EP0000964B1 - Device for the development of an electrostatic charge image with the aid of magnetic brushes. - Google Patents
Device for the development of an electrostatic charge image with the aid of magnetic brushes. Download PDFInfo
- Publication number
- EP0000964B1 EP0000964B1 EP78200120A EP78200120A EP0000964B1 EP 0000964 B1 EP0000964 B1 EP 0000964B1 EP 78200120 A EP78200120 A EP 78200120A EP 78200120 A EP78200120 A EP 78200120A EP 0000964 B1 EP0000964 B1 EP 0000964B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- developing
- developing rollers
- reservoir
- rollers
- powder
- 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
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Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
- G03G15/08—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer
- G03G15/09—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer using magnetic brush
Definitions
- the invention relates to a device for the development of an electrostatic charge image on a moving substrate with the aid of magnetic brushes, which device comprises a trough-shaped reservoir of which two long opposite sloping walls lie in planes which are intersecting at the bottom of the reservoir, developing rollers installed in the upper part of the reservoir with their shafts parallel to the line of intersection of the planes of the sloping walls, each of which rollers consists of a rotatable, non-magnetizable cylinder, in which stationary magnets have been installed, transport means installed between the bottom of the reservoir and the developing rollers, for the transport of the developing powder from the reservoir to the developing rollers, and means for mixing the developing powder.
- a magnetic brush with which charge images can be developed can be formed on the developing rollers of such a device.
- the known developing devices comprise one developing roller, which is partially immersed in a reservoir with developing powder, or which is mounted above the stock of developing powder and is provided with developing powder with the aid of a transport screw or a magnetic transport roller of similar nature to the developing roller.
- An embodiment with a magnetic transport roller is described in U.S. patent specification 3654902.
- a counterrunning roller which moves in opposite direction with regard to the charge image, has this disadvantage to a much lesser degree, but gives a bad development of the half tones. Moreover, when applying a binary developing powder, a counterrunning roller not only transfers toner but also a part of the magnetizable material to the charge image.
- a developing device which does not have the disadvantages mentioned above, is described in the British patent specification 1 373 010.
- the device according to the British patent specification comprises four developing rollers running in the same direction as the charge image.
- the developing powder is supplied to the first developing roller with the aid of a paddle wheel and is transported in a continuous stream over the four developing rollers which have been installed within each other's sphere of influence.
- By the repeated contact with the charge image a relatively long time of contact for the manufacture of copies with a high optical density is guaranteed, in spite of the high copying speed.
- After passing the fourth developing roller that part of the developing powder which has not been used falls into a mixing device via a scraper.
- This mixing device comprises a first row of tubular channels which have been installed in parallel with regard to each other, and a second row of channels which have been installed in parallel with regard to each other, which second row is fixed to the first row and crosses this first row. All these channels have been installed in a sloping way with regard to the free-fall direction of the developing powder, so that the developing powder is always split up into partial streams which arrive at different places in the reservoir.
- the developing device according to the British patent specification 1 373 010 also has various disadvantages.
- the four magnetic brushes on the four developing rollers form a great friction surface between the substrate of the charge image and the developing powder, so that the duration of use of the developing powder is decreased.
- the. device with four developing rollers is constructively less attractive, on the one hand because such a device occupies much space, and a great surface on the substrate, and on the other hand because the construction of the mixing device is complicated.
- the device is only suitable for the development of charge images on a sloping substrate and the paddle wheel causes extra friction forces in the developing powder, so that especially with binary developing powders the particles of the magnetizable material, which is not consumed but is reused again and again, are ageing and consequently have to be renewed more frequently.
- the invention provides for a developing device which has the favourable properties of the developing device according to British patent specification 1 373 010 without the disadvantages of that device.
