CA2067994C - Device for scanning pale colour marks on a printing machine - Google Patents
Device for scanning pale colour marks on a printing machineInfo
- Publication number
- CA2067994C CA2067994C CA002067994A CA2067994A CA2067994C CA 2067994 C CA2067994 C CA 2067994C CA 002067994 A CA002067994 A CA 002067994A CA 2067994 A CA2067994 A CA 2067994A CA 2067994 C CA2067994 C CA 2067994C
- Authority
- CA
- Canada
- Prior art keywords
- stage
- impulses
- fact
- impulse
- mark
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41F—PRINTING MACHINES OR PRESSES
- B41F31/00—Inking arrangements or devices
- B41F31/02—Ducts, containers, supply or metering devices
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41F—PRINTING MACHINES OR PRESSES
- B41F33/00—Indicating, counting, warning, control or safety devices
- B41F33/0081—Devices for scanning register marks
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41F—PRINTING MACHINES OR PRESSES
- B41F33/00—Indicating, counting, warning, control or safety devices
Abstract
The invention relates to a device for scanning marks printed on workpieces travelling under a light source. The device includes at least two parallel mark scanning channels emitting an electric impulse due to the passage of a mark, each channel being sensitive to a particular colour. The device includes, moreover, electronic means for selecting the most respresentative mark impulse among the electric impulses emitted by the channels.
Description
2~799~
The present lnventlon used ln a multl-colour prlntlng machlne refers to a devlce for scannlng varlous colour marks prlnted by varlous prlntlng unlts, the sald marks allowlng subsequently to determlne mlsreglster of lts pertalnlng colour wlth regard to the colour prlnted by the flrst prlntlng unlt and used as reference.
Known devlces such as the one descrlbed ln European Patent No. 0 094 027 publlshed 16 November 1983 operate to satlsfactlon provlded that the yellow, blue or red marks are sufflclently contrasted for belng recognlzed lnfalllbly by the scannlng devlce. Some of these known devlces may operate wlth a flbre optlc llght beam hlttlng the prlnted workplece and dlrectlng the reflected llght onto a scannlng photodlode produclng an electrlc slgnal. In order to enhance the contrast between the electrlc baslc slgnal, correspondlng to a non-prlnted area of the workplece, and an electrlc lmpulse produced by the passlng mark, a fllter, usually of blue colour, ls lnstalled between the flbre optlc and the photodlode.
However, as soon as the prlnted colours fade to paleness especlally so when prlntlng packages wlth pastel yellow, cream or llght blue, the conventlonal devlces are no longer capable of detectlng safely the varlous prlnted marks so that the one or the other reglster control mlght fall to operate correctly. In such cases, lt mlght be approprlate to use a flrst fllter, to present a pale colour ln order to test the quallty of the slgnal obtalned and to repeat the test wlth one or several other fllters so as to select the one most approprlate for all - 1 - ~
' 3t marks. However, the most important phase of the start-up of a printing machine consists in searching the initially unknown position of a concomitant mark, which, though, cannot be reliably carried out without an immediately responsive scanning device.
Such numerous, and indispensible, tests become quickly inhibitive if the printing machine is to be used for accomplishing a great number of different jobs.
The purpose of the present invention is the creation of a detector spotting printed marks whatever their colour, intensity and contrast with regard to the background colour of the flat workpiece it is printed on.
These purposes are attainable by means of a device scanning printed marks since it comprises at least two parallel mark scanning channels each of which emits an electric impulse each time the mark travels through under the light source, the photosensitive unit at the input of the two channels being respon-sive to a colour frequency range distinguishable from the others, as well as electronic means selecting the most representative mark impulse among the electric impulses emitted by the channels.
Appropriately, every mark scanning channel comprises:
- a photosensitive unit generating an electric signal for the voltage value, followed, if required, by - an amplifying stage with automatic gain, fixing at a predetermined rate the basic voltage corresponding to a non-printed area of the workpiece, followed by - a stage converting the oblique sloped electric impulse called forth by the mark travelling under the photosen-sitive unit into a steep sloped electric impulse, every steep slope corresponding to the beginning of the ascent or descent of the associated oblique slope, - and electronic means selecting among the electric impulses originating from the channels at a given moment the impulse appearing or disappearing first.
Hence, owing to this device, the electric impulse with the strongest contrast is regularly retained whatever the quality of the other impulses considered.
A by-problem, however, might somewhat complicate the conception of the selective circuit since a colour mark printed on a white workpiece will bring forth a negative impulse with regard to the basic signal whereas a very reflective, say gold or silver, colour mark, will bring forth an inverted, i.e. posi-tive, impulse with regard to the basic signal. This problem is obviated in that every scanning channel additionally includes before the converting stage a rectifying stage imposing on all electric impulses a variation in the same direction with regard to the basic voltage.
Appropriately, the photosensitive unit includes a photo-diode situated behind a tinted filter and connected to the input of a current/voltage converter.
In accordance with a preferable mode of realization, the rectifying stage includes a first stage for rating the basic voltage, followed by a stage for subtracting the basic voltage 2~67994 68200-127 thereby leaving only positive or negative impulses, followed by a stage for rectifying solely the positive impulses into negative ones, followed by a stage for adding all the impulses and, finally, followed by a stage ensuring the re-addition of the basic voltage.
In accordance with a preferable mode of realization, the converting stage includes a first stage for detecting peaks, followed by a second stage for subtracting the input signal from the threshold detected by the first stage, the difference being applied to a comparator which switches its output as soon as the difference exceeds a predetermined threshold, as well as the first electronic means re-initializing and inverting the detection direction of the peak detecting stage as well as the second elec-tronic means inverting the polarity of the comparative threshold applied to the comparator after a first switch of the latter.
In accordance with a preferable mode of realization, the electronic means for impulse selection include a first OR gate receiving one of the impulses at both of its inputs and whose out-put is connected to the clock input of a first bistable device and as many secondary bistable devices as there are impulses to be analysed, the said impulses being received inverted at their clock input, all the inverted outputs of the secondary bistable devices being connected to the input of an AND gate whose output is connected to the re-initialization input of the first bistable device, the re-initialization input of every secondary bistable device being connected to the non-inverted output of the first 2Q67994 68200-l27 bistable device, and a final line for monitoring electronic means being connected to one of the inputs of the AND gate.
