GB1582490A - Apparatus for determining the optical density distribution of an image bearing member - Google Patents
Apparatus for determining the optical density distribution of an image bearing member Download PDFInfo
- Publication number
- GB1582490A GB1582490A GB37996/77A GB3799677A GB1582490A GB 1582490 A GB1582490 A GB 1582490A GB 37996/77 A GB37996/77 A GB 37996/77A GB 3799677 A GB3799677 A GB 3799677A GB 1582490 A GB1582490 A GB 1582490A
- Authority
- GB
- United Kingdom
- Prior art keywords
- photo
- image bearing
- transducers
- bearing member
- electric
- 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
Links
- 230000003287 optical effect Effects 0.000 title claims description 20
- 230000001105 regulatory effect Effects 0.000 claims description 11
- 230000004907 flux Effects 0.000 claims description 10
- 238000005286 illumination Methods 0.000 claims description 6
- 238000012544 monitoring process Methods 0.000 claims description 5
- 238000007639 printing Methods 0.000 claims description 5
- 238000001914 filtration Methods 0.000 claims description 2
- 238000012806 monitoring device Methods 0.000 claims description 2
- 238000000034 method Methods 0.000 description 4
- 230000003321 amplification Effects 0.000 description 3
- 238000003199 nucleic acid amplification method Methods 0.000 description 3
- 238000000149 argon plasma sintering Methods 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000007645 offset printing Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/86—Investigating moving sheets
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41F—PRINTING MACHINES OR PRESSES
- B41F33/00—Indicating, counting, warning, control or safety devices
- B41F33/0027—Devices for scanning originals, printing formes or the like for determining or presetting the ink supply
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Photometry And Measurement Of Optical Pulse Characteristics (AREA)
- Facsimile Scanning Arrangements (AREA)
- Manufacture Or Reproduction Of Printing Formes (AREA)
- Inking, Control Or Cleaning Of Printing Machines (AREA)
Description
(54) APPARATUS FOR DETERMINING THE
OPTICAL DENSITY DISTRIBUTION OF AN
IMAGE BEARING MEMBER (71) We, SIEMENS AKTIENGESELLSCHAFT, a German company of Berlin and Munich; Germany, 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:
The invention relates to apparatus for determining the optical density distribution of an image bearing member and is particularly, but not exclusively, applicable to apparatus for determining the optical density distribution on the original of a printing plate in a printing machine, wherein the transparent stationary original is adapted to be introduced between illuminating means formed of parallel fluorescent tubes succeeded by a light scattering screen, and zonewise-arranged photo-electric transducers, the luminous flux which passes through a whole zone of the original in each instance serving as a measure of the mean optical density of the respective zone of the original.
Arrangements of this kind are described, for example, in German Auslegeschrift 2 229 500 or in German Offenlegungsschrift 1 761 333.
The mean optical density values thus measured may be used' for pre-setting the inking zone screws or inking zone pumps in relief or offset printing machines.
In the method disclosed in German
Offenlegungsschrift 1 761 333, the individual zones of the transparent original are scanned by photo-electric cells. The scanned values of each zone, which vary over the length of the latter. are applied to a calculating unit for determining the integral optical density distribution, i.e. the mean optical density of the scanned zone The mean value which is formed from the individual scanned values for each zone then constitutes a measure of the setting of the inking zone screw of the respective zone. This known method is rather disadvantageous in regard to the cost of the apparatus, because on the one hand it is necessary to provide a relative movement between the original and the photo-electric cells for the photo-electric scanning of the original, and on the other hand a calculating unit having storage capability for the individual scanned areas is necessary for the formation of the mean value.
For improving such an arrangement, it is known from. German Auslegschrift 2 229 500 to transilluminate each zone of the stationarily arranged original simultaneously over its entire length and to collect the total luminous flux passing through the zone by means of the photo-sensitive surface of a respective single photo-electric element, and to store the information thereby obtained for predetermining the required setting of the inking zone screw. In this method, the mean optical density of a zone is directly obtained as a result of the photo-electric measurement, that is to say there appears at the output of each photo electric element a single signal value which can already form the final information for the setting of an inking zone screw.
