阅读说明：本技术 塑胶地板的对花调整装置 (Pattern-matching adjusting device for plastic floor ) 是由 陆钉毅 于 2019-02-03 设计创作，主要内容包括：本发明提供一种塑胶地板的对花调整装置,其构成包含一辊压设备及调整单元,该辊压设备用以将一基板、一具有图案的印刷层及耐磨层输送至一压延机,利用一压纹辊及压合辊配合辊压成型为塑胶地板；主要是在该压纹辊上设有与该印刷层其图案相同的凹凸压纹,且可令该压纹辊一端设为固定端,另一端为可动端,并在该可动端外缘设置该调整单元。该调整单元一端与该可动端连结,可将一位移的动力作用于该可动端,若该印刷层输送辊压时位置有所偏移,而令其图案的纹路与该凹凸压纹无法准确相对时,可通过该调整单元带动该可动端位移,调整该图案的纹路与该凹凸压纹准确相对,达到对花调整的目的。(The invention provides a register adjusting device of a plastic floor, which comprises a rolling device and an adjusting unit, wherein the rolling device is used for conveying a substrate, a printing layer with patterns and a wear-resistant layer to a calender, and the plastic floor is formed by matching a knurling roller and a pressing roller and rolling and molding; the embossing roller is provided with concave-convex embossing with the same pattern as the printing layer, one end of the embossing roller is a fixed end, the other end of the embossing roller is a movable end, and the adjusting unit is arranged on the outer edge of the movable end. One end of the adjusting unit is connected with the movable end, a displacement power can be acted on the movable end, if the position of the printing layer is deviated when in conveying and rolling, and the lines of the patterns and the concave-convex embossing can not be accurately opposite, the movable end can be driven to displace by the adjusting unit, and the lines of the patterns and the concave-convex embossing can be adjusted to be accurately opposite, so that the aim of adjusting the register is fulfilled.)

1. The utility model provides a register adjusting device on plastic floor, its constitution contains a roll-in equipment, and this roll-in equipment is used for carrying a base plate, printing layer and wearing layer to a calender, utilizes an embossing roll and pressfitting roller cooperation roll-in shaping to plastic floor, its characterized in that: the printing layer is provided with a pattern, the embossing roller is provided with concave-convex embossing which has the same pattern with the printing layer, one end of either the embossing roller or the pressing roller is set as a fixed end, the other end is a movable end, the outer edge of the movable end is connected with an adjusting unit, the adjusting unit is provided with a telescopic rod at one end of at least one power source, the telescopic rod can be driven by the power source to apply a displacement power to the movable end, when the embossing roller is matched with the pressing roller to roll and form the substrate, the printing layer and the wear-resistant layer into a whole, if the conveying position of the printing layer is deviated, and the pattern lines and the concave-convex embossing cannot be accurately opposite, the movable end can be driven by the adjusting unit to displace, and the pattern lines and the concave-convex embossing are adjusted to be accurately opposite.

2. The plastic floor register adjusting device of claim 1, wherein: the embossing roller and the pressing roller on the calender are horizontally arranged oppositely, one end of the embossing roller is the fixed end, the other end of the embossing roller is the movable end, the movable end is arranged on a span plate, the span plate is arranged on the frame of the calender, the adjusting unit is arranged below the frame, two power sources are further arranged, and the telescopic rod at one end of each power source penetrates through the frame and is connected with the span plate.

3. The plastic floor register adjusting device of claim 2, wherein: the two power sources are manually controlled, each power source is a gear box, wherein one outer side of one power source is provided with a linkage handle, the outer side of the opposite end is in transmission connection with the other power source by utilizing a linkage rod, and the linkage rod is provided with a clutch element, so that the two ends of the linkage rod can be in a connected or separated use mode; when the clutch element is connected, the linkage handle rotates to drive the two power sources to operate simultaneously, and if the clutch element is separated, the linkage handle rotates to drive only one power source to operate independently.

4. The plastic floor register adjusting device of claim 1, wherein: the embossing roller and the pressing roller on the calender are vertically and oppositely arranged, one end of the pressing roller is the fixed end, the other end of the pressing roller is the movable end, the movable end is arranged on a cross plate, a slide rail is arranged on the rack of the calender corresponding to the position of the cross plate and can be used for the embedding and the combination of the other end of the cross plate, the adjusting unit is arranged on the outer side of the movable end, the telescopic rod at one end of the power source is connected with the outer side of the movable end, and when the power source drives the telescopic rod to act, the movable end can perform displacement adjustment along the slide rail.

