Device and method for optically scanning a machine-readable label applied to an object

[0001] 1. Technical Field

[0002] The invention to a device and a method for optically scanning a machine-readable label applied to an object.

[0003] 2. Discussion

[0004] Such devices and methods are employed, for example, at the check out lanes of a self-service store to read the objects selected by a customer. The objects to be scanned are items. Checking the items out is supposed to take place automatically so that the presence of a check out person is not needed. The label is, for example, a bar code. One or more scanning devices are arranged on a conveyor device in order to read the label on the product. Care must be taken that the items are brought individually to the scanning device and that the label is read by the scanning device when the object with the side showing the label is lying on the belt. The latter is particularly important since most items have labels in only one place and there is a possibility that the customer places the items on the belt with the side having the label downward. Items placed in this position cannot be read by a scanning device which is positioned above or to the side of the belts. If an item cannot be checked out, it is returned to the customer and the customer is required to place the item one more time in a different position on the belt. This results in a delay when checking the items out.

[0005] From the prior art DE 101 41 429 C1 a device is known for optically scanning labels in which a scanning device is located in a space between two belts. The scanning device allows a label on the underside of an item facing the belts to be read. The scanning device is part of a hollow body. To ensure that even very small objects pass from one belt to the other or arrive at a receiving tray, the gap and the scanning device positioned in the space are kept very narrow. In a second embodiment, the transparent hollow body is in the shape of a cylinder, the axis of which is aligned parallel to the return pulleys of the belts und which rotates at a speed synchronized to the speed of the belts. The disadvantage is that the scanning device involves a cost-intensive special installation because of the requirements mentioned and the transportation and identification of small objects cannot be guaranteed.

[0006] On the other hand, the device in accordance with the invention has the advantage that the objects, independently of their size, can be conducted reliably across the scanning device by an additional transportation device. The transportation device is equipped with several slats or carriers which ensure that the objects are taken individually past the scanning device and are read thereby. There are no special requirements for the size and the shape of the scanning device. The scanning device can be a standard device such as is used in known checkout systems. The apparatus can therefore be produced economically.

[0007] The carriers are advantageously moved at the same speed as the conveyor belt. In this case a relative speed between the carriers and the conveyor belt is avoided which can lead to undesirably high forces affecting the carriers and to a change in position of the objects on the belt because of the friction between the conveyor belt and the objects.

[0008] The carriers are matched regarding their shape and their material to the area in which the device operates and the objects, or goods, offered in that area. Since the carriers are advantageously moved at the same speed as the conveyor belt, no force is exerted on the objects by the carriers in the area of the conveyor belt. There is no exertion of force by the carriers on the objects during the conveyance process until the area of the scanning device. The surface of the scanning device with which the objects come into contact as they are being transported is advantageously smooth in order to minimize the friction between the goods and the surface of the scanning device. When selecting the material and the shape of the carriers care must be taken that the resulting strength of the carriers is adequate to withstand the frictional forces and to transport the objects in a reliable manner across the scanning device.

[0009] It must be taken into account with the shape of the carriers and their position relative to the conveyor belt that both small flat objects as well as objects with a commensurate height can be transported. The distance between the carriers and the conveyor belt as well as the distance between the carriers and the scanning device is advantageously less than the smallest object to be transported in the area of use. In addition, the working surface with which the carriers can interact with the objects is advantageously selected large enough that the largest object to be transported in the area of use is collected and pushed past the scanning device.

[0010] The carriers cover the scanning device and at least one section of the conveyor belt and the receiving tray which the scanning device is facing. In this way it is ensured that the carriers take the objects first from the conveyor belt to the scanning device, than past the scanning device and finally from the scanning device onto the receiving tray.

[0011] Various possibilities exist for bringing the objects into cooperative action with the carriers. To give one example of an embodiment, the transportation device with the carriers extends from the area in which the user places his objects, his items on the conveyor belt to the area of the receiving tray in which the user removes his objects again. With this embodiment the customer is encouraged to place his objects between two carriers on the conveyor belt.

