JP2001292280A - Illuminator and image reader to use the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a miniaturized illuminator having high luminance and an image reader utilizing the illuminator. SOLUTION: The image reader utilizing the illuminator is composed of the illuminator, with which reflected light from the surface of an original 20 illuminated by the light emission of an organic EL element 22 can be emitted from a transparent part, equipped with transparent contact glass 21 having a first side in contact with the original surface and an opposite second side, the organic EL element 22 having a band-like light emitting area formed on the second side along with the outside of the transparent part while setting the second side with the band-like transparent part for forming an information extracting area for extracting light from an area to become the target of image read on the first side through the second side and a wiring means for supplying operating power to the organic EL element 22, a photodetector array 24 located under the transparent part parallel to the transparent part, and a lens array 23 for forming the image of light from the original illuminated by the illuminator on the photodetector array 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device and an image reading device using the same.

[0002]

2. Description of the Related Art Conventionally, as an illumination device of an image processing device such as a facsimile or an image scanner, an LED array in which a large number of LED chips are arranged in a straight line, or its LE.
A D array, a structure combining an LED and a light guide, or a cold cathode discharge tube is used.

FIG. 7 is a schematic diagram of a typical reduced image reading apparatus. The upper surface of the contact glass 2 is the original surface 1
It is. The reflected light from the original illuminated by the illumination device 8 is imaged on the CCD line sensor of the light receiving element 7 via the mirror 3, mirror 4, mirror 5, and imaging lens 6 arranged on the optical path 9. . The image formed on the light receiving element 7 is converted into an image signal.

FIG. 8 is a schematic view of another contact type image reading apparatus. Those having the same functions as those in the above-described example are denoted by the same numerals. The arrangement direction of a large number of lenses of the imaging lens array 6 'is perpendicular to the paper surface. The same applies to the line sensor 7 'as a light receiving element, and each element is arranged along the optical path 9'. Similarly to the above-described device, the reflected light from the document illuminated by the illumination device 8 is imaged on the light receiving element 7 'by the imaging lens array 6' and is converted into an image signal.

[0005] A brief description will be given of the illumination device used in the above-described reduced type reader or the contact type reader. FIG. 9 shows an LED on the printed circuit board 12.
FIG. 2 is a perspective view of a lighting device in which a large number of chips 10 are arranged on a straight line to form an LED array. Each chip 10 has one lead wire
The voltage supplied via the bleeder 3 is divided and supplied by the bleeder resistor 11. If the document surface is to be illuminated more brightly, and if the distance between the document surface and the illuminating device is reduced, it is necessary to compensate for variations in the brightness of each LED chip. Further, the unevenness of the distribution of luminance between the chips becomes remarkable, and the signal processing of the detected image becomes complicated. If the unevenness of the luminance distribution is large, the compensation of the detection signal becomes impossible and the quality after the image processing is deteriorated. In addition, increasing the number of LED chips is not a wise method because the cost increases.

FIG. 10 is a perspective view of still another conventional lighting device. Many LED chips on one surface of the light guide 16
Printed circuit boards 14 arranged on a straight line are arranged,
Power is supplied via the lead 15. The other surface of the light guide 16 is a light projecting surface 1 having a convex cylindrical surface or the like.
It is 7. Since the incident light is diffused inside the light guide, the emitted light has no luminance unevenness and can be condensed on the original surface. However, since the illumination light is obliquely incident on the optical axis, When the document floats, there is a problem that the illuminance is extremely reduced. The above-described illumination device in which the LED array of FIG. 9 and the LED array of FIG. 10 are combined with a light guide is mainly used in a monochrome image reading device.

FIG. 11 shows an arrangement in which an LED chip 18 as a light emitting portion is disposed on an end surface in the longitudinal direction of a light guide 120, and a surface facing an emission surface 21 or an adjacent surface is provided for the purpose of equalizing emission light over the entire length. It is a perspective view of the lighting apparatus which performed various work. For example, a lighting device in which a plurality of total reflection surfaces and irregular reflection surfaces are alternately arranged, and is integrated with the light guide 120. 19 is a lead wire. LE forming the light emitting part
The D chip 18 has a yellow L for monochrome reading.
ED, L for three colors of R, G, B for color reading
An ED chip is provided. In this illuminating device, in order to increase the illuminance on the document surface, LED chips of three colors of R, G, and B are provided for LED reading. To increase the illuminance on the document surface with this type of device, use the LED
Must be enlarged, so that power consumption increases. Further, the design and manufacturing shape of the light guide for making the emitted light uniform over the entire length become complicated, and the number of parts increases. Maintaining accuracy is not easy.

