Mail handling process and device

[0002] 1. Field of the Invention

[0003] The present invention relates to a unit with which items of mail or the like can be automatically accepted.

[0004] More specifically, the present invention relates to units which are capable of simultaneously determining the postal fee for the item of mail and providing the item of mail with the markings to be applied in the case of manual acceptance.

[0005] 2. Description of the Prior Art

[0006] In EP-A-0 264 502 there is described a unit which accepts, weighs and franks letters, and also charges postage. However wherein this unit is only capable of accepting and handling flat letters which fit through a slot.

[0007] EP-A-0 643 374 discloses an electronic franking system for items of mail having a housing and an acceptance compartment for items of mail to be handled wherein the acceptance compartment is arranged in the housing and can be closed by a closure plate. The system also has a control means, a handling plate for the items of mail, at least one measuring means for physical properties of the items of mail wherein an amount for prepayment is calculated from the weight and the dimensions in the control means, and a printing means connected to the control means for applying a prepayment to the item of mail.

[0008] The measuring means includes both a balance and a number of light barriers for the maximum permissible length and width of the item of mail. For measuring the length and width, the item of mail is aligned with respect to two edges of the handling plate which are perpendicular to each other and the dimensions are determined from the coincidence of individual light barriers. The alignment also brings the item of mail into a geometrical relationship which determines the place where the prepayment is applied.

[0009] EP-A-0 647 749 discloses a parcel sorting system which scans the surface of parcels transported on a conveyor belt by a video camera and measures the height of the parcels by an ultrasonic sensor. The address area is captured by a plurality of additional cameras.

[0010] The charges for items sent by mail depend not only on weight but also on their dimensions. Consequently, in a system for the automatic acceptance of items of mail, it must also be possible for their dimensions to be satisfactorily ascertained. In the case of items of mail which are not entirely flat, such as for example relatively thick letters and parcels, under certain circumstances this presents considerable difficulties since, in the attempt to measure the maximum geometrical extent of a relatively large item by means of a camera, there is a measuring uncertainty caused by parallax.

[0011] An object of the present is to specify a unit, and an operating process for such a unit, with which virtually all items of mail allowed to be posted can be accepted, measured and handled.

[0012] The present achieves this object by the customer who is posting the item of mail and depositing it on a handling surface. A line of light barriers measures the thickness of the item of mail and images of the item of mail are created by an electronic camera. With the aid of the images, both the length and width of the item of mail can be ascertained. In addition the position of a marking, in particular of a postage stamp or adhesive label, can be determined and verified and a record of posting can be created without the item necessarily having to be handed over in a particular position.

[0013] An exact measurement of the length and width of the item of mail is made possible by a Fresnel lens being arranged between the handling surface and the camera in such way that its focal point lies at the focal point of the camera optics; the dimensions of the Fresnel lens being greater than the vertical projection of the largest item of mail to be measured onto the handling surface.

[0014] Even relatively large Fresnel lenses can be produced inexpensively. They take up only little space in the direction of the optical axis, with the result that low-cost space-saving measuring systems with which even relatively large items can be accurately measured can be set up.

[0015] The handling surface is preferably light-diffusing surface, with the result that the item of mail to be measured lies on a diffusely illuminated surface. The handling surface may in this case be a translucent diffuser, that is to say a ground-glass screen; the light source preferably being arranged beneath the handling surface and the camera preferably being arranged above it. In the case of a translucent handling surface, the light source, which may also comprise a plurality of lamps, is preferably arranged laterally above the handling surface.

[0016] The imaging of the item of mail, or its outline, onto the CCD element of the electronic camera then makes it possible for the exact dimensions of the items of mail to be ascertained. In addition to a space-saving, technically simple and inexpensive solution for measuring the contour of items of mail, the solution according to the present invention also has a further advantage: if the Fresnel lens is arranged in such a way that it can be operationally moved out of the path of rays of the camera, a photo of the surface of the item of mail can also be taken by the same camera, or another camera alongside, in order, for example, to create a receipt for the acceptance and handling of the item of mail or to evaluate address codes and the like. All that is needed for this purpose, if required, is to provide an additional light source to illuminate the item of mail from above.