5. The plastic floor register adjusting device of claim 4, wherein: the power source is manually controlled, the power source is a gear box, one side of the gear box is convexly provided with a linkage handle, and when the linkage handle rotates, the power source can be driven to operate, so that the telescopic rod can stretch and retract.

6. The plastic floor aligning device according to claim 1, 2 or 4, wherein: the power source is electrically controlled, each power source is a servo motor and is electrically connected with a controller, and the controller can control the power source to run.

7. The plastic floor aligning adjustment device of claim 1, wherein the rolling device further comprises an aligning system, the aligning system at least comprises a first sensor, a second sensor, a tension adjuster, a third sensor, and an electric control unit, the first sensor is disposed at the starting point of the conveying path of the printing layer, and the printing layer is disposed at two sides of the surface of the first sensor, and has a plurality of positioning origins at equal intervals according to a predetermined length distance, the first sensor is configured to transmit information of each positioning origin detected by the printing layer to the electric control unit; the second sensor is used for sensing the angle and the position of the embossing roller during rotation, the outer side surface of the embossing roller is at least provided with an initial origin, and information of each time the initial origin is detected is sent to the electric control unit by the second sensor; the tension adjuster is arranged at a proper position outside the conveying starting end of the printing layer and is used for adjusting the tension of the printing layer during conveying; the third sensor is arranged at the outer side of the embossing roller and the pressing roller for rolling and molding the printing layer or on a conveying path of finished products which are rolled and finished, and is used for sensing whether the positioning original points at the two sides of the printing layer are on a horizontal straight line or generate angle deviation and transmitting signals to the electric control unit.

Technical Field

The invention relates to the creation of roll forming of plastic floor, especially the creation of adjusting the pattern when there is error in roll forming.

Background

A plastic floor is made of plastic material to replace natural wood, and the damage to natural materials is reduced, which is the trend of the development of the present plastic floor products, wherein a pattern on the surface of the plastic floor has a relief three-dimensional effect, and is well received by consumers, as shown in FIG. 10, a background technology is the patent application No. CN201620778488.5, which is the previous design of the present inventor, the previous design is that a pattern aligning system is arranged in a rolling device for rolling and molding a substrate 81, a printing layer 82 and a wear layer 83 into a whole, the pattern aligning system comprises an electric control unit (not shown in the figure), and a film feeding roller 91, a tension sensor 92, a first CCD sensor 93, a laser sensor 94 and an encoder 95 which are electrically connected with the electric control unit, the tension sensor 92 is arranged on the film feeding roller 91 for sensing the tension of the printing layer 82, the first CCD sensor 93 is arranged at the proper position of the start point of the printing layer transportation, the laser sensor 94 is arranged outside the checkered roller 96 and used for detecting the original point mark information of the checkered roller, and the encoder 95 is arranged on the rotating shaft of the checkered roller 96 and used for detecting the speed information of the checkered roller. When the plastic floor is formed by rolling, the numerical values sensed by the first CCD sensor 93 and the laser sensor 94 are transmitted to the electronic control unit, and whether the color code or the node of the printing layer 82 is synchronous with the original point of the patterned roller 96 is judged, if not, the conveying speed of the printing layer 82 is synchronous with the rotation of the patterned roller 96 by adjusting the rotation speed of the patterned roller 96 or adjusting the tension of the printing layer 82 by using the film feeding roller 91, so that when the substrate, the printing layer and the wear-resistant layer are combined into a whole, the pattern or the grain 821 of the printing layer accurately corresponds to the concave-convex embossing on the embossing roller 96, and a three-dimensional patterned structure is presented (as shown in fig. 11).

However, as shown in fig. 12, if the printing layer is angularly displaced during the transportation process, the pattern lines 821 thereof are misaligned with the embossing patterns 961 of the embossing roller 96, and thus cannot be accurately aligned, which results in a defective product.

Disclosure of Invention

The main object of the present invention is to provide an aligning adjustment device for plastic floor, which can adjust the error angle by a simple adjustment mechanism to improve the efficiency and quality of production operation when the printing layer is not accurately opposite to the embossing roller due to the position deviation of one side when the rolling device is used for the rolling formation of the three-dimensional embossing.