In accordance with an appropriate mode of realization, the device includes, moreover, an analog/digital and digital/
analog converter connected to a micro-processor destined to receive from the rectifying stage the basic voltage valve and to feed, on the one hand, the amplifying stage with automatic gain, if present, with an electric signal representative of the gain to be applied and, on the other hand, the converting stage with an electric signal representative of the threshold which is optimal for the comparator. Owing to this latter device, the voltage is permanently held at a rate of about 8 volts, and the comparator detection threshold is fixed at a rate between 200 and 400 milli-volts above the average noise emitted with the basic voltage.
The invention will be better understood by examining a realization mode selected as a non-limitative example described below in conjunction with the attached drawings, in which:
- Figure 1 is a schematic diagram of the device according to the invention, - Figure la is a partial view of a particular execution of the device according to the invention, - Figure 2 is a lay-out of the rectifying circuit operat-ing in the device of Figure 1, - Figure 3 is a lay-out of the converting circuit operating in the device of Figure 1, - Figure 4 is a diagram of the operation carried out by the converter of Figure 3, and - Figure 5 is a lay-out of the selective circuit operating in the device according to Figure 1.
As illustrated by Figure 1, the device according to the invention includes a fibre optic bundle 25 initially transmitting the light emitted by a light source 20 above the printed work-piece 10 provided with colour marks 15 printed on its upper side.
These workpieces might be paper strips or cardboard plates undergoing a manufacturing process. Such marks 15 are printed in an unrestrained area of the workpiece and with the colour printed by each printing unit. The passage of these marks 15 under the input of the fibre optic bundle temporarily modifies more or less the reflected light which, after doubling of the fibre optic, is transmitted to two separate photodiodes 32, 33.
According to the invention, the photodiodes 32, 33 are each rendered sensitive to distinct colours by means of filters 30, 31 situated between the outputs ofthe fibre optics and the photodiodes. So, for instance, the filter 30 can be dark violet enhancing yellow marks whereas the filter 31 is green enhancing blue marks. The electric signals emitted by each photodiode are initially conditioned separately and parallelly by identical processing channels consisting of the circuits 34, 40, 50 and 60, and then compared by a selective circuit 70.
These identical and parallel conditioning channels each include a current/voltage converter 34 producing a voltage variation from the intensity variations occurring within the 2 0 67 9 9~ 68200-l27 photodiode and caused by the mark 15 passing under the fibre optic input. As symbolically represented, this current/voltage converter is made in a known way of an operational amplifier with feedback between its output and its negative input. Clamps symbolically shown at the output allow to put in operation a first or a second feedback circuit, thus modifying the gain of this stage in a relationship of 1 to 10. This voltage signal is then amplified by an amplifying circuit with automatic gain 40 in such a way that the basic signal corresponding to a non-printed area of the workpiece 10 will be fixed at a value of 8 volts.
This explains why, according to the background colour of the printed workpiece 10, to the length of the fibre optic bundle 25, to possible dust particles likely to alter the input or the output of the fibres as well as the filters, the basic voltage received at the output of the current/voltage converter 34 may vary between 150 millivolts and 8 volts.
The electric signal then flows into a rectifying circuit 50, the purpose of which is to gather all colour mark impulses in an identical direction which in the present case is negative, with regard to the basic voltage. In most cases, the marks 15 are printed with colours darker than the background colour and thus cause a reduction of the light reflected on the fibre optic, i.e.
an instantaneous reduction of the current flowing through the photodiode 32 or 33, in other words an impulse with a lower vol-tage than the basic voltage. Inversely, if the marks 15 appear brighter than the background colour or if they are printed with particularly reflective colours such as gold or silver, the reflected light is temporarily stronger than the basic light and the same effect affects the corresponding electric impulse. By making all impulses have a common polarity, this rectifying cir-cuit allows to considerably simplify the subsequent selective circuit.
Figure la represents a device similar to the one of Figure 1 in which the fibre optic 25 has not been doubled. A
light diffusion device 25a has been added to the end of the fibre optic 25 so that the reflected light will be indifferently directed to the filters 30 and 31. The design of the other components of the device including the photodiodes 32 and 33 as well as the current/voltage converters 34 and 35 remains unchanged with regard to the lay-out shown by Figure 1.
If reference is made to Figure 2, this rectifying circuit 50 includes a background rating stage 51, followed by a background subtracting stage 53, followed by the actual rectify-ing stage 55, followed by an impulse adding stage 57, terminated by a background re-adding stage 59.
As illustrated, the background rating stage 51 essential-ly includes the combination of a diode 513 and a capacitor 514 the other line of which is grounded. The operational amplifiers 511 and 512 act as isolators of the stage. By temporarily short-circuiting the diode 513, the switch 515 allows to periodically re-initialize this background rate.
The subtracting stage 53 includes in a known way an operational amplifier 533 receiving the complete signal through the resistor 531 on its positive input as well as the background value to be subtracted through the resistor 532 at its negative input.
At the rectifying stage 55, only positive impulses are amplified and inverted by the operational amplifier 553 compris-ing two diodes 551, 552 in its feedback circuit. The addition, by the operational amplifier 573, of the adding stage 57, fed through its negative clamp with the signal originating directly from the subtracting stage 53 through the resistor 571 as well as with the amplified negative impulses used for balancing the positive impulses, provides at the output of this stage a sequence of impulses of the same amplitude as initially, though with all impulses in the negative direction.
The operational amplifier 593 of the re-adding stage 59 adds the background value transmitted direct from the first background rating stage 51 through the resistor 591 and the impulses emitted by the adding stage 57 through the resistor 592.
If reference is made to Figure 1, the rectifying circuit 50 is followed by a circuit 60 converting the oblique-sloped impulses into steep-sloped ones which latter provide easier subsequent logical processing.
As illustrated on Figure 4, the impulses el and e2 generated by the photodiodes 32 or 33 show a first descending oblique slope corresponding to the progressive penetration of the mark into the fibre optic scanning area, followed by a bottom g 20~799~ 68200-127 level appearing with the mark body passing, and terminated by a second ascending slope corresponding to the mark leaving progres-sively the scanning area.
