JPH0846242A - Linear light source - Google Patents

Abstract

PURPOSE:To obtain a light source at a low cost wherein irregularity of illuminance is little and illuminance characteristics in the width direction of a manuscript is excellent, by forming coating resin so as to cover a light emitting diode and almost coincide with the outer periphery of a light reflecting film. CONSTITUTION:The light from a light-emitting diode 3 formed on a linear light source 14 is reflected by a manuscript 15. The reflected light having differnt intensity according to whether characters are present is converted into an electric signal by a photodetectior 16, which signal is converted into a data signal. The light outputted from a light-emitting diode 3 is scattered downward by reflection at the rough surface of coating resin 8, and most of it is absorbed by light absorption films 12, 13 formed on the periphery of the coating resin 8. The reflected light 17 (flare light) becomes weak and is outputted. Hence the range wherein the coating resin comes into contact with a light reflecting film becomes constant, irregularity of the form of the coating resin becomes little, and irregularity of illuminance is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear light source using a light emitting diode.

[0002]

2. Description of the Related Art Conventionally, a linear light source has been disclosed in, for example, JP-A-2-37.
This is shown in FIG. 5 according to Japanese Patent No. 784. In this figure, a light emitting diode 21 is placed and wired on an electrode (not shown) on a substrate 22. The reflection frame 23 has a reflection portion 24 having a triangular cross section, is fixed to the substrate 22, and the lens 25 is fixed to the reflection frame 23. A silicon resin 26 is formed so as to cover the light emitting diode 21 to improve the illuminance.

[0003]

However, the above-mentioned linear light source has a first drawback that the illuminance varies greatly right above each light emitting diode 21. This is because the inventors of the present invention have investigated the cause and found that the range C in which the substrate 22 and the silicon resin 26 contact each other varies, and the shape of the silicon resin 26 is not constant. Therefore, silicone resin 2
It was found that this is because the radius of curvature of the dome at the tip of 6 is not constant, so that the amount of light collected by the silicone resin 26 varies.

Further, this linear light source has the second drawback that the cost is increased because the expensive lens 25 and the reflecting frame 23 are provided in order to focus the light only upward. Therefore, in order to reduce the cost, the inventor eliminates the reflection frame 23 and the lens 25 as shown in the sectional view of FIG.
A linear light source for illuminating 7 was examined. That is, the reflective coating 28 is formed around the light emitting diode 21 placed on the electrode 29 on the substrate 22, the silicon resin 26 is formed, and the linear light source 30 is configured. Then, for example, as a reading unit of a facsimile apparatus, the light from the linear light source 30 is reflected by the original 27, the reflected light is incident on the light receiving sensor 31, and the intensity of the reflected light that differs depending on the presence or absence of a character on the original 27 causes the light receiving sensor 31. Is converted into an electric signal by.

However, as shown in FIG. 7, the illuminance characteristic in the width direction (D) of the original 27 is bad as shown by the broken line. The two-dot chain line shows the ideal characteristics, and it is desirable that the illuminance is high in a predetermined width range of the original 27 and low in other ranges. However, the characteristic of the broken line is that the illuminance in the area other than the predetermined width is high, so that the original surface outside the predetermined position is irradiated as a reading unit of the facsimile apparatus, and this irradiation light becomes undesired reflected light and enters the light receiving sensor 31, The information about the presence / absence of characters written within the predetermined width is not accurately transmitted to the electric signal.
There is a drawback of. When the inventor investigated the cause,
The coating resin 2 is emitted from the light emitting diode 21.
The light that is diffusely reflected by the rough surface of 6 and travels downward is the reflective coating 2.
This is because the light (flare light) 32 reflected by 8 is emitted, and the flare light 32 irradiates the original 27 in a range other than a predetermined width. Therefore, in consideration of such conventional defects, the present invention provides a linear light source with little variation in illuminance, excellent illuminance characteristics in the document width direction, and low cost.

[0006]

In order to solve the above-mentioned problems, a first aspect of the present invention is directed to a long substrate on which electrodes are formed apart from each other and aligned on a substantially straight line on the electrodes. A plurality of mounted light emitting diodes, a light reflecting coating formed on a substrate and formed into a plurality of substantially circular columns centered on the light emitting diodes so that the light emitting diodes and the vicinity thereof are opened, and the light emitting diodes and It is provided in a substantially dome shape on the light-reflecting coating so that the outer circumference thereof is covered with the outer circumference of each cylinder of the light-reflecting coating, and it is located on the exposed coating resin and outside the coating resin. And a light absorption coating formed above the long edge.