In order to achieve the above object, the present invention provides a registration adjusting device for a plastic floor, which comprises a rolling device for conveying a substrate, a printing layer and a wear layer to a calender, and rolling and forming the plastic floor by using a embossing roller and a pressing roller, wherein the embossing roller and the pressing roller are matched to form the plastic floor, and the registration adjusting device is characterized in that: the printing layer is provided with a pattern, the embossing roller is provided with concave-convex embossing which has the same pattern with the printing layer, one end of either the embossing roller or the pressing roller is set as a fixed end, the other end is a movable end, the outer edge of the movable end is connected with an adjusting unit, the adjusting unit is provided with a telescopic rod at one end of at least one power source, the telescopic rod can be driven by the power source to apply a displacement power to the movable end, when the embossing roller is matched with the pressing roller to roll and form the substrate, the printing layer and the wear-resistant layer into a whole, if the conveying position of the printing layer is deviated, and the pattern lines and the concave-convex embossing cannot be accurately opposite, the movable end can be driven by the adjusting unit to displace, and the pattern lines and the concave-convex embossing are adjusted to be accurately opposite.

The register adjusting device of plastic floor, wherein: the embossing roller and the pressing roller on the calender are horizontally arranged oppositely, one end of the embossing roller is the fixed end, the other end of the embossing roller is the movable end, the movable end is arranged on a span plate, the span plate is arranged on the frame of the calender, the adjusting unit is arranged below the frame, two power sources are further arranged, and the telescopic rod at one end of each power source penetrates through the frame and is connected with the span plate.

The register adjusting device of plastic floor, wherein: the two power sources are manually controlled, each power source is a gear box, wherein one outer side of one power source is provided with a linkage handle, the outer side of the opposite end is in transmission connection with the other power source by utilizing a linkage rod, and the linkage rod is provided with a clutch element, so that the two ends of the linkage rod can be in a connected or separated use mode; when the clutch element is connected, the linkage handle rotates to drive the two power sources to operate simultaneously, and if the clutch element is separated, the linkage handle rotates to drive only one power source to operate independently.

The register adjusting device of plastic floor, wherein: the embossing roller and the pressing roller on the calender are vertically and oppositely arranged, one end of the pressing roller is the fixed end, the other end of the pressing roller is the movable end, the movable end is arranged on a cross plate, a slide rail is arranged on the rack of the calender corresponding to the position of the cross plate and can be used for the embedding and the combination of the other end of the cross plate, the adjusting unit is arranged on the outer side of the movable end, the telescopic rod at one end of the power source is connected with the outer side of the movable end, and when the power source drives the telescopic rod to act, the movable end can perform displacement adjustment along the slide rail.

The register adjusting device of plastic floor, wherein: the power source is manually controlled, the power source is a gear box, one side of the gear box is convexly provided with a linkage handle, and when the linkage handle rotates, the power source can be driven to operate, so that the telescopic rod can stretch and retract.

The register adjusting device of plastic floor, wherein: the power source is electrically controlled, each power source is a servo motor and is electrically connected with a controller, and the controller can control the power source to run.

The register adjusting device of plastic floor, wherein: the rolling equipment is also provided with an alignment system, the alignment system at least comprises a first sensor, a second sensor, a tension regulator, a third sensor and an electric control unit, the first sensor is arranged at the starting point position of the conveying path of the printing layer, the printing layer is corresponding to two sides of the surface of the first sensor, a plurality of positioning original points are arranged at equal intervals according to a preset length distance, and the first sensor is used for transmitting the information of each positioning original point of the printing layer to the electric control unit; the second sensor is used for sensing the angle and the position of the embossing roller during rotation, the outer side surface of the embossing roller is at least provided with an initial origin, and information of each time the initial origin is detected is sent to the electric control unit by the second sensor; the tension adjuster is arranged at a proper position outside the conveying starting end of the printing layer and is used for adjusting the tension of the printing layer during conveying; the third sensor is arranged at the outer side of the embossing roller and the pressing roller for rolling and molding the printing layer or on a conveying path of finished products which are rolled and finished, and is used for sensing whether the positioning original points at the two sides of the printing layer are on a horizontal straight line or generate angle deviation and transmitting signals to the electric control unit.

