GB2077663A - Printing apparatus - Google Patents

Abstract

Printing apparatus particularly for use in weight scales for issuing a cash slip comprises a printing head (25) with two adjacent rows (33, 57) of print elements (30, 31) of which the elements (31) of the second row (57), when viewed in the direction of advance of the carrier (23) to be printed, are aligned with the spaces (36) between the elements (30) of the first row (33) and have an active printing cross-section which conceals at least the open spaces between the printing tracks of the elements (30) of the first row (33). The apparatus is controlled in a first mode by means of a keyboard operating the elements (30, 31) to print alphanumerical symbols, and in a second mode the elements (30, 31) print a bar code. <IMAGE>

Description

SPECIFICATION Printing apparatus This invention relates to printing apparatus.

Weighing scales incorporating printing ap paratus are known for providing information relating to goods, such as kind, quantity an d/or price of the goods, printed on a cash slip. This cash slip may be employed for indicating the price or weight of the goods .and may therefore be attached directly to the ,goods or to their packaging by adhesive means, stapling or the like. Such a cash slip may however also be placed loosely with the goods and the customer can produce the slip at the checkout when he pays for the article and takes possession of it. The sales price, or at least all data necessary for calculating the sales price, is represented on the slip in alphanumerical symbols which can easily be read by the customer so that he is aware of the kind, quality and quantity of the goods.

From this he can decide whether to purchase it or not. The data for calculating the price to be paid, and possibly for recording other data of interest to the management, which may appear on the sales slip must be keyed into the cash register by the sales assistant, which is time-consuming and is liable to error when the assistant is unreliable.

For representing these alphanumerical data, a matrix printer has proved suitable which is equipped with a series of active dot-like print ing elements which are selectively operated electrically whereby symbols appear in dot-like form on a print carrier. For this purpose, the print carrier, the end-portion of which forms the cash slip, is conveyed along whilst syn chronised with the activation of the elements.

As a print carrier, it is recommended that a thermally printable paper strip is employed which produces the dot-like representation of symbols by pulse-type heating of the elements through electrical pulses. A matrix printer of this kind is effective without movable compo nents in the vicinity of the elements; it is simple and economical of manufacture and is characterised by speed of operation and a low incidence of failure. Furthermore, with this kind of matrix printer it is possible to apply not only alphanumerical symbols but also gra phic effects on the cash slip. The disadvan tage of this printer is that the alphanumerical data on the cash slip are not suitable for direct mechanical recognition but always require the intervention of an operator who reads off the data and enters it manually in the recording apparatus.

In the case of apparatus of another known kind, the practice is known of representing data using a graphic code, e.g. a so-called bar code, which is characterised by easy mechani cal recognition. The data in this case are applied to a data carrier in the form of light and dark stripes of differing widths. As the data carrier passes before a reading point in a machine, these data are taken over directly by the machine without the necessity for human intervention. The disadvantage of such devices is that they require expensive printing mechanisms which have a high incidence of failure. Moreover, such data carriers cannot be read directly by the customer who may wish to be informed regarding the nature, quantity or price of an article.In order to provide this facility for the customer, it was found necessary to provide in addition a cash slip with alphanumerical representation of the data of the article. An apparatus of the kind mentioned initially had therefore to be provided additionally.

The object of the present invention is to provide a new form of printing apparatus which will enable the foregoing disadvantages to be overcome in that particular field of application.

According to the present invention there is provided printing apparatus having a printing head and a print carrier movable in synchronised relation thereto, the printing head having a plurality of print elements which are spaced laterally from each other and arranged in a row extending across the direction of motion of the print carrier, the print elements being selectively electrically operable to print data in the form of alphanumerical symbols by means of a series of printed dots; characterised in that the printing head has at least two adjacent rows of print elements of which the elements of the second row (as seen in the direction of advance of the print carrier) are aligned with the open spaces between the elements of the first row and have an active printing cross-section which conceals at least the open spaces between the printing tracks of the elements of the first row and in that at least in one longitudinal area of the print carrier the selective operation of the elements of both rows is so arranged relative to the speed of advance of the print carrier that the data are represented as continuous straightline printing tracks forming a bar code.

In relation to known matrix printers the addition of a further row of elements in the printing head does not require a great deal more space because it only requires electrical control leads for the operation of these extra elements. All other conventional operating elements (for example; those associated with the transport of the print carrier) are employed along with these elements. The simple construction and the rapid, reliable operation of the matrix printer are ensured. In this way, however, the apparatus according to the invention is also capable of representing the data at the same time as graphic codes.