FIG. 12 shows a conventional illuminating device using a cold cathode discharge tube. A high voltage is supplied to the discharge tube 122 from a high voltage generator 124 via electric wires 123 connected by electrodes at both ends. The high voltage generator 124 is supplied with power via a power supply lead 125. The lighting device using the cold cathode discharge tube has an advantage that it can provide a sufficient amount of light, but requires a high voltage generator 124, so that the cost increases. Further, it is necessary to take measures to prevent the discharge noise of the cold cathode discharge tube from affecting the signal processing circuit. Further, the cold cathode discharge tube has a problem that the discharge life is as short as about 3000 hours and is weak against impact.

[0009]

Recently, the resolution required of an image reading apparatus has been increased from 200 dpi to 600 dpi.
Further, the demand for resolution is becoming stricter to 1200 dpi. Accordingly, the lens or the aperture ratio of the lens must be reduced. In addition, since the sensor pitch of the light receiving unit or the image pitch of the CCD becomes narrow, the voltage of the photoelectric conversion output decreases. Normal,
In order to solve these, an amplifier circuit for the sensor output voltage is indispensable in the middle of the sensor and the signal processing circuit, but since the noise is also amplified at the same time,
It is not advisable to improve the image quality because it cannot be expected and the cost increases. Therefore, the best solution for obtaining good image quality is to increase the document surface illuminance. A first object of the present invention is to provide a small-sized and high-luminance surface lighting device. A second object of the present invention is to provide an image reading device using the lighting device.

[0010]

According to a first aspect of the present invention, there is provided a lighting device comprising: a transparent device having a second surface opposed to a first surface with which a document surface is brought into contact; A second contact glass and a band-shaped transparent portion forming an information extraction area for extracting light from the area to be read on the first surface through the second surface are set on the second surface; An organic EL element having a band-shaped light emitting region formed on two surfaces along the outside of the transparent portion; and wiring means for supplying operating power to the organic EL element, and illuminated by light emission of the organic EL element The reflected light from the original surface is emitted from the transparent portion. In the lighting device according to claim 2 of the present invention, the organic EL element is formed parallel to one or both sides of the transparent portion on the second surface. According to a third aspect of the present invention, there is provided the lighting device according to the third aspect, wherein a transparent plate-shaped light guide is formed on one surface of the plate-shaped light guide, and the light is formed on a cylindrical lens surface that is convex in a short direction. And a wiring means for supplying operating power to the organic EL element, the organic EL element being provided on the light guide so as to project light onto the light projecting surface, and emitting light of the organic EL element. The light is emitted from the light projecting surface. According to a fourth aspect of the present invention, there is provided an illumination device according to the first, second, or third aspect, wherein the organic EL element continuously emits monochromatic light or emits R, G, and B emission colors as needed. It is to let.

