METHOD AND MARKING APPARATUS FOR APPLYING A MARKING ON AN OBJECT

Abstract

The invention relates to a method for applying a marking on an object according to image data, wherein the image data comprises pixels with first pixel values and pixels with second pixel values, and wherein the marking to be produced comprises several cells, each cell corresponding to one pixel of the image data, in which at least one light beam is emitted with light emitting means; a deflection direction of scanning means for deflecting the light beam is scanned over the object; when the deflection direction points at a cell corresponding to a pixel with a first pixel value, the light emitting means are activated to produce a mark in that cell; and; when the deflection direction points at a cell corresponding to a pixel with a second pixel value, the light emitting means are deactivated to leave that cell blank. The method is characterized in that the deflection direction is altered in a meander pattern for cells that correspond to pixels with first pixel values, and in a straight movement for cells that correspond to pixels with second pixel values. The invention further relates to a marking apparatus for applying a marking on an object.

Claims

1. A method for applying a marking on an object according to image data, wherein the image data comprises pixels with first pixel values and pixels with second pixel values, and wherein the marking to be produced comprises several cells, each cell corresponding to one pixel of the image data, in which at least one light beam is emitted with light emitting means, a deflection direction of scanning means for deflecting the light beam is scanned over the object, when the deflection direction points at a cell corresponding to a pixel with a first pixel value, the light emitting means are activated to produce a mark in that cell, and when the deflection direction points at a cell corresponding to a pixel with a second pixel value, the light emitting means are deactivated to leave that cell blank, wherein the deflection direction is altered in a meander pattern for cells that correspond to pixels with first pixel values, and in a straight movement for cells that correspond to pixels with second pixel values wherein the meander pattern starts and ends at a boarder of a cell.

2. The method according to claim 1, characterized in that the meander pattern comprises at least two longitudinal movements connected with a loop movement to produce a mark with at least two longitudinal lines connected with a loop.

3. The method according to claim 2, wherein neighbouring longitudinal lines of one mark touch each other.

4. The method according to claim 1, wherein for filling a cell with a mark, the number of longitudinal lines within that cell is equal to D/W, wherein D is the dimension of the cell in a direction perpendicular to the longitudinal lines, and W is the width of a longitudinal line.

5. The method according to claim 2, wherein the cells form a pattern of rows and columns, the deflection direction is scanned over the cells column by column, and the longitudinal lines of the marks are formed in the direction of the rows.

6. The method according to claim 2, wherein the cells form a pattern of rows and columns, the deflection direction is scanned over the cells column by column, and the longitudinal lines of the marks are formed in the direction of the columns.

7. The method according to claim 1, wherein each mark formed in one of the cells corresponding to pixels with first pixel values has an even number of loops.

8. The method according to claim 2, wherein if a mark has been created in a last cell of one column such that the mark ends bordering a next cell of a neighbouring column, and if the next cell corresponds to a pixel with a first pixel value, than the light emitting means stay activated while the deflection direction is moved from the last cell to the next cell.

9. The method according to claim 1, wherein at least one meander pattern spans over neighbouring cells corresponding to pixels with first pixel values such that all longitudinal lines of the mark produced with this meander pattern span over these cells whereas each loop is formed in only one of these neighbouring cells.

10. The method according to claim 1, wherein the meander pattern comprises at least two longitudinal movements connected with a loop movement, and the light emitting means are activated only during the longitudinal movements but not during the loop movements, to produce a mark with at least two longitudinal lines.

11. The method according to claim 1, wherein the meander pattern comprises a zigzag shape in which a produced mark comprises several lines, wherein neighbouring lines are oblique to each other.

12. A marking apparatus for applying a marking on an object according to image data, wherein the image data comprises pixels with first pixel values and pixels with second pixel values, and wherein the marking to be produced comprises several cells, each cell corresponding to one pixel of the image data, the marking apparatus comprising light emitting means for emitting at least one light beam, scanning means for deflecting the light beam, the scanning means being adapted to scan a deflection direction for the light beam over the object, and control means that are adapted to activate the light emitting means when the deflection direction points at a cell corresponding to a pixel with a first pixel value to produce a mark in that cell, and to deactivate the light emitting means when the deflection direction points at a cell corresponding to a pixel with a second pixel value to leave that cell blank, wherein the control means are adapted to alter the deflection direction in a meander pattern for cells that correspond to pixels with first pixel values, and in a straight movement for cells that correspond to pixels with second pixel values wherein the meander pattern starts and ends at a boarder of a cell.