[0017] According to an alternative embodiment of the present invention, it is proposed to design the device mentioned at the beginning in such a way that a Fresnel lens is arranged between the light source and the item of mail and a translucent diffuser is arranged between the item of mail and the camera. In this case, either the side facing the camera of the Fresnel lens itself can be used as the bearing surface, or the bearing surface is a transparent plate arranged between the Fresnel lens and the diffuser.

[0018] Further advantageous refinements and variants of the present invention are represented in the following description and drawing of exemplary embodiments as well as in the patent claims.

[0019] FIG. 1 shows a diagrammatic representation of a mail handling facility in a preferred embodiment.

[0020] FIGS. 2-5 show the facility from FIG. 1 in various stages of operation.

[0021] FIG. 6 shows a diagrammatic representation of a measuring device according to the present invention for measuring the dimensions of mail.

[0022] FIG. 7 shows a diagrammatic representation corresponding to FIG. 6 of an alternative embodiment of the measuring device.

[0023] In FIG. 1, a device 10 for the automatic handling of items of mail is diagrammatically represented in a perspective side view. The device 10 is installed in a housing 12, of which only the contour of the front wall 13 is shown for the sake of better overall clarity. The subassemblies described below are built up on a frame 14, which is displaceably mounted in the housing 12 together with the front wall 13 on telescopic rails (not shown).

[0024] Arranged behind an opening 15 in the front wall 13 is an acceptance compartment 16 which is closed by a sliding door 18. To make the acceptance compartment 16 accessible for a customer, the sliding door 18 can be pushed upward into the position 18arepresented by dash-dotted lines. The acceptance compartment is bounded at the bottom by the weighing plate 20 of an electronic balance 22. Above the sliding door 18, there is articulated on the front wall 24 of the acceptance compartment 16 a closure flap 26 which is able to swivel between a position protruding horizontally into the interior of the device and a swung-down position 26a. The sliding door 18 and the closure flap 26 are driven by a first motor 27. They bound the acceptance compartment 16, wherein the sliding door 18 and the closure flap 26 are not open at the same time. This ensures that, during the acceptance operation, the other parts of the device are not accessible from outside.

[0025] An item of mail 112 to be posted (FIG. 6) is deposited by a customer posting the item onto a handling plate 38, which is located in the acceptance compartment 16 for this purpose, with the sliding door 18aopen and the closure flap 26aswung down. In the embodiment represented, the handling plate 38 forms the base of a drawer 36 which can be pushed through a slot 25 beneath the swung-down closure flap 26ainto the acceptance compartment 16 and over the weighing plate 20.

[0026] Secured above the weighing plate 20 and in the vicinity of a rear opening 28 in the acceptance compartment 16 there is, on the side walls 30 of the latter, a vertical row of light barriers 32 having a line of transmitters 32′ and a line of receivers 32″. Directly behind the sliding door 18 there is installed in the frame 14 a series of reflected light barriers 34, the scanning direction of which points vertically upward. The reflected light barriers 34 are distributed at close intervals over the entire width of the acceptance compartment 16.

[0027] The drawer 36 can be moved on the frame 14 with the aid of a second motor 37 between a position P22 retracted into the acceptance compartment 16 and various positions P58, P56, P60 lying outside the acceptance compartment 16. The drawer 36 has an opaque base 38, transparent side walls 40 and a rear wall 42. On its front side 44 and at the top, the drawer 36 is open. In its position P22 retracted into the acceptance compartment 16, the drawer 36 can be lowered onto the weighing plate 20 by an adjusting drive (not shown). Fitted on the rear wall 42 of the drawer 36 is a swiveling drive 46 on which a turning plate 48 of opaque material is secured such that it can swivel. The swiveling drive 46 makes it possible for the drawer 36 and the turning plate 48 to be swiveled independently of each other above the frame 14 about a swivel axis 50, parallel to the rear wall 42 [in each case through 180°], and lowered downward.