According to another aspect of the present invention, there is provided an image reading apparatus comprising: a transparent contact glass having a second surface opposed to a first surface on which a document surface is brought into contact; A band-shaped transparent portion that forms an information extraction area for extracting light from the area to be read on the first surface through the second surface is set on the second surface;
An organic EL element having a band-shaped light-emitting region formed on the second surface along the outside of the transparent portion; and wiring means for supplying operating power to the organic EL element; An illumination device configured to allow reflected light from the original surface to be emitted from the transparent portion, a light receiving element array disposed parallel to the transparent portion below the transparent portion, and illuminated by the illumination device. And a lens array that forms an image of light from the original on the light receiving element array. The image reading device according to claim 6 of the present invention is:
A transparent contact glass having a second surface opposite to a first surface with which a document surface is brought into contact, a transparent plate-shaped light guide, and a cylindrical member convex on one surface of the light guide in a plane or short direction A contact surface including a light projecting surface formed on a lens surface, an organic EL element provided on the light guide to project light onto the light projecting surface, and wiring means for supplying operating power to the organic EL element An illuminating device arranged toward the second surface of the glass, a light receiving element array arranged parallel to the transparent portion below the transparent portion, and light from a document illuminated by the illuminating device. An image reading device comprising a lens array that forms an image on a light receiving element array. The lighting device invented in order to solve the above-mentioned problem is characterized in that a band-shaped organic EL element is formed on at least one side in the longitudinal direction without blocking the optical axis on a surface of the contact glass facing the document surface, or Organic EL around the optical axis
An element is formed and is configured integrally with the contact glass.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A lighting device according to the present invention and an image reading device using the device will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing a first embodiment of an image reading apparatus according to the present invention. It has a structure that is long in the depth direction of the paper surface. The document 20 is placed in close contact with the contact glass 21. Organic EL as a lighting device
The element 22 is arranged upward below the contact glass 21. The lens array 23 is configured as a 1: 1 optical system for forming an image of the reflected light from the document 20 on the light receiving element 24. The light receiving element 24 converts the supplied light into an image signal via the same-magnification optical system 23, and has a line sensor array. The case 25 supports the contact glass 21, the 1 × optical system 23, and the light receiving element 24.

FIG. 2 is a bottom view showing an embodiment of a lighting device used in the image reading apparatus. An organic EL element 22 that forms a light emitting portion is provided on a contact glass 21. A DC voltage is applied to the organic EL element 22 via the electrode 44. The illustrated axis 26 'is an axis orthogonal to the optical axis 26 shown in FIG. 1, and is a line orthogonal to the paper surface in FIG.

FIG. 3 is a schematic diagram showing the structure of the organic EL element 22 described above. This embodiment has a configuration of an organic EL element emitting yellow light. On a glass substrate (contact glass 21), an anode transparent substrate 22a has a sheet resistance of 10Ω.
/ □ coated with ITO (indium tin oxide, sputter-deposited by Sanyo Vacuum). A TPD having a hole-transporting property represented by the following formula (Formula 1) is formed to a thickness of 400 ° at a deposition rate of 3 ° / sec under 10 ⁻⁶ torr, and a hole-transporting layer 22b is formed. Was formed.

Next, a tris (8-quinolinolato) aluminum complex represented by the following formula (formula 2) is formed on the hole transport layer 22b as an electron transporting light emitting layer 22c.
q) and 3% by weight in the following formula (Formula 3)
Was co-evaporated from separate evaporation sources under a vacuum of 10 ^-6 torrNO to form a film of 300 °. Next, Alq was formed as the electron transport layer 22d at 300 ° C. under a vacuum of 10 ⁻⁶ torr. Finally, as the electron injection layer 22e, 5Å
Lithium fluoride and a back electrode 22f serving as a cathode
000 ° of aluminum was deposited at the same vacuum. When a DC voltage is applied between the anode electrode 22a and the cathode electrode 22f, the luminescent layer 22c has 5
Yellow light emission showing a peak at 60 nm was observed through the glass substrate 21. 20000 cd / at an applied voltage of 10 V
It exhibited a high luminance of m ² .

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In the image reading apparatus shown in FIG.
An appropriate DC voltage is applied with the transparent electrode side of the organic EL element 22 as an anode and the rear electrode side as a cathode to cause the organic EL element to emit light. The document 20 is illuminated through a contact glass 21 and is reflected by the document surface 20. The reflected light is imaged on a line sensor 24 as a light receiving element by a lens array 23 having an equal magnification optical system, and is converted into an image signal.

In the description of this embodiment, a monochromatic light illumination device is used.
The G and B organic EL elements are sequentially arranged in the lateral direction of the contact glass, and a lighting device that emits light alternately in synchronization with the image reading device can be provided.

FIG. 4 shows still another example of the lighting device. On the lower surface of the contact glass 27, an organic EL element 28 is formed around the transparent portion except for a transparent portion so as not to block an optical path immediately below the center of the document. The shaft 30 'is shown in FIG.
Is an axis corresponding to the axis 26 'shown in FIG. Organic EL device 2
A DC voltage is applied to 8 via an electrode 29. The illumination device shown in FIG. 4 can be used in place of the illumination device of the image reading device shown in FIG. In this case, the axis 30 'shown in FIG. 4 should be aligned with the illumination device 26' shown in FIG.