Description

[0051] A better understanding of the invention and various other features and advantages of the present invention will become readily apparent by the following description in connection with the schematic drawings, which are shown by way of example only, and without limitation, wherein the same reference numerals may refer to alike or substantially alike components:

[0052] FIG. 1 shows a marking according to a first prior art;

[0053] FIG. 2 shows in detail printed pixels according to a first prior art;

[0054] FIG. 3 shows a marking according to a second prior art;

[0055] FIG. 4 shows a schematic of forming a marking according to a second prior art;

[0056] FIG. 5 shows a detail of a marking and moving a light beam according to a first embodiment of the invention;

[0057] FIG. 6 shows a detail of a marking and moving a light beam according to a second embodiment of the invention;

[0058] FIG. 7 shows a detail of a marking and moving a light beam according to a third embodiment of the invention;

[0059] FIG. 8 shows a detail of a marking and moving a light beam according to a fourth embodiment of the invention.

[0060] FIG. 1 shows a first prior art of forming a marking 1 also known as dot mode forming. The marking corresponds to image data with pixels arranged in rows and columns. Consequently, also the marking consists of cells 2, 2a arranged in rows or lines 3 and columns 4. Each cell 2 corresponds to one pixel which may have a first pixel value or a second pixel value, e.g. a dark or a bright pixel. A cell 2 is filled with a mark 5 if it corresponds to a first pixel value or left blank if it corresponds to a second pixel value, as shown for cell 2a. In the case of marking e.g. food products or beverages, the marking may contain information such as a best before date or general information about ingredients or similar.

[0061] FIG. 2 shows in detail four neighboring marks 5, i.e. four neighboring cells each being filled with a mark 5. According to the first prior art, a light beam is moved in a spiral shape creating single dots along the spiral to form each pixel 5. In bold lines the path of the deflection direction of the scanning means is indicated for continuing from one cell to the next. During this movement, the light emitting means are usually deactivated, i.e. the bold lines are not part of the marking. This technique belongs to cell-by-cell render methods. It is, however, comparably time consuming.

[0062] FIG. 3 shows a second prior art method of forming a marking 1. A detail of this figure is shown enlarged in FIG. 4. According to the second prior art method a light beam is moved along lines 6 over the whole area of the marking. The light beam is not only moved along one column once, but three times. In this way a mark created in one cell 2 (indicated with a dotted box) consists of three lines next to each other, resulting in roughly a square shape. A cell 2a to be left blank is also scanned three times, with the light emitting means being deactivated.

[0063] When the deflection direction passes the cells to be left blank, the scanning means are often accelerated to a higher scanning speed. When reaching a cell in which a mark is to be produced, the scanning speed is again decelerated. In these cases, an additional waiting time is to be added to allow for undesired vibrations to die out. This again leads to longer marking times. The overall time to produce the marking is again not satisfactory, and often even higher than the time requirements of the method described in connection with FIGS. 1 and 2.

[0064] The invention allows markings to be produced faster. An example of a method of the invention is described with reference to FIG. 5, which shows a marking 1 as well as auxiliary lines that are not part of the marking but useful in explaining the method.

[0065] Again, a marking 1 corresponding to image data is to be formed. The image data comprises pixels with first pixel values, corresponding to a mark 5 that is to be produced in a cell 2, and with second pixel values, corresponding to an empty cell 2a without a mark. The cells 2 corresponding to first pixel values are shown checkered, and the cells 2a corresponding to second pixel values are left blank. One blank cell 2a is indicated with a rectangular frame.

[0066] A light beam is scanned over the area of the marking to produce the marking 1. In areas that are to be left blank, the light beam is deactivated. This scanning motion is carried out with scanning means which have a variable deflection direction for the light beam. FIG. 5 shows the path of the deflection direction 10, i.e., on which areas the deflection direction successively points. The main idea of the invention resides in the shape of this path and in that two different shapes are used dependent on whether the deflection direction points at a cell 2 in which a mark 5 is to be produced or a cell that is to be left empty.

