig. 2 is an explanation of the measured variables,

Fig. 3 shows an embodiment of the device according to the invention in Be tenansicht and

Fig. 4 this execution in supervision.

For a quick, precise and non-contact thickness determination of fibers with a diameter of 0.0007 mm <d <0.3 mm, the analysis of the diffraction pattern, which is created by the diffraction of coherent light on the fiber, is suitable. Fig. 1 shows the selected arrangement. A laser diode 1 with a maximum power of 3 mW serves as the light source. The wavelength of the red light 4 emitted in multimode operation is approximately 670 nm. The diffraction pattern is imaged by a convex lens 6 on a diode array 2 which is attached approximately 2 cm from the hair 9 . The array 2 consists of 512 photodiodes, which are arranged next to each other with a width of 0.0013 mm and a height of 2.5 mm at a distance of 0.0012 mm. The intensity distribution of the diffraction pattern is obtained by reading out the individual photodiodes. A fiber diameter can be determined from this.

Since the hair has an ideally elliptical cross-sectional area, at least three measurements at three different angles per hair are necessary in order to determine the three parameters that characterize the ellipse to be measured, namely the large and small semi-axes a and b and the angle α (alpha) to be determined between the Cartesian coordinate system of the ellipse and the light beam 4 in the first measurement ( FIG. 2). In Fig. 2 the idealized outline 10 of the hair and the apparent ellipse diameter 2 p are shown.

In the tension-stretching apparatus, in which the device according to the invention is preferably used, the hair itself cannot be turned. Therefore, the optical and optoelectronic components shown in FIG. 1 are arranged on a turntable 5 , which is rotated through a total of 180 ° (side view and top view in FIGS. 3 and 4) and the positions 45 °, 90 ° and 135 with high precision ° can control. The center of rotation is hair 9 . After carrying out a complete measurement, ie four measurements at the angles 0 °, 45 °, 90 ° and 135 °, the turntable 5 moves back to the 0 ° position.

In order to be able to evaluate the intensity distribution exactly, the distance between the hair fiber 9 and the array surface 11 must be known exactly and be reproducibly observed while the four measurements are taking place. To make this possible, the apparatus is provided with a centering slide, which can be moved back and forth between two positions on slide rails 12 . Position I is the measuring position and position II is taken during the further transport of the fiber. Above and below the diode array 2 two guide plates 7 are attached to the axis of rotation 3 , each having a funnel-shaped incision 8 . In the carriage position I, the hair 9 is guided through the incisions 8 to the end of the funnel. This represents a position with a defined distance from the array surface 11 or the imaging lens 6. The position is also in the exact center of the beam (beam diameter 0.8 mm). If the sled with the guide plate is in position II, the strand of hair can be transported freely. The guide plates 7 can be moved automatically via a lifting magnet 13 . The entire arrangement is attached to a base plate 14 . The slide rails 12 rest in bearing blocks 15 . The turntable 5 is driven by a motor 16 via gear wheels 17 , 18 .

The hair is out during a measurement in the tension-stretching apparatus fiber less than 60 s at rest. The four take place during this time Individual measurements of the thickness determination and the reverse rotation of the turn plates.

The particular advantage of the invention lies in the possibility of Non-contact determination of circular and non-circular convex cross sections of fibers in the range of 0.0007 mm to 0.3 mm with a single laser light diffraction apparatus, the opti and optoelectronic components can be rotated by the Fiber-formed center of rotation are attached to any angular position ions can start up and the fiber to be measured through a suitable centering slide during the measurement in the in the correct position and kept there at rest.

So z. B. the de cross section of a hair fiber to be regarded in an idealized manner as elliptical can be determined with a few measurements at different angles. In the example, the four angular positions 0 °, 45 °, 90 ° and 135 ° are controlled ( Fig. 4).

Any position can be arranged by angular positions conceivable non-circular, convex fiber cross sections determined will.  

The evaluation of the diffraction pattern by means of Fraunhofer theory enables the automatic determination of the parameters a, b and α (alpha) by determining the apparent ellipse half p ( FIG. 2).

Reference symbol list

1 light source
2 arrangement, array
3 axis
4 beam direction, light beam
5 bracket, turntable
6 converging lens
7 guide plate
8 incision
9 fiber
10 outline
11 array surface
12 slide rail
13 solenoid
14 base plate
15 bearing block
16 engine
17 gear
18 gear

Claims (6)

1. Device for measuring non-circular fiber cross sections, in particular of hair fiber cross sections, characterized by a light source ( 1 ), an arrangement ( 2 ) of light-sensitive elements in the beam direction ( 4 ) of the light source ( 1 ), one by one between the light source ( 1 ) and the Arrangement ( 2 ) ge and perpendicular to the beam direction ( 4 ) of the light source ( 1 ) standing axis ( 3 ) rotatable holder ( 5 ) for the light source ( 1 ) and the arrangement ( 2 ) and one connected to the light sensitive elements Evaluation device, wherein the light source ( 1 ) and the light-sensitive elements are arranged such that, in the presence of a thread-like object in the axis of rotation ( 3 ), a diffraction pattern is formed on the arrangement ( 2 ). 2. Device according to claim 1, characterized, that the light source is designed as a laser. 3. Apparatus according to claim 1, characterized by a collecting lens ( 6 ) arranged between the axis ( 3 ) and the arrangement ( 2 ) and fastened to the holder ( 5 ). 4. The device according to claim 1, characterized by two perpendicular to the axis ( 3 ) movable guide plates ( 7 ) with incisions ( 8 ) for receiving and centering the fiber ( 9 ) in the axis ( 3 ). 5. The device according to claim 1, characterized by locking positions of the rotatable holder ( 5 ) at angular distances between 1 ° and 60 °, preferably at angular distances of 45 °. 6. The device according to claim 1, marked by such an interpretation or arrangement of the components of the Device that the use of the device even at high relative humidity, up to 100%, around the fiber is possible.