CA1137539A - Multiple variable light source printer - Google Patents
Multiple variable light source printerInfo
- Publication number
- CA1137539A CA1137539A CA000344024A CA344024A CA1137539A CA 1137539 A CA1137539 A CA 1137539A CA 000344024 A CA000344024 A CA 000344024A CA 344024 A CA344024 A CA 344024A CA 1137539 A CA1137539 A CA 1137539A
- Authority
- CA
- Canada
- Prior art keywords
- light
- information
- relative movement
- diodes
- light sources
- 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
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
- H04N1/23—Reproducing arrangements
- H04N1/29—Reproducing arrangements involving production of an electrostatic intermediate picture
-
- 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
- G03G15/04036—Details of illuminating systems, e.g. lamps, reflectors
- G03G15/04045—Details of illuminating systems, e.g. lamps, reflectors for exposing image information provided otherwise than by directly projecting the original image onto the photoconductive recording material, e.g. digital copiers
- G03G15/04054—Details of illuminating systems, e.g. lamps, reflectors for exposing image information provided otherwise than by directly projecting the original image onto the photoconductive recording material, e.g. digital copiers by LED arrays
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
- H04N1/024—Details of scanning heads ; Means for illuminating the original
- H04N1/032—Details of scanning heads ; Means for illuminating the original for picture information reproduction
- H04N1/036—Details of scanning heads ; Means for illuminating the original for picture information reproduction for optical reproduction
Landscapes
- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Printers Or Recording Devices Using Electromagnetic And Radiation Means (AREA)
- Electrophotography Using Other Than Carlson'S Method (AREA)
- Silver Salt Photography Or Processing Solution Therefor (AREA)
- Projection-Type Copiers In General (AREA)
- Fax Reproducing Arrangements (AREA)
- Exposure Or Original Feeding In Electrophotography (AREA)
- Combination Of More Than One Step In Electrophotography (AREA)
Abstract
Abstract of the Disclosure A photographic printer for producing a visible image of information received in the form of a plurality of discrete electrical signals in which the signals are applied respectively to a plurality of devices each of which acts as a source of light in response to an electrical signal and which devices are arranged in an array adjacent to a photosensitive surface to direct light thereon in response to said signals thus to produce an image of the information on the surface In its preferred form the printer is an electrophotographic printer in which the photosensitive surface is a charged photoconductor so that light from said sources produces a latent electrostatic image which may be developed and transferred to plain paper, for example.
Description
1~375;~ :
_ck~round of the Invention My invention relates to a photographic printer and more particularly to a photographic printer which responds to electrical signals encoding information to be printed.
Various types of photographic duplicating machines are known in the prior art. For example, the.e is Xnown an ~ -electrophotographic copier incorporating a photoconductor on the surface of which a latent electrostatic is formed for subsequent development and possible transfer to a sheet of paper. These machine~ have the advantage of being fast in operation, of producing copies of good ~uality and of being ~-~
relatively inexpensive for the result produced. It is f' : ~
desirable that the advantageous characteristics of these machine~ be employed in printing data which is encoded in the form of electrical signals. It would be particularly de~irable if an apparatus could be designed which could function both as a traditional photocopier and also a~ a prlnter of electronic information.
- 20 EffortJ have been made in the prior art to useprinters wlth photosensitive surfaces to print electronically encoded information. ~ system embodying one such effort 1 diaclo~ed in I~M ~echnical Disclosure Bulletin, Vol, 19, .
~.', " "
~J
.' ' ' ' . ~ ' , - ~: . .
, No. 7, December 1976. Light from a common light souree ts directed through a thin slit to a plurality of liquid crystal light beam modulators which are activated by electrical signals selcctively to allow light to fall upon a plurality of respective small areas on the surface of a photoc~nductive drum to form a latent electrostatic image of the information represented by the electrical ~ignals.
One difficulty with this apparatus is its large size, which renders it unsuitable for use in a machine whieh is designed to operate both as a printer of electronic ~- information and a conventional photocopier. More signifi-cantly the system requircs a large light source, much of the light produced by which is not used. In addition the source generates excessive heat which results in a further waste of energy.
, SummarY of thc Invention Onc objcct of my invention is to provide a photographic ~rinter which responds to electrically encoded ~nformation.
~0 Another object of my invention i8 to provide a photographic printer which responds both to information in electronic form and to information in optical formO
, ' ' , .
~, 2 A~
s, ~ , , ", . .
, .
' - 11375;}5 , .
A further o~ject of my inventio* is to prov~de a photographic printer which responds to electronically encoded - -'' information while minimi~ing the amount of waste light , . .
generated in the process of convcrting the electronically ~ '-' 5 encoded information into lightO - -- ' ' ~' A still further object of my invention is to pro- ~ :
vide a photographic printer which responds to electronically encoded information and which is relatively small for the result produced thcreby.
Yet another object of my invention is'to provide-a photographic printer which responds to electronic'ally~' ~ ' ~, encoded information which requires very few moving partiO~-~
Other and further o~jects of my invention will .
appear from the following description.
In general my invention.contemplates a printer incorporating a plurality of light sources, each of which is responslve to a rcspective electrical signal to direct light onto a small portion of a photosensitive surface, to direct a pattern of light on the photosensltive surface ~n accordance wlth the information-represented by the electrlcal oignalr. For.example, a plurality of light~emittlng diodes tLEDe) may be arranged in a row across the photoconductlve , .. . .
, ~,,, -3-,. . . .
': , , ', 1137~
drum of a plain paper copier, perpendicular to the direction of motion of thc drum's surface, and in response to ~ignals applied to the LEDsO a latent image of the information represented by the signals would be produced on the drum surface. The latent images thus produced would be developed and transferred to a sheet of suitable copy material.