[0012] With this first embodiment the user takes his objects individually to the carriers, whereas with a second embodiment as an example the carriers on the transportation device are brought to the objects already lying on the conveyor belt from the side or from above. In this case, the area in which the objects are positioned between the carrier bars is restricted to a shorter distance than in the first embodiment.

[0013] In accordance with an advantageous embodiment of the invention, the carriers of the conveying device are attached to two conveying machines. The conveying machines can be conveyor belts or conveyor chains which run to the side and above the belt conveyor and the scanning device. The conveying machines are moved by a drive. In accordance with a further advantageous embodiment of the invention, the drive for the conveyor belt can additionally drive the conveyor device with the carriers.

[0014] In accordance with a further advantageous embodiment of the invention, the carriers are configured as bars or slats. They are attached at their ends to the conveyor belts or chains running above and to the side of the belt conveyors. They accordingly extend across the entire or almost the entire width of the belt conveyor. In this way the entire width of the belt conveyor can be used to place the objects. The distance between the bars or slats is selected depending on the intended use of the device such that the space available is sufficient to be able to place any kind of available object in the area of use between any two bars or slats on the belt conveyor.

[0015] In accordance with a further advantageous embodiment of the invention, the carriers are part of a secondary belt conveyor which has recesses to receive objects. The recesses may be round, oval, rectangular or any type of polygon. The bars or slats which are formed by two successive recesses perpendicular to the conveyor device may be thicker than the sections of the secondary belt conveyor running parallel to the conveyor device. The thickness brings increased stability to the sections running perpendicular to the conveyor device.

[0016] In accordance with a further advantageous embodiment of the invention, the carriers lie directly on the belt conveyor. This ensures that even thin and flat objects are picked up by the carriers and taken across the scanning device.

[0017] In accordance with the method under the invention, objects are automatically read which are provided with a label and which are placed on a belt conveyor of a device for reading in such a way that the label is facing the belt conveyor. If an object is placed on a belt conveyor between two carriers with the side showing the label, it is taken by the carriers past a scanning device and the label is scanned there. Finally, the object is taken to a receiving tray by the carriers.

[0018] Additional advantages and advantageous embodiments of the invention can be found in the following description, the drawing and the claims.

[0021] A device for optically scanning a machine-readable label applied to an object having a first belt conveyor 1, a second belt conveyor 2 and a scanning device 3 is shown in FIGS. 1 and 2. It is also possible to use only belt conveyor 1 and one receiving tray after the scanning device. In the embodiment shown as an example, the scanning device 3 is located between the two belt conveyors 1 and 2. Parallel to the two belt conveyors 1 and 2 runs a supplementary conveyor device 4 which consists essentially of two conveyor belts 5 and 6 and slats 7 located between the conveyor belts. The two conveyor belts 5 and 6 and the slats 7 run directly on the surface of the two belt conveyors 1 and 2 and of the scanning device 3. In order to be able to use as large an area of the belt conveyor 1 as possible when placing objects not shown in the drawing on the belt conveyor 1, the two conveyor belts 5 and 6 run along the sides of the two belt conveyors 1 and 2. The two belt conveyors 1 and 2 are guided by return pulleys 8, 9, 10 and 11. The supplementary conveyor device 4 extending over both belt conveyors 1 and 2 is guided by the two return pulleys 8 and 11. The drive device 13 can drive the two belt conveyors 1 and 2 and the supplementary conveyor device.

[0022] An object can be placed in the pocket or area 12 on/of the first belt conveyor 1 created by the conveyor belts 5 and 6 and by two adjacent slats 7. Only one object should be placed in each of the areas. The first belt conveyor 1 transports the object to the scanning device 3. No force is applied to the objects by the slats 7 until the scanning device 3 is reached. As they pass from the belt conveyor 1 onto the scanning device 3, the objects are taken by the slats 7 of the conveyor device 4 and carried by them across the surface of the scanning device 3 to the second belt conveyor 2. Finally, the objects reach the belt conveyor 2 by way of the slats 7 and, as soon as they are on the belt conveyor 2, passed on by the belt conveyor 2. At the end of the second belt conveyor 2, the objects can be removed again.