FIG. 5 shows still another embodiment of the image reading apparatus according to the present invention. The structure is long in the depth direction of the paper. The document 31 is partially arranged in close contact with the contact glass 32. An organic EL element 35 is provided on the lower surface of the light guide 33 as a light emitting unit. Light emitted from the organic EL element 35 is directed to the document via the light emitting surface 34. The reflected light from the manuscript 31 is a lens array 3 using an equal-magnification optical system.
6 forms an image on the light receiving element 37 of the line sensor type. The case 38 includes the contact glass 32 and the light guide 33.
And a 1 × optical system 36 and a light receiving element 37. The optical axis 39 is the optical axis of the image reading device.

FIG. 6 is a perspective view of a lighting device which can be used in the image reading device shown in FIG. 5, as viewed from below. This lighting device is a lighting device in which the light guide 40 and the light emitting section 42 are integrally formed. A light emitting unit 42 having an organic EL element formed on the lower surface of the light guide 40 is provided, and a DC voltage is applied via an electrode 43. Light projecting surface 41 provided on light guide 40
May be a cylindrical surface having a convex curvature in the short direction. As a result, the document surface can be efficiently illuminated.

In FIG. 5, an appropriate DC voltage is applied with the transparent electrode side of the organic EL element 35 as an anode and the back electrode side as a cathode to cause the organic EL element to emit light. It is reflected at 31.
The reflected light is imaged on a line sensor 37 as a light receiving element by a lens array 36 having an equal magnification optical system, and is converted into an image signal.

(Modification) In the description of this embodiment, a monochromatic light illuminating device is used. However, as a color image reading device, R, G, and B organic EL elements are sequentially provided side by side in the lateral direction. An illumination device that emits light alternately in synchronization with the reading device can be provided.

[0023]

As described above in detail, an integrated bright and efficient lighting device having an organic EL element as a light emitting portion on one surface of the contact glass of the present invention can be obtained. A black-and-white image reading device or a color image reading device smaller than the shape can be obtained.

Further, if a convex cylindrical surface or the like is formed so that the emitted light is linear on the light projecting surface of the light guide, it is bright, the light loss is small, and the light is efficiently condensed on the original surface. By changing the configuration of the organic EL element, a monochromatic illuminating device, a white illuminating device, or an illuminating device of R, G, and B colors can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an embodiment of an image reading apparatus using the first embodiment of the lighting device according to the present invention.

FIG. 2 is a bottom view of the lighting device according to the first embodiment of the present invention;

FIG. 3 is a schematic diagram showing a detailed configuration of an organic EL element having a yellow emission color used in the lighting device shown in FIG. 2;

FIG. 4 is a bottom view of a lighting device according to a second embodiment of the present invention;

FIG. 5 is a schematic diagram showing still another embodiment of the image reading apparatus according to the present invention.

FIG. 6 is a perspective view of a lighting device that can be used in the image reading device shown in FIG. 5 as viewed from below.

FIG. 7 is a schematic diagram of a conventional typical reduced image reading apparatus.

FIG. 8 is a schematic view of another conventional contact image reading apparatus.

FIG. 9 is a perspective view of an LED array-type lighting device in which a large number of LED chips are arranged on a printed circuit board in a straight line.

FIG. 10 is a perspective view of still another lighting device in which a large number of LED chips are arranged on one surface of a light guide in a straight line.

FIG. 11 is a light guide in which a surface opposite to an emission surface or an adjacent surface is variously worked for the purpose of equalizing the emission light over the entire length, for example, a plurality of total reflection surfaces and an irregular reflection surface are alternately arranged. It is a perspective view of the lighting device integrated with the body.

FIG. 12 is a perspective view of an illumination device using a cold cathode discharge tube.

