GB1578166A - Apparatus for electrical digital storage of graphical masters - Google Patents

Abstract

For the digital acquisition of information located on a level original (12), that is to say any graphic representations, the original is placed onto a receiving table (13). Light sources (11) are provided for illuminating the original from the top or light sources (14) for illuminating the original from below. Above the recording table, recording opto-electronics are arranged and these recording opto-electronics can be moved in the X and Y direction relative to the recording table by means of an X-advance device (1, 2) and, respectively, a Y-advance device (4,6). The Y-advance device is coupled to a Y-pulse transmitter. A Y-pulse counter supplies a start pulse for the serial scanning of a photosensor row (9), located in the X-direction of the recording opto-electronics to its control electronics. Each pixel from the photosensor row is converted into a digital word by means of an analog/digital converter. The outputs of the said converter and of the Y-pulse counter are connected to a multiplexer so that the digital pixel signals can be picked up with the associated Y-coordinates at its output. The digital information items relating to the graphic representation thus acquired can be conveniently input into an EDP system. <IMAGE>

Description

(54) IMPROVEMENTS RELATING TO APPARATUS FOR ELECTRICAL DIGITAL STORAGE OF GRAPHICAL MASTERS (71) We, MEssERscHMxTT-BoLKow- BLOHM Gesellschaft mit beschrankter Halftung, of 8000 Munchen, German Federal Republic a Company organised and existing under the laws of the German Federal Republic, do hereby declare the invention, for which we pray that a Patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:: - This invention relates to an apparatus for electric digital storage of analogue information, such as points, lines or any other graphical image, present in a flat master, wherein light reflected from or transmitted through the master is detected by an optical system having a line of photo cells, the master or the cells being moved to effect scanning of the original to divide same into a large number of discrete picture elements.

This invention seeks to provide an apparatus of such a kind enabling the coordinates of an element of the picture information to be defined together with the signal representing the optical density of the element to enable the information obtained to be written to a storage device or fed to a computer.

According to this invention there is provided apparatus for storage of an image of a graphical master in electric digital form wherein light from a discrete elemental point of the master is detected by a photo sensitive means and recorded in a digital electric form together with sufficient information to define the position of the point, the master being scanned line by line whereby an area of the master is recorded as a number of such discrete elemental points, the apparatus having a pulse generator coupled to a drive means effecting scanning of the master in a Y-ordinate direction by moving a table carrying the master or by a photo sensitive means moving thereover and from which a start pulse for the serial scanning of a line of cells forming the photo sensitive means and extending in an Xordinate direction is fed, following which the line of cells or the table is moved in the Yordinate direction to scan the next line, the pulses from the pulse generator being fed to a counter the outut of which, together with the output from an analogue to digital converter serving to convert the analogue signal from each cell into digital form, is fed into a multiplexer from the output of which a digital signal representing the light level of each discrete point together with a signal defining the Y-coordinate of the line scanned is obtained.

With wider masters scanning cannot be effected in a single sweep or strip of which the width corresponds to the length of the line. To scan a wider master it is necessary to make a number of adjoining sweeps and to do this the relative positions of the photosensitive means and the table are made adjustable in the X direction. Each sweep covers a respective strip of the master In order, therefore, to ensure unambiguous indication of the X coordinate also a pulse generator is coupled with a drive means, whereby each time the scanning of a strip is commenced, a digital word corresponding to the serial number of the strip is produced by an X pulse counter, the word being also obtained at the output of the multiplexer.

In a further version of the invention a switchable storage means is connected between the multiplexer and a magnetic tape recording apparatus to match the recording speed of a magnetic tape or other data store to the output of the analogue to digital converters.

It is sufficient for the strips simply to be identified individually in the X direction Each image strip can however be identified with the Y coordinate and the X strip number.

The advantage offered by the invention is that areas of any desired size can be covered in a very short time simply by varying the number of lines forming the strip.

An embodiment according to the invention is described by way of an example with reference to the accompanying drawings, wherein: - Figure 1 shows the optical scanner arrangement, Figure 2 is a block diagram of the electronic arrangement, Figure 3 shows the recording arrangement of the signals with their identification on the magnetic tape, and Figure 4 shows an example of a scanning pattern on a master.

The apparatus of Figure 1 has a photosensitive means 9 movable in both the X and Y directions with an associated optical system 10.

The drive to a movable table 13 or the optical assembly 9, 10, is carried out through lead screws 2 and 6, and it is immaterial whether the table 13 or assembly 9 and 10 is movable. Bars 7 and 8 serve as carriers and guides. The spindles may be rotated by motors 1 and 4 through gears and positionally controlled by pulse generators 3 and 5.

The master 12 of a graphic type, such as a contour map, engineering drawing or the like is held on the table 13 and illuminated by one or other of light sources 11 or 14, mounted above and below the table respectively. With transparent masters transmitted light is used from light source 14 and with other masters incident light from sources 11 is used.

Light from the master 12 either reflected or transmitted is focussed onto the photo sensitive means 9 by the optical system 10.