Brief Description of~the Drawin~s In the accompanying drawings which form part of the instant specification and which are to be read in conjunction therewith and in which like reference numberals are used to indicate like parts in the various views.
PIGURE 1 is a schematic view of the image forming and developing apparatus of an electrophotographic copying machine embodying my multiple variable light source printer.
FIGURE 2 is an elevation of one array of ~ED chips and light pipes which may be used in my multiple variable light source printer.
FIGURE 3 is an elevation of an LED component which may be u~ed in my variable light source printer.
'.
c f~r,~ J~, , ' 1137s;~
r FIGURE 4 is a schematic diagram of one form o~
electrical control circuit which can be used in my variable light source printer.
Description of the Preferred Embodiment S Referring now to FIGURE 1, a photoconductive drum, indicated generally by numeral 2, is coated with a thin layer 4 of photoconductivc material which is applied to a conductive substrate 6. A motor 8 drives a sprocket wheel 10 to drive a chain 12, ~hich drives a sprocket wheel 14, which drives drum 2 in a counterclockwise direction as viewed in FIGURE 1.
The copying apparatus is provided with a charging coro"a 16 which is connected alternatively to one of two voltage ~ources, a positive dcvelopment voltage source 18 or a negative development voltage source 20. Positive develop-ment voltage source 18 has a ~700 volt output which may be connected to corona 16, while negative development voltage ~ource 20 has a -700 volt output which may be connected to corona 16. Both of the voltage sources 18 and 20 are refe~enced to ground. A brush 21 engaging substrate 6 ia grounded. A swLtch 22 is actuated alternatively to connect an alternating currcnt power supply 24 to source 18 or source 20 to cause the corona 16 to apply with a positive charqe .
~37S3~ -. . .
., ~,, or a negative charge to the surface of photoconduc~
layer 4.
After the surface of photoconductor 4 has recelved a charge from the corona lG it moves past an exposure system 26 of any suitable type known to the art which may expoQe - the surface to a light i~nage of a document 28, for example, at an exposure station, indicated generally by the reference character 29. After leaving the station 29, the surface of photoconductor 4 passes a second exposure station, indicated f 10 generally by the reference character 30, at which it may be exposed to a light pattern produced in response to incoming data in the form of electrical signals.
At station 30 I mount respective first and second rows, indicated generally by the reference characters32 and 34, of light emitting diodes 35. It will readily be appreciated by those skilled in the art that the number Gf LEDs required to porform the task at hand is quite large, probably over 2000, based on 250 elernents per inch and at least 8 1j2 inches of paper width. Presently a single in-expen~ive array of LED3 8 1/2 inche~ long cannot be obtained.
I have overcome this problem by the u3e of a multiplicity of component arrays. For example, as indicated in FIGURE 2, row 32 may include a plurality of component arrays each of : . .
, 11375;~g ~, which includes sight active LED chip areas 35 carried by a support 60 for the active areas~ Each of the chips 60, may for example, have a length of 1/4 inch. In order to provide the effect of a continuouq line of LEDs acros-~ the surface of drum 2, I space the chips 60 of cach row 32 and 34 axially of the drum 2 and stagger the rows with respect to each other. The amount of staggering is such that the chips of one row "overlap" the chips of the other row by an axial distance which accounts for the inactive chip areas at the ends of the chips.
Owing to the circumferential spacing of the LEDs of one row with reference to LEDs of the other row, it would be necessary to delay the signals associated with the leading row with reference to the direction of movement of the drum
_ck~round of the Invention My invention relates to a photographic printer and more particularly to a photographic printer which responds to electrical signals encoding information to be printed.
Various types of photographic duplicating machines are known in the prior art. For example, the.e is Xnown an ~ -electrophotographic copier incorporating a photoconductor on the surface of which a latent electrostatic is formed for subsequent development and possible transfer to a sheet of paper. These machine~ have the advantage of being fast in operation, of producing copies of good ~uality and of being ~-~
relatively inexpensive for the result produced. It is f' : ~
desirable that the advantageous characteristics of these machine~ be employed in printing data which is encoded in the form of electrical signals. It would be particularly de~irable if an apparatus could be designed which could function both as a traditional photocopier and also a~ a prlnter of electronic information.
- 20 EffortJ have been made in the prior art to useprinters wlth photosensitive surfaces to print electronically encoded information. ~ system embodying one such effort 1 diaclo~ed in I~M ~echnical Disclosure Bulletin, Vol, 19, .
~.', " "
~J
.' ' ' ' . ~ ' , - ~: . .
, No. 7, December 1976. Light from a common light souree ts directed through a thin slit to a plurality of liquid crystal light beam modulators which are activated by electrical signals selcctively to allow light to fall upon a plurality of respective small areas on the surface of a photoc~nductive drum to form a latent electrostatic image of the information represented by the electrical ~ignals.
One difficulty with this apparatus is its large size, which renders it unsuitable for use in a machine whieh is designed to operate both as a printer of electronic ~- information and a conventional photocopier. More signifi-cantly the system requircs a large light source, much of the light produced by which is not used. In addition the source generates excessive heat which results in a further waste of energy.
, SummarY of thc Invention Onc objcct of my invention is to provide a photographic ~rinter which responds to electrically encoded ~nformation.
~0 Another object of my invention i8 to provide a photographic printer which responds both to information in electronic form and to information in optical formO
, ' ' , .
~, 2 A~
s, ~ , , ", . .
, .
' - 11375;}5 , .