- the developing device according to the invention is a device, as described in the first paragraph, characterized in that a) the device comprises two developing rollers which have been installed out of each other's sphere of influence and the cylinders of these developing rollers have an opposite direction of rotation with which the cylinder surfaces, at the side which is directed towards the substrate, move away from each other, b) the transport means at least consist of a rotatable, non-magnetizable cylinder, installed parallel to the developing rollers, and magnets stationarily installed in the cylinder, for the supply of developing powder between the developing rollers, and c) the mixing means consist of groups of parallelly erected partitions which have been fixed opposite to each other to the sloping walls of the reservoir, and the partitions of the one sloping wall lie in planes making an acute angle with the shafts of the developing rollers and the partitions of
- a charge image is first developed with a counterrunning roller and subsequently with a following roller.
- a high optical density and on the other hand an optimal development of halftones is achieved.
- This combination of properties is not achieved, when the development is first made with a following roller and subsequently with a counterrunning roller.
- iron is then transferred to the image. This has the consequence, that the photoconductor is quickly damaged, and that when the toner image is transferred electrically, the toner is no more transferred round the iron particles and a copy with white spots in the image parts exists.
- the developing device comprises a trough-shaped reservoir 1 with two sloping walls 2 and 3 which lie in planes which are intersecting at the bottom 4 of the reservoir.
- a first developing roller 5 and a second developing roller 6 are installed with their shafts parallel to each other and to the line of intersection of the sloping walls.
- Each of these developing rollers comprises a non-magnetizable metal cylinder 7, 8 which is rotatable in the diretion of the arrow.
- the cylinders of the developing rollers rotate away from each other at the side which is distant from the bottom of the reservoir.
- each developing roller 7 8 At that side and near each developing roller two pairs of guide rollers 9, 10, 11 and 12 have been installed, which convey a photoconductive belt 13 past the developing rollers.
- a stationary magnetic system consisting of a hexagonal soft-iron core 14, 15 is installed.
- each core At a side directed towards the photoconductive belt 13 each core is provided over its full length with a recess 1 6, 17 in which magnet strips have been installed. On these magnet strips a second layer of magnet strips has been installed. All these magnet strips have their south pole directed outwards.
- the first developing roller 5 seen against the direction of rotation of the enveloping cylinder, the following three sides of the core are provided with magnet strips, directed outwards with the north-, north- and south pole respectively.
- a magnet with a south pole directed outwards is indicated with an S and a magnet with a north pole directed outwards is indicated with an N.
- a transport roller 18 is installed with the shaft 25 parallel to the shafts of the developing rollers.
- this transport roller comprises a rotatable, non-magnetizable cylinder and a stationary magnet system consisting of a soft-iron core with hexagonal section which at four successive sides is provided with magnet strips and is directed towards the developing rollers with the two magnet-free sides. The magnet strips are directed outwards alternately with the north- and south pole.
- the cylinder of the transport roller rotates in the same direction as the second developing roller 6 and opposite to the first developing roller 5, as indicated by the arrow-direction.
- the transport roller 18 transports developing powder from the reservoir 1 to the space between the two developing rollers where the developing powder is picked up by the developing rollers.
- a scraper 19, 20 is installed near each developing roller, which scraper extends lengthwise" over the whole cylinder surface of the developing roller and which limits the layer-thickness of the developing powder on the developing roller.
- a plate-shaped scraper 21, 22 is installed on each developing roller, which scraper extends lengthwise of the pertaining developing roller over the whole surface of the cylinder of this roller.
- Each scraper extends in the other direction from the pertaining developing roller up to the top side of the nearest sloping wall 2, 3.
- Both sloping walls are provided with groups of parallel partitions 23, 24 which are installed perpendicularly to the sloping wall and extend from the top side of the sloping wall to the lower part of the reservoir. All partitions on the one sloping wall 2 make an acute angle with the shaft 25 of the transport roller, which is not represented in Fig. 2, and with the shafts of the developing rollers. Seen in the same direction, the partitions on the other sloping wall 3 make an obtuse angle with the shaft 25 of the transport roller and with the shafts of the developing rollers installed parallel to these.
- the developing powder which falls downwards from the scrapers is deflected from the direction of falling into the direction of the ends of the trough-shaped reservoir, in such a way that the deflection on the one sloping wall is directed to the one end and the deflection on the other sloping wall is directed to the other end.