The means 9 comprises a line of detectors and the arrangement is such that a strip of the master of about 50 mm in length is optically reduced to the length of the line of detectors which is about 12.5 mm. An available photo sensitive means comprises 500 separate cells each about 25,u x 25,u and forming the line so that each cell scans an area of about 0.1 x 0.1 mm on the master.

A number of detectors 9 can be used with the optical system 10 being designed accordingly.

The detector means 9 is serially scanned through a control means 19 and drive means 17, as shown in Figure 2, whereby a video signal is generated comprising a number of discrete signals in accordance with a number of cells in the detector means 9. Each signal has a level corresponding to the brightness of the image point at that instant. An amplifier 15 is used to increase the video signal levels from detector 9. In a store 16 the signal levels are retained for a period of about one line scan to enable the values to be converted to digital signals in an analogue to digital converter 18. The conversion produces an eight-bit word and for each image point such an eight-bit word is produced, which is fed in parallel-mode through a multiplexer 23 to fast switching temporary stores 24, 25.The one store 24 or 25 receives the bit stream over a certain period while the other store 25 or 24 generates a bit stream at a rate acceptable to the magnetic tape recording apparatus 26. The alternately switched stores 24 and 25 thus serve to match the photo-sensor scan to the recording speed of the magnetic tape apparatus 26.

In use the Y position pulse counter 20 produces a signal fed to the control means 19 to start the scanning for the read-out of a line by means of the drive 17. The serial line scan is thus commenced. The scan frequency across the line of the photo detectors 9 depends on the travel rate and is such that the reading of a line is terminated before the next line forming the strip is started. The pulse generator 5 actuates a Y pulse counter 20 thus giving to each line scanned a Y coordinate. There is no necessity to produce a separate X coordinate identification for each discrete image point within a line scanned, as this X coordinate can be determined from the image point within a line and the position can thus be defined.

The Y pulse counter 20 can be interrogated so that after each line scanned a word identifying the coordinate is fed to the data store or, after certain number of lines, for example four, which form a group, a word corresponding to the coordinate is fed to the data store.

For the scanning of a master in a number of strips extending in a Y-direction the X-drive system, similar to the Y-drive system provides complete two dimensional mobility of the table 13 or the photo sensitive means 9, 10. At the end of each strip the recording is stopped, the strip length being manually set on the control means 19, and the start of the next strip is indexed in the X direction. The table or photo sensitive means is stepped by the control means 19 in the X direction a distance corresponding to the width of the scanned strip, for example 50 mm. The scanning of the second and each further strip is carried out in the same manner. A pulse generator 3 is associated with an X counter 21 which is incremented by one before the start of line scanning of each new strip this number being recorded through the multiplexer, to effect an unambiguous designation of the X coordinate of the strip. Identification can be provided also through the multiplexer using a code number set by means 22 and fed to the magnetic tape for identification of the master. When the end of the last strip is reached, this having been manually set in the control means 19 the detector means 9 returns to the origin in the X direction while in the Y direction a movement is effected by the length of the scanned strip.

The video signals define, in accordance with the density of the image points, a certain level and the maximum in the example given is represented by the upper of 256 levels (with 8 bits). The stored signal thus contains for practical purposes the entire density range which could be present in the master. By introducing a threshold level it is possible when only black or white masters are to be recorded to define the transition between black and white.

For the recording of coloured masters filters may be incorporated into the light path and only one colour range may be recorded. To record coloured originals therefore they have to be scanned separately for each required colour using appropriate filters.

Figure 3 shows a representative example of a record on magnetic tape, in which four lines strips are combined to form a block and recorded together. Each element of information is represented and recorded as an eight bit word. The letters A to I represent the individual tracks on the tape one for each bit. A data block comprises, from the top to bottom, the identification k of the master in 8 bits, the serial number L of the strip scanned and the block number M, !each block consisting in this case of four lines. The data is followed by the first 500 image cell points of the first line, then the next 500 image cell points of the second line, then the next 500 image c;ell points of the third line up to and including the fourth line.Before each new block M the data for identification, strip number and block number are again recorded so that an unambiguous position is recorded on the tape.

Figure 4 shows an example of the format in which the master is scanned. The optical means 10 and the photo sensitive means 9 and the Y pulse generator 5 are arranged to produce line depth of 0.1 mm in the Ydirection. The master is scanned in strips each of 50mm width and a master measuring 0.5 x 0.5 m, for example, is represented by about 25 x 106 individual elements (5000 elements per full line in the X-direction times 5000 lines in the Y-direction).

If the strip S 1 has been scanned, then the next strip S 2 is scanned and the pulse generator on the drive for the X-feed produces a pulse for recording the position of the new strip and so forth, up to strip S 10.