The detailed structure of this converter 60 will be described in connection with Figure 3 on which four important stages are distinguishable, i.e. a peak detecting stage 61, followed by a stage 62 for subtracting the measured peak from the instantaneous signal, followed by a stage 63 for comparing the difference with a predetermined threshold originating from a stage 64. The result of this comparison is shaped by the opera-tional amplifier 632 the inverted signal of which is generated by the inverter 633. The output of the shaping amplifier 632 is also used as a counter-reactive item destined to invert the direction of the maximum detection rate of the stage 61 and to modify the threshold rate originating from the stage 64.
The peak detecting stage 61 essentially includes a diode 614 (and then 615) acting jointly with a capacitor 613 whose input is controlled by the amplifier 611 and whose output is controlled by the operational amplifier 612. The direction of the maximum detection rate, either in the ascent or descent, is initially determined by the state of the relay 65 selecting either diode 614 or 615. This stage is re-initialized by the relay 644 after a short period added by the inverter 633 by means of the diodes 616 or 617 depending on the case.
The subtracting stage 62 receives the signal originating from the peak detecting stage 61 through the resistor 621 as well 206799~
as through the resistor 622, the instantaneous signal previously amplified by the operational amplifier 619 with a gain of 1. The comparison is ensured by the amplifier 631 receiving the threshold signal at its positive input and the difference signal at its negative input.
As may easily be gathered from Figures 3 and 4, the stage 61 firstly receives the rate of the basic voltage, whereas the output of stage 62 firstly provides a zero signal which is to increase only with the appearance of the descending oblique slope of an impulse. If the oblique slope of this impulse exceeds a predetermined threshold vl with regard to the basic voltage, the output of the operational amplifier 631 will switch and a first steep voltage ascent sll will appear at the output of the inverter 632. This voltage ascent sll begins by causing the selection of the diode 615 enabling the capacitor 613 to be discharged through the diode 617 and then the diode 616 to be connected after a period to be determined by the inverter 633. The stage 61 is then ready for detecting a new maximum though in the descending direction. The first voltage ascent has also caused at the stage 64 a modification of the threshold voltage v2 by grounding the positive input of an operational amplifier.
The stage 61 then detects the rate of the lower bottom level of the impulse el, whereas the output of the subtracting stage 62 remains at zero as long as the bottom level lasts. Once again, with the appearance of the beginning of the ascending oblique slope of the inlet impulse, the difference at the outlet 206~99~
of the stage 62 will increase and even exceed the new threshold v2 of the comparator 631 which then will invert its output signal, thereby causing a sudden descent s12 of the output of the shaping amplifier 632.
In this way, the steep ascending slope of the output impulse sl corresponds more or less to the beginning of the descending oblique slope of the input impulse el, whereas the steep descending slope of the output impulse sl corresponds more or less to the beginning of the reascending oblique slope of the input impulse el.
As may be gathered from Figures 1 and 4, the impulses sl and s2, now castellated, respectively emitted by the channel corresponding to the yellow colour and the channel corresponding to the blue colour are applied to the selective circuit 70 retaining the ascending impulse sl which will descend first and correspond to the initial oblique slope of the most contrasted impulse el.
The mode of realizing the circuit 70 as illustrated by Figure 5 includes a first OR gate "OU" 71 receiving one of the castellated impulses at both of its inputs and whose output is connected to the clock input "CLK" of a first bistable device 72.
The selective circuit 70 includes as many secondary bistable devices 73, 74 as there are impulses to be analysed, these im-pulses being received inverted, i.e. at their clock input "CLK".
All the inverted outlets "Q" of the secondary blstable devices are connected to the input of an AND gate "ET" 75 whose output is connected to the re-initialization input'!-CL"of the first bistable device 72. Moreover, the output "Q" of this first bistable device 72 is also connected to the re-initialization input "CL" of each of the secondary bistable devices 73, 74. A last permitting or interlocking line 85 of the selective circuit 70 is connected to one of the inputs of gate "ET" 75.
At the initial state of the device, all inputs of the gate "ET" 75 are high, thus releasing the first bistable device 72 whose output "Q" is initially low, entailing the interlocking of the bistable devices 73 and 74. With an impulse reaching one of the inputs of the OR gate 71, the output of this gate is high, resulting in the appearance of a high signal on the output gate "Q" of the bistable device 72, which latter brings about the as-cending slope of the output impulse and also releases the bistable devices 73 and 74. The arrival of the ascending slope of the second impulse then has no more effect on the circuit 70. On the other hand, the arrival of the first ascending slope of an inver-ted signal, corresponding actually to the descending slope of this first impulse, will change the state of the corresponding bi-stable device 73, 74 resulting in the immediate lowering of the corresponding output "Q". The gate "ET" 75 will have at least one of its inputs forced low, whereas its output also lowers resulting in the re-initialization of the first bistable device 72, and putting the corresponding output "Q" back to low, thus creating the descending slope of the output impulse. This low signal at the output "Q" of the bistable device 72 also results in the re-initialization of all secondary bistable devices 73, 74 putting all inverted "Q" outputs high and thereby interlocking these bistable devices and preventing the ascent of the subsequent inverted signal. The output of gate "ET" 75 returns to high, which action again releases the bistable device 72 and renders it suited for the subsequent selection as long as a permission to that end is maintained on the line 85.
As may be gathered from Figure 1, the device according to the invention includes moreover an analog/digital and digital/
analog converter 90 acting jointly with a micro-processor 80, this device being capable of receiving on line 81 a value of the basic voltage in order to return to the lines 82 an electric signal corresponding to the gains to be applied to the amplifying cir-cuits 40 and 41 with automatic gain, and to the lines 83 a threshold rate for the comparator 63 of the circuits 60 and 61, the said threshold being fixed between 100 and 400 millivolts above the background noise measured on the basic signal. The micro-processor also transmits to the line 85 a monitoring signal interlocking the selective circuit as long as no mark is awaited.
As may be gathered from the aforesaid comments, the device according to the invention allows to reliably detect a mark travelling through a light beam emitted by the source 20, the said device effectuating an instantaneous selection of the best suited scanning channel for yellow or blue, simultaneously taking into account the colour, the contrast and the intensity of the mark to be considered. For machines expected to carry out 206799~ 68200-127 delicate jobs, it is quite possible to add a third or fourth parallel scanning channel for other well distinguishable colours.
Numerous improvements may be added to this device within the limits of the invention.
