The present invention relates generally to the technique of producing a printing on a foil by means of a thermal transfer ribbon in an ink transfer operation.
The present invention relates in particular to the technique of producing a printing on a foil in a thermal printing operation during a packaging operation in which the foil is used as a packaging foil or as an information foil sheet to be applied to or below a wrap around or packaging foil for packaging a product being an organic or inorganic product. The examples of products relevant in the present context are unlimited ranging from toys, cosmetics, consumer products, foodstuffs, drugs etc. In general, any product which is to be packed in a foil or to be applied with an information printing after the product has been included in a separate package may be relevant in the present context. The invention in general relates to high speed printing and packaging operations in which the foil on which the printing is to be applied is moved at a speed up to several hundred millimeters per second.
It is known to print continuous packaging materials constituting foil materials and other continuous printing media such as paper materials for producing labels with alfanumeric information and symbols, information, logos etc. while using a thermal printing or thermal transfer technique. According to the thermal transfer technique, a thermal transfer ribbon including an ink is heated at specific locations to an elevated temperature causing the ink to be fluid and at the same time, the thermal transfer ribbon is contacted with the print media such as the foil or paper material in question for causing the transfer of the fluid ink to the foil material or paper material. In the ink transfer operation, the thermal transfer ribbon is moved in synchronism with the print media or foil to which the printing is to be applied and the amount of thermal transfer ribbon material which is used in a high speed printing and packaging operation performed at a speed of several hundred millimeters per second may, as will be readily understood, be extremely high as the thermal transfer ribbon is also moved at the same high speed as the foil material amount to a speed of transportation of the order of several hundred meters per second. Examples of prior art thermal printers of the above kind are described in EP 0 157 096, EP 0 176 009, EP 0 294 633, U.S. Pat. Nos. 5,297,879, 3,984,809, 4,650,350, 4,642,655, 4,650,350, 4,712,115, 4,952,085, 5,017,943, 5,121,136, 5,160,943, 5,162,815, 5,372,439, 5,415,482, 5,576,751, 5,609,425 and 5,647,679 to which reference is made and which U.S. patents are hereby incorporated in the present specification by reference.
From the technical field of paper recorders, it is known to utilize a thermal transfer ribbon and produce a printing on a piece of paper by sandwiching the thermal transfer ribbon between a printing head or recorder head and the paper sheet on which the printings are to be produced. It is known in paper recorders of this kind to reduce the speed of the thermal transfer ribbon relative to the speed of the paper sheet for saving the amount of thermal transfer ribbon used and consequently obtain a reduction in costs and improve the economical efficiency of the paper recorder. Examples of paper recorders of this type are shown in Japanese patent publication (Kokoku) No. 62-58917), Japanese patent application laying open (Kokai) No. 63-165169, U.S. Pat. Nos. 5,121,136, 5,372,439 and 5,415,482. Reference is made to the above patent applications and patents and the above US patents are hereby incorporated in the present specification by reference.
An object of the present invention is to provide a novel technique of producing high speed printings on a print media such as a foil allowing substantial material savings as far as the thermal transfer ribbon is concerned without to any substantial extent deteriorating the quality of the printing produced as compared to the prior art thermal printing techniques. It is a further object of the present invention to provide a novel thermal printing technique rendering it possible with a substantial ribbon material saving to establish an even improved printing quality as compared to the prior art thermal printing technique by providing an im-proved utilization of the thermal transfer ribbon material as compared to the utilization of the thermal transfer ribbon material in accordance with the prior art thermal printing technique.
An advantage of the present invention relates to the fact that a thermal transfer ribbon material saving up till 80% may be obtained without to any substantial extent deteriorating the printing quality as compared to the prior art thermal printing technique.
