CA1108221A - Electrostatographic copying - Google Patents
Electrostatographic copyingInfo
- Publication number
- CA1108221A CA1108221A CA274,503A CA274503A CA1108221A CA 1108221 A CA1108221 A CA 1108221A CA 274503 A CA274503 A CA 274503A CA 1108221 A CA1108221 A CA 1108221A
- Authority
- CA
- Canada
- Prior art keywords
- image
- optical axis
- images
- receiving member
- optical
- 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
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
- G03G15/04—Apparatus for electrographic processes using a charge pattern for exposing, i.e. imagewise exposure by optically projecting the original image on a photoconductive recording material
- G03G15/0409—Details of projection optics
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B27/00—Photographic printing apparatus
- G03B27/32—Projection printing apparatus, e.g. enlarger, copying camera
- G03B27/52—Details
- G03B27/522—Projection optics
- G03B27/525—Projection optics for slit exposure
Abstract
ELECTROSTATOGRAPHIC COPYING
Abstract of the Disclosure An electrostatographic reproduction method and apparatus is provided wherein an optical system simultan-eously directs more than one light image of an original onto different parts of a photoconductive imaging layer.
Abstract of the Disclosure An electrostatographic reproduction method and apparatus is provided wherein an optical system simultan-eously directs more than one light image of an original onto different parts of a photoconductive imaging layer.
Description
32.'~i The invention relates electrostatographic copy:ing.
The fo~nation and development of images on the surface of photoconductor rnaterial by electrostatic rneans is well known. m e basic xerographic process as taught by C F Carlson in US Patent no 2,297,691 involves placing a uniform electrostatic charge on a photoconducti~e insulating layerr exposing the layer to a light and shadow image to dissipate the charge on the areas of the layer exposed to the light and deve:Loping the res~Ltirlg electrostatic charge pattern unage hy deposlting on the image a finely divided markiny material referred to in the art as 'toner'. The toner wiLl normally be attracted to those areas of the layer which retain a charge thereby forming a toner image corresponding to the electrostatic charge patters. The powder image rnay then be transferred to a support surface such as paper and perm~nently affixed to the support by any suitable means such as heat fixing or solvent fixing. ~lternatively, the powder image may be fixed to the photocon-ductive layer if elimination of the powder transfer step is desired.
In addition instead of form m g a charge pattern by uniform~y charging a photoconductor followed by image-wise light exposure, a charge pattern rnay be formed by directly charging the layer in image configuration.
Other methods are kncwn for applying marking particles to the imaging surface. Ihcluded within this group are the 'cascade' development technique disclosed by E N Wise in ~S Patent 2,618,552; the p~wder cloud development technique disclosed by C F Carlson in US Patent
The fo~nation and development of images on the surface of photoconductor rnaterial by electrostatic rneans is well known. m e basic xerographic process as taught by C F Carlson in US Patent no 2,297,691 involves placing a uniform electrostatic charge on a photoconducti~e insulating layerr exposing the layer to a light and shadow image to dissipate the charge on the areas of the layer exposed to the light and deve:Loping the res~Ltirlg electrostatic charge pattern unage hy deposlting on the image a finely divided markiny material referred to in the art as 'toner'. The toner wiLl normally be attracted to those areas of the layer which retain a charge thereby forming a toner image corresponding to the electrostatic charge patters. The powder image rnay then be transferred to a support surface such as paper and perm~nently affixed to the support by any suitable means such as heat fixing or solvent fixing. ~lternatively, the powder image may be fixed to the photocon-ductive layer if elimination of the powder transfer step is desired.
In addition instead of form m g a charge pattern by uniform~y charging a photoconductor followed by image-wise light exposure, a charge pattern rnay be formed by directly charging the layer in image configuration.
