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GB2128356A - A method of transferring information to a recording medium - Google Patents

A method of transferring information to a recording medium Download PDF

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Publication number
GB2128356A
GB2128356A GB08227751A GB8227751A GB2128356A GB 2128356 A GB2128356 A GB 2128356A GB 08227751 A GB08227751 A GB 08227751A GB 8227751 A GB8227751 A GB 8227751A GB 2128356 A GB2128356 A GB 2128356A
Authority
GB
United Kingdom
Prior art keywords
light
light beam
surface acoustic
scan
transducers
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.)
Granted
Application number
GB08227751A
Other versions
GB2128356B (en
Inventor
Roger Ernest Cooke
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
STC PLC
Original Assignee
Standard Telephone and Cables PLC
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Standard Telephone and Cables PLC filed Critical Standard Telephone and Cables PLC
Priority to GB08227751A priority Critical patent/GB2128356B/en
Priority to EP83109752A priority patent/EP0104662A3/en
Priority to ES526109A priority patent/ES8500682A1/en
Priority to KR1019830004618A priority patent/KR840006275A/en
Publication of GB2128356A publication Critical patent/GB2128356A/en
Application granted granted Critical
Publication of GB2128356B publication Critical patent/GB2128356B/en
Expired legal-status Critical Current

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
    • H04N1/04—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa
    • H04N1/12—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa using the sheet-feed movement or the medium-advance or the drum-rotation movement as the slow scanning component, e.g. arrangements for the main-scanning
    • H04N1/126—Arrangements for the main scanning
    • H04N1/1275—Arrangements for the main scanning using a solid-state deflector, e.g. an acousto-optic deflector or a semiconductor waveguide device
    • 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
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/29—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the position or the direction of light beams, i.e. deflection
    • G02F1/33—Acousto-optical deflection devices
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/29—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the position or the direction of light beams, i.e. deflection
    • G02F1/33—Acousto-optical deflection devices
    • G02F1/335—Acousto-optical deflection devices having an optical waveguide structure
    • 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
    • H04N1/04—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa
    • H04N1/12—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa using the sheet-feed movement or the medium-advance or the drum-rotation movement as the slow scanning component, e.g. arrangements for the main-scanning
    • 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
    • H04N1/04—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa
    • H04N1/19—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa using multi-element arrays
    • H04N1/195—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa using multi-element arrays the array comprising a two-dimensional array or a combination of two-dimensional arrays
    • H04N1/19505—Scanning picture elements spaced apart from one another in at least one direction
    • 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
    • H04N1/04—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa
    • H04N1/19—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa using multi-element arrays
    • H04N1/195—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa using multi-element arrays the array comprising a two-dimensional array or a combination of two-dimensional arrays
    • H04N1/19505—Scanning picture elements spaced apart from one another in at least one direction
    • H04N1/1951—Scanning picture elements spaced apart from one another in at least one direction in one direction
    • 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
    • H04N1/04—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa
    • H04N1/19—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa using multi-element arrays
    • H04N1/195—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa using multi-element arrays the array comprising a two-dimensional array or a combination of two-dimensional arrays
    • H04N1/19505—Scanning picture elements spaced apart from one another in at least one direction
    • H04N1/19521—Arrangements for moving the elements of the array relative to the scanned image or vice versa
    • H04N1/19526—Optical means
    • H04N1/19536—Refracting elements
    • 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
    • H04N1/04—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa
    • H04N1/203—Simultaneous scanning of two or more separate pictures, e.g. two sides of the same sheet
    • 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
    • H04N1/04—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa
    • H04N1/203—Simultaneous scanning of two or more separate pictures, e.g. two sides of the same sheet
    • H04N1/2032—Simultaneous scanning of two or more separate pictures, e.g. two sides of the same sheet of two pictures corresponding to two sides of a single medium

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Laser Beam Printer (AREA)
  • Facsimile Scanning Arrangements (AREA)

Abstract

Apparatus for transferring information comprising an acousto- optic substrate (22) having on opposite surfaces two separately controllable parallel light paths (20, 21) each provided with transducers (20c, 21c) for independently causing surface waves which propagate across the light paths such that each light path can effect an independent scan of a light beam (20a, 20b) when deflection control signals are applied to the respective transducers. By the use of suitable optics each light beam (20a, 21a) can provide respectively a different part of a line scan on a surface such as a rotating selenium drum. <IMAGE>