- the partitions on each sloping wall are divided in two groups, in such a way that seen in the same direction each first group has a smaller acute respectively smaller obtuse angle with the shafts of the transport roller and the developing rollers than the second group.
- the first group of partitions of the one sloping wall makes an angle of 66° with the shaft of the transport roller and the second group on the same wall makes an angle of 73° with the shaft of the transport roller.
- the angles which the first and second group make with the shaft of the transport roller are 107° and 114° respectively.
- the first developing roller 5 is provided with two north poles beside each other.
- the order south-north-south- north for the position of the magnet poles directed outwards can be applied in the' corresponding developing roller, but in that case a layer of toner can be transferred electrostatically to the cylinder of the developing roller, when developing with binary toner and simultaneous application of a high bias voltage between the photoconductive belt and the developing roller is applied. In this way the developing current and consequently the optical density of the developed image, may start decreasing.
- the layer formed is again wiped away from the developing roller by the developing powder which is supplied between the developing rollers.
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Magnetic Brush Developing In Electrophotography (AREA)
- Dry Development In Electrophotography (AREA)
Description
- The invention relates to a device for the development of an electrostatic charge image on a moving substrate with the aid of magnetic brushes, which device comprises a trough-shaped reservoir of which two long opposite sloping walls lie in planes which are intersecting at the bottom of the reservoir, developing rollers installed in the upper part of the reservoir with their shafts parallel to the line of intersection of the planes of the sloping walls, each of which rollers consists of a rotatable, non-magnetizable cylinder, in which stationary magnets have been installed, transport means installed between the bottom of the reservoir and the developing rollers, for the transport of the developing powder from the reservoir to the developing rollers, and means for mixing the developing powder.
- With the aid of a binary developing powder, consisting of a mixture of a magnetizable powder and a toner powder, or with the aid of a one-component developing powder, in which the magnetizable material has been taken up in the toner particles, a magnetic brush with which charge images can be developed, can be formed on the developing rollers of such a device.
- In a simple embodiment the known developing devices comprise one developing roller, which is partially immersed in a reservoir with developing powder, or which is mounted above the stock of developing powder and is provided with developing powder with the aid of a transport screw or a magnetic transport roller of similar nature to the developing roller. An embodiment with a magnetic transport roller is described in U.S. patent specification 3654902.
- In copying apparatus with a low copying speed a single developing roller which at the side of the charge image moves in the same direction as the charge image, satisfies excellently. However, with copying speeds of about 10 metres per minute and more too little developing powder is transferred by such a single following roller to the charge image, so that copies with a too low optical density are obtained. This effect is even increased, when in case of copying drawings an image with an edge-effect is desired for improving the contour-sharpness. Such an edge-effect can for instance be achieved with the aid of a binary developing powder by increasing the specific resistance of the magnetizable powder. As a result of this the developing speed and consequently the optical density of the copies obtained decreases. A counterrunning roller, which moves in opposite direction with regard to the charge image, has this disadvantage to a much lesser degree, but gives a bad development of the half tones. Moreover, when applying a binary developing powder, a counterrunning roller not only transfers toner but also a part of the magnetizable material to the charge image.
- A developing device which does not have the disadvantages mentioned above, is described in the British patent specification 1 373 010. The device according to the British patent specification comprises four developing rollers running in the same direction as the charge image. The developing powder is supplied to the first developing roller with the aid of a paddle wheel and is transported in a continuous stream over the four developing rollers which have been installed within each other's sphere of influence. By the repeated contact with the charge image a relatively long time of contact for the manufacture of copies with a high optical density is guaranteed, in spite of the high copying speed. After passing the fourth developing roller that part of the developing powder which has not been used, falls into a mixing device via a scraper. This mixing device comprises a first row of tubular channels which have been installed in parallel with regard to each other, and a second row of channels which have been installed in parallel with regard to each other, which second row is fixed to the first row and crosses this first row. All these channels have been installed in a sloping way with regard to the free-fall direction of the developing powder, so that the developing powder is always split up into partial streams which arrive at different places in the reservoir.