A further o~ject of my inventio* is to prov~de a photographic printer which responds to electronically encoded - -'' information while minimi~ing the amount of waste light , . .
generated in the process of convcrting the electronically ~ '-' 5 encoded information into lightO - -- ' ' ~' A still further object of my invention is to pro- ~ :
vide a photographic printer which responds to electronically encoded information and which is relatively small for the result produced thcreby.
Yet another object of my invention is'to provide-a photographic printer which responds to electronic'ally~' ~ ' ~, encoded information which requires very few moving partiO~-~
Other and further o~jects of my invention will .
appear from the following description.
In general my invention.contemplates a printer incorporating a plurality of light sources, each of which is responslve to a rcspective electrical signal to direct light onto a small portion of a photosensitive surface, to direct a pattern of light on the photosensltive surface ~n accordance wlth the information-represented by the electrlcal oignalr. For.example, a plurality of light~emittlng diodes tLEDe) may be arranged in a row across the photoconductlve , .. . .
, ~,,, -3-,. . . .
': , , ', 1137~
drum of a plain paper copier, perpendicular to the direction of motion of thc drum's surface, and in response to ~ignals applied to the LEDsO a latent image of the information represented by the signals would be produced on the drum surface. The latent images thus produced would be developed and transferred to a sheet of suitable copy material.
Brief Description of~the Drawin~s In the accompanying drawings which form part of the instant specification and which are to be read in conjunction therewith and in which like reference numberals are used to indicate like parts in the various views.
PIGURE 1 is a schematic view of the image forming and developing apparatus of an electrophotographic copying machine embodying my multiple variable light source printer.
FIGURE 2 is an elevation of one array of ~ED chips and light pipes which may be used in my multiple variable light source printer.
FIGURE 3 is an elevation of an LED component which may be u~ed in my variable light source printer.
'.
c f~r,~ J~, , ' 1137s;~
r FIGURE 4 is a schematic diagram of one form o~
electrical control circuit which can be used in my variable light source printer.
Description of the Preferred Embodiment S Referring now to FIGURE 1, a photoconductive drum, indicated generally by numeral 2, is coated with a thin layer 4 of photoconductivc material which is applied to a conductive substrate 6. A motor 8 drives a sprocket wheel 10 to drive a chain 12, ~hich drives a sprocket wheel 14, which drives drum 2 in a counterclockwise direction as viewed in FIGURE 1.
The copying apparatus is provided with a charging coro"a 16 which is connected alternatively to one of two voltage ~ources, a positive dcvelopment voltage source 18 or a negative development voltage source 20. Positive develop-ment voltage source 18 has a ~700 volt output which may be connected to corona 16, while negative development voltage ~ource 20 has a -700 volt output which may be connected to corona 16. Both of the voltage sources 18 and 20 are refe~enced to ground. A brush 21 engaging substrate 6 ia grounded. A swLtch 22 is actuated alternatively to connect an alternating currcnt power supply 24 to source 18 or source 20 to cause the corona 16 to apply with a positive charqe .
~37S3~ -. . .
., ~,, or a negative charge to the surface of photoconduc~
layer 4.
After the surface of photoconductor 4 has recelved a charge from the corona lG it moves past an exposure system 26 of any suitable type known to the art which may expoQe - the surface to a light i~nage of a document 28, for example, at an exposure station, indicated generally by the reference character 29. After leaving the station 29, the surface of photoconductor 4 passes a second exposure station, indicated f 10 generally by the reference character 30, at which it may be exposed to a light pattern produced in response to incoming data in the form of electrical signals.
At station 30 I mount respective first and second rows, indicated generally by the reference characters32 and 34, of light emitting diodes 35. It will readily be appreciated by those skilled in the art that the number Gf LEDs required to porform the task at hand is quite large, probably over 2000, based on 250 elernents per inch and at least 8 1j2 inches of paper width. Presently a single in-expen~ive array of LED3 8 1/2 inche~ long cannot be obtained.
I have overcome this problem by the u3e of a multiplicity of component arrays. For example, as indicated in FIGURE 2, row 32 may include a plurality of component arrays each of : . .
, 11375;~g ~, which includes sight active LED chip areas 35 carried by a support 60 for the active areas~ Each of the chips 60, may for example, have a length of 1/4 inch. In order to provide the effect of a continuouq line of LEDs acros-~ the surface of drum 2, I space the chips 60 of cach row 32 and 34 axially of the drum 2 and stagger the rows with respect to each other. The amount of staggering is such that the chips of one row "overlap" the chips of the other row by an axial distance which accounts for the inactive chip areas at the ends of the chips.
Owing to the circumferential spacing of the LEDs of one row with reference to LEDs of the other row, it would be necessary to delay the signals associated with the leading row with reference to the direction of movement of the drum
2 relative to the LEDs. I avoid this necessity by providing a plurality of light pipes 36 associated with the LEDs 35.
orient the light pipe3 36 with first ends 64 thereof ad~acent to the respectivé LED~ 35 of rows 32 and 34 and with the other ends 66 thereof adjacent to the drum 3ur~ace in axially aligned axially relationship and are in close proximity to the drum surface.
In addition to the foregoing problem, it may not be pos~ible to posi~ion the LED active area~ 3$ of a component , ~,' ,1~1 _ ' 1~375~
array a~ close to each other on the supporting chip~ 60 a~
is indicated in FIGURE 2. In ~hiY event I form the active area~ of a componen~ on a chip 60 as a pair of staggered rows of area~ 35a and 35b as indicated in FIGURE 3. In YUCh case it may be necessary to delay the signals to one of the eomponent rows. The problem could be obviated by the u~e of optical filter light pipes.
I provide my apparatus with an electronie eontroller 38 which reeeives information from a data source 40 and con-verts the information into electrical impulses whieh are fedto the respective LE~s in properly timed sequenee to produce a latent eleetrostatie image of the information on the surfaee of drum 2. Data source 40 might, for example, supply digital information ~ueh as is used by eomputers and word procesJing maehines, or other forms of eleetronie in~ormation sueh as faesimile information.
Following the station 30 in the direetion of rotation of drum 2 i9 developing apparatus, indieated gen erally by numeral 42. Apparatus 42 ineludes a developer tank 44 eontalning a liquid toner 46 having negative or positive toner particles~ and a developer electrode 48 whiCh iB connected to the ~lO0 volt output of voltage souree 18 and the -650 volt output of voltage ~ource 20, one or the ..
-8-- r~ .
;
1~375~ :
other of ~hich i8 active depending upon whether positive or negati~e development i~ usedO
Alternative to thc use of light pipe8 36~ lt i~
possible to place LEDs directly adjacent to surface 4 of photoconductive drum 2. For example, as is shown in FIGURE
4, a chip 70 containing a plurality of LEDs 72 could be placed in row 32 and a similar chip 71 could be placed ~ n row 34. Rows 32 and 34 could each be pliaced sufficiently close to the surface of ~kum 2 so that the light from any given LED 72 would fall only upon a small portion o ~urface 4, and thus no optical fiber would be required to guide such light. It should be noted, however, that if, as is ~hown in FlGUREi 4, light from the various light emitting sourceq does not fall upon photoconductive surface 4 in a straight line perpendicular to its path of motion, controller 38 will have to delay the illumina~ioh of tho~e light sources which ar~
leading with respect to the path of motion relative to the lllumination of those light sources which trailing to produce the effect of aligned light sources.
. The number of connections required to control the large number of LEDs necessary ~or creating high resolution printing may be roduccd appreciably by the use of coincident addre3slng. I connect the lines 74A to 74D and 76A to 76D
. . .
, I r ~"~ ~ tJcc~
1~37S3~
of two groups of lines 74 and 76D to the respective ~EDs to form a matrix by virtue of which concomitant energization of only one line of eacll group will result in activation of one and only one LED 35. For example, if line 74A and line 76A are bo~h energized, LED 72A will be activated. Similarly, if line 74D and line 76C are both energized, LED 72B will be activated.
In operation of the apparatus shown in FIGURE 1, it is capable of opcrating as a traditional photocopier merely by using optical image forming apparatus 26 to make a lat~nt image of document 28 upon surface 4 of drum 2 at optical exposure station 29. In conventional electrophoto-graphy, it is most common to use positive development.
Positive development means that toner is applied to those portions of photoconductive s~lrface 4 which, after having been charged with a voltage by corona 16, are not discharged by light. For example, during positive development switch 22 18 POgitiOned 50 as to supply power to positive develop-ment voltage sourcc 18. AB a result, corona 16 will apply approximately a ~700 volt charge to the surface of photo conductive drum 2. As thi~ surface rotates, it will pass optical exposure station 29. ~t this point, an optical image of a portion of document 28 is focused upon surface 4 of drum 2. Where this image contains light~ photocon-/
1 1 3~S39 ductive surface 4 will conduct electricity. This will causccharge deposited on surface 4 by corona 16 to be conducted to conductive substrate 6, reducing the charge on the illuminated portion of surface 4 to around +50 volts. ~hos~
portions of surface 4 upon which no light impinges, however, will not discharge to any appreciable extent. The resulting varied pattern of charge upon photoconductive surface 4 after it has passed optical exposure station 29 is a latent image of the light pattern to which the drum has been subjected.
As drum 2 rotates, thc latent image will pass through developer station 42. Here, negatively charged toner particles will be attracted to those portions of photoconductive surface 2 which have not been discharged, and thus which maintain a charge of approximately +700 volts. A developer electrode 48 will have a voltage of +100 volts applied to it by voltage source 18, preventing negative toner particles from being attracted to those portions of surface 4 which have been dis-charged by light to approximately +50 volts. As a re~ult of the attraction of negatively charged toner partlcles to those portions of surface 4 upon which light is not ~hown, a pattern of toner will be deposited upon surface 4. This pattern of toner can be transferred to a plece of paper by means well~
known ln thc art to producc an electrophotographic copy o document 28, When the apparatus is operatcd as an elcctronic 753~
printer, the only change is that light emitting diodes in electronic exposure station 30 emit light so as to discharge photoconductive surface 4 rathcr than ~he optical image forming apparatus 26 being used to form a ~atent image. It is, however, possible to operate both optical image forming apparatus 26 and elcctronic exposure station 30 at the same time so as to print elcctronically derived information on top of optically derived information.
Light from LEDs 35 which shines on small portions of photoconductive surface 4 causes those portion3 to discharge in the same manner as light from optical image forming apparatus 26. Similarly, those portions o surface 4 upon which no light is directed by the light emitting diodes retain their charge and, when doveloped, attract toner, creating corresponding dar~ spots on any copy which was made from the developed latent image formed by such LEDs. By controlling the timing with which various LEDs are turned on and off as drum 2 rotates past ~hem, it is possible to create upon surface 4 a latent image containing textural or graphic information. The timing at which various LEDs are turned on and off must be accurately coordinated with the rotation of drum 2, just as thc timing with which an electron beam ln a raster scanned telcvision picture has to be accurately coordinatcd with the timing of that picture's scan rateO In -12~
.
' '' ' ~
, :
.
