EP0395867B1 - Holding structure for changeable information supports - Google Patents

Description

The invention relates to a retaining bar for interchangeable, scannerable information carriers with a fastening part for fixing to edge areas of shelves, containers and the like, and with a fixable on the fastening part, formed from a rear wall and a transparent front wall for the information carrier, the rear wall and the Front wall are connected to each other at the base and wherein the upper edge of the rear wall covers the free edge of the front wall covering.

Such a retaining strip is known from DE-C-27 46 118 and FR-A-2 368 104. In this known retaining strip, the fastening part consists, for example, of a locking strip, which can be used in a locking groove on the edge areas of the shelves, containers and the like. A cover strip for covering the edge regions of the shelves, containers and the like, as well as the rear wall and the front wall, which together form the receiving pocket for the information carriers, are connected in one piece to the fastening part. The rear wall and the front wall are connected to one another at the base, for example via a film hinge, and the upper edge of the rear wall covers the free edge of the front wall. The front wall can be released from this overlap by applying slight pressure, the opening pocket opening for the insertion of information material. The receiving pocket can then be closed again by applying slight pressure against the rear wall, the upper edge of the rear wall snapping over the free edge of the front wall and holding it in the closed state.

The holding bar for such information carriers known from EP-A 0 203 209 also belongs to the prior art. This retaining strip consists of a fastening strip and a cover strip which is integral with the lower edge of the fastening strip and which abuts the fastening strip and can be moved away on one side for inserting a label or the like. On the upper edge of the fastening strip, a cover protruding over the upper edge of the cover strip is formed, which is designed as a locking edge. In contrast, the upper edge of the cover strip is designed as an integrally formed locking edge which forms a snap closure with the locking edge of the fastening strip by engaging in and under the locking edge. The retaining strip is made in one piece from polymer material, the cover strip being transparent and allowing the label to be viewed and read properly. The fastening strip, on the other hand, can be made of opaque plastic and forms a fastening surface on the back with which it can be glued to a shelf, for example.

The holding strips known from the prior art are suitable for use on shelves in warehouses, high-bay warehouses and the like. The labels and the like located in the holding strips can be read by the operating personnel as well as by the customers in passing. However, reading with the scanner pen is preferred for newer shelf structures. Such scanner devices work according to the reflection method, also called incident light method. Light emitting diodes are used as the light source, which mainly work in the infrared range.

However, there are also scanner systems that use bright red light diodes.

A photodiode is used as the light receiver in the scanners. Because the transmitter diode and the photodiode have to be accommodated side by side in a very small space, there are integrated systems here which contain the transmitter diode, the photodiode, the filter disk and the amplifier for the photodiode signal. A frequently used system is the HEDS-1000 type from Hewlett-Packard. This sensor works with infrared light of 700 mm wavelength and can be operated regulated or unregulated. When a line of information on the label is scanned with the scanner pen, the infrared light is received by the receiver diode, the width and spacing of the lines being converted as "flickering lights" into an electrical signal which is electronically processed and processed in the scanner system.

Due to the high light intensity of the light-emitting diodes and the scanner receiving diodes, which are usually operated in a controlled manner, there is no impairment of function, e.g. the background of the label on which the line screen is printed fluctuates in color within certain limits or the print of the line screen is different black.

The sensitive scanner systems react extremely susceptibly to, for example, reflected false light, which can originate, for example, from the transparent cover strip. Such a false light gives the scanner pen incorrect information that the evaluation electronics cannot cope with.

This is where the invention comes in, which has set itself the task of preventing, in the case of scanner systems, that false light is reflected by the transparent cover strips, and that incorrect information is thereby given into the scanner system via the scanner pen. According to the invention, it is proposed that the transparent front wall have an approximately uniform, unoriented roughness on its surface at least on one side in the case of a crystal-clear core region.

The retaining strips according to the invention are produced in one piece in the extrusion process, the coextrusion process generally being selected in the present case. With this method, the transparent front wall is extruded in one piece together with the non-transparent rear wall in such a way that the front wall is connected on one side to the rear wall at one longitudinal edge, while the other longitudinal edge remains without connection to the rear wall.

The front wall can then be bent off the rear wall via the latter longitudinal edge, the connection areas between the front wall and the rear wall also being able to be formed as a film hinge. The scanner-readable label is then inserted from above into the gap between the front wall and the rear wall. The front wall is then returned to the rear wall due to the tensions generated during the bending, the label inserted in the receiving pocket being enclosed and being visible to both the human eye and the scanner pen because of the transparency of the front wall.

In the extrusion process, it is an inevitable phenomenon that so-called drawing strips appear on the surface of the extruded profiles.

Such drawing strips can be so small in height that they are barely perceptible to the human eye. However, because the light-emitting diodes in scanner systems have an extremely high light intensity, the drawing grooves on the profile surface, here on the surface of the transparent front wall, are detected by the IR light of the light-emitting diode, and the mountain and valley formations, which enlarge the drawing grooves on the Form profile surface, are shown as additional light-dark transitions via reflections. These insertions appear as reflected false light and pass on incorrect information to the scanner pen, which confuses the evaluation electronics. Wrong information is therefore entered into the evaluation electronics from a label read in this way with a scanner pen. This information is worthless.

The teaching of the invention is now to equalize the longitudinal grooves which inevitably arise during the extrusion process in such a way that such false information to the evaluation electronics is avoided. The problem that has arisen is solved by the invention in such a way that the longitudinal grooves oriented on one side, which arise during extrusion on the profile surface, are equalized by approximately equally deep, non-oriented roughnesses, so that an optically equally rough surface is produced.

This problem solution arises from the knowledge that an optically completely smooth profile surface cannot be achieved in the extrusion process. The inevitably occurring one-sided longitudinal grooves are resolved by the invention into an approximately uniform, unoriented roughness on the surface of the transparent front wall.

This almost uniform, unoriented roughness reduces or completely eliminates disruptive, abrupt light / dark light scattering, which has been recognized as the cause of the false messages for the evaluation electronics in the one-sided drawing marks. With the profile surface designed according to the invention, false light is no longer reflected, which could transmit incorrect information to the scanner pen. The harmful light-dark transitions of the unilaterally oriented extrusion drawing grooves, which are responsible for the undesired additional reflections, are thereby excluded.

Due to the uniform, unoriented roughness of the transparent front wall according to the invention, the surface appears rough and milky, but the core of the front wall remains crystal clear. In this way, no harmful reflections of light can occur through the core of the front wall. The roughness of the surface, which is unoriented according to the invention, then ensures that harmful reflections can no longer also emanate from the surface. The light beam of the scanner pen can therefore penetrate unaffected by harmful secondary reflections up to the bar code of the label used and return the information of the line screen - also unaffected by harmful reflections - to the photodiode via the transmitter diode. The information from the line grid of the label comes into the evaluation electronics without negative side effects and can be processed there accordingly.

The unoriented roughness according to the invention on the surface of the transparent front wall, which can also be referred to as "micro-roughness", can be achieved, for example, by using a for producing the profile in particular with regard to its lubricant, a recipe specifically set is used which, in conjunction with a defined residence time of the melt in the parallel discharge part of the nozzle mouthpiece, leads to the desired unoriented roughness.

An example of a recipe is structured as follows:
100 parts by weight of mass polyvinyl chloride with a K value of 57
2 parts by weight of tin stabilizer
1.5 parts by weight of polymethyl methacrylate - flow modifier
1.2 parts by weight of lubricant mixture of fatty alcohols, wax esters and oxidized polyethylene
This formulation is broken down in an extruder by the action of temperature and screw friction, the residence time of the melt in the parallel discharge part of the nozzle mouthpiece being between 0.04 and 0.07 seconds.

With this recipe and the subsequent dwell time in the parallel discharge part of the nozzle mouthpiece, a profile surface can be achieved in which the surface roughness in the longitudinal and transverse directions is approximately the same. The difference in this roughness depth is less than 3.0µ in the longitudinal and transverse directions. The latter is important for the invention, since a larger difference in surface roughness - as studies have shown - in turn causes additional light-dark transitions and thus harmful reflections.

The microroughness according to the invention can also be generated mechanically on an extruded surface of the profile. For this, grinding, sandblasting and other known methods can be used.

Test series have shown that, in the case of retaining strips equipped according to the invention, light striking the surface of the transparent front wall was uniformly scattered in all directions. As a typical measured value, a difference of less than 2% deviation of the light beam was measured across and along the running direction of the light source. This order of magnitude is negligible, since no harmful reflections via additional light-dark transitions and therefore no reflected false light fall into the photodiode. With surfaces of the transparent front wall not equipped according to the invention, scattered light differences of up to 25% were measured. Such values, which correspond to a roughness depth difference of approximately 4.5µ, cause the harmful reflection of false light and thus the incorrect information that comes into the evaluation electronics via the scanner pen.

The surface roughness according to the invention can equally be present on the outer surface of the transparent front wall and / or on the inner surface of the transparent front wall. In most cases, however, it is sufficient to arrange the approximately uniform, unoriented roughness on the outer surface of the transparent front wall.

Claims (3)

1. Retaining strip for exchangeable, scannable information carriers with a fastening element for attaching to peripheral areas of shelves, containers and similar objects as well as with an information carrier pocket comprising a rear section and a transparent front section capable of being attached to the fastening element, whereby the rear section and the front section are joined together at the base and the upper edge of the rear section enclasps the unattached edge of the front section, characterised by the fact that the transparent front section exhibits a crystal-clear core area and an area of almost uniform, non-oriented surface roughness on at least one side.
2. Retaining strip as described in claim 1, characterised by the fact that the peak-to-valley height of surface roughness is almost uniform in the longitudinal and transverse direction.
3. Retaining strip as described in claims 1 and 2, characterised by the fact that the difference in peak-to-valley height is less than 3.0µ in the longitudinal and transverse direction.