The present lnventlon used ln a multl-colour prlntlng machlne refers to a devlce for scannlng varlous colour marks prlnted by varlous prlntlng unlts, the sald marks allowlng subsequently to determlne mlsreglster of lts pertalnlng colour wlth regard to the colour prlnted by the flrst prlntlng unlt and used as reference.
Known devlces such as the one descrlbed ln European Patent No. 0 094 027 publlshed 16 November 1983 operate to satlsfactlon provlded that the yellow, blue or red marks are sufflclently contrasted for belng recognlzed lnfalllbly by the scannlng devlce. Some of these known devlces may operate wlth a flbre optlc llght beam hlttlng the prlnted workplece and dlrectlng the reflected llght onto a scannlng photodlode produclng an electrlc slgnal. In order to enhance the contrast between the electrlc baslc slgnal, correspondlng to a non-prlnted area of the workplece, and an electrlc lmpulse produced by the passlng mark, a fllter, usually of blue colour, ls lnstalled between the flbre optlc and the photodlode.
However, as soon as the prlnted colours fade to paleness especlally so when prlntlng packages wlth pastel yellow, cream or llght blue, the conventlonal devlces are no longer capable of detectlng safely the varlous prlnted marks so that the one or the other reglster control mlght fall to operate correctly. In such cases, lt mlght be approprlate to use a flrst fllter, to present a pale colour ln order to test the quallty of the slgnal obtalned and to repeat the test wlth one or several other fllters so as to select the one most approprlate for all - 1 - ~
' 3t marks. However, the most important phase of the start-up of a printing machine consists in searching the initially unknown position of a concomitant mark, which, though, cannot be reliably carried out without an immediately responsive scanning device.
Such numerous, and indispensible, tests become quickly inhibitive if the printing machine is to be used for accomplishing a great number of different jobs.
The purpose of the present invention is the creation of a detector spotting printed marks whatever their colour, intensity and contrast with regard to the background colour of the flat workpiece it is printed on.
These purposes are attainable by means of a device scanning printed marks since it comprises at least two parallel mark scanning channels each of which emits an electric impulse each time the mark travels through under the light source, the photosensitive unit at the input of the two channels being respon-sive to a colour frequency range distinguishable from the others, as well as electronic means selecting the most representative mark impulse among the electric impulses emitted by the channels.
Appropriately, every mark scanning channel comprises:
- a photosensitive unit generating an electric signal for the voltage value, followed, if required, by - an amplifying stage with automatic gain, fixing at a predetermined rate the basic voltage corresponding to a non-printed area of the workpiece, followed by - a stage converting the oblique sloped electric impulse called forth by the mark travelling under the photosen-sitive unit into a steep sloped electric impulse, every steep slope corresponding to the beginning of the ascent or descent of the associated oblique slope, - and electronic means selecting among the electric impulses originating from the channels at a given moment the impulse appearing or disappearing first.
Hence, owing to this device, the electric impulse with the strongest contrast is regularly retained whatever the quality of the other impulses considered.
A by-problem, however, might somewhat complicate the conception of the selective circuit since a colour mark printed on a white workpiece will bring forth a negative impulse with regard to the basic signal whereas a very reflective, say gold or silver, colour mark, will bring forth an inverted, i.e. posi-tive, impulse with regard to the basic signal. This problem is obviated in that every scanning channel additionally includes before the converting stage a rectifying stage imposing on all electric impulses a variation in the same direction with regard to the basic voltage.
Appropriately, the photosensitive unit includes a photo-diode situated behind a tinted filter and connected to the input of a current/voltage converter.
In accordance with a preferable mode of realization, the rectifying stage includes a first stage for rating the basic voltage, followed by a stage for subtracting the basic voltage 2~67994 68200-127 thereby leaving only positive or negative impulses, followed by a stage for rectifying solely the positive impulses into negative ones, followed by a stage for adding all the impulses and, finally, followed by a stage ensuring the re-addition of the basic voltage.
In accordance with a preferable mode of realization, the converting stage includes a first stage for detecting peaks, followed by a second stage for subtracting the input signal from the threshold detected by the first stage, the difference being applied to a comparator which switches its output as soon as the difference exceeds a predetermined threshold, as well as the first electronic means re-initializing and inverting the detection direction of the peak detecting stage as well as the second elec-tronic means inverting the polarity of the comparative threshold applied to the comparator after a first switch of the latter.
In accordance with a preferable mode of realization, the electronic means for impulse selection include a first OR gate receiving one of the impulses at both of its inputs and whose out-put is connected to the clock input of a first bistable device and as many secondary bistable devices as there are impulses to be analysed, the said impulses being received inverted at their clock input, all the inverted outputs of the secondary bistable devices being connected to the input of an AND gate whose output is connected to the re-initialization input of the first bistable device, the re-initialization input of every secondary bistable device being connected to the non-inverted output of the first 2Q67994 68200-l27 bistable device, and a final line for monitoring electronic means being connected to one of the inputs of the AND gate.
In accordance with an appropriate mode of realization, the device includes, moreover, an analog/digital and digital/
analog converter connected to a micro-processor destined to receive from the rectifying stage the basic voltage valve and to feed, on the one hand, the amplifying stage with automatic gain, if present, with an electric signal representative of the gain to be applied and, on the other hand, the converting stage with an electric signal representative of the threshold which is optimal for the comparator. Owing to this latter device, the voltage is permanently held at a rate of about 8 volts, and the comparator detection threshold is fixed at a rate between 200 and 400 milli-volts above the average noise emitted with the basic voltage.
The invention will be better understood by examining a realization mode selected as a non-limitative example described below in conjunction with the attached drawings, in which:
- Figure 1 is a schematic diagram of the device according to the invention, - Figure la is a partial view of a particular execution of the device according to the invention, - Figure 2 is a lay-out of the rectifying circuit operat-ing in the device of Figure 1, - Figure 3 is a lay-out of the converting circuit operating in the device of Figure 1, - Figure 4 is a diagram of the operation carried out by the converter of Figure 3, and - Figure 5 is a lay-out of the selective circuit operating in the device according to Figure 1.
As illustrated by Figure 1, the device according to the invention includes a fibre optic bundle 25 initially transmitting the light emitted by a light source 20 above the printed work-piece 10 provided with colour marks 15 printed on its upper side.