[0028] On a side member 52 of the frame 14, a Fresnel lens 54 is articulated in such a way that it can be swiveled under motor power with the aid of a third motor 55 between a position covering the drawer 36 and a position swung out of the displacement path of the drawer. Arranged centrally above the Fresnel lens 54, swung down onto the drawer 36, is an area video camera 56, the angular aperture of which allows the entire surface of the Fresnel lens 54 to be covered. In addition to this camera, fitted centrally above the frame 14 is a high-resolution line video camera 58, the angular aperture of which corresponds to the width of the drawer 36. An application means 60 for markings, in particular adhesive labels 61 and stamps, can be moved by a fourth motor A′ over the entire width of the drawer 36 in the direction of a double-headed arrow A. A fifth motor B′ is able to lower the application means 60 in the direction of the double-headed arrow B onto the drawer 36 and raise it again. The application means 60 comprises a tube 62 which is connected to a vacuum pump (not shown), the lower end 65 of which is surrounded by a flexible pad 64 of a closed-cell foam plastic. The tube 62 can, furthermore, be rotated together with the pad 64 about the longitudinal axis of the tube by the fifth motor B′, as the double-headed arrow C indicates.

[0029] The motors for the abovementioned sequences of movements are connected to a control means 66. The end positions of the sliding door 18, of the closure flap 26, of the swiveling drive 46 and of the Fresnel lens 54 are reported by limit switches (not shown) likewise connected to the control means 66, which controls the drive motors on the basis of these reports. The position of the drawer 36 on its displacement path and the coordinates of the manipulator drives are reported by sensors to the control means 66. Also connected to the latter are the data outputs of the balance 22 and of the cameras 56 and 58 as well as the light barriers 32 and 34. The connections are symbolically represented by connecting arrows a to r. Moreover, a printer 80 may be connected to the control means 66 for outputting a record of a charge.

[0030] In the ready position of the device 10, the sliding door has been moved into the position 18aand the closure flap has been moved into the position 26a. The drawer 36 is in the acceptance compartment 16. Said elements are locked in this position; for example, by a self-locking action typical of motors.

[0031] FIGS. 2 to 5 show the device 10 in various working positions. In FIG. 2, the situation immediately after depositing an item of mail in the drawer 36 is represented. The sliding door 18 is closed and the drawer 36 has been lowered onto the weighing plate 20. In this position, the balance 22 can ascertain the weight of the deposited item of mail and report it to the control system. After the weighing operation, the drawer 36 is raised again and moved out of the acceptance compartment 16 to the rear. After covering a predetermined distance—4 cm in the exemplary embodiment—the reflected light barriers 34 must not receive light reflected from the item of mail any longer. Should this not be the case, the control means 66 interprets this as an indication that the item of mail 112 has become jammed by the sliding door 18. In this case, the drawer 36 is moved back into its rest position and the sliding door 18 is opened. If, on the other hand, all the reflected light barriers 34 are free, the drawer 36 continues its journey. In this case, the entire area of the drawer is swept by the line of light barriers 32 through the transparent side walls 40. Depending on the height of the item of mail, some of the light barrier receivers 32″ are darkened. The number of darkened light barrier receivers 32″ is a measure of the height of the item of mail and is likewise reported to the control means 66. FIG. 3 shows the situation after ending the thickness measurement.

[0032] In FIG. 4, the drawer 36 has reached the coverage zone of the area camera 56 and has been stopped Thereat. The Fresnel lens 54 has been swiveled onto the drawer 36. The opaque base 38 of the drawer 36 is diffusely transilluminated from below. The area camera 56 registers the outlines of the item of mail, which is possible without any parallax thanks to the parallelization of the rays of light through the Fresnel lens 54. The video signal of the area camera 56 is transmitted to the control means 66 and stored therein. As the Fresnel lens 54 is then swiveled away from over the item of mail 112. the high-resolution camera 58 sends to the control means 66 the video signals of an exact copy of the item of mail 112, in which there is contained not only the outlines of this item of mail but also the entire surface with the address area.

[0033] The customer is then requested to enter on a keypad 68 the desired type of dispatch, for example “regular letter”, “express delivery”, or “registered mail”. The control means 66 then calculates, on the basis of this information and the weight, thickness, length and width of the item of mail, the postage to be paid and then indicates this to the customer. At the same time, the item of mail 112 is displayed on a screen 70 in a standardized position, i.e. with edges parallel to the edges of the screen. In the top right-hand corner of the item of mail there is symbolically depicted a prepayment in the form of a label. If the customer agrees to the arrangement of this label, he pays the postage indicated at a paying-in machine 72 and actuates a terminating key. Alternatively, a machine-readable and possibly electronically-cancelable stamp may also be used. If, on the other hand, the customer does not accept the place where the prepayment is to be applied, for example because the label would cover the address area, he can, by pressing a key, turn the image of the item of mail on the screen 70 through 90° in each case, until he has found a place for attaching the label acceptable to him. By means of control keys, the customer can be given the possibility of modifying the proposed position.

[0034] It can also be seen on the screen 70 if the item of mail 112 has been placed in the drawer 36 with the address area facing down. The customer then has the possibility, by actuating a “turn item” key, of turning the item of mail 112 over. This takes place in the following way: the turning plate 48 is swiveled out of its upright position, represented in FIG. 1, onto the drawer 36. Subsequently, the entire arrangement is swiveled to the right through 180°, with the result that the item of mail 112 comes to lie on the turning plate 48. Thereafter, the drawer 36 is swiveled back through 90°. Then, the entire arrangement including drawer 36 and turning plate 48 is moved to the left by the width of the turning plate 48, with the result that the item of mail 112 comes to lie again under the area camera 56 and the high-resolution camera 58. This situation is represented in FIG. 5. With the Fresnel lens 54 swiveled down once again, the cameras 56, 58 then ascertain one after the other the position of the item of mail 112 on the turning plate 48 and, with the Fresnel lens 54 swiveled away, the exact image of the item of mail. The post-office customer then once again has the possibility of determining the place where the label 61 is to be applied to the item of mail 112.

[0035] As an alternative to the described use of the turning plate 48 as a handling plate, after the drawer 36 has been swiveled back, the turning plate 48 may also be swiveled again, with the result that the item of mail in the turned-over position slides into drawer 36 and for further handling.

[0036] After payment of the postage and acceptance of the labeling place on the item of mail 112, a correspondingly printed label 61 is prepared by a label printer 74, connected to the control means 66, and fetched by the application means 60. This takes place by the pad 64 being brought over the label 61 and lowered onto it. The reduced pressure generated in the tube 62 has the effect that the label is sucked onto the pad 64, where it is held in place. The control means 66 then calculates from both the actual position of the item of mail and the customer's placement request the actual place where the label 61 is to be applied and then steers the application means 60 over the desired place of application and prints the label onto the item of mail 112. The fact that the pad is flexible means that the label 61 can also be applied to uneven surfaces.

[0037] If the item of mail was, for example, a registered item, a very accurate electronic image of the front and rear sides of this item of mail is recorded by the high-resolution camera 58 and stored in a search computer, where it can be called and printed out if, for instance, a search is to be made for a lost item of registered mail. It is also possible to print off an image of the item of mail 112 on a record of posting which is then handed to the customer as a receipt.

[0038] After final clearance of an item of mail, the drawer 36 is swiveled down, with the result that the item of mail 112 can slide into a collecting container 76 arranged beneath the frame 14. It is also possible to arrange a plurality of collecting containers 76, 78, for example for regular mail or for registered and express mail, beneath the frame 14. The drawer 36 must then be moved over the corresponding container before the item of mail 112 is tipped off. A container 78 lying at the rear is reached by the item of mail 112 being tipped off from the turning plate 48.

