EP0605547A1 - Label printer and dispenser - Google Patents

Abstract

The disclosed machine (10), which is used to print and dispense labels (16) adhered to a backing strip (14) of backing material, comprises a print member (46) which, in the direction of advance of the strip, is placed at a certain distance upstream of a separating member (54), which is used to take off from the strip a label already printed. To place the maximum number of labels on the covering strip by exploiting the largest possible surface of the strip, the labels are placed on the strip in relatively very close proximity to each other. So that, after dispensing a label, printing of the next label can begin at its leading edge, the liner strip is moved backwards after dispensing a label until that the front edge of the next label is slightly upstream or at the level of the printing member. This control sequence makes it possible to process coating strips in which the distance between adjacent labels is less than the distance separating the printing member and the separator member. If the labels are placed directly against each other, their position is detected by temporarily folding the liner strip over part of the transport path (34, 36). Thus, the space between adjacent labels is enlarged and can therefore be detected by a light beam (40, 42).

Description

LABEL PRINTER AND DISPENSER

BACKGROUND OF THE INVENTION

The invention is directed to a device for the printing and dispensing of labels sticking on a strip-shaped liner of carrier material, comprising a drive means for advancing the liner along a transport path, a printing means for printing on the labels, a separation means for separating a label from the liner and dispensing the label after printing has been performed thereon, a label detection means having a light-emitting and a light-receiving element for detecting the position of a label on the liner during movement of the liner along the transport path, and a control unit for driving the printing means and the drive means in dependence of the output signal received from the label detection means. Further, the invention is directed to a method for the detection of labels closely following each other on a strip-shaped liner of carrier material during movement of the liner.

There are known many devices for the printing and dispensing of labels sticking on a liner. Such devices are used, either as hand-operated instruments or parts of larger devices or systems for sticking labels to automatically supplied objects or the like. For detaching a printed label sticking on the liner, wide use is made of separation means which deflect or bend the liner along such a small radius of curvature that the label, due to its larger stiffness as compared to the liner, separates from the liner in spite of its adhesion thereto. Most of the separation means of known label printers and dispensers are provided as small-diametered shafts extending transversely to the liner or as relatively strongly curved projections for guiding the liner therearound. The label, because of its stiffness, will not follow this curve and thus become detached from the liner. However, also other arrangements of the separation means can be provided.

A common problem in known devices for the printing and dispensing of labels consists in that, for mechanical reasons, a certain distance has to be kept between the printing means for printing or writing on the labels and the separation means. The printing means consists of a printhead, e.g. a thermal printhead or a wire printhead, to be driven by a control unit, and a pressure roller opposite to the printhead, with the printhead being forced against the pressure roller. Also laser diode printheads can be employed. The diameter of the pressure roller must be relatively large so that the peripheral surface of the pressure roller presents a relatively large or long substantially smooth pressure surface area for pressing the printhead thereagainst. The liner passes between the printhead and the pressure roller. The diameter of the pressure roller is too large to allow use of the pressure roller as a separation means since the liner, when being guided about the pressure roller, is not curved sufficiently for effecting detachment of a label. Thus, it is necessitated that the separation means is arranged downstream of the printing means, i.e. in the liner transport direction behind the printing means, at a distance required by constructional conditions. This distance, however, also deteπnines the distance between the confronting edges of two successive labels of the liner the reason being that, if the label following a just discharged label is to be printed starting from its leading or front edge as seen in transport direction, the distance between the rear and front edges of two successive labels must be larger or equal to the distance between the printing means and the separation means. Thus, the close succession of the labels, being advantageous because of the low waste of label material during manufacture of the liner and the attached labels, is subjected to restrictions.

A thermal printer known DE 35 27 632 Al is provided for the printing and dispensing of self-adhesive labels attached to a carrier belt. In this thermal printer, the separation means, arranged opposite to the thermal printhead, is a deflection member formed as an elastic counter-pressure body. This separation means is relatively complicated in construction because it has to resist the high contact pressure of the thermal printhead and the high operating temperature thereof, while at the same time a certain elasticity of the separation means is desired. The separation means is fixed, i.e. is not movable or rotatable so that friction is generated between the carrier belt and the separation means. For detecting the position of the next-to-be-printed label relative to the thermal printhead, there is provided a label detection means comprising a light- emitting and a light-receiving element. This known thermal printhead has been designed for printing on labels immediately abutting each other. However, problems occur during detection of the label position since the detection of the respective position requires an interval to be provided between successive labels. This is because the light permeability in this portion of the liner is deteπnined only by the liner material and thus is larger than in the areas covered by the labels, which results in different output signals of the label detection means and thus is recognized.

It is an object of the invention to provide a device for the printing and dispensing of labels sticking on a strip-shaped liner of carrier material which is adapted for reliable identification of the position of the labels also in liners whose successive labels have their confronting edges immediately abutting each other.

SUMMARY OF THE INVENTION According to the invention, the object is solved in that the transport path in the region of the label detection means of the above device is arranged in such a manner that the liner during movement thereof is given a curvature, with the labelled upper face of the liner being curved convexly, and that the light of the light-emitting element impinging on the liner in the region of the curvature of the transport path is received by the light-receiving element only if the confronting, immediately abutting edges of two successive labels are oriented relative to each other at an angle corresponding to the curvature of the liner, so that the edge of a label on the liner and/or the resulting gap between two successive labels can be detected.

The label printer and dispenser of the invention can be operated with a liner having its labels arranged in such close vicinity to each other that the confronting edges of two successive labels lie immediately against each other or abut each other. Li order to allow detection of a label by its front or rear edge in spite of the mutual contact of the edges, the liner is given a curvature in the part of the transport path passing through the region of the label detection means, the curvature being provided in such orientation that the labelled upper face of the liner is bent convexly. When two successive labels are moved through that portion of the transport path wherein the liner is curved in the above manner, the gap between the confronting edges of the two separate adjoining labels becomes larger due to the bending of the liner corresponding to the convex curvature, so that the light of the light-emitting element of the label detection means for a short time impinges onto portions of the liner where the upper face is not covered by labels or parts of labels. Irrespective of the specific operating principle of the optical label detection means (reflection, transmission or reflection and transmission), the transport path for the liner as provided by the invention establishes conditions wherein the light beam for detecting the label position impinges exclusively onto the liner and/or passes exclusively through the liner, although, in the area of the successive labels, the upper face of the liner has the labels arranged thereon in continuous fashion, i.e. without intervals therebetween.

The device of the invention is adapted for use with liners in which the surface coated with label material has linear, transverse slits provided therein, the depth of said slits being identical with the thickness of the layer of the label material. By these slits, the layer of the label material, originally manufactured as a line of labels, is divided into individual labels. Label liners of this type do not need any edge perforations or similar means for detecting the positions of the individual labels during advance of the liner in the device. The detection of the label edges as provided by the invention allows positioning of the liner relative to the printing means. Therefore, the entire liner surface can be covered with labels so that, in manufacture of the label liner, the incurred waste of material can be as low as zero in extreme cases. The curvature of the portion of the liner passing the region of the label detection means can be realized in various manners. For instance, the liner can be formed as a loop which is maintained by two transport rollers, the mutual distance of the transport rollers being smaller than the length of the respective portion of the liner arranged between them. Further, the above curvature can be obtained by deflection of the liner at a suitably diametered deflection roller abutting the lower face of the liner. Preferably, the transport path in the region of the label detection means is formed by a convexly curved surface which, during movement of the liner relative to the label detection means, has the lower face of the liner facing away from the labels abutting thereon. This construction for forcibly providing a curvature or bending of the liner is relatively simple and failure-proof.

In a preferred embodiment of the device of the invention, the transport path in the region of the label detection means passes between two guide plates. Each of the two guide plates is bent at angles corresponding to those of the other plate. By this arrangement of the transport path, the liner is given the form required for detection of the label edges even if the lower surface of the liner, due to reduced tightening or tensioning, is not in full-faced abutment with the convexly curved surface. The two guide plates provide that the liner has both of its sides abutting against guide elements by which the upper surface of the liner with the attached labels is given a convex curvature. In another preferred embodiment of the invention, the orientation of the label detection means relative to the liner is provided such that the liner crosses the optical axis between the light-emitting element and the light- receiving element, with only one detecting element of the label detection means being arranged on each side of the liner. With this arrangement of the label detection means with respect to the liner, detection of the label edges is carried out after the manner of a transmission light barrier. The label detection means operating according to this principle is comparatively simple in construction.

Another preferred device for the printing and dispensing of labels, wherein detection of the label positions for labels abutting each other on the liner is preferably performed as described above, is provided with a drive means for advancing the liner along a transport path, a printing means for printing on the labels, a separation means for separating a label from the liner and dispensing the label after printing has been performed thereon, a label detection means for detecting the position of a label relative to the printing means, and a control unit for driving the printing means and the drive means. In this device for the printing and dispensing of labels, it is provided that the separation means is arranged at a distance downstream of the printing means, and that, when using a liner wherein the distance between the confronting edges of two successive labels is smaller than the distance between the printing means and the separation means, the control unit - after separation of a label - controls the drive means in such a manner that the liner is first moved backwards until the label detection means detects that the label following the separated label is located before, i.e. upstream of the printing means as seen in advancing direction of the liner.

As initially mentioned, the relatively close arrangement of the printing means and the separation means or resp. the arrangement of the printing means and the separation means at exactly the same height entails constructional problems. A less complicated solution would consist in arranging the printing means and the separation means at a mutual distance. For avoiding the inherent disadvantage of the resulting intervals between the labels of the liner, it is provided in this embodiment of the invention that the liner, after separation of a printed label and prior to the printing of the subsequent label, is first moved backwards until the subsequent label - as seen in advancing direction of the liner during printing - is located before the printing means. The fact that the subsequent label has been moved in reverse direction to a position before the printing means is detected by the label detection means. With the distance between the label detection means and the printing means and the length of the labels being known, detection of this condition can be easily performed. By the above control of the drive means after separation of a previously printed label, liners with closely spaced labels, particularly with labels abutting each other, can be used even in devices for the printing and dispensing of labels wherein the separation means is arranged at a distance from the printing means. Therefore, the more complicated construction wherein the printing means and the separation means are arranged level with each other is not inevitably required.

