EP0618078A2 - Optische Abtastvorrichtung - Google Patents

Optische Abtastvorrichtung Download PDF

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Publication number
EP0618078A2
EP0618078A2 EP94400656A EP94400656A EP0618078A2 EP 0618078 A2 EP0618078 A2 EP 0618078A2 EP 94400656 A EP94400656 A EP 94400656A EP 94400656 A EP94400656 A EP 94400656A EP 0618078 A2 EP0618078 A2 EP 0618078A2
Authority
EP
European Patent Office
Prior art keywords
scanning device
optical scanning
array
semiconductor substrate
led
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.)
Withdrawn
Application number
EP94400656A
Other languages
English (en)
French (fr)
Other versions
EP0618078A3 (de
Inventor
Masashi C/O Sumitomo 3M Limited Nagashima
Hiroyuki C/O Sumitomo 3M Limited Chiba
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.)
3M Co
Original Assignee
Minnesota Mining and Manufacturing Co
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 Minnesota Mining and Manufacturing Co filed Critical Minnesota Mining and Manufacturing Co
Publication of EP0618078A2 publication Critical patent/EP0618078A2/de
Publication of EP0618078A3 publication Critical patent/EP0618078A3/de
Withdrawn legal-status Critical Current

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    • 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

Definitions

  • the present invention relates to an optical scanning device on which an LED array and an auto focussing element are provided in an integrated structure, particularly an optical scanning device which is a two wavelength LED printer provided with an LED for focal adjustment and a recording array which are integrally formed on the recording LED or laser array chip.
  • the optical scanning device such as a printer requires an anti-defocusing mechanism.
  • an auto-focus adjusting technology using a reflected light from a disc in optical disc recording by means of a semiconductor laser has been generally known.
  • This conventional auto-focus adjusting technology for optical disc recording is described below, referring to Fig. 8.
  • 81 is a laser driver
  • 82 is a semiconductor laser
  • 83 is a collimator lens
  • 84 is a beam splitter
  • 85 is a 1/4 ⁇ plate
  • 86 is a focal lens
  • 87 is a lens drive
  • 88 is a disc
  • 89 is a photo detector. A reflected light from the disc 88 is guided to the photo detector 89 through the beam splitter 84 and a defocus deviation is detected.
  • Fig. 9 "Astigmatism" is shown in Fig. 9 as a representative detection method.
  • a light flux which has passed through the cylindrical lens 91 forms a circular spot on a light receiving surface 92 as shown in (d) when the light is focussed but it forms an oval spot as shown in (c) or (e) when the light is defocused.
  • the signal components of the light flux obtained by the 4- divided photo detector 89 (Fig. 8) are subtracted from each other to be used for alignment of the focal lens 93.
  • Figs. 8 and 9 The above prior art shown in Figs. 8 and 9 is an auto focussing technology for optical disc recording and is not an auto focussing technology for the optical scanning device using the optical-element array to which the present invention applies.
  • Japanese Patent Application Laid Open 1990-304515 is known as the auto focussing technology for the optical scanning device.
  • auto focussing is carried out independent of recording by making a wavelength of light flux for recording to be different from that of light flux for auto focussing.
  • the region of a wavelength of a light for auto focussing where printing photosensitive material is not sensitive to this light is selected.
  • the art disclosed in this gazette is an auto focussing technology for a single semiconductor laserflux and is not the auto focussing technology for the optical scanning device using the light-emitting element array to which the present invention applies.
  • the prior art has a problem in that the auto focussing function would be disabled when a laser beam is off or there is no write signal, and has therefore been unapplicable to the auto focussing technology for the optical scanning device using the light-emitting element array.
  • an object of the present invention is, in the optical scanning device using the light emitting element array, to make it unnecessary to align the elements, and to allow simple and accurate focussing, by integrally forming the auto focussing light source element, by which the distance between the object to be scanned and the light emitting element array for scanning can be automatically adjusted together, with the LED array, together on the same chip.
  • the present invention provides an optical scanning device in which a light-emitting element array and an auto focussing light source element for adjusting a distance between the light-emitting element array and an object to be scanned by the light-emitting element array are integrated on a single chip of a semiconductor substrate.
  • the semiconductor substrate is a compound semiconductor substrate
  • the light-emitting element array is an LED array which is formed by a P-N junction in a semiconductor which is provided on the semiconductor substrate and has a composition different from that of the semiconductor substrate
  • the auto focussing light source element is formed by a P-N junction on the compound semiconductor substrate.
  • the semiconductor substrate is a GaAs substrate
  • the LED array is an AIGaAs LED array formed on the GaAs substrate
  • the auto focussing light source element is a GaAs LED formed on a partly cutaway portion of an AIGaAs LED array formed on the GaAs substrate.
  • the optical scanning device is preferably a printer head for recording information on the object to be scanned.
  • the wavelength of the light from the LED array is in the region where a photosensitive material used in printing is sensitive and the wavelength of the light from the auto focussing light source element is in the region where the printing photosensitive material is not sensitive.
  • the semiconductor substrate is a compound semiconductor substrate
  • the light-emitting element array is a laser array formed by a P-N junction in a semiconductor having a composition different from that of the semiconductor substrate
  • the auto focussing light source element is formed by a P-N junction on the compound semiconductor substrate.
  • the optical scanning device using the light-emitting element array alignment of the LEDs can be made unnecessary, and simple and accurate focussing is enabled by integrally forming the auto focusing light source element, for which the distance between the object to be scanned and the light-emitting element array for scanning can be automatically adjusted, and the LED array is together on the same chip.
  • the LED printer as an embodiment but the present invention is not limited to this embodiment and is applicable to an optical scanning device such as a laser printer, scanner, and so fourth.
  • Fig. 1 is a construction of the LED printer according to the embodiment of the present invention.
  • 1 is the LED array chip
  • 2 is the LED array emitting light having a wavelength lambda
  • 3 is the focussing LED emitting light having a wavelength lambda 2
  • 4 is the focal lens
  • 5 is the photosensitive surface of the object to be scanned
  • 6 is the lens
  • 7 is the photo detector
  • 8 is the position control driver for the focal lens.
  • the focussing LED 3 is formed on the LED array chip 1 is an integrated structure. Integration of the focussing LED 3 and the LED 2 on the same chip makes it unnecessary to align elements of the LED array 2 and LED 3 so that simple and accurate focussing becomes possible.
  • the focal position should be controlled to be within ⁇ pm from the photosensitive surface since the focal depth of the focal lens is small.
  • Fig. 2 is a diagram showing the relationship of the LED array 2 for recording, the focussing LED 3 and the photosensitive material with respect to the wavelength.
  • the wavelength X2 of a light from the LED 3 is selected to be out of the range of the sensitivity curve of the material of photosensitive surface 5, and therefore, the recording ton the photosensitive surface 5 is not carried out by a light from the photosensitive surface 5 and converged by the lens 6 to reach the photo detector 7, and the position control driver 8 controls the position of the focal lens 4 according to the output of the photo detector 7 to align the focus of the LED array 2 with the photosensitive surface 5.
  • this auto focussing method the above described conventional astigmatism method, the method for minimizing the spot size disclosed on Tokyo Kokai 1990-304515, and so forth, can be used.
  • the LED array 2 is formed on the semiconductor substrate and the semiconductor which epitaxially grows thereon and has a different composition, and the focussing LED 3 is formed at the semiconductor portion of the substrate.
  • the light-emitting part of the existing LED array 2 is formed by m, for example, epitaxially growing GaAsP or AIGaAs, the GaAs substrate and forming a P-N junction.
  • the light emitting wavelength is generally 660-870 nm with AIGaAs and 660-720 nm with GaAs.
  • the auto focussing function can be provided independent of printing by selecting the wavelength ⁇ 1 for light emission from the GaAs substrate and recording at a position fully away from the wavelength ⁇ 2 for focussing and by selecting a photosensitive material which is not sensitive to the wavelength X2.
  • Fig. 3 to 6 are respectively cross sectional views of chips each being formed by integrating the recording LED array 2 and the focussing LED 3 according to the embodiment of the present invention.
  • 10 and 20 are GaAs substrate, 30 is the insulation layer, and 40 and 50 are the epitaxial layer, the GaAs substrate 20 is an inversion portion of the conductive type of GaAs substrate 10, and the epitaxial layer 50 is an inversion portion of the conductive type of epitaxial layer 40.
  • the boundaries between 10 and 20 and between 40 and 50 are the P-N junction positions respectively.
  • the P-N junction positions are the light-emitting portions from which the light is emitted perpendicularly to the substrate.
  • the wavelength X2 for focussing is obtained from the junction 10-20, and the wavelength AI for recording is obtained from the junction 40-50.
  • n type GaAs is used as the substrate
  • 10 and 40 are the n type and 20 and 50 are the P type
  • 10 and 40 are the p type and 20 and 50 are the n type.
  • a method for forming the LED array part there is a method for diffusing impurities into the epitaxial layer40 through a mask as shown in Fig. 3, or a method for forming a P-N junction during epitaxial growth and separating elements by etching as shown in Fig. 5.
  • a method for forming the focussing LED 3 there is a method for exposing the GaAs substrate by partial etching and simultaneously forming the LED 3 in the impurity diffusing process for the recording LED 2 as shown in Fig. 3 or a method for deep diffusion reaching the substrate only for the focussing LED 3 as shown in Fig. 4.
  • the focussing LED is not limited to one and can be provided at both ends of the LED array chip as shown in Fig. 6. Such provision allows correction of planar position deviation.
  • the thickness of the epitaxial layer is usually a few microns and there is no problem in focussing.
  • the P-N junction of the epitaxial layer is available as a homo junction, single hereto junction or a double hereto junction, and the double hereto junction is particularly preferable because it prevents leaking emission from the GaAs substrate.
  • the p-type layers of the inversion GaAs substrate 20 and the inversion epitaxial layer 50 are formed by thermal diffusion of impurities such as Zn or ion implantation with the insulation layer 30 (Si0 2 etc.) as a mask.
  • Light emission of 550 to 670 nm is enabled by sung AIGaAsP for the epitaxial layer instead of using AIGaAs or GaAs, and light emission of 470 nm is achieved by using ZnSe.
  • These materials are those which can grow on the GaAs substrate and the present invention can be implemented with these materials.
  • Fig. 7 is a cross sectional view showing a laserar- ray and a focussing LED which are integrated on the same chip according to another embodiment of the present invention.
  • 11 is an n-type GaAs substrate
  • 21 is a p-type GaAs layer (a layer for which n is inverted to p by diffusing impurities as in the example described above)
  • 31 is an insulation layer
  • 41 is a AIGaAs layer
  • 51 is a p-type A1 GaAs layer
  • 61 is an A1 GaAs active layer (having a different composition from 41 and 51).
  • the difference between the laser array shown in Fig. 7 and the LED arrays shown in Figs. 3 to 6 is that, in Fig. 7 since the laser beam is emitted from the end face of the substrate, the focussing LED also uses a light from the end face of the substrate.
  • the light emission wavelength from the laser active layer 61 can be selected in a region away from the light emission wavelength from the GaAs LED owing to the composition of A1 x Ga 1-x As.
  • an optical scanning device using an optical element array by integrating an auto focussing light source element capable of automatically adjusting the distance between the object to be scanned and the scanning optical element on the same chip, alignment of the elements becomes unnecessary, and a simple and accurate focussing becomes possible.

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  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Led Device Packages (AREA)
  • Led Devices (AREA)
  • Printers Or Recording Devices Using Electromagnetic And Radiation Means (AREA)
  • Automatic Focus Adjustment (AREA)
EP94400656A 1993-03-29 1994-03-28 Optische Abtastvorrichtung. Withdrawn EP0618078A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP69521/93 1993-03-29
JP6952193A JPH06302855A (ja) 1993-03-29 1993-03-29 光学走査装置

Publications (2)

Publication Number Publication Date
EP0618078A2 true EP0618078A2 (de) 1994-10-05
EP0618078A3 EP0618078A3 (de) 1995-01-04

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP94400656A Withdrawn EP0618078A3 (de) 1993-03-29 1994-03-28 Optische Abtastvorrichtung.

Country Status (2)

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EP (1) EP0618078A3 (de)
JP (1) JPH06302855A (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0785077A3 (de) * 1996-01-22 1998-06-10 Fuji Xerox Co., Ltd. Bildaufzeichnungsgerät mit einer Matrixlichtquelle
EP0916506A3 (de) * 1997-11-11 1999-09-08 Canon Kabushiki Kaisha Bilderzeugungsgerät
US7598973B2 (en) 2004-07-16 2009-10-06 Seiko Epson Corporation Line head and image forming apparatus incorporating the same

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02164561A (ja) * 1988-12-19 1990-06-25 Minolta Camera Co Ltd Ｌｅｄプリンタヘッド
JPH02249667A (ja) * 1989-03-24 1990-10-05 Hitachi Koki Co Ltd Ｌｅｄプリンタ
US5016027A (en) * 1989-12-04 1991-05-14 Hewlett-Packard Company Light output power monitor for a LED printhead
JPH05313092A (ja) * 1992-05-13 1993-11-26 Oki Electric Ind Co Ltd 画像読取・書込装置

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02164561A (ja) * 1988-12-19 1990-06-25 Minolta Camera Co Ltd Ｌｅｄプリンタヘッド
JPH02249667A (ja) * 1989-03-24 1990-10-05 Hitachi Koki Co Ltd Ｌｅｄプリンタ
US5016027A (en) * 1989-12-04 1991-05-14 Hewlett-Packard Company Light output power monitor for a LED printhead
JPH05313092A (ja) * 1992-05-13 1993-11-26 Oki Electric Ind Co Ltd 画像読取・書込装置

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 14, no. 420 (M-1023) 11 September 1990 & JP-A-02 164 561 (MINOLTA CAMER A CO. LTD.) 25 June 1990 *
PATENT ABSTRACTS OF JAPAN vol. 14, no. 575 (M-1062) 20 December 1990 & JP-A-02 249 667 (HITACHI KOKI CO. LTD.) 5 October 1990 *
PATENT ABSTRACTS OF JAPAN vol. 18, no. 126 (P-1702) 02 March 1994 & JP 05 313 092 A (OKI ELECTRIC IND. CO. LTD.) 26 November 1993 *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0785077A3 (de) * 1996-01-22 1998-06-10 Fuji Xerox Co., Ltd. Bildaufzeichnungsgerät mit einer Matrixlichtquelle
US5963242A (en) * 1996-01-22 1999-10-05 Fuji Xerox Co., Ltd. Image recording apparatus with an array light source
EP0916506A3 (de) * 1997-11-11 1999-09-08 Canon Kabushiki Kaisha Bilderzeugungsgerät
US6236416B1 (en) 1997-11-11 2001-05-22 Canon Kabushiki Kaisha Image forming apparatus featuring a plurality of light emission elements on a single chip
US7598973B2 (en) 2004-07-16 2009-10-06 Seiko Epson Corporation Line head and image forming apparatus incorporating the same

Also Published As

Publication number Publication date
EP0618078A3 (de) 1995-01-04
JPH06302855A (ja) 1994-10-28

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