Additionally the data appear on the print carrier as light and dark stripes having a width corresponding to the particular bar code. A suitable graphic code of this kind is the UPC system (Universal Products Code). This type of code is referred to hereinafter as a bar code. Thereby it is possible, with the same apparatus which prints cash slips with the alphanumerical data, also to produce information which is convenient for mechanical recognition. The apparatus according to the invention when used in the field of weighing machines, which issue cash slips, provides cash slips which can be read by sales personnel and customers, and offers the new facility of printing at the same time data for reading by machine without the necessity of involving further effort by personnel.When the keyboard of the weighing scales, is operated, the matrix printer produces not only the cash slip with the normal alphanumerical data, but also, for example on a lower section of the slip, the same data in the form of a machinereadable code. The invention thus provides an apparatus which issues slips for every conceivable purpose, which can be read equally well by humans and by machines.

The dark and light stripes of such a bar code are created simply by rendering the elements from the two rows in the printing head operative or inoperative in pairs according to the width of stripe required by the code. A continuous straight-line printing track is obtained when the train of pulses of the electrical control system for the elements is chosen sufficiently short in relation to the speed of advance of the print carrier, so that the individual dots merge smoothly into one another. In any case, this provides a stripe with sufficiently sharply defined edges for mechanical reading. By the operation of two or more adjacent pairs of elements from the two rows, a stripe is obtained of sufficiently great width for the representation of a given number according to the code. The direction of the stripe produced is determined simply by the direction of motion of the print carrier.

The transition between the numerical representation of a symbol or of the coded representation as bar code, is carried out completely automatically by the apparatus. By the use of control keys or the like on the apparatus, it is possible, if desired, to suppress one or other method of representation of data.

Since, by the offset arrangement of various rows of elements, practically every point of the print carrier is printable, it would be possible to arrange a direction of the code stripes which differs from the direction of motion of the print carrier, e.g. diagonally oblique to the direction of conveyance or at any desired inclination. The most suitable arrangement of the code stripes for any given purpose will be selected.

With two adjoining rows of elements, the active printing cross-section in the second row will, in the simplest case, be dimensioned so that it exactly fills out the open space between the printing tracks of the elements of the other row. For reasons of tolerance, of course, it is not always possible to maintain such a gap-less contact of the dots for a long time, so that, for reliability of operation, it is preferable to allow the printing tracks of the elements of both rows to overlap each other to a greater or lesser extent. This overlap is particularly advantageous for print carriers which, after one activation of a printing point, are not coloured darker when, on the basis of such overlapping, the activation of this point is repeated once or even several times more.Inthis case, it is recommended, for reasons of uniformity of structure of the matrix printer, that the elements of all rows have active printing cross-sections of basically the same dimensions. Because in a bar code, departing from a minimum unit width, multiplication of the stripe-width is required at all points, it is recommended that, with the overlapping arrangement of the two rows of elements, these are offset asymmetrically to one another at least to such an extent that only one marginal area of the printing track of one element from one row is aligned with the space between adjoining printing tracks of elements of the other row.

An arrangement of the elements according to the invention is finally also of advantage for the representation of data with alphanumerical symbols. The dot-like character of the printing is thereby eliminated to a great extent and, from continuous stripes, completed symbols are formed which are also easier for the eye to read. Since multiple elements for the representation of data in alphanumerical symbols may be employed as desired, there is in fact correspondingly reduced wear on the elements in the printing of normal cash slips, so that the utility value of the apparatus is also increased for this manner of use.

As already mentioned, any desired bar code system may be employed. It would therefore be possible to employ the EAN system (European Article Number) in the place of the UPC system already mentioned by way of example Instead of a pulse-type control of the elements of the matrix printer which produces a series of dots on the print carrier as it advances, it would be possible also to employ a continuous control system which produces from start to finish a continuous line as printing track as the print carrier moves relative to it. The latter system could be employed if the elements could stand such a constant load.

Embodiments of the present invention will now be described by way of example in accordance with the accompanying drawings, in which: Figure 1 is a weighing scales incorporating printing apparatus according to the invention for issuing a printed cash slip; Figure 2 is a sectional elevation view through the printing apparatus of the weigh ing scales of Fig. 1; Figure 3 shows a detail of the printing apparatus of Fig. 2 to a larger scale; Figure 4 shows the bar code representation of the numbers "6" and "0" produced by way of example by the component of Fig. 3; Figure 5 is an example of alphanumerical printing by the component of Fig. 3; Figure 6 shows a part of a cash slip produced by the scales of Fig. 1; and Figure 7 illustrates a modification of the detail shown in Fig. 3.