[Explanation of symbols]

 Reference Signs List 20 manuscript 21 contact glass (glass substrate) 22 lighting device (organic EL element) 23 lens array (1 × optical system) 24 line sensor as light receiving element 25 case 26 optical axis 26 ′ axis 27 contact glass 28 forming organic EL element Light emitting section 29 Electrode for applying DC voltage to organic EL element 30 'axis 31 Original document 32 Contact glass 33 Light guide 34 Light emitting surface 35 Organic EL element 36 Lens array (1 × optical system) 37 Light receiving element Line sensor 38 Case 39 Optical axis 40 Light guide 41 Light emitting surface 42 Light emitting portion on which organic EL element is formed 43 Electrode for applying DC voltage to organic EL element 44 Electrode 122 Discharge tube 123 Electric wire 124 High voltage generator 125 lead wire

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[Procedure amendment]

[Submission date] April 24, 2000 (200.4.2
4)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction contents]

Next, a tris (8-quinolinolato) aluminum complex represented by the following formula (formula 2) is formed on the hole transport layer 22b as an electron transporting light emitting layer 22c.
q) and 3% by weight in the following formula (Formula 3)
Was co-evaporated from separate evaporation sources under a vacuum of 10 ^-6 torr to form 300 °. Next, Alq was applied as the electron transport layer 22d under a vacuum of 10 ⁻⁶ torr.
00 ° was formed. Finally, lithium fluoride of 5 ° is used as an electron injection layer 22e, and 20 μm is used as a back electrode 22f serving as a cathode.
00 ° of aluminum was deposited at the same vacuum. When a DC voltage is applied between the anode electrode 22a and the cathode electrode 22f, a rubrene-derived 56
Yellow light emission showing a peak at 0 nm was observed through the glass substrate 21. 20000 cd / m at an applied voltage of 10 V
² showed a high brightness.

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 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Junji Kido 4-3-16 Jonan, Yonezawa-shi, Yamagata F-term in the Graduate School of Engineering, Yamagata University (reference) 2H109 AA02 AA17 AA27 5B047 BC12 BC14 CA19 CB04 CB05 5C051 AA01 BA03 DB01 DB04 DB29 DC04 DC05 DC07 5C072 AA01 BA01 CA05 CA09 DA02 DA21 EA05 LA04

Claims (6)

[Claims] A transparent contact glass having a second surface opposed to a first surface with which a document surface is brought into contact;
A band-shaped transparent portion that forms an information extraction area for extracting light from an area of the surface to be read for image reading through the second surface is set on the second surface, and the second surface is outside the transparent portion. An organic EL element having a band-shaped light emitting region formed along the line, and wiring means for supplying operating power to the organic EL element, and reflected light from a document surface illuminated by light emission of the organic EL element Is configured to be emitted from the transparent part. 2. The organic EL element is formed parallel to one or both sides of a transparent portion of the second surface.
The lighting device according to the above. 3. A transparent plate-shaped light guide, a light projecting surface formed on a cylindrical lens surface that is flat on one surface of the plate-shaped light guide or that is convex in a lateral direction, and the light guide. An organic EL element provided to project light onto the light projecting surface, and wiring means for supplying operating power to the organic EL element,
A lighting device configured to emit light of the organic EL element from the light emitting surface. 4. The organic EL element of the lighting device according to claim 1, 2 or 3, wherein the organic EL element continuously emits monochromatic light or R,
An illuminating device that emits G and B emission colors as needed. 5. A transparent contact glass having a second surface opposed to a first surface with which a document surface is brought into contact, and light from an area of said first surface to be read is transmitted through said second surface. An organic EL having a band-shaped transparent portion forming an information extraction region to be extracted by taking a second surface, and having a band-shaped light-emitting region formed along the outside of the transparent portion on the second surface.
A lighting device comprising: an element, wiring means for supplying operating power to the organic EL element, wherein reflected light from a document surface illuminated by emission of the organic EL element is emitted from the transparent portion; and An image reading device comprising: a light receiving element array arranged below the transparent part in parallel with the transparent part; and a lens array for imaging light from a document illuminated by the illumination device on the light receiving element array. . 6. A transparent contact glass having a second surface opposed to a first surface with which a document surface is brought into contact, a transparent plate-shaped light guide, and one surface of the light guide being flat or short-sided. A projection surface formed on a cylindrical lens surface having a convex shape,
An organic EL element provided to project light on the light projecting surface on the light guide; and wiring means for supplying operating power to the organic EL element, the organic light emitting element being arranged toward the second surface of the contact glass. Illuminating device, a light-receiving element array disposed below the transparent portion in parallel with the transparent portion, and a lens array for imaging light from a document illuminated by the illuminating device on the light-receiving element array And an image reading device.