- However, the developing device according to the British patent specification 1 373 010 also has various disadvantages. The four magnetic brushes on the four developing rollers form a great friction surface between the substrate of the charge image and the developing powder, so that the duration of use of the developing powder is decreased. Further the. device with four developing rollers is constructively less attractive, on the one hand because such a device occupies much space, and a great surface on the substrate, and on the other hand because the construction of the mixing device is complicated. Moreover, the device is only suitable for the development of charge images on a sloping substrate and the paddle wheel causes extra friction forces in the developing powder, so that especially with binary developing powders the particles of the magnetizable material, which is not consumed but is reused again and again, are ageing and consequently have to be renewed more frequently.
- The invention provides for a developing device which has the favourable properties of the developing device according to British patent specification 1 373 010 without the disadvantages of that device. The developing device according to the invention is a device, as described in the first paragraph, characterized in that a) the device comprises two developing rollers which have been installed out of each other's sphere of influence and the cylinders of these developing rollers have an opposite direction of rotation with which the cylinder surfaces, at the side which is directed towards the substrate, move away from each other, b) the transport means at least consist of a rotatable, non-magnetizable cylinder, installed parallel to the developing rollers, and magnets stationarily installed in the cylinder, for the supply of developing powder between the developing rollers, and c) the mixing means consist of groups of parallelly erected partitions which have been fixed opposite to each other to the sloping walls of the reservoir, and the partitions of the one sloping wall lie in planes making an acute angle with the shafts of the developing rollers and the partitions of the other sloping wall, seen in the same direction, lie in planes making an obtuse angle with the shafts of the developing rollers. When applying a developing device according to the invention a charge image is first developed with a counterrunning roller and subsequently with a following roller. In this way on the one hand a high optical density and on the other hand an optimal development of halftones is achieved. This combination of properties is not achieved, when the development is first made with a following roller and subsequently with a counterrunning roller. Moreover, iron is then transferred to the image. This has the consequence, that the photoconductor is quickly damaged, and that when the toner image is transferred electrically, the toner is no more transferred round the iron particles and a copy with white spots in the image parts exists. Although a developing device with a first counterrunning roller and a second following roller is known from
German patent specification 15 22 727, that developing device makes use of external magnets so that magnetizable material arrives in the developed image. This magnetizable material is again removed with additional magnets. This leads to an accelerated ageing of the magnetizable material, and moreover the optical density again becomes lower. Further a transport belt is used for the transport of the developing powder which transport belt causes friction with the developing powder in the reservoir and consequently reduces the duration of life of the powder. Moreover, the developing powder is not mixed sufficiently, because a mixing device is absent. The transport and mixing means in the device according to the invention are extremely effective with a minimum of friction. - The invention is further clarified with the aid of the Figures 1 and 2.
- Fig. 1 schematically represents a developing device according to the invention, seen in a section according to the line I-I' of Fig. 2, perpendicularly on the shafts of the developing rollers.
- Fig. 2 is a plan view, reduced with regard to Fig. 1, of the bottom of the same developing device, stretched out in a plane.