Preferably, the liner, prior to the printing of the subsequent label, is advanced under control of the control means in such a manner that the front edge of the next-to-be-printed label - in advancing direction of the liner - is arranged level with the printing device or immediately before it. Thus, after detachment of a label, the liner is first moved further backwards than required and then, starting from a reference position, is advanced by a specific distance. Thereupon, the front edge of the label to be printed is located at the position of the printing means or directly before it. Thus, the drive means, although being controlled for reverse movement of the liner after separation of a label, has been controlled - already before printing of the next label - for advancing the liner. In other words, the drive means has already been controlled in the manner required for subsequent printing of the label. Thus, when advancing the label for printing, inaccuracies with respect to the distance of the advance movement, resulting from slippage of the drive means due to constructional reasons, are excluded.

Depending on the specific arrangement of the printing means, it may occur that the printhead works uncontrolled at the beginning of a printing process. This is the case especially with microprocessor-controlled thermal printheads. After switching-on of the associated control units, uncontrolled signals are transmitted to the printhead during the initialization routine. For preventing that these signals cause printing on the front edge of a label, which in this case would be undesired, the label destined for printing is located at a small distance immediately before the printing means. The above phenomenon could be evaded in the switched-on state of the control unit by providing suitable circuitry. Such solutions, however, are more complicated than positioning the next label immediately before the printing means or the thermal printhead, respectively. The invention is not restricted to the use of thermal printheads for the printing means. Laser printheads, ink-jet printheads or matrix printheads can also be used. In certain cases, the required pressure forces for pressing these heads against the label material are lower than with thermal printheads.

For automated dispensing of a printed label, another preferred embodiment of the invention provides a further detection means for detecting an object or the like to be provided with a label. The detection signal of this further detection means is supplied to the control unit as the starting or triggering signal for starting the printing and dispensing of the labels. Such a label printer and dispenser can be employed particularly with automatically supplied objects or the like to be labelled. Preferably, in this case, it will be additionally provided that the printed label can be dispensed and attached to said object or the like with a predetermined delay after occurrence of the detection signal of the additional detection means. This predetermined delay period serves for adjusting the position for attachment of the label onto the object or the like. Preferably, input of the information for printing a label to the control unit is performed by an external device. In particular, it can be provided that the control unit has stored therein a plurality of sets of information for printing, to be read out and printed on the successive labels in a specific order. The start oder trigger signal for the device for the printing and dispensing of labels can be generated also in some other manner and by a means other than said additional detection means. In general terms, in an automated label dispenser system, this signal can be outputted by a unit arranged before the label printer and dispenser. In other applications of the device of the invention, the start signal can be generated by actuation of a key (e.g. in an automated weighing means in supermarkets having a keyboard for inputting information on the type of the weighing stock), or it is generated only when the printing data are available, which is quite reasonable in automated label printers and dispensers. In another preferred embodiment of the invention, it is provided that the drive means is arranged as a rotatably driven drive roller for abutment of the liner against a portion of its peripheral surface. Thus, in this embodiment, movement of the liner in both directions is not carried out by a friction roller, i.e. not by spiked rollers or tractor devices, so that the liner need not have perforated edges and, moreover, the entire liner surface can have labels provided thereon.

Preferably, the drive roller also fulfills the function of the pressure roller of the printing means, the printing means in turn being preferably provided with a thermal printhead. The thermal printhead, pressing with relatively high force against the peripheral surface of the drive roller which in so far serves as a pressure roller, clamps the liner between the printhead and the drive roller, which is favorable on the one hand for the printing process itself and on the other hand for a reliable, slip-free transport of the liner.

In another preferred embodiment of the invention, the separation means is provided as a separation shaft extending transversely to the longitudinal extension of the liner and being preferably rotatably supported, with the liner being guided around the separation shaft. The diameter of this separation shaft is selected to be so small that a label sticking to the liner will separate from the liner due to its stiffness in spite of its adhesion while the liner is moved about the separation shaft. Arrangement of the separation means as a simple shaft, being either rotatable or fixed, could hardly be more simple in construction, particularly as compared to those label printers and dispensers wherein the printing means and the separation means are provided opposite to each other. In still another preferred embodiment of the invention, the liner is guided about the drive roller and the separation shaft in such a manner that guidance of the liner about a portion of the drive roller is effected both in a portion located before the separation shaft and in a portion located behind the separation shaft as seen in transport direction. Thus, although only one drive roller is provided, the liner will be subjected to the required moving force on two locations. Preferably, the strip-shaped liner with the still unprinted, unused labels is provided as a wound-up roller, the labels being arranged on the inner face of the liner for protection against damage. It can be desired that a label applied on an object will be later separated therefrom without damaging the object or leaving remnants of adhesive sticking to it. Damages are possible particularly when peeling off labels attached to paper or paper-like material. If, however, low-tack labels (e.g. labels provided with p.s.a. adhesives) are used for solving this problem, there is a risk that the edges of the labels will detach from the liner when being unwound therefrom. For safeguarding that the transport of the liner and particularly the printing process are not disturbed or adversely affected by such occurrences, another preferred embodiment of the invention provides that a pressing means is included by which those edges of the labels which undesirably become separated from the liner already while the respective portion of the liner is being unwound, are pressed against the liner. Preferably, this pressing means abuts the labelled upper surface of the liner along that portion of the liner which has just been unwound from the roll. i a manner similar to that in which the liner with the yet unprinted labels is provided as a roller, the liner itself, after separation of the labels therefrom, can be wound onto a driven reel. An alternative could consist in that the liner, after separation of the labels, will be torn off downstream of the separation means from time to time.

To eliminate the need of manually setting or adapting the label detection means to the currently used liner when the carrier and label materials of the liner are different from each other, another preferred embodiment is provided with a label detection device which is self-adjusting in this regard. Li this label detection means, the control unit receives the output signal of the light-emitting element upon reverse movement of the liner after switching-on of the label printer and dispenser. In the beginning of the reverse movement of the liner, the light of the light-emitting element of the label detection means falls onto a label or onto the liner in the area of a label. At the same time, the output signal of the light-emitting element is detected continuously. Thus, any change of the output signal can be detected by the control unit. If the output signal varies by a certain value or more, it can be recognized that the label detection means does not detect a label anymore but detects merely the liner without a label. Therefore, the output signal of the label detection means has been measured upon detection of only the liner (without label). This measured value is stored as a reference value for the detection of the edge of a label. Therefore, as soon as the label detection means during operation of the label printer and dispenser supplies an output signal coming close to this reference range within certain tolerences - after previously outputting a signal clearly different therefrom - , it is possible to recognize the transition from a label to an area of the liner having no label arranged therein.

Depending on the respective operating principle of the label detection means (optical detection by transmission, reflection, or transmission and reflection), the output signal, upon identification of a label and upon identification of the liner intervals between the labels, will change in a specific, previously known direction. Accordingly, the above self-adjusting label detection means can be used in optical detectors having the most various operating principles. There is no need to wind up the liner during the above reverse movement after switching-on of the device. Formation of a loop of the liner can be tolerated. If no (noteworthy) change of the signal is detected during reverse movement for a certain length of time, this indicates that the liner has no further labels arranged thereon, and a corresponding output signal can be generated.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a plan view of a device for the printing and dispensing of labels sticking on a liner.

Fig. 2 is a longitudinal sectional view of the device according to

Fig. 1. Figs. 3 to 8 are schematized views of the device according to Figs. 1 and 2, for illustrating the positioning of the labelled liner at different times during the printing and dispensing of a label.

Fig. 9 is a block diagram showing the main control unit for 5 controlling the device and the elements of the device electrically connected thereto.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to Figs. 1 and 2, the arrangement of the device 10 10 for the printing and dispensing of labels will be described hereunder. The device 10 is provided with a supply roller 12 having wound thereon a stripshaped liner 14 of carrier material with labels 16 sticking to it. Liner 14 is wound on supply roller 12 in such a manner that the upper face 18 of liner 14, having the labels 16 sticking thereon, is facing towards supply roller 12. 5 Starting from supply roller 12, liner 14 is guided under a pressing means 20 designed as a pressing plate 22 pressing against the upper face 18 of liner 14. Pressing plate 22 has one end pivotably supported on an axis 24 and is resiiiently biased against upper face 18 of liner 14. At its end 26 opposite to pivot axis 24, pressing plate 22 is bent off liner 14. By pressure plate 22, 0 contacting the labels 16, those edges of the labels 16 which undesirably become separated from liner 14 while the latter is unwound are pressed against liner 14 so that the projecting edges of labels cannot lead to malfunction of device 10 during the further transport of liner 14, the printing on the labels 16 thereof and the dispensing of the labels 16. Detachment of the leading label edges in transport direction (cf. arrow 28 in Fig. 2) is to be expected especially with labels 16 sticking to liner 14 with only small adhesive force. Such low-tack labels offer the advantage that, after application on an object or the like, they can be easily removed therefrom without damage to the surface of the object, which is desirable especially with paper material. In the region of pivot axis 24, pressure plate 22 is provided as a roller having the liner 14 guided about a portion of the peripheral surface thereof. Also a holding element 30 is pivotably supported about axis 24, being arranged to the side of pressure plate 22 and supply roller 12. Holding element 30 prevents supply roller 12 from sliding off axis 32 holding supply roller 12. Further, holding element 30 takes pressure plate 22 along with it when being pivoted. Thus, exchange of roller 12 is facilitated. Behind pressure plate 22 as seen in transport direction 28, the transport path for the liner 14 is determined by two guide plates 34,36 arranged at a close distance to each other. When the liner 14 is advanced in transport direction 28, the guide plates 34,36, having curved portions oriented at substantially identical angles, effect a curvature of the portion of the liner 14 arranged therebetween. In the region of guide plates 34,36, there is arranged a label detection means 38 comprising a light-emitting element 40 arranged above the upper guide plate 36 and a light-receiving element 42 arranged below the lower guide plate 34. Guide plates 34,36 have perforations provided therein so that the light beam emitted by the light-emitting element 40 can pass through the gap between the two guide plates 34,36 transversely to liner 14 and then can be received by the light-receiving element 42. The manner of detecting the labels by forced bending of the labelled liner will be described in greater detail later on.