These workpieces might be paper strips or cardboard plates undergoing a manufacturing process. Such marks 15 are printed in an unrestrained area of the workpiece and with the colour printed by each printing unit. The passage of these marks 15 under the input of the fibre optic bundle temporarily modifies more or less the reflected light which, after doubling of the fibre optic, is transmitted to two separate photodiodes 32, 33.
According to the invention, the photodiodes 32, 33 are each rendered sensitive to distinct colours by means of filters 30, 31 situated between the outputs ofthe fibre optics and the photodiodes. So, for instance, the filter 30 can be dark violet enhancing yellow marks whereas the filter 31 is green enhancing blue marks. The electric signals emitted by each photodiode are initially conditioned separately and parallelly by identical processing channels consisting of the circuits 34, 40, 50 and 60, and then compared by a selective circuit 70.
These identical and parallel conditioning channels each include a current/voltage converter 34 producing a voltage variation from the intensity variations occurring within the 2 0 67 9 9~ 68200-l27 photodiode and caused by the mark 15 passing under the fibre optic input. As symbolically represented, this current/voltage converter is made in a known way of an operational amplifier with feedback between its output and its negative input. Clamps symbolically shown at the output allow to put in operation a first or a second feedback circuit, thus modifying the gain of this stage in a relationship of 1 to 10. This voltage signal is then amplified by an amplifying circuit with automatic gain 40 in such a way that the basic signal corresponding to a non-printed area of the workpiece 10 will be fixed at a value of 8 volts.
This explains why, according to the background colour of the printed workpiece 10, to the length of the fibre optic bundle 25, to possible dust particles likely to alter the input or the output of the fibres as well as the filters, the basic voltage received at the output of the current/voltage converter 34 may vary between 150 millivolts and 8 volts.
The electric signal then flows into a rectifying circuit 50, the purpose of which is to gather all colour mark impulses in an identical direction which in the present case is negative, with regard to the basic voltage. In most cases, the marks 15 are printed with colours darker than the background colour and thus cause a reduction of the light reflected on the fibre optic, i.e.
an instantaneous reduction of the current flowing through the photodiode 32 or 33, in other words an impulse with a lower vol-tage than the basic voltage. Inversely, if the marks 15 appear brighter than the background colour or if they are printed with particularly reflective colours such as gold or silver, the reflected light is temporarily stronger than the basic light and the same effect affects the corresponding electric impulse. By making all impulses have a common polarity, this rectifying cir-cuit allows to considerably simplify the subsequent selective circuit.
Figure la represents a device similar to the one of Figure 1 in which the fibre optic 25 has not been doubled. A
light diffusion device 25a has been added to the end of the fibre optic 25 so that the reflected light will be indifferently directed to the filters 30 and 31. The design of the other components of the device including the photodiodes 32 and 33 as well as the current/voltage converters 34 and 35 remains unchanged with regard to the lay-out shown by Figure 1.
If reference is made to Figure 2, this rectifying circuit 50 includes a background rating stage 51, followed by a background subtracting stage 53, followed by the actual rectify-ing stage 55, followed by an impulse adding stage 57, terminated by a background re-adding stage 59.
As illustrated, the background rating stage 51 essential-ly includes the combination of a diode 513 and a capacitor 514 the other line of which is grounded. The operational amplifiers 511 and 512 act as isolators of the stage. By temporarily short-circuiting the diode 513, the switch 515 allows to periodically re-initialize this background rate.
The subtracting stage 53 includes in a known way an operational amplifier 533 receiving the complete signal through the resistor 531 on its positive input as well as the background value to be subtracted through the resistor 532 at its negative input.
At the rectifying stage 55, only positive impulses are amplified and inverted by the operational amplifier 553 compris-ing two diodes 551, 552 in its feedback circuit. The addition, by the operational amplifier 573, of the adding stage 57, fed through its negative clamp with the signal originating directly from the subtracting stage 53 through the resistor 571 as well as with the amplified negative impulses used for balancing the positive impulses, provides at the output of this stage a sequence of impulses of the same amplitude as initially, though with all impulses in the negative direction.
The operational amplifier 593 of the re-adding stage 59 adds the background value transmitted direct from the first background rating stage 51 through the resistor 591 and the impulses emitted by the adding stage 57 through the resistor 592.
If reference is made to Figure 1, the rectifying circuit 50 is followed by a circuit 60 converting the oblique-sloped impulses into steep-sloped ones which latter provide easier subsequent logical processing.
As illustrated on Figure 4, the impulses el and e2 generated by the photodiodes 32 or 33 show a first descending oblique slope corresponding to the progressive penetration of the mark into the fibre optic scanning area, followed by a bottom g 20~799~ 68200-127 level appearing with the mark body passing, and terminated by a second ascending slope corresponding to the mark leaving progres-sively the scanning area.
The detailed structure of this converter 60 will be described in connection with Figure 3 on which four important stages are distinguishable, i.e. a peak detecting stage 61, followed by a stage 62 for subtracting the measured peak from the instantaneous signal, followed by a stage 63 for comparing the difference with a predetermined threshold originating from a stage 64. The result of this comparison is shaped by the opera-tional amplifier 632 the inverted signal of which is generated by the inverter 633. The output of the shaping amplifier 632 is also used as a counter-reactive item destined to invert the direction of the maximum detection rate of the stage 61 and to modify the threshold rate originating from the stage 64.
The peak detecting stage 61 essentially includes a diode 614 (and then 615) acting jointly with a capacitor 613 whose input is controlled by the amplifier 611 and whose output is controlled by the operational amplifier 612. The direction of the maximum detection rate, either in the ascent or descent, is initially determined by the state of the relay 65 selecting either diode 614 or 615. This stage is re-initialized by the relay 644 after a short period added by the inverter 633 by means of the diodes 616 or 617 depending on the case.
The subtracting stage 62 receives the signal originating from the peak detecting stage 61 through the resistor 621 as well 206799~
as through the resistor 622, the instantaneous signal previously amplified by the operational amplifier 619 with a gain of 1. The comparison is ensured by the amplifier 631 receiving the threshold signal at its positive input and the difference signal at its negative input.