Description

SPECIFICATION A method of transferring information to a recording medium This invention relates to a method and apparatus for transferring information, e.g.
electrical signals representing alphanumeric characters or graphics, to a recording medium, e.g.
a sheet of paper.
Apparatus such as teleprinters are well known for transferring information to a recording medium. Such apparatus employ electromechanical means for impressing the characters on the paper. Other apparatus, such as facsimile, employ electrographic techniques in conjunction with specially prepared sensitive paper. Yet again, photocopiers use electrostatic techniques, in which images formed on a selenium drum are subsequently transferred in permanent visual form to plain paper. In the latter apparatus, the images on the selenium drum are formed by scanning the drum with focussed light reflected from an original which is being copied. However, it is possible to transfer information from a remote source, in the form of electrical signals which are used to modulate a light source, via suitable optics, in order to build up images on a selenium drum.These images can then be transferred to paper in the same way as in a photocopier.
Digital electrical signals can directly or indirectly modulate a laser output which, as a focussed spot of light, can be scanned across a rotating drum. The present invention seeks to provide a scanning arrangement for such an information transfer arrangement in which there are no electromechanical moving parts.
According to one aspect of the present invention there is provided a method of transferring information comprising modulating at least one light beam with the information, applying the modulated light beam to a surface acoustic wave device having at least two separately controllable light paths and transducers for causing surface waves in each light path applying deflection control signals to the transducers so as to scan the modulated light beam such that each light path provides respectively a different part of the scan.
According to a second aspect of the invention there is provided an apparatus for transferring information comprising a surface acoustic wave device having at least two separately controllable light paths and transducers for causing surface waves in each light path, means for modulating at least one light beam with information, means for applying the modulated light beam to the surface acoustic wave device, and means for applying a deflection control signal to the transducers so as to scan the modulated light beam such that each light path provides respectively a different part of the scan.
According to a third aspect of the invention there is provided a deflection device for a beam or beams of light comprising an acousto-optic substrate having on opposite surfaces thereof parallel light paths each provided with transducers whereby surface acoustic waves can be caused to propagate across the light paths such that each light path can effect an independent scan of a light beam when deflection control signals are applied to the respective transducers.
Embodiments of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 illustrates a basic surface acoustic wave deflection device for a modulated beam of light; Figure 2 illustrates a pair of surface acoustic wave deflectors formed on opposite surfaces of an acousto-optic substrate; and Figure 3 illustrates how the two deflectors of Figure 2 each provide one half of a line scan.
The basic surface acoustic wave deflection device shown in Figure 1 comprises a substrate 10 supporting a layer 11 of waveguide material in which surface acoustic waves 12 can be propagated from transducer 13. A beam of modulated light from a laser 14 is directed via collimating optics 1 5 onto e.g. a prism 1 6 whereby the light is coupled into the layer of waveguide material, the light propagating in a direction orthogonal to the direction of propagation of the surface acoustic waves.The light is coupled out of the waveguide material by a second prism 1 7 and is focussed by optics 1 8 onto a surface 1 9. When an r.f. signal is applied to the transducer 1 3 a surface acoustic wave pattern is propagated across the path of the light and a Bragg deflection of the light occurs. By suitably modulating the r.f. signal the Bragg deflection can cause a focussed spot of light to scan the surface 19. The surface 1 9 can then be moved incrementally in synchronism with the scanning beam to provide a line-by-line coverage of the surface. The r.f. scanning signals are similarly synchronized with the modulation signals applied to the light.Thus, in printing arrangement characters can be built-up in a manner similar to that already known in certain types of facsimile apparatus in which the scanning of a rotating recording medium is achieved electromechanically. The advantage of the arrangement shown in Figure 1 is that it has no moving parts other than those required to move the surface 19 past the single scanning line position. Hence the scanning and modulation of the light beam can be accomplished noiselessly and at very high speeds.
If the surface 19 is a selenium drum as is used in photocopiers images can be built-up very rapidly on the drum and these images can then be transferred in permanent visual form to paper by standard photocopier techniques.
However, there are various applications in which optical scanning techniques can be adapted to provide high speed work stations with functional needs for data input, output and storage. In particular two surface acoustic wave deflection devices, fabricated in a "back-to-back" configuration on a common substrate, can provide two synchronised scanning operations which in this case are inter-related.
In the arrangement shown in Figures 2 and 3 two surface acoustic wave deflection devices 20, 21 are formed on a common substrate 22. Each deflection device is of the type shown in Figure 1, i.e. each device has its own input and output optical coupling prisms 20a, 21 a, and it r.f. signal transducer 20c, 21 c, for launching surface acoustic waves across the optical path. (For the sake of simplicity all the collimating input optics have been omitted and the output optics are only represented schematically.) The output optics are arranged to that the two scanned outputs 20b, 21 b are directed to scan different parts of the same line. This is shown more cleariy in Figure 3, in which output 20b is shown as scanning one half of a line whilst output 21 b scans the other half of the line.
The optical inputs can be either both derived from a single source, via suitable optics (not shown) or from separate sources (not shown). In the case of a single source the modulated optical signal can be applied to separate deflection devices simultaneously or sequentially. However, the r.f. deflection signals are applied to the two devices sequentially so that the modulated light beams are first scanned by one device across one half of the line and then by the other device across the second half of the line.
When two separate sources are used they are modulated separately in synchronism with the deflection signals applied to the two deflection devices.
The amount of deflection obtainable from a surface acoustic wave device is limited, typically deflections of +1.5 . Thus two devices working in the manner shown in Figure 3 can together achieve a total deflection coverage of about +3 .
To scan a line length of, say 200 mm would require an optical "throw" considerably in excess of 1 metre. To overcome this problem scan expansion optics can be used in the output. Such optics are designed in accordance with weil known optical principles and result in an effective increase in the angle of scan thereby shortening the throw required to achieve the same length of scan. Alternatively two or more pairs of deflection devices working as in Figure 3 can be placed side by side, with appropriate switching electronics to operate them sequentially. Thus two pairs of devices can be arranged so that each device scans 1/4 of the total required line.
Each pair of surface acoustic wave devices effectively doubles the resolution obtainable from a single device for the same length of line scan.