The weighing scales shown in Fig. 1 comprises a goods-receiving portion 11 and an evaluator portion 10, which in fact can also be grouped together to form a single unit but, in the present case, are arranged separately and are interconnected by a connecting lead 14. The goods-receiving portion 11 has a weighing pan 1 3 on which the article 1 2 to be weighed is placed. Within this portion 11 is a weigh cell of any known type which conveys pulses to the evaluator 10 through the connecting lead 14.

The evaluator 10 contains a keyboard 15, the keys of which feed in information concerning the kind, quantity or price of the article 1 2 in question, whereupon the weight obtained, the unit price of the article, e.g. the price per kilogram, and the individual price of the article appear in a display region 16. The evaluator 10 further comprises a matrix printer 20 which prints out all these data in various ways on a cash slip 19, for example as shown in Fig. 6. The basic construction of such a matrix printer is shown in Fig. 2, of which the following description is given: The components of the printer 20 are housed in a casing 1 7 of the evaluator 10 which is closed by a hinged cover 18. It is manifest that a separate housing from that of the evaluator 10 could be employed for this purpose.In the housing is firstly, a dish 21 containing the roll 22 of the paper strip 23 which is printed thermally and is conveyed by way of guide surfaces 24 or the like to the actual printing head 25. The cover 1 8 is provided with an inspection window 27 through which the state of the paper supply on the roll 22 can be checked without opening it. The actual printing head 25 comprises a transporter roller 26 responsible for a defined movement of the strip 23 which passes round the roller 26 and finally emerges through an aperture 28 where it is gripped and can be torn off as a cash slip 1 9 by directing it manually against a tear-off blade 29.

The matrix printer 20 comprises elements 30 which in the present case apply a thermally printed inscription on the paper strip 23. For this purpose, the elements 30 are controllable by electrical pulses. As will be more clearly seen from Fig. 3, the elements 30 are mounted in a flexible plate 32 in a row 33 which extends over the desired breadth of the strip 23 required for recording. As will be seen in Fig. 2, the flexible plate 32 with the elements 30 is maintained in contact with the paper strip 23 passing round the roller 26 by a spring-loaded pressure member 34 in the printing head 25, guide members 35 cooperating with this movement. In order to insulate the elements 30 thermally and electrically from each other in the plate 32 which is of a suitable material, they are spaced laterally apart, as shown at 36 in Fig. 3.The crosssection of the elements 30 effective for printing is shown hatched in Fig. 3. The leads 37 for their individual control, which are also mounted in the flexible plate 32, are insulated from each other and terminate in contact members 38 provided at opposite edges of the plate. When assembled, these contact members 38, here shown as of plug-type, engage in complementary contact members 39 which (see Fig. 2) are mounted on a conductor plate 40 which also carries further components 41, such as memories, for electrical control.

When the matrix printer is operating, the elements 30 are firstly employed for the alphanumerical printing of data or of any desired graphic features. As an example, the representation of the letter "T" is shown in Fig. 5 which would result solely from the control of the aforementioned elements 30.

The control command for this purpose originates from the control system in the evaluator 10 of the weighing scales and is directed in respect of the specific symbol representation of a character PROM belonging to said components 41. By the defined advance of the paper strip 23 in the printing head 25 and by corresponding selective control of the elements 30, the symbol representation is obtained which is shown by way of example in the figure. In two feed-stages of the paper strip 23, firstly a series of adjacent elements 30 are activated, whereby (see Fig. 5) dots 42 appear on the strip 23, which reveal a contour corresponding to the cross-sectional form of the elements 30. Between the dots 42, provided nothing else occurs, gaps 43 remain which are determined by the aforementioned spaces between the elements 30.

The head of the T consists of short printing tracks 44, as shown in Fig. 5. The advance motion 63 between the two rows of printing dots 42 is arranged so that there remains between the two printing stages a narrow gap 45. This gap can be removed either by additional activation of the elements 30 between the two stages or by a correspondingly slower advance 63 of the strip 23 in the region of the printing tracks 44. The vertical gaps 43 between the dots 44 still remain however in this case. The stem of the T is produced similarly by continuing movement 63 of the paper strip 23 with multiple activation of the corresponding element 30 of the row 33 in the printer. Here also, the horizontal gaps 45 between the dot 42 produced on the strip 23 can be removed by employing the means already mentioned.