As may easily be gathered from Figures 3 and 4, the stage 61 firstly receives the rate of the basic voltage, whereas the output of stage 62 firstly provides a zero signal which is to increase only with the appearance of the descending oblique slope of an impulse. If the oblique slope of this impulse exceeds a predetermined threshold vl with regard to the basic voltage, the output of the operational amplifier 631 will switch and a first steep voltage ascent sll will appear at the output of the inverter 632. This voltage ascent sll begins by causing the selection of the diode 615 enabling the capacitor 613 to be discharged through the diode 617 and then the diode 616 to be connected after a period to be determined by the inverter 633. The stage 61 is then ready for detecting a new maximum though in the descending direction. The first voltage ascent has also caused at the stage 64 a modification of the threshold voltage v2 by grounding the positive input of an operational amplifier.
The stage 61 then detects the rate of the lower bottom level of the impulse el, whereas the output of the subtracting stage 62 remains at zero as long as the bottom level lasts. Once again, with the appearance of the beginning of the ascending oblique slope of the inlet impulse, the difference at the outlet 206~99~
of the stage 62 will increase and even exceed the new threshold v2 of the comparator 631 which then will invert its output signal, thereby causing a sudden descent s12 of the output of the shaping amplifier 632.
In this way, the steep ascending slope of the output impulse sl corresponds more or less to the beginning of the descending oblique slope of the input impulse el, whereas the steep descending slope of the output impulse sl corresponds more or less to the beginning of the reascending oblique slope of the input impulse el.
As may be gathered from Figures 1 and 4, the impulses sl and s2, now castellated, respectively emitted by the channel corresponding to the yellow colour and the channel corresponding to the blue colour are applied to the selective circuit 70 retaining the ascending impulse sl which will descend first and correspond to the initial oblique slope of the most contrasted impulse el.
The mode of realizing the circuit 70 as illustrated by Figure 5 includes a first OR gate "OU" 71 receiving one of the castellated impulses at both of its inputs and whose output is connected to the clock input "CLK" of a first bistable device 72.
The selective circuit 70 includes as many secondary bistable devices 73, 74 as there are impulses to be analysed, these im-pulses being received inverted, i.e. at their clock input "CLK".
All the inverted outlets "Q" of the secondary blstable devices are connected to the input of an AND gate "ET" 75 whose output is connected to the re-initialization input'!-CL"of the first bistable device 72. Moreover, the output "Q" of this first bistable device 72 is also connected to the re-initialization input "CL" of each of the secondary bistable devices 73, 74. A last permitting or interlocking line 85 of the selective circuit 70 is connected to one of the inputs of gate "ET" 75.
At the initial state of the device, all inputs of the gate "ET" 75 are high, thus releasing the first bistable device 72 whose output "Q" is initially low, entailing the interlocking of the bistable devices 73 and 74. With an impulse reaching one of the inputs of the OR gate 71, the output of this gate is high, resulting in the appearance of a high signal on the output gate "Q" of the bistable device 72, which latter brings about the as-cending slope of the output impulse and also releases the bistable devices 73 and 74. The arrival of the ascending slope of the second impulse then has no more effect on the circuit 70. On the other hand, the arrival of the first ascending slope of an inver-ted signal, corresponding actually to the descending slope of this first impulse, will change the state of the corresponding bi-stable device 73, 74 resulting in the immediate lowering of the corresponding output "Q". The gate "ET" 75 will have at least one of its inputs forced low, whereas its output also lowers resulting in the re-initialization of the first bistable device 72, and putting the corresponding output "Q" back to low, thus creating the descending slope of the output impulse. This low signal at the output "Q" of the bistable device 72 also results in the re-initialization of all secondary bistable devices 73, 74 putting all inverted "Q" outputs high and thereby interlocking these bistable devices and preventing the ascent of the subsequent inverted signal. The output of gate "ET" 75 returns to high, which action again releases the bistable device 72 and renders it suited for the subsequent selection as long as a permission to that end is maintained on the line 85.
As may be gathered from Figure 1, the device according to the invention includes moreover an analog/digital and digital/
analog converter 90 acting jointly with a micro-processor 80, this device being capable of receiving on line 81 a value of the basic voltage in order to return to the lines 82 an electric signal corresponding to the gains to be applied to the amplifying cir-cuits 40 and 41 with automatic gain, and to the lines 83 a threshold rate for the comparator 63 of the circuits 60 and 61, the said threshold being fixed between 100 and 400 millivolts above the background noise measured on the basic signal. The micro-processor also transmits to the line 85 a monitoring signal interlocking the selective circuit as long as no mark is awaited.
As may be gathered from the aforesaid comments, the device according to the invention allows to reliably detect a mark travelling through a light beam emitted by the source 20, the said device effectuating an instantaneous selection of the best suited scanning channel for yellow or blue, simultaneously taking into account the colour, the contrast and the intensity of the mark to be considered. For machines expected to carry out 206799~ 68200-127 delicate jobs, it is quite possible to add a third or fourth parallel scanning channel for other well distinguishable colours.
Numerous improvements may be added to this device within the limits of the invention.
Claims (10)
1. Device for scanning a mark printed on a plate or web-shaped workpiece travelling under a light source within a printing machine, characterized by the fact that it includes at least two parallel mark scanning channels, fed with scanning data by at least one fibre optic bundle, each of the said channels emitting an electric impulse each time a mark travels through under the light source, a photosensitive unit situated at the input of each channel being responsive to a colour frequency range distinguishable from the frequencies of other channels, as well as electronic means for selecting the most representative mark impulse among the electric impulses emitted by the channels.
2. Device according to claim 1, characterized by the fact that each mark scanning channel includes:
- a photosensitive unit generating an electric signal for the voltage value, followed by - an amplifying stage with automatic gain, fixing at a predetermined rate a basic voltage corresponding to a non-printed area of the workpiece, followed by - a stage converting an oblique-sloped electric impulse caused by the mark travelling under the photosensitive unit into steep sloped electric impulse, every steep slope corresponding to the beginning of the ascent or descent of the associated oblique slope, - and electronic means selecting among the electric impulses originating from the channels at a given moment the impulse appearing or disappearing first.
- a photosensitive unit generating an electric signal for the voltage value, followed by - an amplifying stage with automatic gain, fixing at a predetermined rate a basic voltage corresponding to a non-printed area of the workpiece, followed by - a stage converting an oblique-sloped electric impulse caused by the mark travelling under the photosensitive unit into steep sloped electric impulse, every steep slope corresponding to the beginning of the ascent or descent of the associated oblique slope, - and electronic means selecting among the electric impulses originating from the channels at a given moment the impulse appearing or disappearing first.
3. Device according to claim 2, characterized by the fact that every scanning channel additionally includes before the converting stage a rectifying stage imparting to all electric impulses a variation in one direction with regard to the basic voltage.
4. Device according to claim 3, characterized by the fact that the photosensitive unit includes a photodiode situated behind a colour filter and connected to the input of a current/voltage converter.
5. Device according to claim 3, characterized by the fact that the rectifying stage includes a first stage for providing the basic voltage, the said stage being followed by a stage for subtracting the basic voltage thereby leaving only positive or negative electric impulses, followed by a stage for rectifying solely the positive impulses into negative ones, followed by a stage for adding all the impulses and, finally, followed by a stage ensuring the re-addition of the basic voltage.
6. Device according to any one of claims 2 to 5, characterized by the fact that the converting stage includes a first peak detecting stage, followed by a second stage for subtracting from the input signal the threshold detected by the first stage, the difference being applied to a comparator which switches its output as soon as the difference exceeds a predeter-mined threshold, as well as primary electronic means re-initializing and inverting the detection direction of the peak detecting stage, and secondary electronic means inverting the polarity of the comparative threshold applied to the comparator after a first switching of the latter.
7. Device according to any one of claims 2 to 5, characterized by the fact that an electronic means for impulse selection include an OR gate receiving one of the impulses at each of its inputs, and an output connected to a clock inlet of a first bistable device and as many secondary bistable devices as there are impulses to be analysed, the said impulses being received inverted at their clock inputs, all inverted outlets being connected to the input of an AND gate having an output which is connected to a re-initialization input of the first bistable device, the re-initialization input of every secondary bistable device being connected to the non-inverted output of the first bistable device, and a final line for monitoring the electronic means being connected to the one of the inlets of the AND gate.
8. Device according to any one of claims 2 to 5, characterized by the fact that it includes an analog/digital and digital/analog converter connected to a micro-processor destined to receive from the rectifying stage the basic voltage value and to feed, on the one hand, the amplifying stage with automatic gain, if present, with an electric signal representative for the gain to be applied and, on the other hand, the converting stage with an electric signal representative for a threshold optimal for the comparator.
9. Device according to claim 7 characterized by the fact that it includes an analog/digital and digital/analog converter connected to a micro-processor destined to receive from the rectifying stage the basic voltage value and to feed, on the one hand, the amplifying stage with automatic gain, if present, with an electric signal representative for the gain to be applied and, on the other hand, the converting stage with an electric signal representative for a threshold optimal for the comparator.
10. Device according to claim 6 characterized by the fact that it includes an analog/digital and digital/analog converter connected to a micro-processor destined to receive from the rectifying stage the basic voltage value and to feed, on the one hand, the amplifying stage with automatic gain, if present, with an electric signal representative for the gain to be applied and, on the other hand, the converting stage with an electric signal representative for a threshold optimal for the comparator.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH01327/91-7 | 1991-05-06 | ||
| CH132791A CH686357A5 (en) | 1991-05-06 | 1991-05-06 | A device for reading a mark printed on a plate member or strip. |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2067994A1 CA2067994A1 (en) | 1992-11-07 |
| CA2067994C true CA2067994C (en) | 1996-11-26 |
Family
ID=4207872
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002067994A Expired - Fee Related CA2067994C (en) | 1991-05-06 | 1992-05-05 | Device for scanning pale colour marks on a printing machine |
Country Status (11)
| Country | Link |
|---|---|
| US (1) | US5215011A (en) |
| EP (1) | EP0512448B1 (en) |
| JP (2) | JPH05147197A (en) |
| KR (1) | KR970000777B1 (en) |
| AT (1) | ATE151348T1 (en) |
| CA (1) | CA2067994C (en) |
| CH (1) | CH686357A5 (en) |
| DE (1) | DE69218821T2 (en) |
| DK (1) | DK0512448T3 (en) |
| ES (1) | ES2100248T3 (en) |
| TW (1) | TW276319B (en) |
Families Citing this family (25)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1995016576A1 (en) * | 1993-12-13 | 1995-06-22 | Whittington, Ruth | Machine readable code presentations |
| DE4401535C2 (en) * | 1994-01-20 | 2002-10-24 | Heidelberger Druckmasch Ag | Method for scanning register marks produced in multicolor printing |
| CH690544A5 (en) * | 1995-05-08 | 2000-10-13 | Bobst Sa | Photoelectric detector for a register control device in a rotary printing machine. |
| EP0765748A3 (en) * | 1995-09-29 | 1997-08-13 | Goss Graphics Systems Inc | Device for alignment of images in a control system for a printing press |
| EP0770480B1 (en) * | 1995-10-25 | 2001-12-19 | Heidelberger Druckmaschinen Aktiengesellschaft | Printing press with register control system |
| FR2743079B1 (en) | 1995-12-27 | 1998-02-06 | Inst Francais Du Petrole | PROCESS AND DEVICE FOR SELECTIVE HYDROGENATION BY CATALYTIC DISTILLATION INCLUDING A LIQUID-GAS UPWARD CO-CURRENT REACTION ZONE |
| FR2743080B1 (en) | 1995-12-27 | 1998-02-06 | Inst Francais Du Petrole | PROCESS FOR SELECTIVE REDUCTION OF THE CONTENT OF BENZENE AND LIGHT UNSATURATED COMPOUNDS OF A HYDROCARBON CUP |