The above objects and the above advantage together with numerous other objects, advantages and features which will be evident from the below detailed description of preferred embodiments of the present invention are in accordance with a first aspect of the present invention obtained by means of a method of producing a printing on a surface of a foil by means of energizable printing means and a thermal transfer ribbon including an ink which is transferable in an ink transfer operation at specific locations of the thermal transfer ribbon by heating the specific locations to an elevated temperature by means of the energizable printing means causing the ink to be fluid, comprising the following steps:
arranging the thermal transfer ribbon in facial contact with the surface of the foil,
arranging the energizable printing means in contact with the thermal transfer ribbon opposite to the foil,
moving the foil and the energizable printing means relative to one another at a specific speed while pressing the energizable printing means and the foil together so as to sandwich the thermal transfer ribbon there-between in a constrained state, and while energizing the energizable printing means, and
moving the thermal transfer ribbon relative to the energizable printing means at a reduced speed as compared to the specific speed of the foil relative to the energizable printing means and consequently moving the thermal transfer ribbon relative to the foil for causing the ink of the thermal transfer ribbon to be transferred at the specific locations to the foil at specific areas thereof constituting the printing so as to smear the ink of the thermal transfer ribbon at the specific locations onto the foil through the motion of the thermal transfer ribbon relative to the foil.
Contrary to the prior art thermal printing technique in which the thermal transfer ribbon is moved in synchronism with the foil to which the printing is to be applied in the relative motion of the foil relative to the energizable printing means, it has been realized that the speed of motion of the thermal transfer ribbon relative to the energizable printing means may be reduced as compared to the speed of motion of the foil relative to the energizable printing means providing a substantial saving of thermal transfer ribbon material without reducing or deteriorating the quality of the printings produced. According to the prior art thermal transfer printing technique, the ink is transferred from a thermal transfer ribbon in a process of establishing facial contact between the thermal transfer ribbon and the foil during the process of moving the foil without causing any mutual movement between the thermal transfer ribbon and the foil as it has been considered mandatory to the obtaining of a high quality printing that no deviation between the movement of the thermal transfer ribbon and the foil should be allowed which mutual movement inevitably would deteriorate the printing quality. According to the teachings of the present invention, it has been realized that the quality of the printing process is by no means deteriorated provided the thermal transfer ribbon and the foil are moved relative to one another as the ink transfer process is converted from a facial contact transfer process into a combined facial contact transfer process and a smearing process in which the ink is smeared onto the foil from the thermal transfer ribbon. It is believed that the combined facial contact transfer operation and the smearing transfer operation of the ink from the thermal transfer ribbon to the foil provides an increased utilization of the ink content of the thermal transfer ribbon as compared to the prior art exclusive facial contact transfer operation.
The energizable printing means may according to the teachings of the present invention be constituted by any appropriate heating means for causing local heating at specific locations of the thermal transfer ribbon such as a laser, a pin head or preferably and advantageously a printing head including individual energizable printing elements.
According to a first implementation or embodiment of the method according to the first aspect of the present invention, the foil is moved continuously while the energizable printing means are stationary and the thermal transfer ribbon is moved relative to the foil and relative to the energizable printing means while the energizable printing means are heated during the ink transfer operation and kept stationary relative to the energizable printing means while the energizable printing means are not heated.
According to a second implementation or embodiment of the method according to the first aspect of the present invention, the foil is moved continuously while the energizable printing means are stationary and the thermal transfer ribbon is moved relative to the foil and relative to the energizable printing means while the energizable printing means are heated during the ink transfer operation and moved in the reverse direction relative to the energizable printing means while the energizable printing means are not heated so as to utilize an used part of the thermal transfer ribbon in a subsequent ink transfer operation.
According to a third implementation or embodiment of the method according to the first aspect of the present invention, the foil is moved intermittently and kept stationary during the ink transfer operation while the energizable printing means and the thermal transfer ribbon being moved relative to the stationary foil while the energizable printing means are heated during the ink transfer operation and moved in the reverse direction relative to the energizable printing means while the energizable printing means are not heated so as to utilize an unused part of the thermal transfer ribbon in a subsequent ink transfer operation.
According to a particular aspect of the present invention as far as the thermal transfer ribbon saving aspect is concerned, it has been realized that in numerous instances and in particular in printing on packages, packaging foils or the like, a substantial thermal transfer ribbon saving may be obtained provided the printings to be produced are slightly re-located from one printing operation to another without changing the geometric configuration of the printing. The above described second and third implementation or embodiment of the method according to the first aspect of the present invention constitute embodiments in the present context to be referred to as xe2x80x9cside shift techniquexe2x80x9d and xe2x80x9cretraction techniquexe2x80x9d, respectively, which are to be considered independent aspects of the present invention as will be discussed below.