Compared with the prior art, the invention has the beneficial effects that: when the embossing roller is matched with the pressing roller to roll and form the substrate, the printing layer and the wear-resistant layer into a whole, if the position of one side of the printing layer is deviated to some extent, and the grains of the pattern of the embossing roller cannot be accurately opposite to the concave-convex embossing, the movable end can be driven to move by the adjusting unit, and the grains of the pattern are adjusted to be accurately opposite to the concave-convex embossing. Therefore, the adjustment of the registration angle error can be performed by simple operation by utilizing the mechanism design of the movable end and the arrangement of the adjusting unit, thereby improving the efficiency and the quality of the production operation.

The foregoing objects, features and characteristics of the present invention will be understood from the following detailed description of the preferred embodiments, taken in conjunction with the accompanying drawings.

Drawings

Fig. 1 is a combined plan view of a first embodiment of the present invention.

Fig. 2 is a perspective combination view of the first embodiment of the present invention.

FIG. 3 is a combined plan view of a second embodiment of the invention

Fig. 4 is a schematic view of the electric control of the first embodiment of the present invention.

FIG. 5 is a schematic diagram of the corresponding adjustment operation according to the present invention.

Fig. 6 is a combined plan view of the present invention applied to a register system.

FIG. 7 is a schematic view of the positioning origin and printing unit of the printed layer of the present invention.

FIG. 8 is a schematic diagram of a printing simulation layer and a printing unit of the computing module of the present invention.

FIGS. 9A and 9B are schematic diagrams of the print unit and the computing module simulating the average division of the embossing roller according to the present invention.

Fig. 10 is a combined plan view of existing authoring.

Fig. 11 is a schematic view of a roll printed layer of a prior art embossing roll.

Fig. 12 is a schematic view showing a positional shift of a printed layer of a conventional art.

Description of reference numerals: a substrate 11; a print layer 12; locating the origins 121, 121'; a printing unit 122; a wear-resistant layer 13; a rolling device 20; a printing layer rolling and conveying machine 21; a wear layer winder 22; a calender 30; a frame 31; a slide rail 311; a fixed thickness roller 32; a pre-application roller 33; an embossing roller 34; concave-convex embossing 341; a starting origin 342; a press-fit roller 35; a fixed end 36; a movable end 37; straddle 38, 38'; a heater 39; a registration system 40; a first sensor 41; a second sensor 42; a tension adjuster 43; a third sensor 44; an electronic control unit 50; an arithmetic module 51; an adjustment unit 60; power sources 61, 61'; an extension rod 62; a linkage rod 63; linkage handles 64, 64'; the clutch element 65; a controller 66; the individual frame plates 71.

Detailed Description

Referring to fig. 1 to 9, the present invention provides a registration adjusting device for a plastic floor, which comprises a substrate 11, a printing layer 12 with a pattern, a transparent wear layer 13, a rolling device 20 and an adjusting unit 60, wherein:

the rolling device 20 includes a rolling machine 30, and a printing layer rolling machine 21 and a wear layer rolling machine 22 for conveying the printing layer 12 and the wear layer 13 to the rolling machine 30.

The calender is a conventional machine, and can be a vertical four-roller structure, or a horizontal four-roller, horizontal five-roller, horizontal six-roller structure, in this case, the calender 30 with horizontal five-roller is taken as an illustrative embodiment, and the structure is that a frame 31 is provided with a fixed thickness roller 32, a pre-sticking roller 33, an embossing roller 34 and a pressing roller 35, and a heater 39 is arranged at a position corresponding to an outer side of the pre-sticking roller 33, and the outer surface of the embossing roller 34 is mainly formed with concave-convex embossings 341 with the same pattern as the printing layer 12. During molding, the substrate 11, the printing layer 12 and the wear layer 13 are respectively conveyed to the pre-pasting roller 33 to be overlaid and pre-pasted, and are heated by the heater 39, and then the embossing roller 34 and the pressing roller 35 are matched to be rolled and molded into the plastic floor with three-dimensional embossing.

The invention is mainly characterized in that: when the embossing roller 34 and the pressing roller 35 are assembled on the frame 31, one end of either is a fixed end 36, and the other end is a movable end 37, and the adjusting unit 60 is disposed outside the movable end 37. The selection of the movable end 37 depends on the combination arrangement of the embossing roller 34 and the nip roller 35.

First, as shown in fig. 1, when the embossing roller 34 and the pressing roller 35 are horizontally disposed opposite to each other, one end of the embossing roller 34 is locked on the frame 31 to be a fixed end 36, the other end is assembled on an independent frame plate 71 to be a movable end 37, the independent frame plate 71 of the movable end 37 is disposed on a span plate 38, the span plate 38 is disposed on the frame 31, and the adjusting unit 60 is disposed below the frame 31 corresponding to the movable end 37.

Furthermore, as shown in fig. 3, when the embossing roller 34 and the pressing roller 35 are vertically disposed oppositely, one end of the pressing roller 35 is a fixed end 36 fixed on the frame, and the other end is disposed on an independent frame plate 71 to form a movable end 37, the independent frame plate 71 of the movable end 37 is disposed on a span plate 38 ', and a slide rail 311 is disposed below the frame 31 corresponding to the span plate 38 ', so that the other end of the span plate 38 ' can be embedded and combined on the slide rail 311; the adjusting unit 60 is disposed outside the frame 31 corresponding to the movable end 37.

The adjusting unit 60 is disposed at an outer side or a lower position corresponding to the movable end 37, and one end of the adjusting unit is linked with the movable end 37 for driving the movable end 37 to perform a fine adjustment displacement of the position. The structure at least comprises a power source 61 and an expansion link 62 arranged at one end of the power source 61, the expansion link 62 can be driven by the power source 61 to apply a displacement power to the movable end 37, and the power source 61 can be controlled manually or electrically. The detailed implementation structure is described later:

first, as shown in fig. 1 and 2, when the adjusting unit 60 is disposed below the movable end 37 of the embossing roll 34, two power sources 61 may be provided, and the telescopic rod 62 at one end of each power source 61 is inserted into the frame 31 and then interlocked with the straddle 38.

If the power sources 61 of this embodiment are manually controlled, each power source 61 is internally provided with a gear box of a gear transmission mechanism, and an external side of one power source 61 is provided with a linking handle 64, and an external side of the opposite end is in transmission connection with another power source 61' by using a linking rod 63, and the linking rod 63 is provided with a clutch element 65, so that two ends of the linking rod 63 can be connected or disconnected for use. When the clutch element 65 is connected, the two power sources 61, 61' can be driven to rotate simultaneously by the rotation of the linking handle 64, so as to drive the movable end 37 to move up and down horizontally; when the clutch element 65 is disengaged, the rotation of the linking handle 64 can only drive a power source 61 to operate alone, so as to drive the movable end 37 to perform the ascending and descending adjustment with an inclined angle on one side.

As shown in fig. 4, if the adjusting unit 60 is electrically controlled, each of the power sources 61 can be a servo motor and is electrically connected to a controller 66, and the controller 66 can control the operation of the power source 61 through an electronic signal to drive the movable end 37 to move.

Furthermore, as shown in fig. 3 and 5, when the adjusting unit 60 is disposed outside the movable end 37 of the pressing roller 35, a single power source 61 can be disposed, the telescopic rod 62 at one end of the power source 61 is connected to the outside of the independent frame plate 71, and when the power source 61 drives the telescopic rod 62 to operate, the movable end 37 can move and adjust along the slide rail 311. The power source 61 of this embodiment can be manually controlled, the power source 61 is a gear box, and a linking handle 64 'is protruded from one side of the gear box, and when the linking handle 64' rotates, the gear mechanism inside the power source 61 can be driven to rotate, so that the telescopic rod 62 can be extended and retracted.

Thus, by using the matching mechanism design of the movable end 37 and the adjusting unit 60, when the embossing roller 34 cooperates with the pressing roller 35 to roll and form the substrate 11, the printing layer 12 and the wear layer 13 into a whole, if the position of one side of the printing layer 12 is shifted, and the pattern lines of the pattern cannot be accurately opposite to the concave-convex embossing 341, the adjusting unit 60 can drive the movable end 37 to move, and the pattern lines of the pattern can be adjusted to be accurately opposite to the concave-convex embossing 341.

