GB2143103A - Integrated circuit electro- optical imaging system - Google Patents

Integrated circuit electro- optical imaging system Download PDF

Info

Publication number
GB2143103A
GB2143103A GB08420587A GB8420587A GB2143103A GB 2143103 A GB2143103 A GB 2143103A GB 08420587 A GB08420587 A GB 08420587A GB 8420587 A GB8420587 A GB 8420587A GB 2143103 A GB2143103 A GB 2143103A
Authority
GB
United Kingdom
Prior art keywords
convertor
image
charge
liquid crystal
switch
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
GB08420587A
Other versions
GB2143103B (en
GB8420587D0 (en
Inventor
Colin Barr
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.)
Unisys Corp
Original Assignee
Burroughs Corp
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
Priority claimed from GB8041058A external-priority patent/GB2090100B/en
Application filed by Burroughs Corp filed Critical Burroughs Corp
Priority to GB08420587A priority Critical patent/GB2143103B/en
Publication of GB8420587D0 publication Critical patent/GB8420587D0/en
Publication of GB2143103A publication Critical patent/GB2143103A/en
Application granted granted Critical
Publication of GB2143103B publication Critical patent/GB2143103B/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
    • H04N1/024—Details of scanning heads ; Means for illuminating the original
    • H04N1/028—Details of scanning heads ; Means for illuminating the original for picture information pick-up
    • H04N1/02805—Details of scanning heads ; Means for illuminating the original for picture information pick-up with photodetectors arranged in a two-dimensional array
    • 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
    • H04N1/028—Details of scanning heads ; Means for illuminating the original for picture information pick-up
    • H04N1/03—Details of scanning heads ; Means for illuminating the original for picture information pick-up with photodetectors arranged in a substantially linear array
    • 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
    • H04N1/19589—Optical means, e.g. an optical fibre bundle, for mapping the whole or a part of a scanned image onto the array
    • 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
    • H04N1/40—Picture signal circuits
    • H04N1/40056—Circuits for driving or energising particular reading heads or original illumination means
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
    • H04N23/50—Constructional details
    • H04N23/54—Mounting of pick-up tubes, electronic image sensors, deviation or focusing coils
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N2201/00—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof
    • H04N2201/024—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof deleted
    • H04N2201/02493—Additional optical elements not otherwise provided for, e.g. filters, polarising plates, masks or apertures
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N2201/00—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof
    • H04N2201/04—Scanning arrangements
    • H04N2201/0402—Arrangements not specific to a particular one of the scanning methods covered by groups H04N1/04 - H04N1/207
    • H04N2201/0426—Scanning an image in a series of contiguous zones

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Solid State Image Pick-Up Elements (AREA)
  • Transforming Light Signals Into Electric Signals (AREA)

Abstract

An electro-optical imaging system uses a charge-coupled bucket- brigade photo-sensitive image convertor (16) where the necessity for preventing the acquisition of additional incident-light induced charge by light-representative electrical charge packets as they pass to the output port of the convertor (16) is removed by the use of a liquid crystal light transmission cell (14) which can be made transparent for the acquisition of charge by the convertor (16) and opaque for the shifting of the charges to the output port. The convertor (16) is housed in an integrated circuit package (80) in whose top cover (86) the light transmission cell (14) is set. <IMAGE>

Description

SPECIFICATION Integrated Circuit Electro-optical Imaging System The present invention relates to an electrooptical imaging system for converting an optical image into an electrical signal representative thereof.
Electro-optical imaging systems are widely used in applications ranging from real-time video to character recognition in documents used in association with data processing systems.
An important class of such systems involves the use of a bucket-brigade charge-coupled image convertor. Such convertors are well known in the art and comprise one or more shift-register coupled chains of photosensitive elements where each of the elements can accumulate electrical charge representative of the light incident thereon and where the electrical charge so accumulated can be passed down the chain or chains, from element to element to an output port. The image to be electro-optically converted is focused onto the chain or chains of elements, a time is allowed for the electrical charge to accumulate, and then the charges are moved, as output, to the port.
Those areas which receive little light during the charge accumulation period accumulate little electrical charge, and those areas which receive much light accumulate larger electrical charges.
The movement of the charges down a chain does not inhibit the charge accumulation process.
Thus, a charge packet from an element in receipt of a dim portion of the image can pass through an element which is in recepit of a bright portion. The amount of charge in the package is added to, the amount of addition being greater the further from the port that the charge originating element lies.
This process degrades the sharpness of edges in the image the effect being known as "smearing", and further limits the dynamic range of the charge-coupled device by placing a lower limit on the darkness representative signal.
In order to reduce the spurious charge accumulation effect various modifications have been applied to the design of the charge-coupled device. In a first scheme each chain of photosensitive, charge accumulating elements has provided, in parallel therewith a shift register chain which is shielded from the light. The accumulated charges are first shifted in parallel into the light shielded chain and thereafter moved, serially down the light shielded chain, to the port. In a second scheme intermediate lightimmune storage is provided on the charge coupled device. The charges from the photosensitive chain are shifted very rapidly into the intermediate storage so that the amount of time of exposure to extraneous charge-accumulating light in other elements is minimised.Thereafter the charges, or representations thereof, can be presented to the output port at a desired rate of presentation by their retrieval from the intermediate storage. While both of these schemes are successful in eliminating or reducing the accumulation of unwanted charge, they both have the disadvantage of rerluiring the addition of further elements onto a photosensitive device whose cost is already high and where the areal density of photosensitive elements is generally required to be increased rather than decreased.
The fabrication of such charge-coupled devices has, in common with the fabrication of all other semiconductor devices, an individual device fabrication failure rate which rises steeply with the area of the device. The elimination of such extra structures on a charge-coupled photoimaging convertor would reduce the area of the device. This real reduction would be of particular use in those devices where plural rows of photoreceptive elements are serially accessed to provide representations of whole areas of images.
The increased yield of these large-area devices would considerably reduce their cost.
In one area of use of electro-optical imaging systems, namely the machine reading of documents, it is usual to employ a single-chain charge-coupled image convertor, the image of the document to be read being focused onto the single chain and the document swept across the field of view so that the image of the document is obtained as a series of strips akin to a television picture. While the single chain image convertor is of a relatively low cost, it ideally still requires the addition of spurious charge accumulation preventative measures as described, and its use requires the inclusion of mechanical components for moving the document or its image. Such components presenting cost precision and reliability problems.
It is a problem that the number of photosensors per unit area in charge-coupled, bucket-brigade electro-optical image convertors is sometimes not sufficient for adequate resolution of the components in an image. The image can be focused, at increased size, onto more than one device, but this can prove costly and the resulting, fainter incident image can cause signal to noise ratio problems.
Accordingly, it is desirable to provide an electro-optical image converting system wherein the accumulation of spurious charge, as described, is preventable without recourse to additional structures on the device itself. It is further desirable to provide such an image convertor which is free of mechanical moving parts. It is yet further desirable to provide such an image convertor where the resolution can be improved over that obtainable using a single charge coupled device without recourse to the use of more than one charge coupled device.
The term "charge coupled image convertor" is hereinafter used to define a photosensitive, semiconducting device comprising a plurality of semiconducting sites each of which can accumulate an electrical charge representative of the light incident thereon wherein an ordered sequence of the plurality of charges from said plurality of sites, or a representation thereof, can be moved to an output port.
According to a first aspect the present invention consists in an optical imaging system for providing an electrical representation of an image, said system comprising a charge-coupled image convertor, a focusing apparatus for focusing the image onto said charge-coupled image convertor, a liquid crystal light-transmitting switch; and a controller, where said controller is operable to perform an image capture sequence for the capture of a single image, said image capture sequence including the steps of; in a first step, placing said liquid crystal light-transmitting switch in a first state to allow the incidence of said focused image onto said image convertor simultaneously with causing said charge-coupled image convertorto operate in a first manner to accumulate electrical charges representative of said focused image; and in a second, subsequent step, placing said liquid crystal light transmitting switch in a second state to prevent the incidence of said focused image onto said charge-coupled image convertor simultaneously with causing said charge-coupled image convertor to operate in a second manner to move said electrical charges to an output port of said charge-coupled image convertor, said system further comprising an integrated circuit package for holding said bucketbrigade charge-coupled image convertor, said package comprising a cover, said liquid crystal light-transmitting switch being set into said cover.
According to a second aspect the present invention consists in an electro-optical imaging device comprising an integrated circuit package for holding a bucket-brigade charge-coupled image convertor, said package comprising a liquid crystal light-transmitting switch in the cover thereof, said light-transmitting switch being operable in a first state to allow incidence of a focused image onto said convertor, for said convertor to be operated in a first manner to accumulate electrical charges representative of said image and said light-transmitting switch being operable thereafter in a second state to prevent incidence of said image onto said convertor for said convertor to operate in a second manner to move said electrical charges to an output port of said convertor.
According to a third aspect the present invention consists in an integrated circuit package for holding a bucket-brigade charge-coupled image convertor, said package comprising a liquid crystal light-transmitting switch in the cover thereof, said light-transmitting switch being operable in a first state to allow incidence of a focused image onto said convertor, for said convertor to be operated in a first manner to accumulate electrical charges representative of said image and said light-transmitting switch being operable thereafter in a second state to prevent incidence of said image onto said convertor for said convertor to operate in a second manner to move said electrical charges to an output port of said convertor.
The invention is hereinafter described with reference to an automatic document reader. It is to be understood that this represents only an example of its use and not a limitation thereon.
In a preferred embodiment a focusing system throws an image, preferably that of a stationary document, onto the surface of a bucket-brigade charge-coupled electro-optical image convertor comprising a plurality of chains of photosensitive elements. A light transmitting cell is interposed in the path of the image to the convertor, between the focusing system and the convertor. The cell is operable to transmit light for the accumulation of charges on the convertor and to prevent the through passage of light for the shifting of charges to the port of the convertor. The cell is a liquid crystal device. The liquid crystal lighttransmitting cell is provided in the top cover of the integrated circuit package housing the convertor.
The invention is further explained, by way of an example, by the following description in conjunction with the appended drawings, in which: Figure 1 shows a schematic representation of the system of the preferred embodiment, and Figure 2 shows a cross-sectional view of the integrated circuit package containing the chargecoupled, bucket-brigade image convertor of the preferred system of Figure 1 together with the integral liquid-crystal light transmission cell over its sensitive surface.
Figure 1 shows the first preferred embodiment.
A lens 10 throws an image of a document 12 through a light-transmitting liquid crystal panel 14 onto a charge-coupled image convertor 16. A controller 18 receives a ready signal on an input line 20. The ready signal is indicative of a request for commencement of image conversion and can be derived from a detector for the presence and correct positioning of the document 1 2, from an operator usable switch or the like, or from any external controller such as a supervisory data processing system. The controller 1 8 provides a panel controlling output on the panel control line 22 whereby it can cause the panel to be opaque or transparent.The controller 1 8 also provides an output on the shifting initialising line 24 whereby it can signal to whatever apparatus controls the shifting of the charge packets from the convertor 1 6 that the shifting should begin.
On receipt of the ready signal the controller 1 8 causes the panel 14 to be transparent for a predetermined time. The controller 1 8 thereafter causes the panel to become opaque and signals the commencement of charge shifting on the initialising line 24.
Those skilled in the art will appreciate that the time during which the panel 14 is transparent can be controlled in response to the overall brightness of the image, and that the controller 18 can be inhibited from commencing its image converting routine until whatever equipment is controlling the movement of the charge packages from the convertor 1 6 has completed its task.
Figure 2 shows the manner in which the optical switch 14 and the convertor in the preferred embodiment whose system is shown in Figure 1 are combined in a single integrated circuit package.
An integrated circuit package 80 contains the bucket-brigade charge-coupled photo-image convertor 1 6 whose sensitive area is covered by the selectably-operable light-transmitting optical switch 14 which comprises a liquid crystal and which is integral with the cover 86 of the package 80.

Claims (6)

1. An optical imaging system for providing an electrical representation of an image, said system comprising a charge-coupled image convertor, a focusing apparatus for focusing the image onto said charge-coupled image convertor, a liquid crystal light-transmitting switch; and a controller, where said controller is operable to perform an image capture sequence for the capture of a single image, said image capture sequence including the steps of; in a first step, placing said liquid crystal light-transmitting switch in a first state to allow the incidence of said focused image onto said image convertor simultaneously with causing said charge-coupled image convertor to operate in a first manner to accumulate electrical charges representative of said focused image; and in a second, subsequent step, placing said liquid crystal light transmitting switch in a second state to prevent the incidence of said focused image onto said charge-coupled image convertor simultaneously with causing said charge-coupled image convertor to operate in a second manner to move said electrical charges to an output port of said charge-coupled image convertor, said system further comprising an integrated circuit package for holding said bucket-brigade charge-coupled image convertor, said package comprising a cover, said liquid crystal light-transmitting switch being set into said cover.
2. An optical imaging system according to Claim 1, wherein said controller is operable to perform said image capture sequence in response to receipt of an initiating signal where said first step includes the provision of a first electrical command signal to said liquid crystal switch to cause said liquid crystal switch to operate in said first manner together with the provision of a command to said image convertor for causing said image convertor to operate in said first state, and where said second step includes the provision of a second electrical command signal to said liquid crystal switch to cause said liquid crystal switch to operate in said second state together with the provision of a command including a charge-shifting clock signal to said image convertor for causing said image convertor to operate in said second manner.
3. An electro-optical imaging device comprising an integrated circuit package for holding a bucket-brigade charge-coupled image convertor, said package comprising a liquid crystal light-transmitting switch in the cover thereof, said light-transmitting switch being operable in a first state to allow incidence of a focused image onto said convertor, for said convertor to be operated in a first manner to accumulate electrical charges representative of said image and said light transmitting switch being operable thereafter in a second state to prevent incidence of said image onto said convertor for said convertor to operate in a second manner to move said electrical charges to an output port of said convertor.
4. An optical imaging system substantially as described with reference to Figures 1 and 2 of the appended drawings.
5. An integrated circuit package for holding a bucket-brigade charge-coupled image convertor, said package comprising a liquid crystal lighttransmitting switch in the cover thereof, said light-transmitting switch being operable in a first state to allow incidence of a focused image onto said convertor, for said convertor to be operated in a first manner to accumulate electrical charges representative of said image and said lighttransmitting switch being operable thereafter in a second state to prevent incidence of said image onto said convertor for said convertor to operate in a second manner to move said electrical charges to an output port of said convertor.
6. An optical imaging system substantially as described with reference to Figure 2 of the appended drawings.
GB08420587A 1980-12-22 1984-08-14 Integrated circuit electro-optical imaging system Expired GB2143103B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB08420587A GB2143103B (en) 1980-12-22 1984-08-14 Integrated circuit electro-optical imaging system

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8041058A GB2090100B (en) 1980-12-22 1980-12-22 Electro-optical imaging system
GB08420587A GB2143103B (en) 1980-12-22 1984-08-14 Integrated circuit electro-optical imaging system

Publications (3)

Publication Number Publication Date
GB8420587D0 GB8420587D0 (en) 1984-09-19
GB2143103A true GB2143103A (en) 1985-01-30
GB2143103B GB2143103B (en) 1985-07-24

Family

ID=26277946

Family Applications (1)

Application Number Title Priority Date Filing Date
GB08420587A Expired GB2143103B (en) 1980-12-22 1984-08-14 Integrated circuit electro-optical imaging system

Country Status (1)

Country Link
GB (1) GB2143103B (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0277378A1 (en) * 1986-12-11 1988-08-10 Koninklijke Philips Electronics N.V. Camera
EP0354029A2 (en) * 1988-08-04 1990-02-07 Xerox Corporation Electronically variable MTF filter for image sensor arrays

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1494013A (en) * 1974-11-15 1977-12-07 Japan Suncrux Co Ltd Liquid crystal display device
GB1578004A (en) * 1977-07-26 1980-10-29 Bbc Brown Boveri & Cie Instrument having a liquid crystal display
GB1579088A (en) * 1977-02-17 1980-11-12 Bbc Brown Boveri & Cie Electro-optical display installed in a housing and use of the display

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1494013A (en) * 1974-11-15 1977-12-07 Japan Suncrux Co Ltd Liquid crystal display device
GB1579088A (en) * 1977-02-17 1980-11-12 Bbc Brown Boveri & Cie Electro-optical display installed in a housing and use of the display
GB1578004A (en) * 1977-07-26 1980-10-29 Bbc Brown Boveri & Cie Instrument having a liquid crystal display

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0277378A1 (en) * 1986-12-11 1988-08-10 Koninklijke Philips Electronics N.V. Camera
EP0354029A2 (en) * 1988-08-04 1990-02-07 Xerox Corporation Electronically variable MTF filter for image sensor arrays
EP0354029A3 (en) * 1988-08-04 1991-09-25 Xerox Corporation Electronically variable mtf filter for image sensor arrays

Also Published As

Publication number Publication date
GB2143103B (en) 1985-07-24
GB8420587D0 (en) 1984-09-19

Similar Documents

Publication Publication Date Title
US4516032A (en) Electro-optical imaging system
US4816679A (en) Radiation image read-out apparatus
US4149091A (en) Scanning apparatus
US4489350A (en) Solid-state image pickup device
KR900000331B1 (en) Video camera apparatus
CN100474899C (en) Solid-state image pickup apparatus with error due to the characteristic of output circuit corrected
JP2501656B2 (en) Image scanning device
US4146786A (en) Scanner with modular array of photocells
US4819074A (en) Electronic still camera
US4752831A (en) Focusing system for camera apparatus
US4013832A (en) Solid state image modulator
US5036397A (en) Method of driving a CCD sensor by changing the transfer pulse period relative to the shift pulse period
GB2089169A (en) An electronic camera
GB2140244A (en) Film scanner
EP0398228A3 (en) Solid image pickup apparatus for eliminating smear
GB2143103A (en) Integrated circuit electro- optical imaging system
US5955725A (en) Digitizing CCD array system
GB1601146A (en) Raster scanner
US4641022A (en) Range finding device with a spatial low-pass filter
US4122352A (en) Scanning array configuration
JP2515781B2 (en) Method and device for operating a radiation sensor
US4755875A (en) Telecine apparatus including an electro-optical image transducer illuminated by a bias light source
US4314747A (en) Light shielding device for automatic focus detecting
DE130796T1 (en) TELEVISION CAMERA WITH AN AUTOMATIC FOCUSING DEVICE.
US5473155A (en) Photometric sensor

Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee

Effective date: 19951222