In accordance with the thermal transfer ribbon saving aspect of the present invention, a specific ink transfer operation is preferably performed utilizing a part of the thermal transfer ribbon not previously used in a preceding ink transfer operation and preferably further, the part of the thermal transfer ribbon used for the specific ink transfer operation being positioned at least partly transversly offset relative to that part of the thermal transfer ribbon used in a preceding ink transfer operation in order to use the maximum amount of the thermal transfer ribbon as compared to a printing technique not involving xe2x80x9cside shifting techniquexe2x80x9d or xe2x80x9cretraction techniquexe2x80x9d.
The method according to the first aspect of the present invention may be operated at a high production rate corresponding to a high specific speed of the foil relative to the energizable printing means of the order of 50-1,000 mm/sec, such as of the order of 100-500 mm/sec, pre-ferably of the order of 200-500 mm/sec, while said reduced speed constitutes 20-98%, such as 20-50% or 50-98% of said specific speed or alternatively constitutes 20-30%, 30-40%, 40-50%, 50-60%, 60-70%, 70-80or 90-98% of said specific speed. Alternatively, the specific speed may be of the order of 100-200 mm/sec, 200-300 mm/sec, 300-400 mm/sec, 400-500 mm/sec, 500-600 mm/sec, 600-700 mm/sec, 700-800 mm/sec, 800-900 mm/sec or 900-1,000 mm/sec, while said reduced speed constitutes 20-30%, 30-40%, 40-50%, 50-60%, 60-70%, 70-80%, 80-90% or 90-98% of said specific speed.
The foil material to which the printing is to be applied may be any appropriate plastics or inorganic or organic material such as a PE or a PVC foil, a woven or non-woven plastic foil or a paper foil, aluminum foil or a combination thereof.
The printing head which according to the presently preferred embodiment of the method according to the first aspect of the present invention constitutes the energizable printing means may preferably include energizable printing elements arranged at a mutual spacing of the order of 0.05 mm-1 mm, such as of the order of 0.1 mm-0.5 mm, preferably approximately 0.1 mm.
The above objects and the above advantage together with numerous other objects, advantages and features which will be evident from the below detailed description of preferred embodiments of the present invention are in accordance with a second aspect of the present invention obtained by means of a method of producing a printing on a surface of a foil by means of energizable printing means and a thermal transfer ribbon including an ink which is transferable in an ink transfer operation at specific locations of the thermal transfer ribbon by heating the specific locations to an elevated temperature by means of the energizable printing means causing the ink to be fluid, comprising the following steps:
arranging the thermal transfer ribbon in facial contact with the surface of the foil,
arranging the energizable printing means in contact with the thermal transfer ribbon opposite to the foil, and
moving the foil and the energizable printing means relative to one another at a specific speed while pressing the energizable printing means and the foil together so as to sandwich the thermal transfer ribbon there-between in a constrained state, and while energizing the energizable printing means, for causing the ink of the thermal transfer ribbon to be transferred at the specific locations to the foil at specific areas thereof constituting the printing, the foil being moved continuously while the energizable printing means are stationary and the thermal transfer ribbon being moved relative to the energizable printing means while the energizable printing means are heated during the ink transfer operation and moved in the reverse direction relative to the energizable printing means while the energizable printing means are not heated so as to utilize an used part of the thermal transfer ribbon in a subsequent ink transfer operation. The method according to the second aspect of the present invention may advantageously be implemented in accordance with the above described preferred and advantageous implementations or embodiments of the method according to the first aspect of the present invention.
The above objects and the above advantage together with numerous other objects, advantages and features which will be evident from the below detailed description of preferred embodiments of the present invention are in accordance with a third aspect of the present invention obtained by means of a a method of producing a printing on a surface of a foil by means of energizable printing means and a thermal transfer ribbon including an ink which is transferable in an ink transfer operation at specific locations of said thermal transfer ribbon by heating said specific locations to an elevated temperature by means of said energizable printing means causing said ink to be fluid, comprising the following steps:
arranging said thermal transfer ribbon in facial contact with said surface of said foil,
arranging said energizable printing means in contact with said thermal transfer ribbon opposite to said foil, and
moving said foil and said energizable printing means relative to one another at a specific speed while pressing said energizable printing means and said foil together so as to sandwich said thermal transfer ribbon there-between in a constrained state, and while energizing said energizable printing means, for causing said ink of said thermal transfer ribbon to be transferred at said specific locations to said foil at specific areas thereof constituting said printing said foil being moved continuously while said energizable printing means are stationary and said thermal transfer ribbon being moved relative to said foil and relative to said energizable printing means while said energizable printing means are heated during said ink transfer operation and moved in the reverse direction relative to said energizable printing means while said energizable printing means are not heated so as to utilize an used part of said thermal transfer ribbon in a subsequent ink transfer operation. The method according to the third aspect of the present invention may advantageously be implemented in accordance with the above described preferred and advantageous implementations or embodiments of the method according to the first aspect of the present invention.