11~75;~9 a m~nner an~logous to the manncr in which controller3 for video monitor~ convert digital information into a ~erie~
of dots which rcpresent alphanumeric characters upon a televiYion screen, controller 38 conver~s digital informa-tion from source 40 into a series of properly timed dot~created by electronic exposure station 30 upon the surface o~ photoconductive drum 2. Alternatively, data source 40 could supply controller 38 with facsimile information which conveys graphic information in terms of dots along scan lines. Such facsimile information could easily be converted by controller 38 into a corresponding pattern of timed LED
illuminations along thc line of dots which can be created by elec~ronic exposure station 30.
Most documents contain a much greater light area than darX area. Therefore, in order to save electricity and prevent unnecessary light and heat near the site of the electrophotographic process, it may be desirable to use nega~ive development in conjunction with electro~ic exposure station 30. In negative development, toner particles are attracted to those portions of thc photoconductive surface 4 which have been illuminated by lightO rather than to those portions which remain unilluminated. When operating in the negative dcvelopment mode, switch 22 is positioned ~o a~ to connect power supply 24 to negative development voltage , 5~3~
~ource 20. As a result, a charge of -700 volts is ~uppli~d to corona 16. A chargc o approximately -700 volts i~
placed on the surface of photoconductive drum 2~ A~ that charged surface passes electronic exposure station 30, those - 5 portions of it which are illuminated by LEDs will conduct electrons toward conductive sub3trate 6, thus losing much of their negative charge. As a result, those portions of surface 4 which are illuminated by LEDs will have their - voltage reduced to approximately -50 volts, whereas those portions which have not been illuminated will remain at approximately -700 volts. As a result, a latent electro-photographic image will be produced on the surface of drum 2. As this latent image pa~se~ through developing station 42, neqative toner particles will be attracted to those portion3 of the drum which have been discharged to approxi-mately -50 volts. This is because development electrode 48 is supplied by voltage source 20 with a voltage of -650 volts, creating a field which causes negative toner particles to migraté toward those portions of photoconductive surface 4 which are charged with -50 volts and which cause~ those toner particles to be repelled from the portions of photoconductivc surface 4 which still have a charge of appro~imately -700 volts. A~ a result, a distribution of toner will be placed upon photoconductive surface 4 which can be transferred to ,.
a piece of paper so aq to make a copy by mean~ well-known in the electrophotographic art, It will be seen that I have accomplished the objects of my inventionO I have provided a printer of electronic information which taXes advantage of the high speed of many printing processes which use photosensitive surfaces. I have provided means of producing photocopier~
which are able to print eleceronic information, as well as creating conventional photocopies. Furthermore, I have provided a means for converting electronic information into light information for the use of printing processe-q which use photosensitive surfaces, which means do not waste ligbt energy and spa~e and which do not have many moving parts.
ItlwlIl be understood that certain eatures and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of my claims. It is further obvious that various changcs may be madc in details within the scope of my claims without departing from the spirit of my invention. It is, therefore, to be under-~tood that my invcntion is not to be limited to the specific details shown and de~cribed.
~aving thus described my invention, what I clalm
orient the light pipe3 36 with first ends 64 thereof ad~acent to the respectivé LED~ 35 of rows 32 and 34 and with the other ends 66 thereof adjacent to the drum 3ur~ace in axially aligned axially relationship and are in close proximity to the drum surface.
In addition to the foregoing problem, it may not be pos~ible to posi~ion the LED active area~ 3$ of a component , ~,' ,1~1 _ ' 1~375~
array a~ close to each other on the supporting chip~ 60 a~
is indicated in FIGURE 2. In ~hiY event I form the active area~ of a componen~ on a chip 60 as a pair of staggered rows of area~ 35a and 35b as indicated in FIGURE 3. In YUCh case it may be necessary to delay the signals to one of the eomponent rows. The problem could be obviated by the u~e of optical filter light pipes.
I provide my apparatus with an electronie eontroller 38 which reeeives information from a data source 40 and con-verts the information into electrical impulses whieh are fedto the respective LE~s in properly timed sequenee to produce a latent eleetrostatie image of the information on the surfaee of drum 2. Data source 40 might, for example, supply digital information ~ueh as is used by eomputers and word procesJing maehines, or other forms of eleetronie in~ormation sueh as faesimile information.
Following the station 30 in the direetion of rotation of drum 2 i9 developing apparatus, indieated gen erally by numeral 42. Apparatus 42 ineludes a developer tank 44 eontalning a liquid toner 46 having negative or positive toner particles~ and a developer electrode 48 whiCh iB connected to the ~lO0 volt output of voltage souree 18 and the -650 volt output of voltage ~ource 20, one or the ..
-8-- r~ .
;
1~375~ :
other of ~hich i8 active depending upon whether positive or negati~e development i~ usedO
Alternative to thc use of light pipe8 36~ lt i~
possible to place LEDs directly adjacent to surface 4 of photoconductive drum 2. For example, as is shown in FIGURE
4, a chip 70 containing a plurality of LEDs 72 could be placed in row 32 and a similar chip 71 could be placed ~ n row 34. Rows 32 and 34 could each be pliaced sufficiently close to the surface of ~kum 2 so that the light from any given LED 72 would fall only upon a small portion o ~urface 4, and thus no optical fiber would be required to guide such light. It should be noted, however, that if, as is ~hown in FlGUREi 4, light from the various light emitting sourceq does not fall upon photoconductive surface 4 in a straight line perpendicular to its path of motion, controller 38 will have to delay the illumina~ioh of tho~e light sources which ar~
leading with respect to the path of motion relative to the lllumination of those light sources which trailing to produce the effect of aligned light sources.
. The number of connections required to control the large number of LEDs necessary ~or creating high resolution printing may be roduccd appreciably by the use of coincident addre3slng. I connect the lines 74A to 74D and 76A to 76D
. . .
, I r ~"~ ~ tJcc~
1~37S3~
of two groups of lines 74 and 76D to the respective ~EDs to form a matrix by virtue of which concomitant energization of only one line of eacll group will result in activation of one and only one LED 35. For example, if line 74A and line 76A are bo~h energized, LED 72A will be activated. Similarly, if line 74D and line 76C are both energized, LED 72B will be activated.
In operation of the apparatus shown in FIGURE 1, it is capable of opcrating as a traditional photocopier merely by using optical image forming apparatus 26 to make a lat~nt image of document 28 upon surface 4 of drum 2 at optical exposure station 29. In conventional electrophoto-graphy, it is most common to use positive development.
Positive development means that toner is applied to those portions of photoconductive s~lrface 4 which, after having been charged with a voltage by corona 16, are not discharged by light. For example, during positive development switch 22 18 POgitiOned 50 as to supply power to positive develop-ment voltage sourcc 18. AB a result, corona 16 will apply approximately a ~700 volt charge to the surface of photo conductive drum 2. As thi~ surface rotates, it will pass optical exposure station 29. ~t this point, an optical image of a portion of document 28 is focused upon surface 4 of drum 2. Where this image contains light~ photocon-/
1 1 3~S39 ductive surface 4 will conduct electricity. This will causccharge deposited on surface 4 by corona 16 to be conducted to conductive substrate 6, reducing the charge on the illuminated portion of surface 4 to around +50 volts. ~hos~
portions of surface 4 upon which no light impinges, however, will not discharge to any appreciable extent. The resulting varied pattern of charge upon photoconductive surface 4 after it has passed optical exposure station 29 is a latent image of the light pattern to which the drum has been subjected.
As drum 2 rotates, thc latent image will pass through developer station 42. Here, negatively charged toner particles will be attracted to those portions of photoconductive surface 2 which have not been discharged, and thus which maintain a charge of approximately +700 volts. A developer electrode 48 will have a voltage of +100 volts applied to it by voltage source 18, preventing negative toner particles from being attracted to those portions of surface 4 which have been dis-charged by light to approximately +50 volts. As a re~ult of the attraction of negatively charged toner partlcles to those portions of surface 4 upon which light is not ~hown, a pattern of toner will be deposited upon surface 4. This pattern of toner can be transferred to a plece of paper by means well~
known ln thc art to producc an electrophotographic copy o document 28, When the apparatus is operatcd as an elcctronic 753~
printer, the only change is that light emitting diodes in electronic exposure station 30 emit light so as to discharge photoconductive surface 4 rathcr than ~he optical image forming apparatus 26 being used to form a ~atent image. It is, however, possible to operate both optical image forming apparatus 26 and elcctronic exposure station 30 at the same time so as to print elcctronically derived information on top of optically derived information.
Light from LEDs 35 which shines on small portions of photoconductive surface 4 causes those portion3 to discharge in the same manner as light from optical image forming apparatus 26. Similarly, those portions o surface 4 upon which no light is directed by the light emitting diodes retain their charge and, when doveloped, attract toner, creating corresponding dar~ spots on any copy which was made from the developed latent image formed by such LEDs. By controlling the timing with which various LEDs are turned on and off as drum 2 rotates past ~hem, it is possible to create upon surface 4 a latent image containing textural or graphic information. The timing at which various LEDs are turned on and off must be accurately coordinated with the rotation of drum 2, just as thc timing with which an electron beam ln a raster scanned telcvision picture has to be accurately coordinatcd with the timing of that picture's scan rateO In -12~
.
' '' ' ~
, :
.
11~75;~9 a m~nner an~logous to the manncr in which controller3 for video monitor~ convert digital information into a ~erie~
of dots which rcpresent alphanumeric characters upon a televiYion screen, controller 38 conver~s digital informa-tion from source 40 into a series of properly timed dot~created by electronic exposure station 30 upon the surface o~ photoconductive drum 2. Alternatively, data source 40 could supply controller 38 with facsimile information which conveys graphic information in terms of dots along scan lines. Such facsimile information could easily be converted by controller 38 into a corresponding pattern of timed LED
illuminations along thc line of dots which can be created by elec~ronic exposure station 30.
Most documents contain a much greater light area than darX area. Therefore, in order to save electricity and prevent unnecessary light and heat near the site of the electrophotographic process, it may be desirable to use nega~ive development in conjunction with electro~ic exposure station 30. In negative development, toner particles are attracted to those portions of thc photoconductive surface 4 which have been illuminated by lightO rather than to those portions which remain unilluminated. When operating in the negative dcvelopment mode, switch 22 is positioned ~o a~ to connect power supply 24 to negative development voltage , 5~3~
~ource 20. As a result, a charge of -700 volts is ~uppli~d to corona 16. A chargc o approximately -700 volts i~
placed on the surface of photoconductive drum 2~ A~ that charged surface passes electronic exposure station 30, those - 5 portions of it which are illuminated by LEDs will conduct electrons toward conductive sub3trate 6, thus losing much of their negative charge. As a result, those portions of surface 4 which are illuminated by LEDs will have their - voltage reduced to approximately -50 volts, whereas those portions which have not been illuminated will remain at approximately -700 volts. As a result, a latent electro-photographic image will be produced on the surface of drum 2. As this latent image pa~se~ through developing station 42, neqative toner particles will be attracted to those portion3 of the drum which have been discharged to approxi-mately -50 volts. This is because development electrode 48 is supplied by voltage source 20 with a voltage of -650 volts, creating a field which causes negative toner particles to migraté toward those portions of photoconductive surface 4 which are charged with -50 volts and which cause~ those toner particles to be repelled from the portions of photoconductivc surface 4 which still have a charge of appro~imately -700 volts. A~ a result, a distribution of toner will be placed upon photoconductive surface 4 which can be transferred to ,.
a piece of paper so aq to make a copy by mean~ well-known in the electrophotographic art, It will be seen that I have accomplished the objects of my inventionO I have provided a printer of electronic information which taXes advantage of the high speed of many printing processes which use photosensitive surfaces. I have provided means of producing photocopier~
which are able to print eleceronic information, as well as creating conventional photocopies. Furthermore, I have provided a means for converting electronic information into light information for the use of printing processe-q which use photosensitive surfaces, which means do not waste ligbt energy and spa~e and which do not have many moving parts.
ItlwlIl be understood that certain eatures and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of my claims. It is further obvious that various changcs may be madc in details within the scope of my claims without departing from the spirit of my invention. It is, therefore, to be under-~tood that my invcntion is not to be limited to the specific details shown and de~cribed.
~aving thus described my invention, what I clalm
Claims (11)
1. In an electrostatic copying machine in which the surface of a photoconductive element is moved relative to and successively past a charging station at which a uniform electrostatic charge is applied over said surface and a developing station at which said surface is subjected to the action of a developer to develop any latent electrostatic image which might be present on said surface, apparatus located between said charging station and said developing station for enabling said machine to reproduce electrically encoded information including a pair of rows of semiconductor chips, a plurality of light-emitting diodes formed on each chip and disposed along the chip row, the chips of each row being spaced in a direction generally perpendicular to the direction of said relative movement, said rows being spaced in the direction of said relative movement, means including means mounting said chips adjacent to the path of relative movement of said surface for causing light from said diodes to impinge on said surface along a line generally perpendicular to the direction of relative movement o f said surface, and means for applying electrical signals encoding information to said diodes to energize said diodes to produce a latent electrostatic image of said information on said surface.
2. In an electrostatic copying machine in which the surface of a photoconductive element is moved relative to and successively past a charging station at which a uniform electrostatic charge is applied over said surface and a developing station at which said surface is subjected to the action of a developer to develop any latent electrostatic image which might be present on said surface, apparatus located between said charging station and said developing station for enabling said machine to reproduce electrically encoded information including a semiconductor chip, respective rows of light-emitting diodes formed on said chip, the light-emitting diodes of each row being spaced in a direction generally perpendicular to the direction of said relative movement, said rows being spaced in the direction of said relative movement, means including means mounting said chip adjacent to the path of relative movement of said surface for causing light from said diodes to impinge on said surface along a line generally perpendicular to the direction of relative movement of said surface, and means for applying electrical signals encoding information to said light-emitting diodes to energize said diodes to produce a latent electrostatic image of said information on said surface.
3. In an electrostatic copying machine in which the surface of a photoconductive element is moved relative to and successively past a charging station at which a uniform electrostatic charge is applied over said surface and a developing station at which said surface is subjected to the action of a developer to develop any latent electrostatic image which might be present on said surface, apparatus located between said charging station and said developing station for enabling said machine to reproduce electrically encoded information including a pair of rows of light-emitting diodes, diodes of each row being spaced in a direction generally perpendicular to the direction of said relative movement, said rows being spaced in the direction of said relative movement, means including means mounting said diodes adjacent to the path of relative movement of said surface, and respective light pipes for causing light from said diodes to impinge on said surface along a line generally perpendicular to the direction of relative movement of said surface, and means for applying electrical signals encoding information to said diodes to energize said diodes to produce a latent electrostatic image of said information on said surface.
4. In an electrostatic copying machine in which the surface of a photoconductive element is moved relative to and successively past a charging station at which a uniform electrostatic charge is applied over said surface and a developing station at which said surface is subjected to the action of a developer to develop any latent electrostatic image which might be present on said surface, apparatus located between said charging station and said developing station for enabling said machine to reproduce electrically encoded information including a pair of rows of individual light sources, light sources of each row being spaced in a direction generally perpendicular to the direction of said relative movement, said rows being spaced in the direction of said relative movement, said sources being individually energizable in response to electrical signals applied thereto, means including means mounting said sources adjacent to the path of relative movement of said surface for causing light from said sources to impinge on said surface along a line generally perpendicular to the direction of relative movement of said surface, and means for applying electrical signals encoding information to said light sources to energize said sources to produce a latent electrostatic image of said information on said surface.
5. In an electrostatic copying machine in which the surface photoconductive element is moved relative to and successively past a charging station at which a uniform electrostatic charge is applied over said surface and a developing station at which said surface is subjected to the action of a developer to develop any latent electrostatic image which might be present on said surface, apparatus located between said charging station and said developing station for enabling said machine to reproduce electrically encoded information including a plurality of individual light sources, each of said light sources being energizable in response to the application of an electrical signal thereto, means including means mounting said light sources adjacent to the path of relative movement of said surface and respective light pipes associated with said sources for causing light from said sources to impinge on said surface along a line generally perpendicular to the direction of said relative movement, and means for applying electrical signals encoding said information to said light sources to produce a latent electrostatic image of said information.
6. In an electrostatic copying machine is which the surface of a photoconductive element is moved relative to and successively past a charging station at which a uniform electrostatic charge is applied over said surface and a developing station at which said surface is subjected to the action of a developer to develop any latent electrostatic image which might be present on said surface, apparatus located between said charging station and said developing station for enabling said machine to reproduce electrically encoded information including a plurality of individual light sources, each of said light sources being energizable in response to the application of an electrical signal thereto, means including means mounting said light sources adjacent to the path of relative movement of said surface for causing light from said sources to impinge on said surface along a line generally perpendicular to the direction of said relative movement, and means for applying electrical signals encoding said information to said light sources to produce a latent electrostatic image of said information.
7. Photoelectrostatic printing apparatus of the type in which the surface of a photoconductive element moves relative to and successively past a charging station and an exposure station and a developer station including in combination, means at said charging station for applying to said surface a uniform electrostatic charge of a predetermined polarity, a plurality of individual light sources at said exposure station, said light sources being energizable in response to electrical signals applied thereto, means for applying to said sources electrical signals encoding information to be reproduced to cause said sources to expose to light areas of the surface corresponding to the encoded information and mean at said developer station for subjecting said surface to a developer incorporating toner particles carrying a charge of a certain polarity, the polarity of said surface charge and the polarity of said toner particle charge being such that said toner particles migrate to said exposed areas of said surface.
8. In a printing device adapted to reproduce information encoded in the form of electrical signals, a plurality of individual light sources, each of said light sources adapted to be energized in response to an electrical signal applied thereto, means mounting said light sources adjacent to said surface and means including a matrix of electrical conductors for applying signals encoding said information to said sources.
9. In a printing device adapted to reproduce information encoded in the form of electrical signals, means providing a photosensitive surface, a plurality of light-emitting diodes, means mounting said diodes adjacent to said surface, respective light pipes for conducting light from said diodes to said surface, and means for applying electrical signals encoding said information to said diodes. ~
10. In a printing device adapted to reproduce information encoded in the form of electrical signals, means providing a photosensitive surface, a plurality of light emitting diodes, means mounting said diodes adjacent to said surface, and means for applying said electrical signals to said diodes.
11. In a printing device adapted to reproduce information encoded in the form of electrical signals, means providing a photosensitive surface, a plurality of individual light sources; each of said light sources adapted to be energized in response to an electrical signal applied thereto, means mounting said light sources adjacent to said surface and means for applying said electrical signals to said light sources.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US1447179A | 1979-02-23 | 1979-02-23 | |
| US014,471 | 1979-02-23 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1137539A true CA1137539A (en) | 1982-12-14 |
Family
ID=21765708
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000344024A Expired CA1137539A (en) | 1979-02-23 | 1980-01-18 | Multiple variable light source printer |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS55120067A (en) |
| CA (1) | CA1137539A (en) |
| DE (1) | DE3006725A1 (en) |
| FR (1) | FR2453436A1 (en) |
| GB (1) | GB2042746A (en) |
Families Citing this family (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4455562A (en) * | 1981-08-14 | 1984-06-19 | Pitney Bowes Inc. | Control of a light emitting diode array |
| EP0026452A3 (en) * | 1979-09-26 | 1981-07-22 | Siemens Aktiengesellschaft | Device for the production of charge patterns on a photoconductive image carrier |
| US4344691A (en) * | 1980-06-23 | 1982-08-17 | International Business Machines Corporation | Zonal concentrator for accurate erasure of photoconductor charge |
| EP0051886A1 (en) * | 1980-11-10 | 1982-05-19 | Agfa-Gevaert N.V. | Recording system |
| US4527886A (en) * | 1981-05-12 | 1985-07-09 | Kyoto Ceramic Co., Ltd. | Electrophotographic recording apparatus having both functions of copying and printing |
| WO1982004353A1 (en) * | 1981-05-26 | 1982-12-09 | Haydn Victor Purdy | Light emitting diode array devices and image transfer systems |
| FR2513509A1 (en) * | 1981-09-25 | 1983-04-01 | Coucy Rene | METHOD AND DEVICE FOR REALIZING TOMOGRAPHIC IMAGES |
| GB2120040A (en) * | 1982-04-29 | 1983-11-23 | Itt Creed | Facsimile recorder |
| JPS6370874A (en) | 1986-09-12 | 1988-03-31 | Sharp Corp | Correct/reverse image forming device |
| US4857958A (en) * | 1987-03-25 | 1989-08-15 | Kabushiki Kaisha Toshiba | Electronic copying apparatus having function of partially changing image reproduced from original image |
| JPH03132636A (en) * | 1989-10-18 | 1991-06-06 | Brother Ind Ltd | Image forming device |
| US4975729A (en) * | 1990-01-22 | 1990-12-04 | Photon Imaging Corp. | Electronic printer using a fiber optic bundle and a linear, one-dimensional light source |
| GB9926394D0 (en) | 1999-11-09 | 2000-01-12 | Univ Warwick | Digital photographic reproduction apparatus |
| GB201209142D0 (en) * | 2012-05-24 | 2012-07-04 | Lumejet Holdings Ltd | Media exposure device |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3952311A (en) * | 1972-04-24 | 1976-04-20 | The Laitram Corporation | Electro-optical printing system |
| US4000495A (en) * | 1974-11-25 | 1976-12-28 | Pirtle William W | System for recording information on a photosensitive material |
-
1979
- 1979-12-31 GB GB7944601A patent/GB2042746A/en not_active Withdrawn
-
1980
- 1980-01-18 CA CA000344024A patent/CA1137539A/en not_active Expired
- 1980-01-26 JP JP744080A patent/JPS55120067A/en active Pending
- 1980-02-20 FR FR8003723A patent/FR2453436A1/en not_active Withdrawn
- 1980-02-22 DE DE19803006725 patent/DE3006725A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| JPS55120067A (en) | 1980-09-16 |
| GB2042746A (en) | 1980-09-24 |
| DE3006725A1 (en) | 1980-09-04 |
| FR2453436A1 (en) | 1980-10-31 |
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| MKEX | Expiry |