Claims (12)

1. A method of transferring information comprising modulating at least one light beam with the information, applying the modulated light beam to a surface acoustic wave device having at least two separately controllable light paths and transducers for causing surface waves in each light path applying deflection control signals to the transducers so as to scan the modulated light beam such that each light path provides respectively a different part of the scan.
2. A method according to claim 1, wherein the surface acoustic wave device comprises two parallel light paths with respective transducers formed on opposite surfaces of an acousto-optic substrate.
3. A method according to claim 1 or claim 2, wherein two separate light beams are independently modulated sequentially and in synchronism with deflection control signals applied independently and sequentially to the two separately controllable light paths.
4. A method according to any preceding claim including interposing scan expansion optics between the surface acoustic wave device and a surface scanned by the modulated light beam(s).
5. A method of transferring information substantially as described with reference to the accompanying drawings.
6. An apparatus for transferring information comprising a surface acoustic wave device having at least two separately controllable light paths and transducers for causing surface waves in each light path, means for modulating at least one light beam with information, means for applying the modulated light beam to the surface acoustic wave device, and means for applying a deflection control signal to the transducers so as to scan the modulated light beam such that each light path provides respectively a different part of the scan.
7. Apparatus according to claim 6, wherein the surface acoustic wave device comprises two parallel light paths with respective transducers formed on opposite surfaces of an acousto-optic substrate.
8. Apparatus according to claim 6 or claim 7 including two separately modulatable light sources each producing an individual light beam, means for modulating the two sources independently and sequentially in synchronism with deflection control signals applied independently and sequentially to the two separately controllable light paths.
9. Apparatus according to any preceding claim including scan expansion optics interposed between the surface acoustic wave device and a surface scanned by the modulated light beam(s).
10. Apparatus according to any preceding claim including a selenium drum scannable by the modulated light beam(s).
11. Apparatus for the transfer of information substantially as described with reference to the accompanying drawings.
12. A deflection device for a beam or beams of light comprising an acousto-optic substrate having on opposite surfaces thereof parallel light paths each provided with transducers whereby surface acoustic waves can be caused to propagate across the light paths such that each light path can effect an independent scan of a light beam when deflection control signals are applied to the respective transducers.
GB08227751A 1982-09-29 1982-09-29 A method of transferring information to a recording medium Expired GB2128356B (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
GB08227751A GB2128356B (en) 1982-09-29 1982-09-29 A method of transferring information to a recording medium
EP83109752A EP0104662A3 (en) 1982-09-29 1983-09-29 Method and apparatus for transferring information signals to and/or off a recording medium
ES526109A ES8500682A1 (en) 1982-09-29 1983-09-29 A method of transferring information to a recording medium
KR1019830004618A KR840006275A (en) 1982-09-29 1983-09-29 Method and apparatus for quickly transferring information to record carrier

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB08227751A GB2128356B (en) 1982-09-29 1982-09-29 A method of transferring information to a recording medium

Publications (2)

Publication Number Publication Date
GB2128356A true GB2128356A (en) 1984-04-26
GB2128356B GB2128356B (en) 1986-07-02

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB08227751A Expired GB2128356B (en) 1982-09-29 1982-09-29 A method of transferring information to a recording medium

Country Status (3)

Country Link
KR (1) KR840006275A (en)
ES (1) ES8500682A1 (en)
GB (1) GB2128356B (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2167202A (en) * 1984-11-16 1986-05-21 Stc Plc Data storage systems

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1580364A (en) * 1976-03-26 1980-12-03 Eastman Kodak Co Acoustooptic diffraction

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1580364A (en) * 1976-03-26 1980-12-03 Eastman Kodak Co Acoustooptic diffraction

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2167202A (en) * 1984-11-16 1986-05-21 Stc Plc Data storage systems

Also Published As

Publication number Publication date
ES526109A0 (en) 1984-07-01
KR840006275A (en) 1984-11-22
GB2128356B (en) 1986-07-02
ES8500682A1 (en) 1984-07-01

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PCNP Patent ceased through non-payment of renewal fee