A problem in these known arrangements is the possible lack of uniformity of the illumination produced by the illuminating means. In the particular case of fluorescent tubes, the light distribution is determined by the characteristics of the fluorescent tubes and by the geometrical arrangement of the tubes in relation to one another. Even the presence of a light scattering screen affords only a limited aid and makes it possible to provide uniformity of illumination only to a limited extent, because otherwise the light intensity would fall too much and the subsequent photo-electric amplification would involve inadmissibly high expenditure.
In the known arrangements, therefore, it is substantially unavoidable that, for example, the ends of the zones will receive a luminous flux which differs from the luminous flux at the cetres of the zones. If a zonewise light sensing with only one photoelectric element is chosen, as mentioned in the foregoing, the danger arises that the total luminous flux passing through a zone of the original will produce an output signal which does not correspond with sufficient accuracy to the actual mean optical density in the zone, because the incident light itself is uneven. The invention therefore proceeds along a different course, namely that of using a respective set of photo-electric transducers for each zone, which course is rejected in the aforesaid printed publication.
According to the present invention there is provided apparatus for determining the optical density distribution of an image bearing member, the apparatus comprising support means for supporting the image bearing camber, illuminating means for diffusely illuminating the member, and a plurality of sets of photo-electric transducers arranged for receiving light from illuminating means via the member, the sets of transducers being arranged for receiving light as aforesaid via respective different zones of the member and the transducers of each set being arranged to receive light via different portions of the respective zone, the apparatus being such that the image bearing member is stationary with respect to the photo-electric transducers when the apparatus is in use, and the apparatus further comprising, for each said set of transducers, a respective summing device to which the transducers of that set are connected via respective signal adjusting devices so that each summing device sums the adjusted signals from the transducers in the respective associated set and thereby forms a signal representative of the mean optical density of the respective associated zone, photo-electric transducer means arranged for receiving light from the illuminating means directly, means for comparing the output of the transducer means with a desired signal value, and regulating means for regulating the illumination provided by said illuminating means in dependence upon the comparison.
In this way, it may be ensured that there is provided an adjusted compensation for any non-uniformity in the light distribution from the illuminating means.
Particularly favourable conditions may be obtained by arranging the photo-electric transducer means to monitor an area of illumination which corresponds to the size of one of the zones and which lies parallel to these zones.
As an additional sensing means, there may be provided a sensor which senses an edge of the image bearing member and produces a signal by way of a sequentially connected evaluating unit in the event of absence of an image bearing member.
In addition, further monitoring may be advantageous in which the sum current of the fluorescent tubes connected in parallel to a regulating unit is monitored.
The invention will be more particularly described with reference to an embodiment illustrated by way of example in the single figure of the drawing.
In the present case, there is used as a light source 1 a series of fluorescent tubes 2 disposed parallel to one another, of which the light is rendered more uniform by a
Scattering screen 3 which absorbs substantially 50% of the light emitted by the fluorescent tubes 2. The light passing through the scattering screen 3 transilluminates a negative 4 which forms the transparent original and which can be laid in a drawer 5.
There are allocated to each of the parallel zones 8 of the negative 4 three transducer elements 9 consisting of operational amplifiers with photo-diodes. The negative 4 is stationary with respect to the transducer elements 9 when the apparatus is in use. The transducer elements 9 are disposed on a base plate 7 which is situated at the lower end of a lattice-form box 6 lying below the negative 4. Due to this arrangement and the distance of photo-diodes of the transducer elements 9 from the negative 4 to be sensed, it is provided that any error caused by the non-perpendicular incidence of the scattered light upon the photo-sensitive layer of the photo-diodes can be kept small. The output voltages of the transducer elements 9 associated with a zone 8 are applied through adjusting devices in the form of potentiometers 10 to a respective common summing amplifier 11 whose amplification is adjustable as indicated by the potentiometer 26.
In this way, the amplification of each operational amplifier and of the summing amplifier 11 can be separately adjusted. by means of the potentiometers 10 and 26, and differences in brightness due to uneven distrbution of the luminous flux from the light source 1 can thus be balanced out.
As indicated by the reference numeral 22, the output signals set up at the outputs of the summing amplifiers 11, representing the mean optical densities of the respective zones 8, can then be picked up in sequence and processed in a computer 23. Instead of the immediate further processing in a computer, recording on other data carriers such as a magnetic tape, for example, is alternatively possible.
For regulating the light source 1 to a constant brightness value, there is provided on the base plate 7, parallel with the zones 8 of the negative 4 which are to be sensed, a further zone 12 having three photo-electric transducer elements 13 which, while being illuminated directly by the light source 1, are not covered by the negative 4. The luminous flux thus falling upon the transducer elements 13 is measured and converted into an electrical value proportional to the luminous flux of the light source 1.
This value, which is passed through a potentiometer 14, is compared in an integral action controller 15 with a desired value which can be taken from a potentiometer 16. A regulating unit 17 is activated in dependece upon the difference between the actual and desired values and provides the supply voltage for the parallel-connected fluorescent tubes 2.
In order that it may be ascertained whether a fluorescent tube has failed, there is additionally provided next to a filtering choke 19 a lamp failure monitoring device 18 in the form of a two-step switch having hysteresis, which measures the sum current of the fluorescent tubes 2. When this current falls below the adjustable hysteresis value owing to failure of one or more tubes, a warning signal is emitted.
An additional monitoring means is provided to enable it to be ascertained whether there is any negative 4 present in the drawer 5. For this purpose, there is provided a light beam switch 24 associated with an edge of the negative 4, that is to say a further sensing element which operates a warning device 21 by way of a sequentially connected evaluating unit 20 when the negative 4 is absent.
Monitoring of the negative in regard to its correct position in relation to the fluorescent tubes 2 is also provided by ascertaning by means of a limit switch 25 whether the drawer 5 in which the negative 4 is situated is correctly closed.
WHAT WE CLAIM IS:
1. Apparatus for determining the optical density distribution of an image bearing member, the apparatus comprising support means for supporting the image bearing member, illuminating means for diffusely illuminating the member, and a plurality of sets of photo-electric transducers arranged for receiving light from the illuminating means via the member, the sets of transducers being arranged for receiving light as aforesaid via respective different zones of the member and the transducers of each set being arranged to receive light via different portions of the respective zone, the apparatus being such that the image bearing member is stationary with respect to the photo-electric transducers when the apparatus is in use, and the apparatus further
comprising, for each said set of transducers,
a respective summing device to which the
transducers of that set are connected via
respective signal adjusting devices so that
each summing device sums the. adjusted
signals from the transducers in the respec tive associated set and thereby forms a
signal representative of the mean optical
density of the respective associated zone,
photo-electric transducer means arranged
for receiving light from the illuminating
means directly, means for comparing the
output of the transducer means-with a
desired signal value, and regulating means
for regulating the illumination provided by
said illuminating means in dependence upon
the comparison.
2. Apparatus according to claim 1,
wherein in each of said sets the photo
electric transducers are spaced apart by a
predetermined distance; and are at a prede
termined distance from the support means
whereby they will be at a predetermined
distance from the image bearing member
when the apparatus is in use.
3. Apparatus according to claim 1 or 2,
which is suitable for determining the optical
density -distribution of, as said image bear
ing member, the original of a printing plate.
4. Apparatus according to claim 1, 2 or
3, wherein said illuminating means compris
es parallel fluorescent tubes and a succeed
ing scattering screen.
5. Apparatus according to any one of
the preceding claims, wherein said image
bearing member is to be a transparent image
bearing member and said support means is
arrnged between the illuminating means and
the plurality of sets of photo-electric trans
ducers.
6. Apparatus according to any one of
the preceding claims, wherein said photo
electric transducer means comprises a plu
rality of photo-electric transducers, and
there is a further summing device connected
between said plurality of photo-electric
transducers and said comparing means.
7. Apparatus according to any one of
the preceding claims, wherein said photo
electric transducer means is arranged to
monitor a zone which corresponds to the
size of one of said zones and which lies
parallel to said zones.
8. Apparatus according to claim 4 or
any one of claims 5 to 7 when appended
either directly or indirectly to claim 4,
wherein the zones extend in directions
transversely to the directions of extent of
said parallel fluorescent tubes.
9. Apparatus according to any one of
the preceding claims, wherein each set of
photo-electric transducers comprises at least
three photo-electric transducers lying in a
row parallel with the direction of the associ
ated zone.
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (15)
1. Apparatus for determining the optical density distribution of an image bearing member, the apparatus comprising support means for supporting the image bearing member, illuminating means for diffusely illuminating the member, and a plurality of sets of photo-electric transducers arranged for receiving light from the illuminating means via the member, the sets of transducers being arranged for receiving light as aforesaid via respective different zones of the member and the transducers of each set being arranged to receive light via different portions of the respective zone, the apparatus being such that the image bearing member is stationary with respect to the photo-electric transducers when the apparatus is in use, and the apparatus further
comprising, for each said set of transducers,
a respective summing device to which the
transducers of that set are connected via
respective signal adjusting devices so that
each summing device sums the. adjusted
signals from the transducers in the respec tive associated set and thereby forms a
signal representative of the mean optical
density of the respective associated zone,
photo-electric transducer means arranged
for receiving light from the illuminating
means directly, means for comparing the
output of the transducer means-with a
desired signal value, and regulating means
for regulating the illumination provided by
said illuminating means in dependence upon
the comparison.
2. Apparatus according to claim 1,
wherein in each of said sets the photo
electric transducers are spaced apart by a
predetermined distance; and are at a prede
termined distance from the support means
whereby they will be at a predetermined
distance from the image bearing member
when the apparatus is in use.
3. Apparatus according to claim 1 or 2,
which is suitable for determining the optical
density -distribution of, as said image bear
ing member, the original of a printing plate.
4. Apparatus according to claim 1, 2 or
3, wherein said illuminating means compris
es parallel fluorescent tubes and a succeed
ing scattering screen.
5. Apparatus according to any one of
the preceding claims, wherein said image
bearing member is to be a transparent image
bearing member and said support means is
arrnged between the illuminating means and
the plurality of sets of photo-electric trans
ducers.
6. Apparatus according to any one of
the preceding claims, wherein said photo
electric transducer means comprises a plu
rality of photo-electric transducers, and
there is a further summing device connected
between said plurality of photo-electric
transducers and said comparing means.
7. Apparatus according to any one of
the preceding claims, wherein said photo
electric transducer means is arranged to
monitor a zone which corresponds to the
size of one of said zones and which lies
parallel to said zones.
8. Apparatus according to claim 4 or
any one of claims 5 to 7 when appended
either directly or indirectly to claim 4,
wherein the zones extend in directions
transversely to the directions of extent of
said parallel fluorescent tubes.
9. Apparatus according to any one of
the preceding claims, wherein each set of
photo-electric transducers comprises at least
three photo-electric transducers lying in a
row parallel with the direction of the associ
ated zone.
10. Apparatus according to any one of
the preceding claims, and comprising a sensing means for providing a signal when no image bearing member is present.
11. Apparatus according to claim 10, wherein said sensing means comprises a sensor associated with an edge region of an image bearing member, and a sequentially connected evaluating device.
12. Apparatus according to claim 4, or any one of claims 5 to 11 when appended either directly or indirectly to claim 4, wherein the fluorescent tubes are connected electrically in parallel to the regulating means, and the sum current of the fluorescent tubes is monitored.
13. Apparatus for determining the optical density distribution of an image bearing member, the apparatus being substantially as hereinbefore described with reference to the single figure of the accompanying drawing.
14. Apparatus according to any one of the preceding claims, when an image bearing member is supported by said support means.
15. A printing machine comprising apparatus according to claim 3 or any one of claims 4 to 14 when appended either directly or indirectly to claim 3.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2641130A DE2641130C3 (en) | 1976-09-13 | 1976-09-13 | Device for determining the density of a print template |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1582490A true GB1582490A (en) | 1981-01-07 |
Family
ID=5987788
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB37996/77A Expired GB1582490A (en) | 1976-09-13 | 1977-09-12 | Apparatus for determining the optical density distribution of an image bearing member |
Country Status (5)
| Country | Link |
|---|---|
| DE (1) | DE2641130C3 (en) |
| FI (1) | FI61761C (en) |
| FR (1) | FR2364124A1 (en) |
| GB (1) | GB1582490A (en) |
| SE (1) | SE411867B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4210343A1 (en) * | 1992-03-30 | 1993-10-14 | Berthold Lab Prof Dr | Light intensity distribution measurement for optical densitometry or fluorescence measurement - has linear objective lens system, photoelectric sensor and illumination system all of equal length extending over whole width of sample. |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4180741A (en) * | 1978-06-07 | 1979-12-25 | Harris Corporation | Apparatus for determining image areas for printing with calibration |
| DE3029273A1 (en) * | 1979-08-03 | 1981-02-19 | Dainippon Printing Co Ltd | DEVICE FOR MEASURING THE PRINT IMAGE AREA OF AN OFFSET PRINT PLATE |
| DE3009690C2 (en) * | 1980-03-13 | 1982-06-24 | Heimann Gmbh, 6200 Wiesbaden | Optical arrangement for measuring the mean gray value of a reflecting surface |
| JPS57142548A (en) * | 1981-02-27 | 1982-09-03 | Dainippon Screen Mfg Co Ltd | Photographic density detector for film |
| DE3309443A1 (en) * | 1982-05-29 | 1983-12-08 | Heidelberger Druckmaschinen Ag, 6900 Heidelberg | METHOD FOR DETERMINING THE SURFACE COVERAGE OF A PRINT ORIGINAL OR PRINT PLATE FOR PRINTING MACHINES |
| DE3322665A1 (en) * | 1983-06-23 | 1985-01-03 | Siemens AG, 1000 Berlin und 8000 München | COLOR DENSITY MEASURING DEVICE |
| DD276656A1 (en) * | 1988-11-07 | 1990-03-07 | Polygraph Leipzig | DEVICE FOR DETERMINING THE PRINTING FLUID PART OF PRINTING MACHINES |
| DE4022020A1 (en) * | 1990-07-11 | 1992-01-16 | Gao Ges Automation Org | DEVICE AND METHOD FOR CHECKING DOCUMENTS |
-
1976
- 1976-09-13 DE DE2641130A patent/DE2641130C3/en not_active Expired
-
1977
- 1977-08-16 FI FI772448A patent/FI61761C/en not_active IP Right Cessation
- 1977-09-06 SE SE7709984A patent/SE411867B/en unknown
- 1977-09-12 FR FR7727474A patent/FR2364124A1/en active Granted
- 1977-09-12 GB GB37996/77A patent/GB1582490A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4210343A1 (en) * | 1992-03-30 | 1993-10-14 | Berthold Lab Prof Dr | Light intensity distribution measurement for optical densitometry or fluorescence measurement - has linear objective lens system, photoelectric sensor and illumination system all of equal length extending over whole width of sample. |
Also Published As
| Publication number | Publication date |
|---|---|
| FI772448A (en) | 1978-03-14 |
| FI61761B (en) | 1982-05-31 |
| DE2641130B2 (en) | 1979-08-16 |
| FR2364124B3 (en) | 1980-06-27 |
| DE2641130C3 (en) | 1980-05-08 |
| FR2364124A1 (en) | 1978-04-07 |
| FI61761C (en) | 1982-09-10 |
| DE2641130A1 (en) | 1978-03-16 |
| SE411867B (en) | 1980-02-11 |
| SE7709984L (en) | 1978-03-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PS | Patent sealed [section 19, patents act 1949] | ||
| PCNP | Patent ceased through non-payment of renewal fee |