A drive roller 44 (schematically shown in Fig. 9), to be driven in both rotational directions by a step motor 43, and a printing means 46 are arranged behind guide plates 34,36 in transport direction 28. The printing means 46 comprises a thermal printhead 48 forcibly pressing against drive roller 44 in the direction of arrow 50, and a thermal printhead holding element 52 for manually moving the thermal printhead 48 away from the peripheral surface of drive roller 44 against the pressing force. Liner 14 is clampingly held between thermal printhead 48 and drive roller 44. Liner 14 is moved upon rotation of drive roller 44. Apart from its driving function, drive roller 44 also acts as the pressing roller of printing means 46. The intensity of the printing of labels (degree of blackening in black-and-white printing) can be manually set by a setting means indicated at 51 in Fig. 9. Downstream of drive roller 44, a separation means 54 is arranged for separating a label 16 from liner 14 after the label has been printed by thermal printhead 48. Separation means 54 is provided with a separation shaft 56 having the liner 14 guided thereabout. Separation shaft 56 is arranged behind drive roller 44 in transport direction 28 and is of relatively small diameter. Thus, the radius by which liner 14 is deflected by separation shaft 56 is rather small so that a label 16, due to its stiffness, will become detached from liner 14 although being adhesively attached thereto. Fig. 2 illustrates the situation in which the largest part a of label 16 has already separated from liner 14 while the label sticks to liner 14 only with its rear portion. The separated label extends substantially tangentially to separation shaft 56 while abutting a pressure roller 58 of separation means 54 in its front area. By means of this pressure roller 58, label 16 is pressed onto the object to be labelled. Pressure roller 58 is supported for rotation on two holding arms 60 which in turn are connected to a housing 62 accommodating the drive means for the individual rollers, the printing means and a control means for control of the overall device 10.

After being guided about separation shaft 56, the liner 14 is guided back in the direction of supply roller 12, thus being guided about drive roller 44, abuttingly sliding along an abutment face 64 arranged at lower guide plate 34 and finally being wound up on a winding roller 66 being rotatably driven by a DC motor 65 (cf. block diagram of Fig. 9). Li the region between separation shaft 56 and winding roller 66, there will be arranged exclusively the liner 14 without its labels 16 which have been separated on separation shaft 56. The device 10 is further provided with an additional detection means 68 comprising, in a manner similar to label detection means 38, a light- emitting element 70 and a light-receiving element 72. Detection means 68 serves for detection of objects 73 automatically supplied to device 10; in dependence of the detection signal of detection means 68, the whole device 10 is triggered. Detection means 68 is arranged at the end of housing 62 of device 10 opposite to pressing roller 58. For control of the whole device 10, it is essential that the position of the labels relative to printing means 46 can be detected and determined. To this purpose, there is provided the label detection means 38 for optical detection of the labels. Optical detection is based on the fact that the intensity of the light received by light-receiving element 42 when the light of light-emitting element 40 is incident only on the liner 14, is different from the case when the light of light-emitting element 40 is incident on a label 16. To make optimum use of the surface of liner 14 for accommodation of labels, the labels 16 are arranged so closely to each other that the confronting edges of two successive labels contact each other. If the strip-shaped liner 14 would extend in straight linear fashion, then, during movement of liner 14, the light of light- emitting element 40 would impinge only on labels 16 because practically no gap would be left anymore between successive labels 16. For enlarging the infinitesimally small gap 74 between two successive labels 16 so as to allow detection of the label position, the liner 14 with the labels 16 thereon is guided between the two guide plates 34,36 so as to be reliably bent during advancing movement. The lower guide plate 36, supporting the unlabelled lower face of liner 14, is provided with a convexly curved surface 75 at the position of the label detection means 38. The curvature of this surface 75 is so strong that the two confronting edges of two successive labels 16 in the instant of moving over the curved surface 75 are moved apart from each other by the bending of the liner 14 to such an extent that the light beam of light-emitting element 40 impinges directly on the liner 14 between the two edges facing each other. By the curvature of the liner 14, there is generated a gap 74 formed as a V. In the drawings, the interval between the labels 16 is shown at an enlarged scale for the sake of clarity. If the drawings were true to scale, the labels 16 would follow each other without any visible gap therebetween. After passing through the liner 14, said light beam is received by light-receiving element 42 of label detection means 38. In spite of the mutual abutment of the labels 16, the forced bending of the liner 14 makes it possible to provide areas wherein the liner 14 is exposed for detection of the label position. As evident from Fig. 4, the whole device 10 - i.e. the drive motors 43 and 65 for drive roller 44 and winding roller 66, resp., as well as the thermal printhead 48 is controlled by a control unit 76, e.g. a microprocessor. Microprocessor 76 receives signals from the two detection means 38,68 and includes an interface for connecting microprocessor 76 to a superordinate control unit, e.g. a PC computer (indicated by 78 in Fig. 9). The microprocessor 76 generates drive signals for the drive motors 43 and 65 of drive roller 44 and winding roller 66 and for the thermal printhead 48. Further, microprocessor 76 is connected to a serial RAM memory 78 for storing the information for printing a label, which in turn is supplied to microprocessor 76 via the interface with the superordinate control unit. The microprocessor 76 is also connected to a character generator and program ROM memory 82. Additional terminals are provided for adjustment of the degree of blackness of the printing ink (to be set by setting means 51) and the label position (to be set by a setting means indicated by 84 in Fig. 9) onto which the label is to be applied on the object detected by detection means 68. The microprocessor 76 is provided with still another terminal for receiving signals from devices connected in advance of device 10. Electrical connection of device 10 is provided by a flat cable 86 having an edgeboard connector 88. All of the elements of the device 10 are arranged on one side so that the transport path of liner 14 is accessible from one longitudinal side. There is no need for automatic infeed mechanisms and infeed control processes for the rollers. The thermal printhead 48 can be withdrawn from drive roller 44 against the pressing force of a spring (not shown) acting in the direction of arrow 90 by moving a handle 92 towards a fixed plate or the like shown at 94. The device 10 shown in the Figures and described herein can either be part of a system for labelling automatically supplied objects or be used as a hand-held labelling device or label dispenser for generating a label with a specific print upon actuation of a key. The device 10 can be used e.g. in a microfilm print system with a folding machine (indicated by 96 in Fig. 9) for providing the folded sheets with individually printed labels at certain locations. The folded copy paper sheet is automatically supplied to the device 10 wherein an approaching sheet is detected by detection means 68. The control process and the operation of the device 10 after switching-on, prior to a printing process, during a printing process and after separation of a label will be described hereunder with reference to Figs. 3 to 8.

Before the device 10 is switched on, the next label 16 to be printed is still located in a waiting position immediately before printhead 48 where it has been placed in the last control process prior to the last switch-off. After device 10 has been switched on again, the liner 14 is moved backwards, which is effected by corresponding control of the drive means for drive roller 44 (Fig. 3). In doing so, the reversed portion of the liner 14 is not taken up by supply roller 12 but is kept in the manner of a loop or the like. During this reverse movement of the liner 14, the output signal of the light-emitting element 40 is permanently detected by the label detection means 38 and is checked for its maximum value. As soon as a maximum value is detected, it is recognized that the light of the light-emitting element 40 impinges on that portion of liner 14 which is located at a position before the foremost label; no label is arranged in that portion (Fig. 4). As soon as this maximum value, i.e. a massive change of the output signal of the light-receiving element 42, is registered, the reverse transport is stopped and the measured value is stored as a reference value. If, in later operation of device 10, the light-receiving element 42 of label detection means 38 outputs an identical signal or a signal within the range of the maximum value, the gap 74 between two successive labels is located exactly in the position of detection means 38, i.e. exactly at the optical axis of label detection means 38. Should no considerable change of the output signal be detected during the backward movement of liner 14, this indicates an undesired condition like "load paper" or "end of paper", and microprocessor 76 generates an electrical warning signal at one of its terminals, to be converted into an acoustic warning signal by a beeper or loudspeaker 98. Subsequent to the reverse movement, the liner 14 is moved in forward direction, namely by a distance depending on the length of the label and the distance between label detection means 38 and thermal printhead 48. The extent of this advance movement of is such that the leading end of the foremost label in transport direction is located immediately before thermal printhead 48. This situation is shown in Fig. 5; in this respect, it should be noted that, in this position of the foremost label 16, the label detection means 38 not necessarily detects the gap 74 between the foremost label and the subsequent label. Whether the label detection means 38 in this position of the foremost label will detect the liner without a label or a label, depends on the length of the labels. The device 10 remains in the condition shown in Fig. 5 until the detection means 68 detects an approaching sheet 73 (cf. Fig. 6) coming from the folding machine. Before, the superordinate control unit has transmitted to microprocessor 76 these data which are to be printed on the next label provided for printing. These data are stored in the serial RAM memory 80. As soon as the detection means 68 detects the folded copy paper sheet 73, the device 10 starts the printing process, with the thermal printhead 48 printing on the foremost label corresponding to the information received before from microprocessor 76 (cf. Fig. 6).

Upon receipt of a further signal outputted from the device - in this case, a folding machine 96 - arranged in advance of the device 10, microprocessor 76 controls the drive roller 44 for delivery of the printed label. This control can be performed after a time delay, the illustrated position of the copy paper sheet 73 being adjustable by the setting of the time delay through setting means 84. Only upon complete discharge of the to-be-attached label, the leading edge thereof will contact the supplied copy paper sheet 73. This situation is illustrated in Fig. 7.

Since the distance between adjacent labels from each other is zero or minimal and negligible (Li so far, the Figures do not represent to real conditions) whereas a distance does exist between separation shaft 56 and drive roller 44 as well as thermal printhead 48, the subsequent label has already been moved beyond thermal printhead 48 (cf. Fig. 8). Li order to print onto this label starting from its foremost edge, drive roller 44 is driven in reverse direction so that the liner moves backwards which is illustrated by arrow 100 in Fig. 8. The thus reversely moved liner forms a small loop before the supply roller, which can be tolerated and does not impair the function of the device 10. This reverse transport is continued until the label detection means detects the gap 74 between two successive labels, e.g. between the foremost label and the subsequent label. Starting from this reference position, the liner is then advanced until the leading edge of the foremost label is located directly before thermal printhead 48. Thus, after dispensing of a label, a reverse movement of the liner is performed for moving the foremost label backwards to a position which - as seen in transport direction - is located before thermal printhead 48; subsequently, the label will be positioned in such a manner that its leading edge is located immediately before thermal printhead 48 (Fig. 5). The extent to which the liner has to be moved backwards after discharge of a label, depends on the length of the label and the distance of the label detection means 38 to the thermal printhead 48. If the output signal of the light-receiving element 42 changes not at all or only insignificantly, it is to be assumed that the label detection means 38 has detected only the liner without a label thereon. Thus, in this case, the previously dispensed label has been the last label on the liner. In this manner, the end of the liner where no labels are arranged anymore can be detected. Non-detection of a label after previous dispensing of a printed label is recognized by microprocessor 76 which thereon will activate the beeper or loudspeaker 98 for indicating this state.

Thus, the device 10, immediately after having been switched on, carries out the operations described above with reference to Figs. 3 and 4. For dispensing a label, including transfer thereof to the waiting position, printing and actual discharge thereof, and reverse movement of the liner after label dispensing, the operations described above with reference to Figs. 5 to 8 are performed as many times as labels are printed and dispensed. In the above description, the entire label printing and dispensing device 10 has been exemplified by that case that an optical means is used for the label detection means. However, the invention is not restricted to this type of a label detection means. Generally, the detection means used can be any device capable of detecting the gap between two successive labels generated by forced bending of the liner as provided by the invention. Li this respect, for instance, there could be considered a mechanical detection means operating in the manner of a feeler wherein an actuating element, e.g. a arm or the like, lies on the upper face of the liner. As soon as this arm enters the gap generated between two labels, its position is changed, and a corresponding signal will be emitted by the switch actuated by the arm. Since, however, the gap is of comparatively small width and of little depth (label thickness), such sensor or feeler detection means have to fulfill high demands with respect to the reliability of gap detection in view of the allowable change of position which is extremely small while the arm rests on the label and while the arm has entered the gap. Mechanical detection means can be used also for detection of the object to be provided with the label.

Claims

CLAIMS:

1. A device for the printing and dispensing of labels sticking on a strip-shaped liner of carrier material, comprising a drive means for advancing the liner along a transport path; a printing means for printing on the labels; a separation means for separating a label from the liner and dispensing the label after printing; a label detection means having a light-emitting and a light- receiving element for detecting the position of a label on the liner during movement of the liner along the transport path; a control unit for controlling the printing means and the drive means in dependence of the output signal received from the label detec¬ tion means; transport path curvature means for causing the liner, while being moved, to have a curvature such that the upper face of the liner provided with the labels is curved convexly; and wherein the light-receiving element receives the light of the light- emitting element impinging on the liner in the region of the curvature of the transport path, only if the confronting, closely abutting edges of two successive labels are oriented relative to each other at an angle corresponding to the curvature of the liner, so that the edge of a label on the liner and/or the resulting gap between two successive labels can be detected.

2. The device according to claim 1, wherein the transport path curvature means in the area of the label detection means is formed by a convexly curved surface for abutment with the lower face of the liner facing away from the labels.

3. The device according to claim 1 wherein the transport path in the area of the label detection means passes between two guide plates being mutually corresponding bent.

4. The device according to claim 1 wherein the label detection means is oriented in such a manner relative to the liner that the liner crosses the optical axis between the light-emitting element and the light-receiving element of the label detection means.

5. A device for the printing and dispensing of labels sticking on a strip-shaped liner of carrier material, comprising a drive means for advancing the liner along a transport path; a printing means for printing on the labels; a separation means for separating a label from the liner and dispensing the label after printing has been performed 13, thereon, the distances between the printing means and the separation means being greater than the distance between the confronting edges of two successive labels; a label detection means for detecting the position of a label relative to the printing means; and a control unit for controlling the printing means and the drive means wherein the control unit after separation of a label controls the drive means in such a manner that the liner is moved backwards until the label detection means detects that the label following the separated label is located before the printing means as seen in advancing direction of the liner.