The above objects and the above advantage together with numerous other objects, advantages and features which will be evident from the below detailed description of preferred embodiments of the present invention are in accordance with a fourth aspect of the present invention obtained by means of a method of producing a plurality of individual printings on a surface of a foil by means of energizable printing means and a thermal transfer ribbon defining a specific width along a transversal direction thereof and including an ink which is transferable in an ink transfer operation by heating the thermal transfer ribbon at specific locations thereof to an elevated temperature by means of the energizable printing means causing the ink to be fluid, each of the printings defining a maximum dimension along a direction coinciding with the transversal direction constituting no more than 50% of the width, comprising the following steps:
(a) arranging the thermal transfer ribbon in facial contact with the surface of the foil,
(b) arranging the energizable printing means in contact with the thermal transfer ribbon opposite to the foil,
(c) moving the foil and the energizable printing means relative to one another at a specific speed and moving the thermal transfer ribbon relative to the energizable printing means in the ink transfer operation while pressing the energizable printing means and the foil together so as to sandwich the thermal transfer ribbon therebetween in a constrained state, and simultaneously energizing the energizable printing means causing the ink to be transferred to the foil at a first area thereof producing a first printing on the foil at one of the longitudinal edges of the thermal transfer ribbon,
(d) relocating the thermal transfer ribbon relative to the energizable printing means while the energizable printing means are not heated so as to utilize an unused part of the thermal transfer ribbon and repeating step (c) to provide a second printing on the foil at the opposite longitudinal edge of the thermal transfer ribbon.
The above objects and the above advantage together with numerous other objects, advantages and features which will be evident from the below detailed description of preferred embodiments of the present invention are in accordance with a fifth aspect of the present invention obtained by means of a thermal printer for producing a printing on the surface of a foil in an ink transfer operation, comprising:
means for supplying the foil to the thermal printer,
a thermal transfer ribbon including an ink which is transferable in the ink transfer operation at specific locations of the thermal transfer ribbon by heating the specific locations to an elevated temperature causing the ink to be fluid,
means for arranging the thermal transfer ribbon i facial contact with the surface of the foil,
energizable printing means for heating the specific locations of the thermal transfer ribbon to the elevated temperature in the ink transfer operation,
means for energizing the energizable printing means,
means for pressing the energizable printing means and the foil together so as to sandwich the thermal transfer ribbon therebetween in a constrained state,
means for moving the foil and the energizable printing means relative to one another at a specific speed while pressing the energizable printing means and the foil together and while energizing the energizable printing means, and
means for moving the thermal transfer ribbon relative to the energizable printing means at a reduced speed as compared to the specific speed of the foil relative to the energizable printing means and consequently moving the thermal transfer ribbon relative to the foil for causing the ink of the thermal transfer ribbon to be transferred at the specific locations to the foil at specific areas thereof constituting the printing so as to smear the ink of the thermal transfer ribbon at the specific locations onto the foil through the motion of the thermal transfer ribbon relative to the foil.
The above objects and the above advantage together with numerous other objects, advantages and features which will be evident from the below detailed description of preferred embodiments of the present invention are in accordance with a sixth aspect of the present invention obtained by means of a thermal printer for producing a printing on the surface of a foil in an ink transfer operation, comprising:
means for supplying the foil to the thermal printer,
a thermal transfer ribbon including an ink which is transferable in the ink transfer operation at specific locations of the thermal transfer ribbon by heating the specific locations to an elevated temperature causing the ink to be fluid,
means for arranging the thermal transfer ribbon i facial contact with the surface of the foil,
energizable printing means for heating the specific locations of the thermal transfer ribbon to the elevated temperature in the ink transfer operation,
means for energizing the energizable printing means,
means for pressing the energizable printing means and the foil together so as to sandwich the thermal transfer ribbon therebetween in a constrained state,
means for moving the foil and the energizable printing means relative to one another at a specific speed while pressing the energizable printing means and the foil together and while energizing the energizable printing means, and
means for moving the thermal transfer ribbon relative to the energizable printing means at a reduced speed as compared to the specific speed of the foil relative to the energizable printing means and consequent-ly moving the thermal transfer ribbon relative to the foil for causing the ink of the thermal transfer ribbon to be transferred at the specific locations to the foil at specific areas thereof constituting the printing the energizable printing means being stationary and the means for moving the foil and the energizable printing means relative to one another causing the foil to move relative to the energizable printing means in a continuous motion and the means for moving the thermal transfer ribbon relative to the energizable printing means moving the thermal transfer ribbon relative to the energiz-able printing means at the reduced speed while the energizable printing means are heated during the ink transfer operation and moving the thermal transfer ribbon relative to the energizable printing means in the reverse direction relative to the energizable printing means while the energizable printing means are not heating so as to utilize an unused part of the thermal transfer ribbon in a subsequent ink transfer operation.
The above objects and the above advantage together with numerous other objects, advantages and features which will be evident from the below detailed description of preferred embodiments of the present invention are in accordance with a seventh aspect of the present invention obtained by means of a thermal printer for producing a printing on the surface of a foil in an ink transfer operation, comprising:
means for supplying the foil to the thermal printer,
a thermal transfer ribbon including an ink which is transferable in the ink transfer operation at specific locations of the thermal transfer ribbon by heating the specific locations to an elevated temperature causing the ink to be fluid,
means for arranging the thermal transfer ribbon i facial contact with the surface of the foil,
energizable printing means for heating the specific locations of the thermal transfer ribbon to the elevated temperature in the ink transfer operation,
means for energizing the energizable printing means,
means for pressing the energizable printing means and the foil together so as to sandwich the thermal transfer ribbon therebetween in a constrained state,
means for moving the foil and the energizable printing means relative to one another at a specific speed while pressing the energizable printing means and the foil together and while energizing the energizable printing means, and
means for moving the thermal transfer ribbon relative to the energizable printing means at a reduced speed as compared to the specific speed of the foil relative to the energizable printing means and consequent-ly moving the thermal transfer ribbon relative to the foil for causing the ink of the thermal transfer ribbon to be transferred at the specific locations to the foil at specific areas thereof constituting the printing the means for moving the foil and the energizable printing means relative to one another causing the foil to move intermittently and maintaining the foil stationary during the ink transfer operation and causing the energizable printing means to move relative to the stationary foil and the means for moving the thermal transfer ribbon relative to the energizable printing means moving the thermal transfer ribbon relative to the energizable printing means at the reduced speed while the energizable printing means are heated during the ink transfer operation and moving the thermal transfer ribbon in the reverse direction relative to the energizable printing means while the energizable printing means are not heated so as to utilize an unused part of the thermal transfer ribbon in a subsequent ink transfer operation.
The above objects and the above advantage together with numerous other objects, advantages and features which will be evident from the below detailed description of preferred embodiments of the present invention are in accordance with a eighth aspect of the present invention obtained by means of a thermal printer for producing a plurality of individual printings on the surface of a foil in an ink transfer operation, comprising:
means for supplying said foil to said thermal printer,
a thermal transfer ribbon defining a specific width along a trans-versal direction thereof each of said printings defining a maximum dimension along a direction coinciding with said transversal direction constituting no more than 50% of said width and including an ink which is transferable in said ink transfer operation at specific locations of said thermal transfer ribbon by heating said specific locations to an elevated temperature causing said ink to be fluid,
means for arranging said thermal transfer ribbon i facial contact with said surface of said foil,
energizable printing means for heating said specific locations of said thermal transfer ribbon to said elevated temperature in said ink transfer operation,
means for energizing said energizable printing means,
means for pressing said energizable printing means and said foil together so as to sandwich said thermal transfer ribbon therebetween in a constrained state,
means for moving said foil and said energizable printing means relative to one another at a specific speed
means for moving said thermal transfer ribbon relative to said energizable printing means in said ink transfer operation while pressing said energizable printing means and said foil together and while energizing said energizable printing means causing said ink to be transferred to said foil at a first area thereof producing a first printing on said foil at one of the longitudinal edges of said thermal transfer ribbon, and
said means for moving said thermal transfer ribbon relative to said energizable printing means causing said thermal transfer ribbon to be relocated relative to said energizable printing means while said energizable printing means are not heated so as to utilize an unused part of said thermal transfer ribbon.