Other methods are kncwn for applying marking particles to the imaging surface. Ihcluded within this group are the 'cascade' development technique disclosed by E N Wise in ~S Patent 2,618,552; the p~wder cloud development technique disclosed by C F Carlson in US Patent
2,221,776; and magnetic brush process disclosed, for example, in US
Patent 2,847,063 A liquid technique for developing electrostatic charge patterns is the liquid development process disclosed by R W Gundlach in ~S Patent 3,084,043. In this method, a charge pattern is developed or made visible by presenting to the image surface a liquid developer on the surface of a developer dispensing member having a plurality of raised portions defining a substantially regular patterned surface and a plurality of portions depressed below the raised portions. The depressed portions contain a liquid developer which is maintained out of contact with the electrostato-graphic imaging surface. When the raised areas of the developer application are brought into contact with the imaging surface bearing a charge pattern, the developer creeps up the sides of raised portions in contact only with the charged area of the imaging surface, and is deposited thereon.
In accordance with one aspect of this invention there is provided an optical system for projecting an image of an object from an object station, along an optical axis, to an image receiving member, including: a lens disposed on said optical axis between said object station and said image i receiving member to form and project an image of said object along said optical axis, optlcal means diposed on said optical axis on the image side of said lens to form at least two identical images from said projected image and to direct said identical images to separate portions of said image receiving member so as to simultaneously form thereon identical imayes of said object, and developer means adja-cent said image receiving member to sequentially clevelop said identically ~ormed images.
æz~l Electrostatographic reproduction methods and apparatus according to -the invention will now be described by way of example with reference to the accompanying drawings in which:
,~
Fig 1 is a sche~atic representation of a simplified xerographic system showing the various major process steps and their relationship ta one another; and Fig 2 sh~s diagrammatically the layout of the optical s~stern of the apparatus.
Referring now to Fig 1, there is shown a xerographic drum r~mber 1 comprising photoconductive imagirg layer of seleniurn coated on a resilient substrate. In operation, tne xerographic member 1 is charged in the usual ~anner at charging station 4. The ~ember 1 is then exposed simultaneously to a light image at a first exposure station 5 and a second exposure station 6 in order to forrn simMltaneously two charge patterns. ~oth chc~rging and exposing are disclosed in US Patent 2,297,691.
m e electrostatic images thus formed a~rethen made visible in se~uence at a developing station 7 where liquid developer is applied to the photoconductive surface. The developing station 7 coA~prises an applicator roller having a pattern of recesses on its surface. m e images, no~ visible, are then transferred sequentic~lly to receiver r~3mbers at a transfer station 9.
At the transfer station 9, paper sheets 11 entralrAed over a roller 11 are pressed irA turn into contact wlth the in~ges on the sur~ace of the .
me~ber 1 and the images are transferred to the paper sheet 10 to form the final copies. Any developer material remaining on the xerographic member 1 after the transfer station 9 is removed from the surface of the ~ember 1 by a doctor blade 14. ~eveloper material doctored frcm the xerographic n~ber is collected in a tray 15. The member 1 is then charged to start the next sequence of operation.
The apparatus of Fig 1 depicts a typical apparatus and t~pical Configurations of imaging surface and applicator roller except that more than one e~posure station is provided for simultaneous e~posure o~ llght ima~es. It is to be understood that other configurations are possible, for example, the member 1 could be a belt contacted by a roller at developing station 7. Li~ewise, other forrns ofdevelopment may be used such as cascade or maynetic brush development.
' Referring to Fig 2, a platen 20 supports an original 21 to be copied. Below the platen 20 an optical scanning system comprises a full-rate mirror 22 which directs a light image of the original 21 onto t~o half rate mirrors 23 and 24, at right angles to one another, which direct in turn the image towards a lens 25. (The position of the mirrors 23 and 24 tcwar~s the end of scan are shot~n dott~dinFig. 2.) From the lens 2S, the light image is reflected by a ~ir~or 26 towards a mirror 27. Interposed between mirrors 26 and 27 is ca beam-splitter 28 arranged to reflect one light image ta~ards a mirror 29 and trclnsmit another light in~ge towards the mirror 27. qwo light images thus .
!
2~
provided are reflected respectively to exposui-e stations S and 6 by the mirror 29 and a mi.rror 30.
It will be appreciated that campared to prior art apparatus which exposes one light image at a time, the described e~odiement can produce twice the number of copies for example for a given speed of the member 1.
m e optical path has been chosen such that the angles of incidence of the light beam are small. Although the angles of incidence ~
couls be arranged to be relatively higher, the lay-out of the optical .
system shown in the drawings is preferred in the described e~bodiment because the sizes of -the miirrors and beamrsplitter can be kept to a mini~um. Further, the optical axes of the ~urrors 26 and 30 are in line with the incident beam from the lens 25 and the optical axis of the mirror 27 is at right angles to the incident beam. This fascilitates adjustments and simplifies the design of the murror mountings (no~ shcwn).
... ,.,,. . ~ .... ,.,, . ,, .
In another e~bodiement we provide an optical system whic~ directs three light images sinmltaneously onto the surface of the n~nber 1 enabling the rate of producing co~ies to be further increased. It will be appreciated that within the scope of the invention four and nxhe light images of an original be arranged to be simultaneously directed to-wardsthe member 1 or an equivalent support for a photoconductive layer as requir.ed. The number of images that can be used s~multaneously is of .
course dependent on the surface area of the photoconductive layer c~nd it ~. I
is intended to be within the scope of the invention that -t~ or more llght images can be arranged to be directed simultaneously and side by side onto a photoconductive layer.
~ general, the il~?rov~nent provided by the invention is an increase in output of copies from any particular electrostatographic copying system. m e speed oE rota-tion oE a drum, such as member 1, or movement of a belt, is limited m~inly in practice by mechanical considerations.
The response of the photoconductive layer to light images for example in prior art apparatus tends to operate well withinits time limitations.
I'hus, having achieved a n~ n speed Eor nember 1 or a belt, and in the case where a scanning op-tical systern is used the r~ m speed of that system, no further increase in output of copies is possible. Clearly, scme gradual improve~ents are to be expected in the operational speeds but the invention enables the current rate of producing copies to be increased by around two fold, threefold or more by novelly si~ultaneously exposing ~o or m~re light images oE a single original.
In ~he described embodiernent, a single developing station is provided. In other arrangements two, or more, developing stations can be provided to develope respectively the t~70, or ~ore, electrostatic images simultaneously rather than sequentially. Iikewlse, two or ~ore, transfer stations and/or c~arging stations can be provided with such number of cleaning stations as are then required.
- 7 ~
Further, it will be appreciated that the invention may ~e used 1:
with an electronically controlled writing system in which the light image is ormed b~ a m~dulated scanning laser bean. In such a case, the laser beam is directed towards the ~irror 26 and split into t~o (or more) Farts by a beam splitter such as beam splitter 28. 1 .
Whilst a particular embx~lY~lt of the invention has keen described above, it will be appreciated that various mc~ifications may be made b~ one skilled in the art without; departing frcm the scope of the invention as defined in the appended claIms.
- ~ i .
......
. :. ., : . .
.
:: i .
Patent 2,847,063 A liquid technique for developing electrostatic charge patterns is the liquid development process disclosed by R W Gundlach in ~S Patent 3,084,043. In this method, a charge pattern is developed or made visible by presenting to the image surface a liquid developer on the surface of a developer dispensing member having a plurality of raised portions defining a substantially regular patterned surface and a plurality of portions depressed below the raised portions. The depressed portions contain a liquid developer which is maintained out of contact with the electrostato-graphic imaging surface. When the raised areas of the developer application are brought into contact with the imaging surface bearing a charge pattern, the developer creeps up the sides of raised portions in contact only with the charged area of the imaging surface, and is deposited thereon.
In accordance with one aspect of this invention there is provided an optical system for projecting an image of an object from an object station, along an optical axis, to an image receiving member, including: a lens disposed on said optical axis between said object station and said image i receiving member to form and project an image of said object along said optical axis, optlcal means diposed on said optical axis on the image side of said lens to form at least two identical images from said projected image and to direct said identical images to separate portions of said image receiving member so as to simultaneously form thereon identical imayes of said object, and developer means adja-cent said image receiving member to sequentially clevelop said identically ~ormed images.
æz~l Electrostatographic reproduction methods and apparatus according to -the invention will now be described by way of example with reference to the accompanying drawings in which:
,~
Fig 1 is a sche~atic representation of a simplified xerographic system showing the various major process steps and their relationship ta one another; and Fig 2 sh~s diagrammatically the layout of the optical s~stern of the apparatus.
Referring now to Fig 1, there is shown a xerographic drum r~mber 1 comprising photoconductive imagirg layer of seleniurn coated on a resilient substrate. In operation, tne xerographic member 1 is charged in the usual ~anner at charging station 4. The ~ember 1 is then exposed simultaneously to a light image at a first exposure station 5 and a second exposure station 6 in order to forrn simMltaneously two charge patterns. ~oth chc~rging and exposing are disclosed in US Patent 2,297,691.
m e electrostatic images thus formed a~rethen made visible in se~uence at a developing station 7 where liquid developer is applied to the photoconductive surface. The developing station 7 coA~prises an applicator roller having a pattern of recesses on its surface. m e images, no~ visible, are then transferred sequentic~lly to receiver r~3mbers at a transfer station 9.
At the transfer station 9, paper sheets 11 entralrAed over a roller 11 are pressed irA turn into contact wlth the in~ges on the sur~ace of the .
me~ber 1 and the images are transferred to the paper sheet 10 to form the final copies. Any developer material remaining on the xerographic member 1 after the transfer station 9 is removed from the surface of the ~ember 1 by a doctor blade 14. ~eveloper material doctored frcm the xerographic n~ber is collected in a tray 15. The member 1 is then charged to start the next sequence of operation.
The apparatus of Fig 1 depicts a typical apparatus and t~pical Configurations of imaging surface and applicator roller except that more than one e~posure station is provided for simultaneous e~posure o~ llght ima~es. It is to be understood that other configurations are possible, for example, the member 1 could be a belt contacted by a roller at developing station 7. Li~ewise, other forrns ofdevelopment may be used such as cascade or maynetic brush development.
' Referring to Fig 2, a platen 20 supports an original 21 to be copied. Below the platen 20 an optical scanning system comprises a full-rate mirror 22 which directs a light image of the original 21 onto t~o half rate mirrors 23 and 24, at right angles to one another, which direct in turn the image towards a lens 25. (The position of the mirrors 23 and 24 tcwar~s the end of scan are shot~n dott~dinFig. 2.) From the lens 2S, the light image is reflected by a ~ir~or 26 towards a mirror 27. Interposed between mirrors 26 and 27 is ca beam-splitter 28 arranged to reflect one light image ta~ards a mirror 29 and trclnsmit another light in~ge towards the mirror 27. qwo light images thus .
!
2~
provided are reflected respectively to exposui-e stations S and 6 by the mirror 29 and a mi.rror 30.
It will be appreciated that campared to prior art apparatus which exposes one light image at a time, the described e~odiement can produce twice the number of copies for example for a given speed of the member 1.
m e optical path has been chosen such that the angles of incidence of the light beam are small. Although the angles of incidence ~
couls be arranged to be relatively higher, the lay-out of the optical .
system shown in the drawings is preferred in the described e~bodiment because the sizes of -the miirrors and beamrsplitter can be kept to a mini~um. Further, the optical axes of the ~urrors 26 and 30 are in line with the incident beam from the lens 25 and the optical axis of the mirror 27 is at right angles to the incident beam. This fascilitates adjustments and simplifies the design of the murror mountings (no~ shcwn).
... ,.,,. . ~ .... ,.,, . ,, .
In another e~bodiement we provide an optical system whic~ directs three light images sinmltaneously onto the surface of the n~nber 1 enabling the rate of producing co~ies to be further increased. It will be appreciated that within the scope of the invention four and nxhe light images of an original be arranged to be simultaneously directed to-wardsthe member 1 or an equivalent support for a photoconductive layer as requir.ed. The number of images that can be used s~multaneously is of .
course dependent on the surface area of the photoconductive layer c~nd it ~. I
is intended to be within the scope of the invention that -t~ or more llght images can be arranged to be directed simultaneously and side by side onto a photoconductive layer.
~ general, the il~?rov~nent provided by the invention is an increase in output of copies from any particular electrostatographic copying system. m e speed oE rota-tion oE a drum, such as member 1, or movement of a belt, is limited m~inly in practice by mechanical considerations.
The response of the photoconductive layer to light images for example in prior art apparatus tends to operate well withinits time limitations.
I'hus, having achieved a n~ n speed Eor nember 1 or a belt, and in the case where a scanning op-tical systern is used the r~ m speed of that system, no further increase in output of copies is possible. Clearly, scme gradual improve~ents are to be expected in the operational speeds but the invention enables the current rate of producing copies to be increased by around two fold, threefold or more by novelly si~ultaneously exposing ~o or m~re light images oE a single original.
In ~he described embodiernent, a single developing station is provided. In other arrangements two, or more, developing stations can be provided to develope respectively the t~70, or ~ore, electrostatic images simultaneously rather than sequentially. Iikewlse, two or ~ore, transfer stations and/or c~arging stations can be provided with such number of cleaning stations as are then required.
- 7 ~
Further, it will be appreciated that the invention may ~e used 1:
with an electronically controlled writing system in which the light image is ormed b~ a m~dulated scanning laser bean. In such a case, the laser beam is directed towards the ~irror 26 and split into t~o (or more) Farts by a beam splitter such as beam splitter 28. 1 .
Whilst a particular embx~lY~lt of the invention has keen described above, it will be appreciated that various mc~ifications may be made b~ one skilled in the art without; departing frcm the scope of the invention as defined in the appended claIms.
- ~ i .
......
. :. ., : . .
.
:: i .
Claims (2)
1. An optical system for projecting an image of an object from an object station, along an optical axis, to an image receiving member, including:
a lens disposed on said optical axis between said object station and said image receiving member to form and project an image of said object along said optical axis, optical means disposed on said optical axis on the image side of said lens to form at least two identical images from said projected image and to direct said identical images to separate portions of said image receiving member so as to simultaneously form thereon identical images of said object, and developer means adjacent said image receiving member to sequentially develop said identically formed images.
a lens disposed on said optical axis between said object station and said image receiving member to form and project an image of said object along said optical axis, optical means disposed on said optical axis on the image side of said lens to form at least two identical images from said projected image and to direct said identical images to separate portions of said image receiving member so as to simultaneously form thereon identical images of said object, and developer means adjacent said image receiving member to sequentially develop said identically formed images.
2. The optical system of claim 1 wherein said optical means comprises a beam divider disposed on said optical axis on the image side of said lens to transmit said image along a transmission component of said optical axis and to reflect said image along a reflection component, and a reflector means disposed on said transmission and said reflection components of said optical axis to direct respectively said transmission and said reflection components of said optical axis substantially radially to separate portions of said image receiving member as to simultaneously form thereon twin images of said object.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1275776A GB1543406A (en) | 1976-03-30 | 1976-03-30 | Electrostatographic copying |
| GB12757 | 1976-03-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1108221A true CA1108221A (en) | 1981-09-01 |
Family
ID=10010569
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA274,503A Expired CA1108221A (en) | 1976-03-30 | 1977-03-22 | Electrostatographic copying |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS52119333A (en) |
| CA (1) | CA1108221A (en) |
| DE (1) | DE2706612A1 (en) |
| FR (1) | FR2346748A1 (en) |
| GB (1) | GB1543406A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS54119250A (en) * | 1978-03-09 | 1979-09-17 | Ricoh Co Ltd | Exposure device of electronic copier |
| US4593995A (en) * | 1984-06-11 | 1986-06-10 | Eastman Kodak Company | Method and apparatus for producing multiple sets of copies of a document |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1317273A (en) * | 1969-05-31 | 1973-05-16 | Canon Kk | Electrophotography |
| US3667842A (en) * | 1970-06-17 | 1972-06-06 | Xerox Corp | Imaging apparatus |
-
1976
- 1976-03-30 GB GB1275776A patent/GB1543406A/en not_active Expired
-
1977
- 1977-02-16 DE DE19772706612 patent/DE2706612A1/en not_active Ceased
- 1977-03-22 JP JP3145577A patent/JPS52119333A/en active Pending
- 1977-03-22 CA CA274,503A patent/CA1108221A/en not_active Expired
- 1977-03-30 FR FR7709561A patent/FR2346748A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| FR2346748A1 (en) | 1977-10-28 |
| JPS52119333A (en) | 1977-10-06 |
| DE2706612A1 (en) | 1977-10-13 |
| FR2346748B1 (en) | 1983-08-12 |
| GB1543406A (en) | 1979-04-04 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |