Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
  • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
  • B41J2/435—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of radiation to a printing material or impression-transfer material
  • B41J2/447—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of radiation to a printing material or impression-transfer material using arrays of radiation sources
  • B41J2/45—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of radiation to a printing material or impression-transfer material using arrays of radiation sources using light-emitting diode [LED] or laser arrays
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L25/00—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof
  • H01L25/03—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes
  • H01L25/04—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes the devices not having separate containers
  • H01L25/075—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes the devices not having separate containers the devices being of a type provided for in group H01L33/00
  • H01L25/0753—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes the devices not having separate containers the devices being of a type provided for in group H01L33/00 the devices being arranged next to each other
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
  • H01L27/15—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission
  • H01L27/153—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission in a repetitive configuration, e.g. LED bars
  • H01L27/156—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission in a repetitive configuration, e.g. LED bars two-dimensional 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
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
  • H01L2924/0001—Technical content checked by a classifier
  • H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
  • H01L2924/30—Technical effects
  • H01L2924/301—Electrical effects
  • H01L2924/3011—Impedance

Definitions

• This invention relates generally to light emitting diode array devices, particularly in the form of hybrid integrated circuit modules, and to ways of utilising these devices, particularly in image transfer systems. •
• a display which can be transferred to expose a photosensitive recording surface, such as a film or paper, or alternatively a photocopying receptor such as a selenium drum or zinc oxide paper.
• a photosensitive recording surface such as a film or paper
• a photocopying receptor such as a selenium drum or zinc oxide paper.
• the invention in an image transfer system one can achieve a high speed, high resolution optical printer.
• the invention also has application to high speed, high resolution photo ⁇ type-setting, and, at lower resolutions, intelligent copiers, plotters and similar devices having a graphics output.
• Visual display devices incorporating light emitting diodes as electroluminescent elements, such as gallium- 25 arsenide-phosphide light emitting diodes are well known.
• OMPI WPO Generally speaking these visual display devices are divided into two types, hybrid -devices and monolithic devices.
• the monolithic type of device the light emitting diodes are formed in a semiconductor crystal substrate/ for example 5 by using etching techniques.
• the known hybrid type device a number of light emitting diode chips are mounted on a single substrate.
• 2C another plane perpendicular to the display plane.
• a plurality of these modules are designed to be stacked side- by-side to produce rows and columns of display elements in a two-dimensional array.
• the individual diodes are spaced so as to achieve about 40
• US patent No. 3947840 describes a visual display device comprising light emitting diodes having associated memory and drive circuits, in which the diodes are etched into the reverse side of a monolithic transparent planar
• OMPI emitting diode display devices and indicates therein that very small LED devices.are often desired in order to
• the yield of small luminescent ele ⁇ ments is necessarily only a fraction of that which is theoretically possible.
• OMPI the use of the aforesaid LED array, which enables the light emitted by the individual diodes to be transmitted with high efficiency to a sensitive recording surface.
• the light emitting diode array devices of the present invention make use of a hybrid circuit module which integrates the successful and tested yield of a first production process which produces an LED chip, and a second production process which pro- lO cutes a chip consisting of random access memory and LED driving circuits.
• array 15 be assembled in a linear manner, for example for thepurpose of paper marking, into arrays of appropriate lengths to match particular widths of printed output pages.
• arrays 2O0 mm or more in total length could be used.
• a light emitting device comprising a substrate, a first chip mounted on the substrate and provided with_a plurality of light emitting diodes arranged in a substantially linear array and with individual first contact means associated with each diode extending to one side of the diode array, a second chip mounted on the sub ⁇ strate spaced from and at said one side of said first chip and provided with accessible memory and driving means for said diodes and with individual second contact means, and
• 2C means connecting each of said first contact means to said second contact means.
• a light emitting device com ⁇ prising a substrate, a first chip mounted on the substrate
• the first contact means are aligned with said second contact means and said connecting means comprises individual wires bonded to said respective con ⁇ tact means.
• the arrangement in which two memory/driver chips are arranged one on each side of. the diode chip has particular advantages.
• the diode -chip contact means which are elec ⁇ trically connected to the diode electrodes, and which have of necessity to be insulated from one another, are made more effective bybringing out alternate contactmeans, i.e. leads, to opposite sides of a centre line.
• This technique in which the driving circuits are placed independently on both sides of the centre line which defines the luminescent elements considerably improves the yield.
• a further advantage is that the "half-sized" driving circuits benefit from a disproportionately increased yield.
• diodes are placed in a single straight-line high density array, or in a staggered row with alternate diodes offset to one side and to the other side of a central axis. In the latter case, more complex memory may be necessary in order to
• each of the first and second chips is of substantially the same thickness, whereby the upper surfaces of the chips lie substantially in a common plane. This simplifies the interconnections between the diode chip and the IC chip or chips, and also ensures optimum thermal impedance.
• the incoming signal In conventional scanning techniques it is usual for the incoming signal to be used to modulate the resolvable areas synchronously, i.e. the signal sequentially scans and activates adjacent areas of active material, each area being only briefly exposed to the signal for a short cycle time which is directly proportional to the length of the total line beam scan.
• the signal sequentially scans and activates adjacent areas of active material, each area being only briefly exposed to the signal for a short cycle time which is directly proportional to the length of the total line beam scan.
• each one would be processed for one unit time in every 8000.
• each active luminescent element i-.e. diode
• the electronic scan rate need not be rigidly synchron ⁇ ised with the line displacement mechanism. Elimination of this rigid electro-mechanical synchrony renders the device of the present invention, and its operation, more practical and economic.
• a further advantage of incorporating a latch assoc ⁇ iated with each elemental area of the diode array is that simultaneous entry can be achieved at several places within the line, and as desired, in order to improve appar ⁇ ent bandwidth limitations. In dealing with a line of type, similarly shaped symbols can be addressed simultaneously
• the light emitting device comprises a plurality of modules each comprising a substrate and first and second inter ⁇ connected chips, the width of each substrate being equal to the length of the diode array carried thereby, and the modules being assembled in side-by-side abutting contact to provide an extended continuous linear diode array.
• an image transfer system comprising a light emitting device of the type referred to above, in combination with light-transmitting means having an input end fixedly mounted to receive light from said diode array and an output end remote from said input end.
• the light-transmitting means may comprise an array of fibre optic filaments, or a linear array of icro- lenses for example.
• the present invention also includes a method of making a light emitting device of the type referred to above, which comprises the steps of mounting the first chip on a substrate with the length dimension of the diode array across the width of the substrate, mounting the or each second chip alongside the first chip, and ultra- sonically bonding individual connecting wires between each of said first contact means and a respective one of said second contact means.
• Fig. 1 is a schematic plan view of a light emitting diode array device in accordance with the present invention
• OMPI ' RN ⁇ C Fig. 2 is an illustration of an alternative way in which the individual diodes can be arranged in a row;
• Fig. 3 is a schematic side elevation illustrating the use of the device of Fig. 1 ' in a first embodiment of image transfer system in accordance with the invention
• Fig. 4 is a schematic view, similar to Fig. 3, but showing an alternative image transfer device.
• Fig. 5 is a view, similar to Fig. 4, but showing yet another alternative image transfer device.
• the device 10 is constructed as a hybrid circuit module comprising a number of chips mounted on a ceramic substrate 12.
• the module is rectangular in plan view.
• a first chip 14 (hereinafter referred to as the LED chip) is positioned centrally on the substrate 12, for example by gluing with the chip exactly at right-angles to the longer sides of the substrate.
• the individual light emitting diodes are indicated at 16 and have their- active luminescent faces at the upper surface of the chip.
• the individual diodes 16 are spaced from each other, but are provided at extremely high densities in terms of numbers of diodes per unit length of the chip.
• Linear arrays of diodes have been produced successfully at densities of between 3O0 and 600 diodes per inch, achieving good yields on yellow and red emitting materials in particular. With diodes emitting in the red, i.e. at about 655 nm, and with active areas at 49 ⁇ pitch, densities of the order of 1000 diodes per inch have been achieved with good yields.
• each module 10 approx ⁇ imately l/8th inch long, with the ends of the diode chips 14 and the longer edges of the substrate 10 being finely ground to permit the assembly of a plurality of such modules side-by-side to build up a continuous extended linear diode array.
• One such additional module is indicated
• a diode chip 14 having a linear array of LED elements 16 with the chip machine sawn so as to be precisely 0.128 inches in length (or 0.256 inch or another such preferred dimension related to acceptable yields) while carrying the appropri ⁇ ate number of separate whole diode elements, i.e. 128 elements in a length of 0.128 inches.
• the particular dimensions and densities referred to herein are given by way of example only.
• the ceramic substrate 12 has a width exactly equal to the selected width of the LED chip 14, but has its other dimension nominal. This latter dimension is chosen so as to provide a conveniently sized support for connections, clamping means, etc.
• the LED chip 14 is provided with contact means indicated generally at 18, and associated one with each diode element 16.
• These contacts or leads 18 are for example of aluminium, laid down on the chip by a suitable " masking technique. As an alternative to aluminium, gold may be used as the contact material.
• Each contact 18 is connected at one end to one of the diode electrodes, the other diode electrode being connected to external circuitry (not shown) .
• Each contact 18 comprises a relatively narrow finger portion 20 which, towards the sides of the chip, is enlarged to form a relatively wide plate portion 22. As shown in Fig. 1, the contacts 18 extend alternately towards one side and towards the other side of the chip, from the individual diodes 16. This hasadvantages, as described above, particularly at the extremely high densities used.
• each IC chip 24 On each side of the LED chip 1 , on the flat top surface of the substrate 12, there is mounted an IC chip 24, fabricated quite separately from the LED chip 14. Each IC chip 24 has the same width as that of the LED chip 14 and is glued for example to the surface of the substrate.
• Each IC chip 24 consists of a 64 x 1 bit static random access memory and 64 constant current LED drivers; each • memory bit can be accessed through 6 address bits, chip enable and read/write signals. There are two data pins, 5 data in and data out. Data out has the samepolarity as the input data and its output driver is a constant current LED driver.
• the 64 bits of RAM also output in parallel, and each output, drives a constant current LED driver.
• An external reference, voltage is used to adjust the current lO through the drivers. This external voltage can in turn be adjusted by varying the. value of external resistors.
• the height ofthe chip is less than 128 mils and is fabricated with N-channel silicon gate technology.
• each of the chips 24 bears half the number of active memories related to the preferred LED number, i.e. 64 memories for 128 LEDs.
• a special feature of the memory/driver chips 24 is that, whereas it is common practice to construct the elemental memory cells so as to
• each memory bit shall be strong enough to drive one LED element directly.
• the driving outputs of the IC chips 24 are again formed as contacts 26, for example of aluminium or gold, and these contacts 26 are disposed linearly with the same spacing as the facing contacts 18 extending to the side of the centrally positioned diode chip 14.
• An important feature of the present invention is the connection of the diode contacts 18 with the driver contacts 26.
• the connection between the pairs of con ⁇ tacts is effected by the use of extremely thin wire, for example aluminium or gold wire, connected at each end to r.5 the respective contact plates.
• the wires 28 therefore have a substantial degree of inherent rigidity because of their short length.
• the connection between each wire end and the associated contact plate is preferably effected by ultrasonic bonding. This involves placing the wire end in contact with the contact plate and subjecting the wire to ultrasonic vibration which effects the bonding between the wire and the plate. As is -illustrated in Fig. 1, it is desirable for the bonding of the wires to alternate contact plates 22 or 26 to be effected in a staggered manner, in order to minimise the danger of bridg ⁇ ing the gaps between the contacts.
• the wires 28 may be encapsulated, for example in a resin paste which is cured, in order to increase the sta ⁇ bility of the connections and to permit mechanical handling of the device. This encapsulation may be particularly necessary if the wires 28 are relatively long.
• Alternative ways of making interconnections between the respective contacts may be used. For example, in one alternative method, the chips are mounted on the substrate, the chips are then masked so as to leave the contact areas exposed, a metal is deposited over the exposed contact areas so as to short all the connectors together, and then, where gaps existed between adjacent contacts prior to the shorting process, these are re-established and extended across the bridged gap by means of a laser-trimming device, as is known in the art.
• Each random access memory in the chips 24 is addressed by means of an on-board address decoding circuit, as is common to random access memories. For an array of 128 latched memories this would necessitate 7 addressing wires, plus a data wire which signifies whether the addressed memory should be energised or not, plus an overall clock wire so as to synchronise multiple memory operation.
• These addressing and data wires which are indicated gener ⁇ ally at 30 in Fig. 1, together with the necessary two power wires, are brought out on the side of each chip 24 opposite to the side adjacent to the LED chip 14. Further contact plates 32 along the edge of the chips 24 are conn ⁇ ected by bonded wires ' 34 to the address/data wires 30.
• a memory/driver chip 24 is provided at each side of the- LED chip 14, one could alternatively use just one memory/driver chip 24 with twice the memory and driver capacity, and with all the contacts from the diodes 16 then extending to one side of the LED chip 14. This arrangement could be practical at lower densities of diode elements. It is also advantageous if the thickness of all the chips is substantially the same, not only to simplify the interconnections through the wires 28, but also to create conditions for optimum thermal impedance.
• Fig. 2 shows one alternative way of arranging the diode elements 16 in a row so as still to achieve the benefits of the substantially linear array.
• the diodes 16 are alternately offset to one side and to the other side of the longitudinal axis 36 of the diode array.
• the light emitting device of the present invention is designed for use as part of an image transfer system whereby a light image is transmitted to a photosensitive .surface.
• any composite image which may be energised, however it is made visible, has to be mechan ⁇ ically displaced in a direction at right-angles to the longitudinal axis 36 of the array. This may be achieved by intermittent displacements, or by the continuous move- ment of an image-carrying medium.
• the effect of movement of a recording material across them is to produce adjacent and parallel stripes, the length of which can be determined by measuring the movement of the material across them and selectively switching the LEDs to construct elementally any pattern or combination of separate patterns, such as high resolution typographic images in elemental construction appropriate to different point sizes.
• an image transfer system incorporating the afore ⁇ said modules it is necessary to combine the modules with suitable image transfer means in order to enable faithful recording, without edge fall-off commonly found in conven- tional optical systems, on the photosensitive sheet material or on an indirect image record carrier.
• image trans ⁇ fer means can be combined with the LED modules in appro ⁇ priate systems during manufacture.
• Fig. 3 shows one embodiment of image transfer system.
• a linear array of fibre optic filaments 40 is positioned above the light-emitting LED chip 14.
• the fibre optic array comprises large numbers of fibres, for example of 6 ⁇ diameter, so that a bundle of fibres is associated with each diode. This improves the resolution.
• the length of the fibre array is of course equal to the length of the diode array and the fibre array is mounted between two supports 42, 43 which sandwich the fibres between them and mount them fixedly relative to the diodes.
• the supports 42, 43 may be glass plates for example.
• the bottom of the 5 fibre array projects slightly below the bottom of the supports 42, 43, and the bottom of the fibres, i.e. their input ends, are arranged to be in very close proximity to the diodes.
• the other, i.e output, ends of the fibres are flush or slightly below the top surface of the supports
• the output ends of the fibres may either be in close proximity to or actually in contact with the surface of
• the photosensitive material may be for example zinc oxide paper, suitable-for "dry” development, or photographic emulsion on film or paper, normally requiring “wet” development.
• a selenium drum 50 serves as an intermediate trans ⁇ fer medium to the final record medium (typically toner- carrying plain paper) , the drum because of its limited life and rigid surface is unsuitable for intimate contact with the rigid surface of a knife-like fibre-optic array.
• the " conjugate distance of the micro-lenses, in the manufactured form previously referred to, is. such that mechanical adjustments such as focussing are unnecessary, and adjustment-free pre-machining of the mounting means is a practical feature.
• the above-described arrangement can be made suitable for direct recording on to flexible carriers, such as zinc oxide or photographic paper, with appropriate- speed compensation, and without removing the drum, by replacing the knife-like optical fibre array with a micro-lens array 52 to which is added a removable optical glass 54.
• the focal length of the micro-lens array is foreshortened by about one third, thus enabling photo ⁇ sensitive material to travel in immediate contact with the surface 56 of the optical glass, accepting the high resol ⁇ ution image in the manner of and with the convenience of the previously described contact method.
• the glass sur- face 56 should have suitable curvature so that the "feed on” and “feed off” of the recording material, being closer than the focussed image, ensures suitable contact.
• a pressure pad may optionally be introduced.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Physics & Mathematics (AREA)
• Computer Hardware Design (AREA)
• General Physics & Mathematics (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• General Health & Medical Sciences (AREA)
• Signal Processing (AREA)
• Multimedia (AREA)
• Toxicology (AREA)
• Health & Medical Sciences (AREA)
• Optics & Photonics (AREA)
• Printers Or Recording Devices Using Electromagnetic And Radiation Means (AREA)
• Led Device Packages (AREA)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (3)

Cited By (5)

Citations (6)

• 1982
  • 1982-05-26 WO PCT/GB1982/000152 patent/WO1982004353A1/en not_active Application Discontinuation
  • 1982-05-26 EP EP19820901523 patent/EP0079904A1/en not_active Withdrawn
  • 1982-05-26 JP JP50159182A patent/JPS58500817A/ja active Pending

Patent Citations (6)

Non-Patent Citations (2)

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