As mentioned above, as shown in fig. 5, when the position of the printing layer 12 is shifted, the shifted side is located at the movable end 37, because the printing layer 12 is located at the fixed end 36 side and located at the movable end 37 side for adjustment when the calibration is performed at the beginning of the production operation, if the position at the movable end 37 side is shifted and the pattern grain is staggered from the concave-convex embossing 341, the adjustment unit 60 can drive the movable end 37 to move in the direction of the concave-convex embossing 341 so that the pattern grain and the concave-convex embossing 341 are overlapped in parallel, thereby achieving the purpose of adjusting the registration, and as shown in fig. 6 to 9A and 9B, when the plastic floor production equipment with three-dimensional embossing comprises a registration system 40, the adjustment unit 60 can be electrically connected to the electronic control unit 50 for controlling the registration system 40.

The registration system 40 comprises a first sensor 41, a second sensor 42, a tension adjuster 43, and a third sensor 44, wherein:

the first sensor 41 can be an electric eye or a camera, and is disposed at the starting position of the transportation path of the printing layer 12, and as shown in fig. 7, the printing layer 12 is disposed at a plurality of positioning origins 121 at equal intervals according to a predetermined length distance corresponding to the outer side of the first sensor 41, the length between each positioning origin 121 and the other adjacent positioning origins 121' is based on the circumferential length of the embossing roller 34, so as to form a printing unit 122, and in practical applications, the circumferential length of the embossing roller 34 is preferably slightly greater than the length of the printing unit 122. The first sensor 41 is used to transmit the information of each positioning origin 121 of the printing layer 12 to the electronic control unit 50.

The second sensor 42 is used to sense the angle and position of the embossing roller 34 during rotation, and at least one starting point 342 is disposed at a suitable position of the embossing roller 34, and the second sensor 42 is used to transmit the information of each detection of the starting point 342 to the electronic control unit 50.

The initial origin 342 can be disposed at a suitable position on an outer side of the embossing roll 34, the initial origin 342 can be a signal receiving element, the second sensor 42 can emit a light signal, and when the embossing roll 34 rotates, the light signal emitted by the second sensor 42 contacts the initial origin 342 to transmit a sensed signal to the electronic control unit 50.

The tension adjuster 43 is provided at an appropriate position outside the transport start end of the printed layer 12, and adjusts the tension when the printed layer 12 is transported.

The third sensor 44 can be disposed outside the embossing roller 34 and the pressing roller 35 for roll-forming the printing layer 12, or on the conveying path of the finished product after roll-forming, for sensing whether the positioning origin 121 on both sides of the printing layer 12 is on a horizontal straight line or generates an angular deviation, and transmitting a signal to the electronic control unit 50.

The electronic control unit 50 is electrically connected to the rolling device 20, the calender 30, the registration system 40 and the adjustment unit 60, and has a computing module 51, when receiving the sensing signal of each positioning origin 121 of the printing layer 12, the computing module 51 performs a number of average divisions on each printing unit 122 as shown in fig. 8, and constructs a simulation state of continuous transportation according to the stroke distance and the transportation speed of the printing layer 12 from the transportation origin to the embossing roller 34.

As shown in fig. 9A and 9B, when the electronic control unit 50 receives the signal of the initial origin 342 of the embossing roller 34, the computing module 51 is used to simulate the circumferential length of the embossing roller 34 to divide a plurality of the embossing roller 34 into a number equal to the number of the simulated divisions of the printing unit 122, and then the simulated data of the printing layer 12 is compared with the simulated data of the embossing roller 34 to determine whether the embossing 34 is exactly opposite to the pattern of the printing layer 12 when the embossing roller 34 rolls and molds the substrate 11, the printing layer 12 and the wear layer 13, and if the speed of the printing layer 12 is too fast or too slow, the tension of the printing layer 12 can be adjusted by the tension adjuster 43 to adjust the tension of the printing layer 12, so as to adjust the error between the 341 of the embossing roller 34 and the pattern of the printing layer 12. Secondly, if the electronic control unit 50 receives the signal that the printed layer 12 side generates deviation, the deviation value can be calculated by the deviation angle, and then the adjustment unit 60 is controlled to drive the movable end 37 to correct the deviation value, so that the pattern lines and the concave-convex embossing 341 are accurately opposite.

The foregoing description is intended to be illustrative rather than limiting, and it will be appreciated by those skilled in the art that many modifications, variations or equivalents may be made without departing from the spirit and scope of the invention as defined in the appended claims.