- The developing device according to the Figures 1 and 2 comprises a trough-shaped reservoir 1 with two sloping
walls roller 5 and a second developingroller 6 are installed with their shafts parallel to each other and to the line of intersection of the sloping walls. Each of these developing rollers comprises anon-magnetizable metal cylinder guide rollers photoconductive belt 13 past the developing rollers. In eachnon-magnetizable cylinder 7, 8 a stationary magnetic system, consisting of a hexagonal soft-iron core photoconductive belt 13 each core is provided over its full length with a recess 1 6, 17 in which magnet strips have been installed. On these magnet strips a second layer of magnet strips has been installed. All these magnet strips have their south pole directed outwards. In the first developingroller 5, seen against the direction of rotation of the enveloping cylinder, the following three sides of the core are provided with magnet strips, directed outwards with the north-, north- and south pole respectively. In the second developingroller 6, also seen against the direction of rotation of the pertaining cylinder, the following three sides of the core are provided with magnet strips, directed outwards with the north-, south- and north pole respectively. In Fig. 1 a magnet with a south pole directed outwards is indicated with an S and a magnet with a north pole directed outwards is indicated with an N. - Below the developing rollers a
transport roller 18 is installed with theshaft 25 parallel to the shafts of the developing rollers. Just like the two developing rollers this transport roller comprises a rotatable, non-magnetizable cylinder and a stationary magnet system consisting of a soft-iron core with hexagonal section which at four successive sides is provided with magnet strips and is directed towards the developing rollers with the two magnet-free sides. The magnet strips are directed outwards alternately with the north- and south pole. The cylinder of the transport roller rotates in the same direction as the second developingroller 6 and opposite to the first developingroller 5, as indicated by the arrow-direction. Thetransport roller 18 transports developing powder from the reservoir 1 to the space between the two developing rollers where the developing powder is picked up by the developing rollers. In this space ascraper scraper 19, 20 a plate-shaped scraper sloping wall - Both sloping walls are provided with groups of
parallel partitions wall 2 make an acute angle with theshaft 25 of the transport roller, which is not represented in Fig. 2, and with the shafts of the developing rollers. Seen in the same direction, the partitions on the othersloping wall 3 make an obtuse angle with theshaft 25 of the transport roller and with the shafts of the developing rollers installed parallel to these. In this way it is achieved, that the developing powder which falls downwards from the scrapers, is deflected from the direction of falling into the direction of the ends of the trough-shaped reservoir, in such a way that the deflection on the one sloping wall is directed to the one end and the deflection on the other sloping wall is directed to the other end. When all partitions are installed parallel to each other, the developing powder may sometimes accumulate at one end of the reservoir, for instance when the reservoir is not installed horizontally. Therefore in the preferred embodiment the partitions on each sloping wall are divided in two groups, in such a way that seen in the same direction each first group has a smaller acute respectively smaller obtuse angle with the shafts of the transport roller and the developing rollers than the second group. In the situation according to Fig. 2, in which the sloping walls are stretched out in a plane, the first group of partitions of the one sloping wall makes an angle of 66° with the shaft of the transport roller and the second group on the same wall makes an angle of 73° with the shaft of the transport roller. On the other sloping wall, seen in the same direction, the angles which the first and second group make with the shaft of the transport roller are 107° and 114° respectively. With this installation a light accumulation of developing powder occurs in the centre of the reservoir but this does not cause any trouble. The angles indicated result in optimal mixing, but they are not critical. When the developing unit has a length of 21 cm, concentration-differences can be eliminated within 30 seconds. For thistest 2% of developing powder, calculated on the weight of the iron powder, was added to the iron powder at an end of the reservoir which only contained iron powder. A good mixing is also obtained, when the acute angles are adjusted to values between 50° and 80° and the obtuse angles are adjusted to values between 100 and 130°. - In the developing device described above the first developing
roller 5 is provided with two north poles beside each other. In an alternative embodiment also the order south-north-south- north for the position of the magnet poles directed outwards can be applied in the' corresponding developing roller, but in that case a layer of toner can be transferred electrostatically to the cylinder of the developing roller, when developing with binary toner and simultaneous application of a high bias voltage between the photoconductive belt and the developing roller is applied. In this way the developing current and consequently the optical density of the developed image, may start decreasing. When two like poles have been installed beside each other, the layer formed is again wiped away from the developing roller by the developing powder which is supplied between the developing rollers. Two like poles beside each other are superfluous in the second developingroller 6, possibly because any layer of toner formed is automatically wiped away from the developing roller, because the surface of the second developing roller moves oppositely to the surface of the transport roller in the nip with the transport roller. Of course the problem of the formation of a toner layer on the developing rollers can also be eliminated by applying, according to another alternative embodiment of the developing device according to the invention, instead of one transport roller, two smaller transport rollers, which with regard to the pertaining developing rollers are rotatable in the proper direction.