[0067] At the start of the marking process, the deflection direction points at a location 11, e.g. a top left corner of a first cell in a first column. This cell corresponds to a first pixel value and thus a mark is to be produced in that cell. The light emitting means are hence activated. The deflection direction and thus the light beam are moved in a meander pattern within that cell. That is, the deflection direction is moved to the right to produce a longitudinal line, than downwards to produce a loop part, and then left to produce another longitudinal line. Further loops and longitudinal lines may follow within that cell.

[0068] In the example shown, all cells of the first column correspond to first pixel values. Hence, the light emitting means stay activated while the scanning over the next cells in the first column continues. In this way, the light beam meanders downwards and produces in each of these cells a meander mark. After concluding with the first column, the deflection direction is moved from position 12 to position 13 which is a starting point in the neighboring cell of the next column. During this movement no light beam is emitted. Starting from position 13, the meander movement continues along this column upwards until a cell 2a is reached that is to be left blank. Now the light beam is turned off and, instead of a meander pattern, the deflection direction is moved in a straight line 8 to reach the next cell at point 14, where the light beam is turned on and a meander pattern follows. When scanning of this column is concluded at point 15, scanning of the next column (to the right) follows. As point 15 directly touches the cell of the next column, the light beam need not be turned off, in contrast to the jump from point 12 to point 13.

[0069] A distance between longitudinal lines in one cell 2 is preferably chosen to correspond to the thickness or width of one line; in that way, no gap is left between the lines.

[0070] Instructions for such a meander pattern to be input to the control unit may be expressed as follows, in particular when starting at point 11: [0071] Step A) Move the deflection direction in the row direction for as much as the cell width minus one light beam width by subtracting the light beam width the produced line has a length equal to the cell width, i.e. the dimension of the cell in the direction of the rows; in this way the longitudinal line starting from point 11 is produced; [0072] Step B) Move in the row direction for as much as (cell height minus light beam width) divided by (longitudinal lines per cell minus one); the cell height minus light beam width indicates the distance from the center of the first longitudinal line to the last longitudinal line to be produced in that cell; this distance is to be divided by the number of steps in the row direction, which is one lower than the number of longitudinal lines per cell; [0073] Now steps A) and B) are repeated, but with each pair of consecutive longitudinal lines being counter to each other, in particular being antiparallel, until the end of the cell is reached after a step A). [0074] If now the next cell is also to be filled with a mark, the preceding steps are continued. Otherwise, a straight line movement in the row direction follows until the next cell to be filled with a mark is reached or until the end of the column is reached. [0075] When a column end is reached, the deflection direction is moved to the next column, and this column and any following columns are processed in the afore-described way until the whole marking is produced.

[0076] In general, markings are larger than the one shown in FIG. 5.

[0077] With respect to FIG. 6, another embodiment of the invention will be described. FIG. 6 differs from FIG. 5 in the shape of the meander pattern. In FIG. 6, a meander again starts with a longitudinal line. This line is, however, not perpendicular to a row direction 4, but at another angle thereto. The line thus has a component in the row direction and a component in the column direction. Furthermore, the line is slightly bent to progress in the row direction. A loop of such a meander is formed by reversing the speed of the movement component in the row direction; the movement component in the column direction is kept constant.

[0078] Another embodiment of the invention is shown in FIG. 7. In this case, a meander comprises straight lines with a component is the row direction and a component in the column direction. Each second straight line is parallel to each other.

[0079] FIG. 8 shows a further variant of the invention. The meander movement of the deflection direction is equal to the one described with reference to FIG. 5. However, the light emitting means are activated only during the longitudinal line movements but not during the loop movements, i.e., the movements in the row direction. As a consequence, the mark produced in one cell 2 consists of several longitudinal lines that are not connected to each other.

[0080] The method and the marking apparatus according to the invention allow to form a marking 1 on an object fast, efficiently and with a reduced likelihood of being distorted. In particular, the method does not have as much delay time as the prior art, thus it can be performed faster. By selecting the width of the light beam a high quality marking 1 in particular with a high readability can be formed.