| GB9603582D0 (en) | 1996-02-20 | 1996-04-17 | Hewlett Packard Co | Method of accessing service resource items that are for use in a telecommunications system |
| FR2743081B1 (en) | 1995-12-27 | 1998-01-30 | Inst Francais Du Petrole | PROCESS FOR SELECTIVE REDUCTION OF THE CONTENT OF BENZENE AND LIGHT UNSATURATED COMPOUNDS OF A HYDROCARBON CUP |
| US6069890A (en) | 1996-06-26 | 2000-05-30 | Bell Atlantic Network Services, Inc. | Internet telephone service |
| US6154445A (en) | 1996-04-18 | 2000-11-28 | Bell Atlantic Network Services, Inc. | Telephony communication via varied redundant networks |
| US5828075A (en) * | 1996-10-11 | 1998-10-27 | Hurletron, Incorporated | Apparatus for scanning colored registration marks |
| US6078582A (en) | 1996-12-18 | 2000-06-20 | Bell Atlantic Network Services, Inc. | Internet long distance telephone service |
| US6137869A (en) | 1997-09-16 | 2000-10-24 | Bell Atlantic Network Services, Inc. | Network session management |
| US6574216B1 (en) | 1997-03-11 | 2003-06-03 | Verizon Services Corp. | Packet data network voice call quality monitoring |
| US6870827B1 (en) | 1997-03-19 | 2005-03-22 | Verizon Services Corp. | Voice call alternative routing through PSTN and internet networks |
| US6292479B1 (en) | 1997-03-19 | 2001-09-18 | Bell Atlantic Network Services, Inc. | Transport of caller identification information through diverse communication networks |
| CH694184A5 (en) | 2000-12-27 | 2004-08-31 | Bobst Sa | Device read rep'rage marks in a multicolour printing machine. |
| US6591746B2 (en) | 2001-06-13 | 2003-07-15 | Hurletron, Incorporated | Registration system for printing press |
| US7013803B2 (en) | 2002-02-06 | 2006-03-21 | Quad/Tech, Inc. | Color registration control system for a printing press |
| US7253929B2 (en) * | 2002-02-06 | 2007-08-07 | Quad/Tech, Inc. | Camera assembly for a printing press |
| US7074978B2 (en) * | 2003-02-25 | 2006-07-11 | Abb Lummus Global Inc. | Process for the production of alkylbenzene |
| DE102008049908A1 (en) * | 2008-10-02 | 2010-04-08 | Robert Bosch Gmbh | Method for generating a detection signal and detection device |
| US8238538B2 (en) | 2009-05-28 | 2012-08-07 | Comcast Cable Communications, Llc | Stateful home phone service |
| JP6292759B2 (en) * | 2013-03-12 | 2018-03-14 | 住友重機械工業株式会社 | Mark sensor and mark determination method using light detection element |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4546700A (en) * | 1981-12-30 | 1985-10-15 | Kollmorgen Technologies Corporation | Method and apparatus for sensing and maintaining color registration |
| JPS58190703A (en) * | 1982-04-30 | 1983-11-07 | Dainippon Printing Co Ltd | Register mark sensor for printing machine |
| US4534288A (en) * | 1982-05-06 | 1985-08-13 | Harris Graphics Corporation | Method and apparatus for registering overlapping printed images |
| DE3311352C1 (en) * | 1983-03-29 | 1984-03-15 | Ingenieurbüro Rudolf Weber KG, 6100 Darmstadt | Detector for recording marks |
| JPS6174846A (en) * | 1984-09-20 | 1986-04-17 | Nireko:Kk | Automatic registering apparatus |
| FR2578486B1 (en) * | 1985-03-08 | 1987-06-12 | Bertin & Cie | METHOD AND DEVICE FOR POSITIONING OBJECTS IN RELATION TO OTHERS, IN PARTICULAR COLOR PRINTING ROLLERS IN A ROTARY OFFSET PRESS |
| US5076163A (en) * | 1986-04-07 | 1991-12-31 | Quad/Tech, Inc. | Web registration control system |
| CA1339689C (en) * | 1986-04-18 | 1998-02-24 | Andre Kudelski | Apparatus for interactive communication between a pay televisiion subscriber and a decoder |
| DE3643721A1 (en) * | 1986-12-20 | 1988-06-30 | Heidelberger Druckmasch Ag | PRINT CONTROL STRIP |
| US4947348A (en) * | 1987-03-25 | 1990-08-07 | Kollmorgen Corporation | Densitometer method and system for identifying and analyzing printed targets |
| FI78025C (en) * | 1987-08-31 | 1989-06-12 | Valtion Teknillinen | Procedure for quality control of printing |
| DE3812099C2 (en) * | 1988-04-12 | 1995-01-26 | Heidelberger Druckmasch Ag | Process for color control of an offset printing press |
| JP2786216B2 (en) * | 1988-12-20 | 1998-08-13 | 東芝メカトロニクス株式会社 | Picture area ratio measuring device |
| CH680117A5 (en) * | 1989-07-15 | 1992-06-30 | Bobst Sa | |
| DE4109744C2 (en) * | 1991-03-25 | 1994-01-20 | Heidelberger Druckmasch Ag | Method for determining the area coverage of a printing template, in particular a printing plate, and device for performing the method |
-
1991
- 1991-05-06 CH CH132791A patent/CH686357A5/en not_active IP Right Cessation
-
1992
- 1992-04-30 TW TW081103067A patent/TW276319B/zh active
- 1992-05-02 AT AT92107486T patent/ATE151348T1/en not_active IP Right Cessation
- 1992-05-02 DK DK92107486.0T patent/DK0512448T3/en not_active Application Discontinuation
- 1992-05-02 EP EP92107486A patent/EP0512448B1/en not_active Expired - Lifetime
- 1992-05-02 ES ES92107486T patent/ES2100248T3/en not_active Expired - Lifetime
- 1992-05-02 DE DE69218821T patent/DE69218821T2/en not_active Expired - Lifetime
- 1992-05-04 KR KR1019920007580A patent/KR970000777B1/en not_active IP Right Cessation
- 1992-05-05 CA CA002067994A patent/CA2067994C/en not_active Expired - Fee Related
- 1992-05-06 JP JP4113736A patent/JPH05147197A/en active Pending
- 1992-05-06 US US07/879,776 patent/US5215011A/en not_active Expired - Lifetime
-
1997
- 1997-03-13 JP JP1997001647U patent/JP3041439U/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH05147197A (en) | 1993-06-15 |
| DE69218821T2 (en) | 1997-10-16 |
| ATE151348T1 (en) | 1997-04-15 |
| EP0512448B1 (en) | 1997-04-09 |
| TW276319B (en) | 1996-05-21 |
| CA2067994A1 (en) | 1992-11-07 |
| KR920021317A (en) | 1992-12-18 |
| KR970000777B1 (en) | 1997-01-20 |
| ES2100248T3 (en) | 1997-06-16 |
| US5215011A (en) | 1993-06-01 |
| CH686357A5 (en) | 1996-03-15 |
| EP0512448A1 (en) | 1992-11-11 |
| DE69218821D1 (en) | 1997-05-15 |
| DK0512448T3 (en) | 1997-10-27 |
| JP3041439U (en) | 1997-09-19 |
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| EEER | Examination request | ||
| MKLA | Lapsed |