Claims (2)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
NL7709230A NL7709230A (en) | 1977-08-22 | 1977-08-22 | DEVICE FOR DEVELOPING CHARGING IMAGES USING MAGNET BRUSHES. |
NL7709230 | 1977-08-22 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0000964A1 EP0000964A1 (en) | 1979-03-07 |
EP0000964B1 true EP0000964B1 (en) | 1981-11-11 |
Family
ID=19829044
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP78200120A Expired EP0000964B1 (en) | 1977-08-22 | 1978-07-27 | Device for the development of an electrostatic charge image with the aid of magnetic brushes. |
Country Status (5)
Country | Link |
---|---|
US (1) | US4235193A (en) |
EP (1) | EP0000964B1 (en) |
JP (1) | JPS5435741A (en) |
DE (1) | DE2861312D1 (en) |
NL (1) | NL7709230A (en) |
Families Citing this family (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
NL7709230A (en) * | 1977-08-22 | 1977-12-30 | Oce Van Der Grinten Nv | DEVICE FOR DEVELOPING CHARGING IMAGES USING MAGNET BRUSHES. |
JPS55111974A (en) * | 1979-02-21 | 1980-08-29 | Ricoh Co Ltd | Dry type developing device |
US4292921A (en) * | 1979-04-04 | 1981-10-06 | Eastman Kodak Company | Electrographic development apparatus |
DE3010647A1 (en) * | 1980-03-20 | 1981-10-01 | Agfa-Gevaert Ag, 5090 Leverkusen | DEVELOPMENT DEVICE FOR AN ELECTROPHOTOGRAPHIC COPIER |
FR2521069A2 (en) * | 1982-02-11 | 1983-08-12 | Cii Honeywell Bull | DEVICE FOR APPLYING SOLID PARTICLES ON THE RECORDING MEDIUM OF A NON-IMPACT PRINTER |
US4671207A (en) * | 1985-12-11 | 1987-06-09 | Eastman Kodak Company | Magnetic brush development apparatus |
JP2938904B2 (en) * | 1988-12-19 | 1999-08-25 | 株式会社リコー | Developing device |
US5385801A (en) * | 1990-07-12 | 1995-01-31 | Minolta Camera Kabushiki Kaisha | Method of developing electrostatic latent image |
JP3221195B2 (en) * | 1993-12-03 | 2001-10-22 | 日立工機株式会社 | Developing device for electrophotographic equipment |
US5495319A (en) * | 1994-06-06 | 1996-02-27 | Hewlett-Packard Company | Developing housing having a plurality of angled ribs |
DE19636783B4 (en) * | 1995-09-12 | 2005-12-08 | Fuji Xerox Co., Ltd. | Electrophotographic image forming apparatus |
JP2018125319A (en) * | 2015-06-18 | 2018-08-09 | ソニー株式会社 | Module, method of manufacturing the same, and electronic device |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2706816C3 (en) * | 1977-02-17 | 1979-12-13 | Siemens Ag, 1000 Berlin Und 8000 Muenchen | Device for developing charge images applied to an intermediate carrier with the aid of a developer mixture |
US4131357A (en) * | 1977-03-21 | 1978-12-26 | Xerox Corporation | Sequentially activated development system for an electrophotographic printer |
NL7709230A (en) * | 1977-08-22 | 1977-12-30 | Oce Van Der Grinten Nv | DEVICE FOR DEVELOPING CHARGING IMAGES USING MAGNET BRUSHES. |
-
1977
- 1977-08-22 NL NL7709230A patent/NL7709230A/en not_active Application Discontinuation
-
1978
- 1978-07-07 JP JP8282678A patent/JPS5435741A/en active Pending
- 1978-07-27 DE DE7878200120T patent/DE2861312D1/en not_active Expired
- 1978-07-27 EP EP78200120A patent/EP0000964B1/en not_active Expired
- 1978-08-11 US US05/933,111 patent/US4235193A/en not_active Expired - Lifetime
Also Published As
Publication number | Publication date |
---|---|
DE2861312D1 (en) | 1982-01-14 |
NL7709230A (en) | 1977-12-30 |
US4235193A (en) | 1980-11-25 |
JPS5435741A (en) | 1979-03-16 |
EP0000964A1 (en) | 1979-03-07 |
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