In addition to the graphic information 46 and alphanumerical symbols shown on the cash slip 19 in Fig. 6, the matrix printer according to the invention is also capable however of producing a bar code 50 for mechanical recognition, employing for produc ing the code the same elements 30 and also similar extra elements 31. The alphanumerical symbols 47 may appear at the top of the cash slip 1 9 as fixed information. This information includes a reference 52 to the branch of the trading firm, to which might be added the aforementioned graphic information 46 and also unit columns 51 showing for example the unit of weight, the unit price of the goods per weight unit, and the individual price of the article.Then appear the variable data 49 entered in the appropriate unit column 51 which already appear as numbers in the display region 1 6 of the evaluator 10, visually as a whole or in part. On one part of the cash slip 1 9 however, these variable data 49, insofar as they relate to mechanical recognition, are produced by the aforementioned bar code 50 as dark stripes 53 and light stripes 54, both of varying widths. The arrangement and widths of the stripes depend upon the coding used and numerical symbol represented thereby.This is now explained in more detail with reference to Fig. 4 which gives the following information: The bar code shown by way of example in Fig. 4 represents the numbers by the differing arrangement and width of, in each case, two dark stripes 53 and two light stripes 54 on seven module tracks 55, each indicated in Fig. 4 by chain-dotted lines, on a character field 56 relevant to each number. In Fig. 4 two such character fields 56 are shown, one for the number "6" in the left-hand field, and the other for the number "0" in the righthand field in the case of this coding. Apart from these character fields 56 containing the coded numbers, the bar code system 50 comprises further coded information for the reading machine, for example delineator zones between adjoining character fields.This information however is also produced by light and dark stripes with the unit width of a module track 55, so that the illustration in Fig. 4 is sufficient to explain the invention.

In Fig. 4 the number "6" in the left-hand field is produced by the following coding of the seven module tracks 55: lightdark light-dark-dark--dark-dark. This gives an arrangement of one narrow dark strip 53 between two light stripes 54, followed by a dark stripe 53 extending over four module tracks.

In the right-hand field of Fig. 4 the individual module tracks 55 are coloured as follows for the number "0": light-light-light- darkjark-light-dark. This gives a broad light stripe 54, followed by a narrow dark stripe 53, then an even narrower light stripe 54, and finally an equally narrow dark stripe 53.

This arrangement is produced by suitable continuous operation, or non-operation, of the various elements 30, 31 in Fig. 3, whilst the paper strip continues to advance by the requisite distance during printing of the bar code 50. In addition to the row 33 of elements, a further row 57 of the aforementioned extra elements 31 is provided on the plate 32.

These elements 31 are offset relative to the elements 30 of the row 33 above, so that, as seen in the direction of conveyance of the paper strip 23, they are aligned with the aforementioned spaces 36 between the elements 30. Moreover, the elements 31 of this adjacent row 57 have an effective printing cross-section such that, during printing of the dots, the vertical gaps 43 between the dots 44 of the elements 30, described with reference to Fig. 5, can be reliably concealed. For reasons of safety, the effective printing crosssections of both these elements 30 and 31 are so chosen that the relevant printed dots at least partly overlap each other.

In order to represent the left-hand dark stripe 53 of the left-hand character field 56 (see Fig. 4) which extends over only one module track 55, the two elements 30, 31 aligned therewith of the two rows 33, 57 (see chain-dotted lines in Fig. 3) are continuously operated in the printing head. If, for reasons of their working life, these elements 30, 31 may be operated only in pulse manner, the train of pulses is so selected relative to the speed of conveyance of the paper strip 23 that, as was already explained with reference to Fig. 5 above, the horizontal gaps 45 in Fig.

5 between successive dots 42 of a printing track 44 disappear. In this way, the continuous dark stripe 53 shown in Fig. 4 is then also produced.

The two light stripes 54 situated next to it, in Fig. 4 are produced, in the printing of the entire bar code 50, simply by omitting to operating the relevant elements 30, 31 of the two rows 33, 57 which are associated with each other following the chain-dotted line between Figs. 3 and 4. The very broad dark stripe 53 shown in the left-hand character field 56 in Fig. 4 is produced simply by operating four pairs of adjacent elements 30, 31 to produce this code 50, as the four module tracks 55 show.

