JPH09247361A - Linear illuminator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the lighting efficiency of the linear illuminator, increase document surface illuminance, and minimize illuminance variance. SOLUTION: On a circuit board 81, LED chips 82 are mounted at certain equal intervals by using a die mounter, and on them, a 1st transparent plate 83A and a 2nd transparent plate 83B which has a triangular-wave surface 84 on its incidence surface are optically mounted by using high-transmissivity UV setting type insulating resin. As for the linear illuminator which is thus manufactured, illumination lights emitted by the LED chips 82 pass through the transparent plate 83A and are guided to its projection surface without being diffused in a vertical scanning direction, and further diffused only in a horizontal scanning direction by the triangular-wave surface 84 formed on the incident surface of the 2nd transparent plate 83B, so that the lights pass through the 2nd transparent plate 83B and are guided to a document without being diffused in the vertical scanning direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear illumination device that linearly illuminates a document surface in a main scanning direction in an optical image reading device, for example.

[0002]

2. Description of the Related Art A conventional linear illumination device will be described by taking an optical reading device as an example for convenience.

In recent years, optical image reading devices have been widely used as reading devices for facsimiles, scanners, bar code readers, etc., and an LED array in which LED chips are arranged in a line in a document illumination system of this type of device. Is used.

An example of the linear illumination device used in the above-mentioned conventional optical document reading device will be described below with reference to the drawings.

FIG. 10 is a structural diagram of a conventional optical image reading apparatus. In FIG. 10, 101 is an original, and 102 is an LE as a linear illumination device that illuminates the original.
D array, 103 is a rod lens array that guides the light information reflected by the original with an equal magnification, and 104 is a photoelectric conversion element array that takes in the light information guided by the rod lens array 103 and converts it into an electrical signal. Further, FIG. 11 shows a structure of a conventional LED array, in which a plurality of LED chips 112 are linearly arranged on a substrate 111 having a circuit conductor layer.

The operation of the optical image reading device and the linear illumination device configured as described above will be described below.

First, the original 101 to be read is irradiated with the light from the LED array 102, and the reflected light is erected at the same magnification by the rod lens array 103 and the photoelectric conversion element array 104 is used.
Then, the original was read by converting it into an electric signal.

[0008]

However, in the linear light source device (LED array) 102 having the above configuration,
Due to the directional characteristics of the LED chip 112, the illumination efficiency is low (spreads in the sub-scanning direction), and the illuminance of the document surface is greatly varied, which deteriorates the image reading performance. In addition, it is necessary to keep a certain distance from the original 101 to the LED array 102, the size of the unit itself becomes large, and more LED chips are used, which causes a cost increase.

[0009]

In order to solve the above-mentioned problems, the linear illumination device of the present invention has a conventional LED array L
On the ED chip, one or two transparent plates that have been processed with a triangular wave or the like in the main scanning direction are provided on the light input / output surface, or the portion of the circuit board on which the LED chip is mounted and its periphery are mirror-finished. Optimizing the directional characteristics of the LED chip by forming a concave shape (narrow in the sub-scanning direction and wide in the main-scanning direction)
However, the configuration is such that the transmission efficiency of light is improved.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The linear lighting device of the present invention is a transparent linear lighting device (LED array) on which an input / output surface of light is subjected to a process such as a triangular wave in the main scanning direction on an LED chip. Optimizing the directional characteristics of the LED chip (narrow in the sub-scanning direction, main scanning by providing a plate, forming a recess in the area where the LED chip is mounted on the circuit board and its periphery, and making the surface a mirror surface). (Wide in the direction) to improve the light transmission efficiency.

As a result, it is possible to increase the illuminance on the document surface, suppress variations in illuminance on the document surface, and further improve the image reading performance. Further, the distance from the LED array to the document surface can be shortened, the cost can be reduced by reducing the number of LED chips, and the size and weight of the optical document reading device itself can be reduced.

The linear lighting device of the present invention will be described below with reference to the drawings. 1A and 1B are a sectional view and a plan view, respectively, showing the basic configuration of the linear lighting device of the present invention. 11 is a circuit board, 12 is an LED chip mounted in a line on the circuit board, and 13 is each LED
It is a transparent plate arranged close to the upper surface of the chip 12.

With respect to the linear lighting device having the above basic structure, the present invention is a linear lighting device in which the transparent plate 13 is subjected to various optical treatments.

(First Embodiment) A first embodiment of the linear lighting device of the present invention will be described with reference to FIG. FIG. 2 is a side view showing the configuration of the linear lighting device according to the first embodiment. As shown in the figure, a plurality of LED chips 22 are mounted in a line on the circuit board 21 and
A transparent plate 23 having a triangular wave surface (sawtooth wave surface) 24 on the entrance surface and / or the exit surface is provided on the D chip 22.

The linear illumination device according to the first embodiment configured as described above will be described more specifically.
First, the LED chips 22 are mounted on the circuit board 21 at a predetermined pitch using a die mounter. As the LED chip 22, a GaP or a high-luminance LED chip is used which is a resin-molded bare chip of a quaternary system such as AlGaInP. In the case of a linear illumination device for reading a color image, R (red), G (green), B
The LED chips of three colors (blue) may be mounted alternately.

Next, a transparent plate 23 having a triangular wave surface (sawtooth wave surface) 24 on the entrance surface and / or the exit surface is formed on the LED chip 22 by injection molding with a transparent resin such as glass or acrylic resin or polycarbonate. It is implemented using a dynamic method. The transparent plate 23 has substantially the same length (illumination width) as the circuit board 21, and has a thickness of LED.
The width of the chip 22 in the lateral direction (sub-scanning direction) or larger than that is the width, and the width has a dimension of the distance from the LED chip 22 to the illuminated document surface.
As an optical mounting method, an acrylate-based highly transparent ultraviolet curable insulating resin is used, and after aligning the transparent plate 23 with the LED chip 22, ultraviolet light is irradiated to cure it. A highly transparent thermosetting insulating resin such as an epoxy resin may be used instead of the highly transparent ultraviolet curable insulating resin. As for the transparent resin used for the transparent plate, a thermosetting resin is suitable for improving the dimensional accuracy of injection molding.

The operation principle and characteristics of the linear illumination device according to the third embodiment thus manufactured will be described. The illumination light output from the LED chip 22 is guided to the other end through the transparent plate 23 and illuminates the document in the vicinity thereof. At this time, since the illumination light is diffused only in the main scanning direction due to the triangular wave surface (sawtooth wave surface) on the incident surface and / or the exit surface, the unevenness of the illuminance of the document surface is small (compared to the conventional LED array. Since the illumination light is guided in the sub-scanning direction without being diffused, the document surface can be efficiently illuminated linearly (conventional LE).
The illuminance is about 3 times that of the D array). As a result, the number of LED chips could be reduced to about 1/3 as compared with the conventional LED array.

Similarly, in order to suppress variations in the illuminance of the original, it is also effective to use a transparent plate 63 having a plurality of cavities (triangular prisms or cylinders) as shown in FIG. 6 (side view) (depending on the cavities. Illumination light is diffused in the main scanning direction). Similarly, in order to increase the illumination efficiency of the original, the transparent plate 3 having an R on the exit surface as shown in FIG. 3 (cross-sectional view) in the sub-scanning direction.
3 or a transparent plate 43 whose thickness (width in the sub-scanning direction) becomes smaller as it goes from the entrance surface to the exit surface as shown in FIG. 4 (cross-sectional view). Further FIG.
If a transparent plate 53 having an emission surface inclined with respect to the sub-scanning direction as shown in (cross-sectional view) is used, the linear illumination position can be freely changed, and the degree of freedom in designing the optical image reading device itself can be increased. In addition, the device itself can be downsized.

(Second Embodiment) A second embodiment of the linear illumination device of the present invention will be described with reference to FIGS. 7 and 8. FIGS. 7 and 8A and 8B are a side view and a cross-sectional view, respectively, showing the configuration of the linear lighting device according to the second embodiment. As shown in the figure, the circuit board 71 (81)
A plurality of LED chips 72 (82) are mounted in a row on the upper side, and the first transparent plate 73 is mounted on each LED chip 72 (82).
A (83A) and the second transparent plate 73B (8
3B) is provided. In the configuration of FIG. 7, a triangular wave (sawtooth surface) 74 is provided on the emission surface of the first transparent plate, and
In the above configuration, a triangular wave (sawtooth wave surface) 84 is provided on the incident surface of the second transparent plate.

The linear illumination device according to the second embodiment having the above-described structure will be described more specifically.
First, using a die mounter, the LED chip 72 (8
2) is mounted on the circuit board 71 (81) at a predetermined pitch. As the LED chip 72 (82), if a GaP or a high brightness LED chip is required, a quaternary system such as AlGaI is used.
A bare chip of nP or the like molded with resin is used.
In the case of a linear illumination device for reading a color image, LED chips of three colors R (red), G (green), and B (blue) may be alternately arranged and mounted.

Next, on the LED chip 72 (82), a first transparent plate 73A having a triangular wave surface (sawtooth wave surface) 74 on the emission surface by injection molding of a transparent resin such as glass or acrylic or polycarbonate, and the first. The second transparent plate 73B is mounted using an optical method. In this configuration, the first transparent plate 83A and the second transparent plate transparent plate 83B having a triangular wave surface (sawtooth surface) 84 on the incident surface may be mounted by using an optical connection method. The first and second transparent plates 73A (83A) and 73B (83B) have the same length (illumination width) as the circuit board 71 (81) and a short thickness of the LED chip 72 (82). Direction (sub scanning direction)
The width (or the width of the first and second transparent plates) has a dimension of the distance from the LED chip 72 (82) to the illuminated document surface. As the optical mounting method, an acrylate-based highly transparent UV-curable insulating resin is used, and the LED chip 72 is used.
After aligning the first transparent plate 73A (83A) with (82), it is cured by irradiation with ultraviolet light. A highly transparent thermosetting insulating resin such as an epoxy resin may be used instead of the highly transparent ultraviolet curable insulating resin. Further, the second transparent plate 73B (83B) is placed close to the first transparent plate 73A (83A) by a jig, or only the both ends of the first and second transparent plates in the main scanning direction are bonded. You may adhere with an agent. Regarding the transparent resin used for the transparent plate,
Thermosetting resins are suitable for improving the dimensional accuracy of injection molding.

The operation principle and characteristics of the linear illumination device according to the third embodiment thus manufactured will be described. The illumination light output from the LED chip 72 is guided to the other end without being diffused in the sub-scanning direction through the first transparent plate 73A, and main scanning is performed by the triangular wave surface (sawtooth wave surface) 74 on the exit surface. The light is diffused only in the direction, and is further guided to the exit surface through the second transparent plate 73B without being diffused in the sub-scanning direction, and the document surface in the vicinity thereof is illuminated linearly efficiently and without variation. In addition, this configuration has the same effect even when the first transparent plate 83A and the second transparent plate 83B having a triangular wave surface (sawtooth wave surface) 84 on the incident surface are used. At this time, since the illumination light is diffused only in the main scanning direction by the triangular wave surface (sawtooth wave surface) on the incident surface and / or the exit surface, the unevenness of the illuminance of the document surface is small (compared to the conventional LED array. About 1/3) done,
Further, since the illumination light is guided in the sub-scanning direction without being diffused, the document surface can be efficiently illuminated linearly (the illuminance is approximately four times that of the conventional LED array). As a result, the number of LED chips could be reduced to about 1/4 as compared with the conventional LED array.

(Third Embodiment) Next, a third embodiment of the linear lighting device of the present invention will be described with reference to FIG. In FIG. 9, (a) is a side sectional view of an LED array used in the linear lighting device according to the third embodiment,
(B) is a plan view thereof. As shown in FIG. 9, a plurality of LED chips 92 are mounted in a line on the circuit board 91, and the concave reflection surface 23 is formed at the portion where each LED chip 92 is mounted and its periphery.

The linear illumination device according to the third embodiment having the above-described structure will be described more specifically.
First, an insulating resin is applied to the surface of an aluminum substrate to form an insulating layer, and a circuit conductor layer is provided on the insulating layer, whereby the circuit board 91 is manufactured. Further, a concave reflection surface 93 having a predetermined shape is formed on the surface of the circuit board 91 by pressing.
Since the surface of the concave reflection surface 93 is the circuit conductor layer, the light incident on the surface is reflected in a predetermined direction (especially, in order to increase the reflectance, the surface of the concave reflection surface is plated with gold). Next, the LED chip 92 is die-bonded to the concave reflection surface 93 of the circuit board 91 by a die mounter, and further wire-bonded to complete the mounting. Further, various transparent plates used in the first and second embodiments are mounted on the upper surface.

The operation principle and characteristics of the linear illumination device according to the third embodiment thus manufactured will be described. Of the illumination light output from the LED chip 92, the light component emitted forward is directly guided to the transparent plate. The light components emitted laterally and rearward are reflected by the concave reflecting surface 93, travel forward, and are guided to the transparent plate.

In this way, in the conventional LED array, the amount of light used for illumination is changed to that of the conventional LED by utilizing the components of light emitted laterally and backward which did not contribute to the illumination light. It is about twice as much. Further, by changing the shape of the concave reflection surface 93, the illuminance on the document surface and its variation can be freely changed.

[0027]

As described above, according to the present invention, it is possible to provide a linear illuminating device which has a high efficiency of illuminating a document surface and a small illuminance variation, and is small in size and capable of reading an image with high quality and high resolution at a low cost. -A lightweight optical image reading device can be realized.

[Brief description of drawings]

FIG. 1A is a side view showing a basic configuration of a linear lighting device of the present invention. FIG. 1B is a plan view showing a basic configuration of a linear lighting device of the present invention.

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

FIG. 3 is a sectional view of the linear lighting device according to the first embodiment of the present invention.

FIG. 4 is a sectional view of the linear lighting device according to the first embodiment of the present invention.

FIG. 5 is a sectional view of the linear lighting device according to the first embodiment of the present invention.

FIG. 6 is a side view of the linear lighting device according to the first embodiment of the present invention.

FIG. 7A is a side view of a linear lighting device according to a second embodiment of the present invention. FIG. 7B is a cross-sectional view of the linear lighting device according to a second embodiment of the present invention.

FIG. 8A is a side view of the linear lighting device according to the second embodiment of the present invention. FIG. 8B is a sectional view of the linear lighting device according to the second embodiment of the present invention.

FIG. 9 (a) is a side sectional view of an LED array used in the linear lighting device according to the third embodiment of the present invention. (B) An LED array used in the linear lighting device according to the third embodiment of the present invention. Plan view

FIG. 10 is a sectional view of an optical image reading device.

FIG. 11 is a configuration diagram of a conventional LED array.

[Explanation of symbols]

 11 Circuit Board 12 LED Chip 13 Transparent Plate 21 Circuit Board 22 LED Chip 23 Transparent Plate 24 Triangular Wave Front (Sawtooth Surface) 33 Transparent Plate 43 Transparent Plate 53 Transparent Plate 63 Transparent Plate 71 Circuit Board 72 LED Chip 73A First Transparent Plate 73B Second transparent plate 74 Triangular wave surface (sawtooth surface) 81 Circuit board 82 LED chip 83A First transparent plate 83B Second transparent plate 84 Triangular wave surface (sawtooth surface) 91 Circuit board 92 LED chip 93 Concave reflection surface 101 original 102 LED array 103 rod lens array 104 photoelectric conversion element array 111 substrate 112 LED chip

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroki Hongo 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (18)

[Claims] 1. A light emitting device array arranged in a line on a circuit board, and a transparent plate provided on the arranged light emitting device array, wherein the length of the transparent plate is the arrangement of the light emitting device arrays. Is approximately equal to the length of the light emitting element array, and the thickness is about the same as or larger than the width of the light emitting element in the direction orthogonal to the array direction of the light emitting element array, and the width is approximately equal to the distance from the light emitting element array to the document to be irradiated. Linear illumination device, wherein a triangular wave surface having a specific angle and a specific pitch is arranged in an array direction of the light emitting element array on an incident surface of the transparent plate on which light from the light emitting element array is incident. . 2. A light emitting element array arranged in a line on a circuit board, and a transparent plate provided on the arranged light emitting element array, wherein the length of the transparent plate is the arrangement of the light emitting element arrays. Is approximately equal to the length of the light emitting element array, and the thickness is approximately the same as or larger than the width of the light emitting element in the direction orthogonal to the array direction of the light emitting element array, and the width is substantially equal to the distance from the light emitting element array to the document to be irradiated. In the linear illumination device, a linear illumination having a configuration in which a triangular wave surface having a specific angle and a pitch is arranged in an array direction of the light emitting element array on an emission surface of the transparent plate from which the light from the light emitting element array is emitted. apparatus. 3. A light emitting element array arranged in a line on a circuit board, and a transparent plate provided on the arranged light emitting element array, wherein the length of the transparent plate is the arrangement of the light emitting element arrays. Is approximately equal to the length of the light emitting element array, and the thickness is about the same as or larger than the width of the light emitting element in the direction orthogonal to the array direction of the light emitting element array, and the width is approximately equal to the distance from the light emitting element array to the document to be irradiated. In the flat illumination device, triangular wave fronts having a specific angle and pitch are arranged on the transparent plate on both the incident surface on which the light from the light emitting element array is incident and the exit surface on which the light is emitted. A linear lighting device that is lined up in one direction. 4. A light emitting element array arranged in a line on a circuit board, and a transparent plate provided on the arranged light emitting element array, wherein the length of the transparent plate is the arrangement of the light emitting element arrays. Is approximately equal to the length of the light emitting element array, and the thickness is about the same as or larger than the width of the light emitting element in the direction orthogonal to the array direction of the light emitting element array, and the width is approximately equal to the distance from the light emitting element array to the document to be irradiated. In the linear illumination device, the emission surface of the transparent plate is R-shaped in the sub-scanning direction. 5. A light emitting device array arranged in a line on a circuit board, and a transparent plate provided on the arranged light emitting device array, wherein the length of the transparent plate is the arrangement of the light emitting device arrays. Is approximately equal to the length of the light emitting element array, and the thickness is about the same as or larger than the width of the light emitting element in the direction orthogonal to the array direction of the light emitting element array, and the width is approximately equal to the distance from the light emitting element array to the document to be irradiated. In the linear illumination device, the thickness of the transparent plate decreases from the light incident surface to the light emission surface. 6. A light emitting element array arranged in a line on a circuit board, and a transparent plate provided on the arranged light emitting element array, wherein the length of the transparent plate is the arrangement of the light emitting element arrays. Is approximately equal to the length of the light emitting element array, and the thickness is about the same as or larger than the width of the light emitting element in the direction orthogonal to the array direction of the light emitting element array, and the width is approximately equal to the distance from the light emitting element array to the document to be irradiated. In the linear illumination device, the light emitting surface of the transparent plate has a structure inclined with respect to the sub-scanning direction. 7. A light emitting element array arranged in a line on a circuit board, and a transparent plate provided on the arranged light emitting element array, wherein the length of the transparent plate is the arrangement of the light emitting element arrays. Is approximately equal to the length of the light emitting element array, and the thickness is about the same as or larger than the width of the light emitting element in the direction orthogonal to the array direction of the light emitting element array, and the width is approximately equal to the distance from the light emitting element array to the document to be irradiated. In the linear illumination device, a plurality of cavities are formed in the transparent plate to provide regions having different refractive indexes to diffuse light. 8. The linear illumination device according to claim 7, wherein the shape of the cavity is a cylinder having a central axis in the sub-scanning direction. 9. The linear illuminator according to claim 7, wherein the shape of the cavity is a triangular prism having a central axis in the sub-scanning direction, and one of the vertices points vertically to the incident surface of the transparent plate. 10. A light emitting element array arranged in a line on a circuit board, a first transparent plate provided on the arranged light emitting element array, and a light emitting surface of the first transparent plate in proximity to the light emitting surface. A second transparent plate provided with an incident surface thereof, the lengths of the first and second transparent plates being substantially equal to the array length of the light emitting element array, and the first and second transparent plates. Has the same or larger thickness as the width of the light emitting element in the direction orthogonal to the array direction of the light emitting element array, and the sum of the widths of the first and second transparent plates is irradiated from the light emitting element array. In a linear lighting device having a distance substantially equal to the distance to the original, a linear wave structure in which triangular wavefronts having a specific angle and pitch are arranged in the light emitting element array array direction on the light emitting surface of the first transparent plate. Lighting equipment. 11. A light emitting element array arranged in a line on a circuit board, a first transparent plate provided on the arranged light emitting element array, and a light emitting surface of the first transparent plate in proximity to the light emitting surface. A second transparent plate member provided with an incident surface thereof, the lengths of the first and second transparent plates being substantially equal to the array length of the light emitting device array, and the first and second transparent plates. The thickness of the plate is the same as or larger than the width of the light emitting element in the direction orthogonal to the array direction of the light emitting element array, and the sum of the widths of the first and second transparent plates is irradiated from the light emitting element array. In the linear illumination device having a distance substantially equal to the distance to the original, a line having a configuration in which triangular wave fronts having a specific angle and pitch are arranged in the light emitting element array arrangement direction on the light incident surface of the second transparent plate. Lighting device. 12. The emission surface of the second transparent plate is R in the sub-scanning direction.
The linear lighting device according to claim 10 or 11, which is provided with. 13. The linear illumination device according to claim 10, wherein the widths of the first and second transparent plates in the sub-scanning direction become smaller from the light incident surface to the light emitting surface. 14. The linear illumination device according to claim 10, wherein the light emitting surface of the second transparent plate has a structure inclined with respect to the sub-scanning direction. 15. The linear illumination device according to claim 10 or 11, wherein a plurality of cavities are formed in the first and second transparent plates to provide regions having different refractive indexes to diffuse light. . 16. The linear illumination device according to claim 15, wherein the shape of the cavity is a cylinder having a central axis in the sub-scanning direction. 17. The linear illumination device according to claim 15, wherein the shape of the cavity is a triangular prism having a central axis in the sub-scanning direction, and one of the vertices points vertically to the incident surface of the transparent plate. 18. The linear structure according to claim 1, further comprising a concave reflection surface provided in a portion where each light emitting element of the light emitting element array is mounted on the circuit board and in the vicinity thereof. Lighting equipment.