WHAT WE CLAIM IS: 1. Apparatus for storage of an image of a graphical master in electric digital form wherein light from a discrete elemental point of the master is detected by a photo sensitive means and recorded in a digital electric form together with sufficient information to define the position of the point, the master being scanned line by line whereby an area of the master is recorded as a number of such discrete elemental points, the apparatus having a pulse generator coupled to a drive means effecting scanning of the master in a Y-ordinate direction by moving a table carrying the master or by a photo sensitive means moving thereover and from which a start pulse for the serial scanning of a line of cells forming the photo sensitive means and extending in an X-ordinate direction is fed, following which the line of cells or the table is moved in the Y-ordinate direction to scan the next line, the pulses from the pulse generator being fed to a counter the output of which, together with the output from an analogue to digital converter serving to convert the analogue signal from each cell into digital form, is fed into a multiplexer from the output of which a digital signal representing the light level of each discrete point together with a signal defining the Y-coordinate of the line scanned is obtained.

2. An apparatus in accordance with Claim 1, wherein a number of lines scanned form a strip extending in the Y-ordinate direction, the anea of the master being recorded as a number of contiguous strips, a pulse generator coupled with the drive means providing a digital word identifying the position of the strip, said word being fed into the multiplexer.

3. An apparatus in accordance with Claim 2, wherein each strip has a Y-coordinate identification for each line there -in and an X-coordinate number for the start of the lines in the strip.

4. An apparatus in accordance with Claim 1 or 2 or 3, wherein a storage means is arranged to match the output signal rate from the multiplexer to the recording speed of a magnetic tape recording apparatus and

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. master. When the end of the last strip is reached, this having been manually set in the control means 19 the detector means 9 returns to the origin in the X direction while in the Y direction a movement is effected by the length of the scanned strip. The video signals define, in accordance with the density of the image points, a certain level and the maximum in the example given is represented by the upper of 256 levels (with 8 bits). The stored signal thus contains for practical purposes the entire density range which could be present in the master. By introducing a threshold level it is possible when only black or white masters are to be recorded to define the transition between black and white. For the recording of coloured masters filters may be incorporated into the light path and only one colour range may be recorded. To record coloured originals therefore they have to be scanned separately for each required colour using appropriate filters. Figure 3 shows a representative example of a record on magnetic tape, in which four lines strips are combined to form a block and recorded together. Each element of information is represented and recorded as an eight bit word. The letters A to I represent the individual tracks on the tape one for each bit. A data block comprises, from the top to bottom, the identification k of the master in 8 bits, the serial number L of the strip scanned and the block number M, !each block consisting in this case of four lines. The data is followed by the first 500 image cell points of the first line, then the next 500 image cell points of the second line, then the next 500 image c;ell points of the third line up to and including the fourth line.Before each new block M the data for identification, strip number and block number are again recorded so that an unambiguous position is recorded on the tape. Figure 4 shows an example of the format in which the master is scanned. The optical means 10 and the photo sensitive means 9 and the Y pulse generator 5 are arranged to produce line depth of 0.1 mm in the Ydirection. The master is scanned in strips each of 50mm width and a master measuring 0.5 x 0.5 m, for example, is represented by about 25 x 106 individual elements (5000 elements per full line in the X-direction times 5000 lines in the Y-direction). If the strip S 1 has been scanned, then the next strip S 2 is scanned and the pulse generator on the drive for the X-feed produces a pulse for recording the position of the new strip and so forth, up to strip S 10. WHAT WE CLAIM IS:

1. Apparatus for storage of an image of a graphical master in electric digital form wherein light from a discrete elemental point of the master is detected by a photo sensitive means and recorded in a digital electric form together with sufficient information to define the position of the point, the master being scanned line by line whereby an area of the master is recorded as a number of such discrete elemental points, the apparatus having a pulse generator coupled to a drive means effecting scanning of the master in a Y-ordinate direction by moving a table carrying the master or by a photo sensitive means moving thereover and from which a start pulse for the serial scanning of a line of cells forming the photo sensitive means and extending in an X-ordinate direction is fed, following which the line of cells or the table is moved in the Y-ordinate direction to scan the next line, the pulses from the pulse generator being fed to a counter the output of which, together with the output from an analogue to digital converter serving to convert the analogue signal from each cell into digital form, is fed into a multiplexer from the output of which a digital signal representing the light level of each discrete point together with a signal defining the Y-coordinate of the line scanned is obtained.

2. An apparatus in accordance with Claim 1, wherein a number of lines scanned form a strip extending in the Y-ordinate direction, the anea of the master being recorded as a number of contiguous strips, a pulse generator coupled with the drive means providing a digital word identifying the position of the strip, said word being fed into the multiplexer.

3. An apparatus in accordance with Claim 2, wherein each strip has a Y-coordinate identification for each line there -in and an X-coordinate number for the start of the lines in the strip.

4. An apparatus in accordance with Claim 1 or 2 or 3, wherein a storage means is arranged to match the output signal rate from the multiplexer to the recording speed of a magnetic tape recording apparatus and

is connected between the multiplexer and a magnetic tape recording apparatus.

5. An apparatus for electrical recording of masters constructed and arranged to function substantially as herein described with reference to and as shown in the accompanying drawings.