[0039] In FIG. 6, there can be seen a ground glass plate 110 which forms a translucent diffuser and on which the item of mail 112 to be measured rests. Beneath the ground glass plate 110 there is a light source 114. Arranged above the ground glass plate 110 at a distance which corresponds to the thickest item of mail to be processed is a Fresnel lens 116, the area dimensions of which are greater than the extent of the largest item of mail to be processed. Arranged above the Fresnel lens 116 is an electronic camera 118. The camera 118 and the Fresnel lens 116 are arranged in relation to each other in such a way that the focal point of the two coincides. Since only the image rays running parallel to the optical axis are captured by the camera 118 through the Fresnel lens 116, the outline of the item of mail 112, which stands out from the diffusely illuminated ground glass plate 110, is captured without parallax by the camera 118. The height or thickness of the item of mail 112 can, in turn, be sensed by a—line light barrier 120, 122.

[0040] For purposes of acknowledging receipt or for further handling of the item of mail 112, the upper side of the mail be photographed. For this purpose, the Fresnel lens 116 is arranged in such a way that it can be moved out of the path of rays of the camera 118. This may take place in the way indicated in FIG. 6 by the Fresnel lens 116 being mounted such that it can swivel about a vertical axis 124. Furthermore, in the case of the embodiment according to FIG. 6, a further light source 126 is arranged above the ground glass plate 110 to be able to illuminate the upper side of the item of mail 112 if it is to be photographed by the camera 118. For this photo, the light source 114 is switched off and the light source 126 is switched on. The adjustment of the Fresnel lens 116 and the switching over of the illumination do not require any great technical expenditure. Consequently, both the contour of the item of mail 112 can be measured without parallax and a copy of its surface can be created by means of just one camera.

[0041] FIG. 7 shows an embodiment which differs from that according to FIG. 6 only in the arrangement of the light source and possibly the design of the handling surface. The same parts are provided with the same reference numerals. In the case of the embodiment according to FIG. 7, the light source 114 is arranged above the handling surface 110, the latter in turn being designed as a light-diffusing surface. It may be a ground glass plate, as in the case of FIG. 6, or else an opaque, plate. The arrangement of the Fresnel lens 116 and of the camera 118 is as shown in FIG. 6. This solution has the advantage in that there is no switching over of the illumination when the Fresnel lens 116 is moved out of the path of rays of the camera 118 for photographing the surface of the item of mail 112.

[0042] Various modifications to the facility described are possible without going beyond the scope of the invention. Indeed, instead of sensing the thickness of the item of mail with the aid of a line of light barriers, it is possible to lower onto the item of mail from above a pressure plate aligned parallel with the base 38 of the drawer 36. The displacement path is then a measure of the thickness of the item of mail. This arrangement has the advantage in that convex items of mail can be pressed flat and creases can be bent down. This makes it possible for the thickness to be ascertained more exactly.

[0043] Instead of application means for labels, there may be fitted on the manipulator a printing head, preferably an ink-jet printing head, by means of which a franking mark can be printed directly onto the item of mail.

[0044] The image of the outline and the exact recording of the item of mail 112 can be created by means of a single camera i.e., the high-resolution line video camera 54 alone. The video signals of the high-resolution video image, which are sent to the control means 66, can be subjected to a text recognition process in the control means 66, with the aim of automatically sensing, for example, the ZIP code from the address. With this information, a letter sorting installation can be directly controlled, or else the ZIP code can be printed onto the item of mail 112 or onto the label 61 in a coding which can be read by downstream letter sorting installations, such that the item of mail 112 may be automatically diverted for continued conveyanceto, for example, a respective collecting container 76, 78. The ZIP code thus determined can be offered to the customer via the screen 70 for verification or correction via the kay pad 68.