The second aspect of the present invention is to provide a long substrate on which electrodes are formed separately from each other, a plurality of light emitting diodes mounted on the electrodes aligned in a substantially straight line, and a plurality of light emitting diodes on the substrate. The light-reflecting coating is formed on the light-emitting diode and its vicinity so that the light-emitting diode and its vicinity are open, and the light-reflecting coating is formed on a plurality of substantially cylinders. The light-reflecting coating covers the light-emitting diode and its vicinity on the inner wall of each cylinder. An exposed coating resin is provided on the light reflecting coating in a substantially dome shape so as to be surrounded, and a light absorbing coating formed outside the coating resin and formed above the long edge of the substrate. It is provided.

[0008]

As described above, according to the first aspect of the present invention, the light-emitting diode and the light-emitting diode are provided in the vicinity of the light-emitting diode so as to open the light-emitting diode and the vicinity thereof. The coating resin is provided so that they substantially match. In this way, the outer periphery of the coating resin is regulated by the outer periphery of the light reflection coating, so that the contact range between the coating resin and the light reflection coating is constant, and the variation in the shape of the coating resin is reduced.

In the second aspect of the present invention, a light-reflecting coating having a substantially cylindrical shape centering on the light-emitting diode is provided so as to open the light-emitting diode and its vicinity, and the light-emitting diode is covered so as to be surrounded by the inner wall of the light-reflecting coating. Provide coating resin. In this way, the outer periphery of the coating resin is regulated by the inner wall of the light-reflecting coating, so that variations in the shape of the coating resin are reduced.

Further, in the first and second aspects of the present invention, the light emitted from the light emitting diode, diffusely reflected by the rough surface of the coating resin and traveling downward is almost absorbed by the light absorbing coating provided around the coating resin. It In this way, the light (flare light) that is not absorbed and reflected by the light absorbing coating becomes weak, and the illuminance outside the predetermined range on the document surface due to the emission of the flare light is significantly reduced.

In the first and second aspects of the present invention, since the flare light is limited by the light absorbing film, the light from the exposed coating resin travels almost upward.
Costs are reduced because expensive lenses and reflective frames, unlike in the past, are not required.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a plan view of a linear light source according to this embodiment,
2 is a sectional view taken along line AA of FIG. In these figures, the substrate 1 is, for example, a long substrate having a width of 11 mm and a length of 240 mm, and is made of glass epoxy resin or the like. Electrodes 2a, 2b, 2c, 2d made of gold plating are formed.

Each light emitting diode 3 is mounted and fixed on each of the electrodes 2a to 2d and the like via a conductive adhesive so as to be aligned on a substantially straight line, and the alignment pitch is, for example, about 10 mm. For example, one side of the light emitting diode 3 is 0.2 to 0.4.
It is a substantially cubic cube of mm and is made of gallium phosphide or gallium arsenide phosphide and is wired to the other electrodes 2b to 2d by metal thin wires.

The light reflecting coating 4 is made of a light reflecting material such as a white paint or a white resist such as epoxy resin, and is composed of a thick film layer 5 and a thin film layer 6. The thick film layer 5 is formed in a substantially columnar shape with each light emitting diode 3 and the vicinity thereof being opened, that is, except for the region 7, with each light emitting diode 3 being substantially at the center.
They are provided on a to 2d and the substrate 1. Specifically, the thick film layer 5 has, for example, a diameter of about 2 to 6 mm and each electrode 2a.
The height from ˜2d is about 30-60 μm.

The thin film layer 6 is formed on the electrodes 2a to 2d and the substrate 1 in a region not including the thick film layer 5 and has a thickness of about 15 to 20 μm. Specifically, except for the above-mentioned region 7, the thickness of the electrodes 2a to 2d and the substrate 1 is about 15 to 2
The thick film layer 5 is formed by printing a white resist of 0 μm and then printing the white resist for a second time on a predetermined circular portion on the white resist by a mask pattern. It is desirable that the thick film layer 5 be thick, but if it is too thick, a non-uniform film is formed.
60 μm is desirable.

The coating resin 8 is made of, for example, an epoxy resin, covers the light emitting diode 3 and its vicinity,
Further, it is formed on the thick film layer 5 so as to expose the upper part in a substantially dome shape so that the outer circumference thereof substantially matches the outer circumference 9 of the thick film layer 5. In this way, the coating resin 8 is formed into the thick film layer 5 having a substantially cylindrical shape.
Since it is provided above, the outer circumference 9 of the thick film layer 5 has a particularly large surface tension, so that the coating resin 8 does not spread and the outer circumference thereof coincides with the outer circumference 9 of the thick film layer 5. Therefore, the range in which the coating resin 8 and the thick film layer 5 contact each other becomes constant, and the variation in the shape of the coating resin 8 is reduced. As a result, the radius of curvature of the dome at the tip of the coating resin 8 becomes substantially constant, and the amount of collected light becomes substantially constant, so that there is less variation in illuminance right above each light emitting diode 3.