Regarding the printing of the remaining numbers, this is effected in a similar manner.

The picture thus obtained can be seen in the lower part of the cash slip 1 9 in Fig. 6, where the code 50 of the variable data 49 of the article is reproduced. This cash slip 1 9 is easily read in the field 48, 49 by the customer. The mechanical reading device can also acquire the same information in the bar code 50. Both are produced during printing of the same cash slip 1 9 with one and the same matrix printer 25.

In the case of Fig. 5, the printing of the alphanumerical symbol merely by using the elements 30 of the one row 33 has been explained. This was done in fact only for better understanding. In practice, it is advisable, also for the alphanumerical symbols 47 in the cash slip of Fig. 6, to employ as far as possible all elements 30, 31 of the available rows 33, 57 in order to utilise uniformly and to the fullest extent all elements available.

This results not only in a longer working life but also in greater clarity of the symbols because thereby the gaps 43 remaining in the paper strip 23 in Fig. 5 also disappear.

In the embodiment of Fig. 7 a modified arrangement of the Fig. 3 printing head 25 is shown, so that the same reference numerals are employed as in the previous embodiment.

The previous description applies generally.

The essential difference is chiefly that the elements 31 also have an effective printing cross-section corresponding to that of the elements 30 of the row 33 above. Thereby, the spaces 36 in the row 33 of elements are to be found as spaces 58 between the elements 31 of the row 57. The centre of the elements 31 could be aligned approximately with the open space 36 between the elements 30, but in Fig. 7 an asymmetrical offset arrangement of the two rows 33, 57 of elements is chosen, so that the printing tracks 59, 60 of the elements 31, 30 overlap each other at one side by a much greater width 61 than on the other side 62, as is shown by the finely dotted lines in Fig. 7.In so far as a module track corresponding to the representation of Figs. 3 and 4 is obtained in each case from the two printing tracks 60, 59 of pairs of elements 30, 31 lying obliquely above one another, it is possible here also to represent the light or dark stripes of a bar code by doubling or multiplying further the module tracks 55 because the differences in this doubling on the basis of the narrow overlapping widths 62 of two module tracks are extremely small and reliably prevent any errors in mechanical reading. On the other hand, for the representation of the alphanumerical symbols in the cash slip, printing dots are obtained from the elements 30, 31 of the two rows 33, 57 which have the same dimensions of cross-section.

As has already been mentioned, it might be possible to employ more than simply two rows 33, 57 of elements to represent the bar codes and alphanumerical symbols of a cash slip 1 9. It is unnecessary for the rows 33, 57 to be arranged exactly across the direction of conveyance of the paper strip; they may adopt another arrangement of the plate 32 on which they are mounted because this could be easily compensated by suitable operation of the elements. The essential is to overlap the arrangement of the various printing tracks of the elements 30, 31 so that continuous dark and light stripes are obtained. The "printing density" within these light and dark stripes must in any case be so calculated that errors cannot occur in the mechanical reading of the code.

Claims (7)

1. Printing apparatus having a printing head and a print carrier movable in synchronised relation thereto the printing head having a plurality of print elements which are spaced laterally from each other and arranged in a row extending across the direction of motion of the print carrier, the print elements being selectively electrically operable to print data in the form of alphanumerical symbols by means of a series of printed dots; characterised in that the printing head has at least two adjacent rows of print elements of which the elements of the second row (as seen in the direction of advance of the print carrier) are aligned with the open spaces between the elements of the first row and have an active printing cross-section which conceals at least the open spaces between the printing tracks of the elements of the first row, and in that at least in one longitudinal area of the print carrier the selective operation of the elements of both rows is so arranged relative to the speed of advance of the print carrier that the data are represented as continuous straightline printing tracks forming a bar code.

2. Apparatus according to claim 1, wherein adjacent printing tracks od the elements from both rows overlap each other.

3. An apparatus according to claim 1 or 2, wherein the active printing cross-sections of the print elements from both rows are approximately the same.

4. An apparatus according to claim 2 or 3, wherein the two rows of elements are asymmetrically offset.

5. Printing apparatus as claimed in claim 1 and substantially as hereinbefore described with reference to either of the embodiments illustrated in the drawings.

6. Weighing scales comprising means for producing a cash slip and printing apparatus as claimed in any preceding claim arranged to print data on said cash slip in accordance with weight-derived information provided by said weighing scales.

7. Weighing scales as claimed in claim 6 and substantially as hereinbefore described with reference to the accompanying drawings.