6. The device according to claim 5, wherein the liner, prior to the printing of a label, is advanced by the drive means and under control of the control means in such a manner that, as seen in advancing direction of the liner, the front edge of the label to be printed is arranged level with the printing device or immediately before it.

7. The device according to claim 5 and further including an object detection means for detecting an object or the like to be provided with a label, the detection signal of said object detection means being supplied to the control unit as a starting signal for starting the printing and dispensing of the labels.

8. The device according to claim 1 wherein a start signal for starting the printing and dispensing of the labels can be supplied to the control unit.

9. The device according to claim 7 wherein the printed label can be dispensed and applied to said object or the like with a predetermined delay after occurrence of the detection signal of the additional detection means or of the external start signal.

10. The device according to claim 1 wherein the information for printing a label can be supplied to the control unit from an external device.

11. The device according to claim 1 wherein the drive means is provided as a rotatably driven drive roller having the liner pressed on a portion of its peripheral surface.

12. The device according to claim 11, wherein the printing means comprises a thermal printhead pressing against the peripheral surface of the drive roller, the liner passing between the thermal printhead and the drive roller.

13. The device according to claim 1 wherein the separation means is provided as a separation shaft extending transversely to the longitudinal extension of the liner and having the liner guided there-around, the diameter of this separation shaft being selected such that a label sticking to the liner will separate from the liner due to its stiffness in spite of its adhesion when the liner is advanced around the separation shaft.

14. The device according to claim 13, wherein the drive roller and the separation shaft are arranged in such a manner relative to each other that a portion of the liner located before the separation shaft as well as a portion of the liner located behind the separation shaft are guided about a portion of the drive roller.

15. The device according to claim 1 wherein the liner with the labels thereon is provided in wound-up condition, with the labels being arranged on the inner surface of the wound-up liner, and in that a pressing means is provided by which the edges of the labels, possibly becoming separated while the liner is unwound, are pressed against the liner, said pressing means abutting the labelled upper surface of the liner along that portion of the liner which has just been unwound from the roll.

16. The device according to claim 15, wherein the liner can be wound onto a driven roller after separation of the labels.

17. The device according to claim 1 wherein prior to an advance movement of the liner for printing the next label, at least one label is located between the label detection means and the printing means.

18. The device according to claim 16, wherein the control unit after switching-on controls the drive means for backward movement of the liner, that the control means can detect the change of the output signal of the label detection means occurring upon transition from the detection of a label to the detection of only the liner without a label thereon, and that the level of the output signal outputted upon detection of the liner without a label thereon can be stored as a reference value for the detection of the edge of a label.

19. The device according to claim 18, wherein the liner after switching-on is moved backwards without winding up the backwardly moved portion of the liner having the labels provided thereon.

20. A device for the printing and dispensing of successive labels sticking on a strip-shaped liner of carrier material, comprising a drive means for advancing the liner along a transport path; a printing means for printing on the labels; a separation means for separating a label from the liner and dispensing the label after printing; a label detection means for detecting the interval between two successive labels on the liner during movement of the liner along the transport path; a control unit for controlling the printing means and the drive means in dependence of the output signal received from the label detection means; and the transport path in the area of the label detection means is arranged in such a manner that the liner, while being moved, is provided with a curvature such that the upper face of the liner provided with the labels is curved convexly and the confronting, closely abutting edges of two successive labels are oriented relative to each other at an angle corresponding to the curvature of the liner, so that the edge of a label on the liner and/or the resulting gap between two successive labels can be detected by the label detection means.

21. A device for the detection of labels closely following each other on a strip-shaped liner of carrier material during movement of the liner, using a label detection means, comprising a transport path provided in or at the label detection means for movement of the liner therealong, and the transport path in the area of the label detection means is arranged in such a manner that the liner, while being moved, is provided with a curvature such that the upper face of the liner provided with the labels is curved convexly and the confronting, closely abutting edges of two successive labels are oriented relative to each other at an angle corresponding to the curvature of the liner, so that the edge of a label on the liner and/or the resulting gap between two successive labels can be detected by the label detection means.

22. A method for the detection of labels closely following each other on a strip-shaped liner of carrier material during movement of the liner, using a label detection means, the method characterized in that the liner with the closely adjacent labels sticking thereon is moved to pass by the label detection means while being curved such that the labelled upper face of the liner is convexly curved for generating a gap between the confronting edges of two successive labels, and the label detection means detects the thus generated gap.

23. The method according to claim 22 wherein the label detection means comprises a light-emitting and a light-receiving element and that the light emitted by the light-emitting element and directed onto the lower or upper face of the liner is received by the light-receiving element when the light impinges on the liner in the region of the gap generated by the convex curvature of the upper face of the liner.