To provide such a coating resin 8, an automatic potting device is used. In this device, an injection needle is attached to one end of a syringe-like container and a main body is attached to the other end via a tube. It is a thing. The transparent epoxy resin or the like described above is enclosed in this container, and pressurized air is supplied to the tube from the main body.

When the switch attached to the main body is turned on,
After detecting the position of the light emitting diode 3, air is controlled to be supplied for a predetermined time. As a result, a predetermined amount (about 0.002 cc) of epoxy resin is dropped and provided so as to cover the light emitting diode 3 as a center.
Next, the substrate 1 is moved by a predetermined amount, the position of the adjacent light emitting diode 3 is detected, and the same work is performed.

Coating resin 8 thus obtained
The diameter of the thick film layer 5 is about 2 to 6 mm, and the height from the surface of the thick film layer 5 is about 1 to 3 mm. The long edges 10, 1 of the substrate 1 are located outside each thick film layer 5.
Light absorption coatings 12 and 13 are provided on the substrate 1 via a thin film layer 6. The light absorption coatings 12 and 13 are made of a black resist such as epoxy resin and made of a material that absorbs light well.

For example, in the reading section of the facsimile apparatus, the document 15 is arranged above the linear light source 14 by 5 to 15 mm and inclined to the linear light source 14 by, for example, 45 °. The light receiving sensor 16 is, for example, 45 degrees from the original 15.
It is tilted and placed close to it. Light receiving sensor 1
Reference numeral 6 denotes a plurality of light receiving regions in which N-type impurities such as boron are selectively diffused and aligned in the vicinity of the surface of a semiconductor substrate made of silicon, and individual electrodes which are in ohmic contact with the light receiving regions.
It is composed of a scanning circuit for taking out the electric charge accumulated in each light receiving region in time series, and an amplifier (not shown) for amplifying an output signal from the circuit and outputting a data signal.

In this reading device, the light from the light emitting diode 3 provided in the linear light source 14 is reflected by the original 15, and the reflected light having different intensity depending on the presence or absence of characters on the original 15 is received by the light receiving sensor 16. It is converted into an electrical signal, which is converted into a data signal.

Then, the light is emitted from the light emitting diode 3,
Light diffusely reflected on the rough surface of the coating resin 8 and traveling downward is almost absorbed by the light absorbing coatings 12 and 13 provided around the coating resin 8. The light 17 (flare light) that is not absorbed and reflected by the light absorbing films 12 and 13 becomes weak, and the illuminance outside the predetermined range on the surface of the original 15 due to the emission of the flare light 17 is significantly reduced. . As a result, the information on the presence / absence of characters in the original 15 is accurately output as an electric signal in the light receiving sensor 16.

In FIG. 7, the illuminance characteristic of the linear light source 14 of this embodiment is shown by a solid line. From this characteristic diagram, it can be seen that the illuminance is remarkably reduced in a region outside the predetermined width (for example, 1 to 10 mm) of the document 15. This is because the flare light 17 described above becomes weak. Also, it can be seen that the illuminance is higher in the area of the predetermined width than the conventional one. Since the outer periphery of the coating resin 8 is regulated by the outer periphery of the light reflecting film 4, a relatively large amount of the coating resin 8 can be provided, and the radius of curvature can be made smaller than in the past to form a dome shape. This is because the amount of light that collects in the area increases.

Further, a second embodiment in which variations in illuminance are smaller than those in the first embodiment will be described with reference to FIGS. 3 and 4. 3 is a plan view of the linear light source according to this embodiment, and FIG. 4 is a cross-sectional view taken along the line BB of FIG. In these figures, the light reflecting coating 4a is made of a light reflecting material such as a white resist and is composed of a thick film layer 5a and a thin film layer 6a.

The thick film layer 5a is formed in a substantially cylindrical shape with each light emitting diode 3 and its vicinity being opened and the light emitting diode 3 being substantially at the center, on the electrodes 2a to 2d and the substrate 1. It is provided. Specifically, the thick film layer 5a has, for example, an inner diameter of about 2 to 6 mm and a width of about 0.5 m.
m, the height from each electrode 2a to 2d is about 30 to 60 μm.
Is. The thin film layer 6a is formed on each of the electrodes 2a to 2d and the substrate 1 in a region not including the thick film layer 5a, and has a thickness of about 15 to 20 μm.

The coating resin 8a is made of, for example, an epoxy resin or the like, covers the light emitting diode 3 and its vicinity, and is surrounded by the inner wall of the thick film layer 5a.
2d and on the substrate 1. In this way
Since the outer periphery of the coating resin 8a is regulated by the inner wall of the thick film layer 5a, there is little variation in the shape of the coating resin 8a. That is, the radius of curvature of the dome at the tip of the coating resin 8a becomes substantially constant.

On the long edge of the substrate 1 with the thin film layer 6a interposed, the light absorbing coatings 12 and 1 made of, for example, a black resist.
3 is provided. These members constitute the linear light source 18 of this embodiment.