The present invention in particular relates to a thermal printer in which the proper positioning of the printing head or the energizable printing means relative to the thermal transfer ribbon be reestablished or maintained irrespective of any deviation of the transportation of the foil past the energizable printing means during a preceding printing operation. It has been realised that the proper operation of the thermal printer is highly dependent on the accuracy of positioning of the energizable printing means relative to the thermal transfer ribbon. In particular, it has been realised that a self-aligning structure is of the outmost importance to the obtainment of a reliable and thermal printer. Consequently, according to an eighth aspect of the present invention, a thermal printer is provided comprising:
means for supplying the foil to the thermal printer,
a thermal transfer ribbon including an ink which is transferable in the ink transfer operation at specific locations of the thermal transfer ribbon by heating the specific locations to an elevated temperature causing the ink to be fluid,
means for arranging the thermal transfer ribbon i facial contact with the surface of the foil,
energizable printing means for heating the specific locations of the thermal transfer ribbon to the elevated temperature in the ink transfer operation,
means for energizing the energizable printing means,
means for moving the energizable printing means towards the foil so as to sandwich the thermal transfer ribbon therebetween in a constrained state and for moving the energizable printing means away from the foil,
means for moving the foil and the energizable printing means relative to one another at a specific speed while pressing the energizable printing means and the foil together and while energizing the energizable printing means, and
means for moving the thermal transfer ribbon relative to the energizable printing means along a specific direction of motion,
the means for moving the energizable printing means towards and away from the foil including a supporting structure, the energizable printing means being pivotably mounted in the supporting structure for allowing the energizable printing means to pivote transversally relative to the specific direction of motion of the thermal transfer ribbon, the supporting structure including a biasing element for biasing the energising printing means in the pivotable mounting towards a specific initial position for self-aligning the energizable printing means in the specific initial position. Particular aspect features and advantages of the above thermal printer according to the eighth aspect of the present invention will be evident from the below detailed description of presently preferred embodiments of the thermal printer.
Still further, it has been realised that the proper operation of the thermal printer may be unintentionally deteriorated or ruined provided the mecahnical drive elements of the thermal printer be exposed to unintentional tampering during for instance the operation of cleaning the thermal printer or the operation of replacing a used thermal transfer ribbon with an unused or new thermal transfer ribbon. In order to improve the reliability of the thermal printer and also provide a more easy serviceble thermal printer, a thermal printer has been provided according to an eighth aspect of the present invention, which thermal printer comprises:
means for supplying the foil to the thermal printer,
a thermal transfer ribbon including an ink which is transferable in the ink transfer operation at specific locations of the thermal transfer ribbon by heating the specific locations to an elevated temperature causing the ink to be fluid,
means for arranging the thermal transfer ribbon i facial contact with the surface of the foil,
energizable printing means for heating the specific locations of the thermal transfer ribbon to the elevated temperature in the ink transfer operation,
means for energizing the energizable printing means,
means for moving the energizable printing means towards the foil so as to sandwich the thermal transfer ribbon therebetween in a constrained state and for moving the energizable printing means away from the foil, the means for moving the energizable printing means towards and away from the foil including an actuator means,
means for moving the foil and the energizable printing means relative to one another at a specific speed while pressing the energizable printing means and the foil together and while energizing the energizable printing means, and
means for moving the thermal transfer ribbon relative to the energizable printing means at a reduced speed as compared to the specific speed of the foil relative to the energizable printing means and consequently moving the thermal transfer ribbon relative to the foil for causing the ink of the thermal transfer ribbon to be transferred at the specific locations to the foil at specific areas thereof constituting the printing said thermal transfer ribbon being delivered from a delivery reel, being moved past the energizable printing means and being received by a take-up reel, the means for moving the thermal transfer ribbon relative to the energizable printing means including a roller driven by a motor,
the thermal printer further including a housing wall, the reels and the energizable printing means being exposed at an outer side of the housing wall, and the actuator means and the motor driving the roller being concealed behind the housing wall.