For example, in a reading device of a facsimile machine, the light emitted from the light emitting diode 3 and diffusedly reflected at the interface of the dome-shaped coating resin 8a (light spreading laterally of the linear light source) is absorbed by the light absorbing film 12a. Absorbed by. Therefore, the flare light 19 reflected by the light absorption coating 12a
Becomes extremely weak, and the amount of light (illuminance) for illuminating a region outside the predetermined width of the document 15 is reduced to such an extent that there is no practical problem. As a result, the information on the presence / absence of characters in the original 15 is accurately output as an electric signal in the light receiving sensor 16.
The illuminance characteristic of the linear light source 18 is almost the same as that shown by the solid line in FIG.

Further, in the above-mentioned first and second embodiments,
Epoxy resin is illustrated as the coating resin 8 or 8a. This is because these linear light sources do not have the conventional reflection frame and lens, and therefore may be touched by the operator's hand during manufacturing. A resin is used. Further, instead of the epoxy resin, another resin having high hardness may be used.

[0030]

As described above, according to the first aspect of the present invention, a light-reflecting coating of a substantially cylindrical shape is provided with the light-emitting diode and its vicinity as the center so that the light-emitting diode and its vicinity are opened. The coating resin is provided so as to substantially match the outer circumference. In this way, the outer periphery of the coating resin is regulated by the outer periphery of the light reflection coating, so that the contact range between the coating resin and the light reflection coating is constant, and the variation in the shape of the coating resin is reduced.
Therefore, variations in illuminance are reduced.

According to the second aspect of the present invention, a light-reflecting coating having a substantially cylindrical shape centering on the light-emitting diode is provided so as to open the light-emitting diode and its vicinity, and the light-emitting diode is covered to be surrounded by the inner wall of the light-reflecting coating. Provide coating resin. In this way, the outer periphery of the coating resin is regulated by the inner wall of the light-reflecting coating, so that variations in the shape of the coating resin are reduced. Therefore, variations in illuminance are reduced.

Further, in the first and second aspects of the present invention, the light emitted from the light emitting diode, diffusely reflected by the rough surface of the coating resin and traveling downward is almost absorbed by the light absorbing coating provided around the coating resin. It The light (flare light) that is not absorbed and reflected by the light absorption coating becomes weak, and the illuminance outside the predetermined range on the document surface due to the emission of this flare light is significantly reduced.

Further, in the first and second aspects of the present invention, since the light which spreads laterally is limited by the light absorbing film, the light from the exposed coating resin travels almost upward, so that an expensive lens as in the prior art is used. No need for a reflective frame, and the cost is low.

[Brief description of drawings]

FIG. 1 is a plan view of a linear light source according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a plan view of a linear light source according to a second embodiment of the present invention.

4 is a sectional view taken along line BB of FIG.

FIG. 5 is a sectional view of a conventional linear light source.

FIG. 6 is a cross-sectional view of a linear light source obtained by improving the conventional linear light source.

FIG. 7 is an illuminance characteristic in the width direction of a document.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2a, 2b, 2c, 2d Electrode 3 Light emitting diode 4, 4a Light reflecting coating 5, 5a Thick film layer 8, 8a Coating resin 12, 13 Light absorbing coating

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location G02B 27/00 (72) Inventor Tatsuya Motoike 3-201 Minamiyoshikata, Tottori City, Tottori Prefecture Tottori Sanyo Electric Co., Ltd. Within the corporation

Claims (2)

[Claims] 1. A long substrate having electrodes formed separately from each other, a plurality of light emitting diodes mounted on the electrodes aligned in a substantially straight line, and arranged on the substrate, A light-reflecting coating formed in a plurality of substantially circular columns centering on the light-emitting diode so that the light-emitting diode and its vicinity are opened, and the light-reflecting coating covering the light-emitting diode and its vicinity and having an outer periphery thereof. It is provided in a substantially dome shape on the light-reflecting coating so as to be substantially coincident with the outer circumference of the cylinder, and is provided on the exposed coating resin and on the outer side of the coating resin and above the long edge of the substrate. A linear light source characterized by comprising a light absorbing coating. 2. A long substrate having electrodes formed separately from each other, a plurality of light emitting diodes mounted on the electrodes aligned in a substantially straight line, and arranged on the substrate, A light-reflecting coating formed in a plurality of substantially cylindrical shapes centering on the light-emitting diode so that the light-emitting diode and its vicinity are opened, and an inner wall of each cylinder of the light-reflecting coating that covers the light-emitting diode and its vicinity. Surrounded by the light-reflecting coating in a substantially dome shape, and the exposed coating resin and the light-absorbing coating provided outside the coating resin and above the long edge of the substrate. A linear light source characterized by comprising: