JP4069416B2 - Light-emitting diode light source unit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a light emitting diode light source unit including a printed wiring board on which a light emitting diode element is surface-mounted.
[0002]
[Prior art]
The light-emitting diode light source unit as described above is used as a light source for facsimiles, scanners, and the like, but various geometric optical devices are used to increase the illuminance. In a conventional light-emitting diode light source unit (see, for example, Patent Document 1), a plurality of light-emitting diode elements are arranged on the substrate in the longitudinal direction of the substrate at predetermined intervals, and white resin portions are formed on both sides of the light-emitting diode element array. The transparent resin portion is formed and disposed between the white resin portions. Each light-emitting diode element is die-bonded to the pattern portion of the substrate, and the upper surface of the light-emitting diode element is wire-bonded to the pattern portion of the substrate. The white resin part is a transparent resin synthesized with a white dye, a resin having a high viscosity and a semi-liquid, and a fast solidification rate, and the two white resin parts are provided on both sides of the light emitting diode element. Closely applied to the longitudinal direction of the substrate (semi-elliptical cross section) and solidified by heat treatment, and one white resin part is a part of the wire bonding wire and the pattern part. It is completely covered and protected. The light emitted from the side surface of the light emitting diode element is reflected by the white resin part, and the reflected light is refracted at the boundary between the transparent resin part and the outside air, and can be focused above the light emitting diode element. Yes.
[0003]
In still another light-emitting diode light source unit (see, for example, Patent Document 2), a circuit board on which light-emitting diode elements are mounted in a straight line is attached to a resin-made mounting base, and a part of the mounting base is part of the circuit board. It extends to the light emitting diode mounting surface, and the tip thereof reaches both sides of the light emitting diode, and an inclined surface is formed on the light emitting diode. The inclined surface is mirror-finished and forms a light reflecting surface of the light emitting diode. This light reflecting surface reflects the light from the lateral surface or the front surface of the light emitting diode element, and contributes to obtaining high illuminance.
[0004]
[Patent Document 1]
JP-A-5-029665 (paragraph number 0010-0013, FIG. 2)
[0005]
[Patent Document 2]
JP-A-6-291939 (paragraph number 0029-0030, FIG. 3)
[0006]
[Problems to be solved by the invention]
According to Patent Document 1, the white resin portion as a reflector is formed by directly applying to a printed wiring board, so that the distance from each light emitting diode element and the shape of the reflecting surface are likely to vary. This is a light emitting diode array. Cause illuminance variation. In addition, the mounting base on which the reflector is formed according to the above-mentioned Patent Document 2 holds and supports the entire printed wiring board, increases the overall structure of the light-emitting diode light source unit, and has a large space restriction. Has a problem that it is difficult to apply.
In view of the above circumstances, an object of the present invention is to provide a light-emitting diode light source unit including a reflector that is compact but has a high rigidity and ensures a reflective surface shape that does not vary in the extending direction of the light-emitting diode array. That is.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, in a light emitting diode light source unit having a printed wiring board for surface mounting light emitting diode elements according to the present invention, a light emitting diode array produced by surface mounting a plurality of light emitting diode elements in rows. A reflector unit composed of a reflector extending along both sides and a frame supporting the reflector is mounted on the printed circuit board, and the frame and the reflector are integrally molded, and the frame The body has a rectangular shape composed of a long side portion and a short side portion, and the long side portion and the short side portion have a larger cross-sectional area than the reflector, and the reflector covers the length of the light emitting diode array. Both ends of which are connected to the short side of the frame surrounding the reflector, and a wiring run for the light emitting diode element. Is laid so as to be positioned in a gap between the reflector and the long side portions, a bonding wire connecting the wiring lands and the light emitting diode element is across the reflector.
[0008]
In this configuration, a reflector unit including a reflector firmly supported by a frame is mounted on a printed wiring board so that the reflector is along the extending direction of the LED array on both sides of the LED array. By doing so, the light beam emitted from the light emitting diode element can be efficiently directed toward the object to be illuminated. This reflector is separate from the printed circuit board and can be manufactured with high processing accuracy. Moreover, since the reflector which has a relatively small cross section and is likely to cause a problem in rigidity is firmly supported by the frame body in the present invention, the rigidity thereof is sufficient. Furthermore, since it can be handled together with the frame as a reflector unit at the time of mounting, the mounting operation is simple and accurate.
Even if the overall structure is compact, the higher the rigidity, the easier the surface mounting work. Therefore, in the reflector unit of the present invention, the frame body is laid out so as to surround the reflector. Specifically, for example, the frame is arranged in a rectangle, and the reflector is arranged between the short sides facing each other. Moreover, integrally forming the frame and the reflector contributes to a reduction in manufacturing cost. In addition, the wiring land for the light emitting diode element is laid out so as to be located in a gap between the frame and the reflector, and the bonding wire connecting the light emitting diode element and the wiring land extends over the reflector. By being stretched, there is an advantage that the space of the printed wiring board can be effectively used.
[0009]
Since the reflector according to the present invention is surface-mounted on the printed wiring board as a reflector unit integrated with the frame body, the operation is easier than mounting the reflector alone, but to further improve the mounting accuracy. In addition, in a preferred embodiment of the present invention, a reflector reference hole is provided in the frame of the reflector unit, a substrate reference hole is provided in the printed wiring board, and the reflector reference hole is used as the substrate reference hole. By aligning, the reflector is positioned relative to the light emitting diode array.
[0010]
As a material for the reflector, a liquid crystalline polymer having high reflectivity and high heat resistance is preferable.
[0011]
Other features and advantages of the present invention will become apparent from the following description of embodiments using the drawings.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
FIGS. 1 and 2 are an external view and an exploded view, respectively, of a film scanner that employs a light emitting diode light source unit according to the present invention. The film scanner includes a light source device A, a film carrier unit B, a lens unit C, a photoelectric conversion unit D, and a control device E. The developed photographic film F supported by the film carrier unit B is irradiated with the light from the light source device A, and the light transmitted through the photographic film F is guided to the photoelectric conversion unit D by the lens unit C. The photoelectric conversion unit D In the CCD (Charge Coupled Device) type line sensor built-in, the image of the photographic film F is acquired as digital signal image data corresponding to the three primary colors of R (red), G (green), and B (blue). The light intensity that fluctuates due to scratches and dust on the photographic film F is converted into a digital signal by infrared light (IR) and acquired as image data for scratch correction.
[0013]
The light source device A has a light emitting diode array LED (a green light emitting diode array to be described later) configured by arranging a plurality of light emitting diode elements in a row in the main scanning direction so as to generate three primary colors and infrared light as will be described later. G-LED, blue light-emitting diode array B-LED, and red / infrared light-emitting diode array R1, R2, and IR-LED). The film carrier unit B reciprocates the photographic film F in the sub-scanning direction and uses a fill carrier unit B corresponding to a plurality of types of photographic films F such as 135 size, 240 size and 120/220 size films. It is configured so that it can be exchanged. The lens unit C functions to form an image of the photographic film F supported on the film carrier B on the CCD line sensor built in the photoelectric conversion unit D, and expands in accordance with the number of pixels to be acquired. A zoom-type optical lens is provided so that the rate can be changed. The photoelectric conversion unit includes a three-line CCD line sensor corresponding to the three primary colors R (red), G (green), and B (blue), and a one-line CCD line sensor that senses infrared light (IR). Built in.
[0014]
As shown in FIGS. 2 and 3, the light source device A includes an upper case 10 made of a resin molded product and a lower case 20 made of an aluminum alloy. The upper case 10 has a structure in which a flat upper table portion 11 and a box portion 12 projecting to the lower surface side of the upper table portion 11 are integrally formed. The cover 13 is provided. The lower case 20 integrally includes a bottom wall portion 21 and a side wall portion 22, and a plurality of fins 23 are integrally formed as heat radiators on the outer surfaces of the bottom wall portion 21 and the side wall portion 22. The light source device A includes a pair of fans 24 that supply cooling air to the fins 23.
[0015]
An opening 11A having a set width is formed in the upper table portion 11 of the upper case 10 in a posture along the main scanning direction so as to irradiate light rays upward, and a cylindrical condenser lens 30 is formed inside the opening 11A. In addition, an ND filter 31 is disposed at a position below the condensing lens 30. The ND filter 31 is slidably supported in a state in which the ND filter 31 is disposed below the condenser lens 30 and in a state in which the ND filter 31 is accommodated in the cover 13, and an electromagnetic solenoid type electric actuator 14 provided in the cover 13. It is linked to a crank mechanism 15 that is operated by a driving force from the. The ND filter 31 is disposed below the main condenser lens 30 when adjusting the CCD of the photoelectric conversion unit D, thereby reducing the amount of light from the light source device A and adjusting the photoelectric conversion unit D with an appropriate amount of light. To do.
[0016]
Further, inside the box portion 12, a dichroic first mirror M1 and a cylindrical first lens Le1 are provided at a lower position on the extension of the optical axis L of the condenser lens 30, and a first mirror M1 is provided. Is provided with a dichroic second mirror M2 at a position adjacent to the second mirror M2, a cylindrical second lens Le2 for guiding the light beam to the reflection side of the second mirror M2, and a cylindrical beam for guiding the light beam to the transmission side of the second mirror M2. A third lens Le3 of the mold is provided.
[0017]
A light emitting diode array G-LED made up of a plurality of chip-like green light emitting diode elements 9 arranged linearly in the main scanning direction with respect to the bottom wall portion 21 of the lower case 20, and linear in the main scanning direction. And a first printed wiring board P1 provided with a light emitting diode array B-LED composed of a plurality of blue light emitting diode elements 9 arranged in a chip shape, and a first printed circuit board P1 with respect to the side wall portion 22 of the lower case 20. Second printed wiring board on which light-emitting diode arrays R1, R2, and IR-LEDs formed by arranging red, second red, and infrared light-emitting diode elements 9 in this order in a straight line in the main scanning direction are formed. P2 is provided. Then, by combining the upper case 10 with the lower case 20 in an overlapping manner, the green light emitting diode array G-LED is disposed at the focal position of the first lens Le1, and the focal position of the second lens Le2. The blue light-emitting diode array B-LED is arranged at the center, and the first red, second red, and infrared light-emitting diode arrays R1, R2, and IR-LED are arranged at the focal position of the third lens Le3.
[0018]
The green light emitting diode element 9 has a wavelength of 400 to 480 nm, the blue light emitting diode element 9 has a wavelength of 520 to 560 nm, a first red light emitting diode element 9 and a second red light emitting diode element 9; The combined wavelength is 620 to 750 nm, and the infrared light emitting diode element 9 has a wavelength of 830 to 950 nm. The first mirror M1 has a performance of transmitting light having a wavelength (400 to 480 nm) from the green light-emitting diode element 9 and reflecting light having a wavelength other than this, and the second mirror M2 is a first mirror M2. The red light, the second red light, the infrared light, and the light rays having wavelengths (620 to 750 nm and 830 to 950 nm) from the light emitting diode element 9 are transmitted, and the light rays from the blue light emitting diode element 9 (520 to 560 nm) are reflected. The one with the performance is used.
[0019]
With this configuration, the light from the green light-emitting diode array G-LED is transmitted to the condensing lens 30 through the first mirror M1 while being collimated by the first lens Le1, and is emitted into the blue light-emitting diode array B. -The light beam from the LED is reflected by the second mirror M2 in the state of being collimated by the second lens Le2, and then reflected by the first mirror M1 to be guided to the condensing lens 30, and the first red, first The light rays from the two red and infrared light emitting diode arrays R1, R2, and IR-LED are reflected by the first mirror M1 after passing through the second mirror M2 in the state of being collimated by the third lens Le3. Are guided to the condenser lens 30, and these light beams are condensed by the condenser lens 30 onto the scanning region of the photographic film F in the film carrier unit B.
[0020]
As is apparent from FIG. 4, it corresponds to the light emitting diode array LED (generic name of the above-described three types of light emitting diode arrays) formed on the printed wiring board P (generic name of the first printed wiring board P1 and the second printed wiring board P2). In order to determine the focal position of the lens Le (a general term for the above-described three types of lenses), a positioning pin 17 protrudes from the box portion 12 of the upper case 10 and comes into contact with the lens Le. Is formed. Further, a reference surface 19 that contacts the printed wiring board P is formed in a portion of the box portion 12 that faces the bottom wall surface 21 and the side wall surface 22. At both end portions of the lens Le (first lens Le1, second lens Le2, third lens Le3), support pieces 33 that come into contact with the positioning surface 18 are integrally formed, and the pin 17 is engaged. A screw hole 36 through which the pin hole 34 and the fixing screw 35 penetrate is formed. The structure for supporting the condenser lens 30 on the upper case 10 is the same as the structure for supporting the lens Le on the box portion 12 except that the positioning pins 17 are not used, and the support formed on both ends of the condenser lens 30. A screw 35 that is formed in the piece 33 and is inserted into the screw hole 36 is screwed into the upper case 10.
[0021]
The first printed wiring board P1 is also provided with a pin hole portion 40 with which the pin 17 engages. The first printed wiring board P1 is fixed to the bottom wall portion 21 with screws 41, and the second printed The wiring board P2 is fixed to the side wall portion 22 by screws 41 (see FIG. 2). When supporting the first and second printed wiring boards P1 and P2 with respect to the bottom wall portion 21 and the side wall portion 22 of the lower case 20, silicon grease is applied to improve the thermal conductivity at the boundary surface. Has been.
[0022]
With the configuration described above, when the first, second, and third lenses Le1, Le2, and Le3 are supported with respect to the box portion 12, the pin 17 is inserted into the pin hole portion 34 of the support piece 33 at the lens end portion. In this state, the lenses Le1, Le2, and Le3 are supported with high accuracy with respect to the box portion 12 by tightening the screws 35 inserted into the screw holes 36. Thereafter, the upper case 10 and the lower case 20 are connected in an overlapping manner, whereby the pins 17 formed on the bottom surface side of the box portion 12 are supported by the corresponding bottom wall portion 21 of the first printed wiring board P1. The relative position of the lower case 20 with respect to the upper case 10 is determined at the same time as entering the pin hole 40 and determining the relative position with the first printed wiring board P1, and as a result, the third lens Le3 and the second printed wiring board are determined. The relative position with respect to P2 is also determined.
[0023]
The printed wiring board P uses a relatively thick aluminum base material 45 as a material having high thermal conductivity, and the chip-like light emitting diode element 9 described above is mainly used for the printed wiring board P. A plurality of chip resistors CR are provided along the forming direction of the light emitting diode elements 9 while being arranged in a line along the scanning direction. This chip resistor CR has the same resistance value and the same size, and transfers heat generated when the chip resistor CR is energized to the printed wiring board P and eventually to the light emitting diode element 9. Thus, the temperature distribution of the plurality of light emitting diode elements 9 is made uniform at an appropriate temperature.
[0024]
Hereinafter, the structure of the printed wiring board P will be described in detail with reference to FIG. FIG. 5 shows the manufacturing procedure of the printed wiring board P and the surface mounting procedure of the parts. However, this procedure shows an example and does not limit the present invention.
As described above, the printed wiring board P forms an insulating ceramic layer 46 by coating the surface of the aluminum base material 45 with a ceramic material (FIGS. 5A and 5B). A printed wiring W made of a copper foil film or a gold foil film or a surface mounting pad X is formed on the upper surface (FIG. 5C), and a resist film made of an insulating resin is formed on the upper surface of the printed wiring board P. 47 is formed (FIG. 5D).
[0025]
The light-emitting diode element 9 and the reflector unit 50 including the rectangular frame 51 and the reflector 52 that are integrally formed are surface-mounted on the printed wiring board P thus manufactured. In this embodiment, alignment by pins and holes is also adopted when the reflector unit 50 is mounted on the printed wiring board P. For this reason, reflector reference holes 50a are provided at two locations on the frame 51 of the reflector unit 50, and substrate reference holes 40a are also provided at corresponding positions on the printed wiring board P. By inserting a common pin 50b into both the holes 50a and 40a, the reflector unit 50 can be reliably mounted at a predetermined position on the printed wiring board P (FIG. 5 (e)). Thereby, the reflecting surface 52a of the reflector 52 of the reflecting unit 50 is accurately opposed to the light emitting diode element 9 mounted on the surface mounting pad X.
[0026]
Finally, a bonding wire 61 is stretched between the electronic component such as the light emitting diode element 9 and the printed wiring W (FIG. 5 (f)). Thereby, the basic structure of the light-emitting diode light source unit is completed. In addition to the aluminum, the substrate 45 can be a copper plate or a metal alloy. Of course, it is also possible to use a resin material.
[0027]
FIG. 6 shows an external view before the surface mounting of the light emitting diode element 9 and the reflector unit 50 on the printed wiring board P, FIG. 7 shows an external view after the surface mounting, and FIG. 8 shows a plan view after the surface mounting. However, as is apparent from FIG. 6 in particular, a blank area having a larger area than the surface mount pad X is left so that the ceramic layer 46 is exposed around the surface mount pad X for the light emitting diode element 9. Thus, a resist 47 is formed. The ceramic layer 46 is formed by coating a ceramic material on the aluminum substrate 45, and its reflection characteristic is much higher than that of the resist 47 and the like. Therefore, the ceramic layer 46 exposed to the outside of the surface mounting pad X functions as a back reflection surface of the light emitted from the light emitting diode element 9, and emits light together with the reflection surface 52a of the reflector unit 50 described below. This contributes to increasing the illuminance on the object to be illuminated (here, photographic film F) by the diode array LED. In order to reinforce this purpose, a coating method in which a ceramic having particularly excellent reflection characteristics is selected as an insulating layer material to be coated on the surface of the metal substrate 45 or a mirror surface is obtained as much as possible. It is desirable to choose.
[0028]
The reflector unit 50 shown in FIG. 9 is made of a liquid crystalline polymer, and includes a rectangular frame 51 and two reflectors 52 each having a long side 51a and a short side 51b facing each other. ing. The reflector 52 having a substantially right-angled cross section has a length sufficient to cover the length of the light emitting diode array LED formation direction (main scanning direction), and both ends of the reflector 52 surround the reflector 52. It is connected to the opposing short side part 51b of the frame 51 on the rectangular shape. The long side portion 51a and the short side portion 51b have a larger cross-sectional area than the reflector 52 and are rectangular, so that the rigidity is high and the reflector 52 can be firmly supported. The reflector 52 is formed with an inclined reflecting surface 52a that faces the light emitting diode element 9 in a mounted state, and the inclined reflecting surface 52a transmits light from the light emitting diode element 9 to the illumination object. Reflect toward you.
[0029]
As is apparent from FIG. 10 which is a cross-sectional view of a region where the light emitting diode element 9 is mounted on the printed wiring board P, the bonding wire 61 from the light emitting diode element 9 to the printed wiring (wiring land) W jumps over the reflector 52. Is provided. For this reason, the wiring land W connected by the light emitting diode element 9 and the bonding wire 61 is laid out so as to be positioned in a gap formed between the reflector 52 and the frame 51 of the mounted reflection unit 50. Incidentally, in this embodiment, the height of the reflector 52 is about 1 mm, and the distance between the reflector 52 and the light emitting diode element 9 is about 0.5 mm.
[0030]
As is apparent from FIGS. 7 and 8, the printed wiring W includes a light emitting wiring portion 53 that supplies power to the light emitting diode element 9, a heating wiring portion 54 that supplies power to the chip resistor CR, and a temperature measuring means. A measurement wiring portion 55 for applying a voltage to the chip-like thermistor S is formed. The light-emitting diode array LED is provided with a plurality of units, one unit of which seven chip-shaped light-emitting diode elements 9 are electrically connected in series. In the light emitting wiring portion 53, a power terminal 53a for supplying power to one unit of the light emitting diode element 9 and a relay terminal 53b formed independently along the arrangement direction of the light emitting diode elements 9 are formed. . The heating wiring portion 54 is formed with terminals 54 a that are connected to the electrodes CRa at both ends of the chip resistor CR by solder 60. Further, the measurement wiring part 55 is formed with terminals 55a connected to the electrodes Sa at both ends of the thermistor S by solder 60.
[0031]
In the above-described embodiment, the holes 34 and 40 and the pins 17 are used to position and fix the printed wiring board P and the lens Le to the box portion 12 of the upper case 10, and the reflector unit 50 is positioned on the printed wiring board P. The holes 40a and 50a and the pins 50b are used for the alignment and fixing. However, the reflector unit 50 is lengthened, and the reflector unit 50 is aligned and fixed with the common pins together with the printed wiring board P and the lens Le. May be. Further, when the reflector unit 50 is mounted on the printed wiring board P, the hole-pin alignment method is not adopted, and the reflection of the substrate reference hole 40a of the printed wiring board P or the reflection unit 50 is simply used as a positioning reference point. It is also possible to use the body reference hole 50a.
[0032]
The light-emitting diode light source unit according to the present invention can be applied to a light source of an electrostatic copying machine or a flat bed scanner, for example, in addition to the above embodiment.
[Brief description of the drawings]
1 is an external view of a film scanner employing a light-emitting diode light source unit according to the present invention. FIG. 2 is an exploded view of the film scanner according to FIG. 1. FIG. 3 is a cross-sectional view of the film scanner according to FIG. FIG. 5 is a schematic view showing a manufacturing procedure for a light-emitting diode light source unit according to the present invention. FIG. 6 is an external view before a light-emitting diode element or reflector unit is surface-mounted on a printed wiring board. External view after light-emitting diode elements and reflector units are surface-mounted on a printed wiring board [FIG. 8] Plan view after light-emitting diode elements and reflector units are surface-mounted on a printed wiring board [FIG. 9] Reflector unit Perspective view [FIG. 10] Cross-sectional view of a region where a light-emitting diode element is mounted on a printed wiring board
9 Light emitting diode 40a Substrate reference hole 45 Base material 46 Ceramic layer 47 Resist 50 Reflector unit 50a Reflection reference hole 50b Alignment pin 51 Frame 52 Reflector 52a Reflecting surface 61 Bonding wire LED Light emitting diode array P Printed wiring board W Pattern wiring (Wiring land)
X Surface mount pad

Claims (3)

In a light emitting diode light source unit comprising a printed wiring board on which a light emitting diode element is surface-mounted,
A reflector unit comprising a reflector extending along both sides of a light-emitting diode array created by surface-mounting a plurality of light-emitting diode elements in a row and a frame supporting the reflector is mounted on the printed wiring board Has been
The frame body and the reflector are integrally formed, the frame body has a rectangular shape composed of a long side portion and a short side portion, and the long side portion and the short side portion have a larger cross-sectional area than the reflector. The reflector has a length sufficient to cover the length of the light-emitting diode array, and both ends thereof are connected to the short side of the frame surrounding the reflector, and
A wiring land for the light emitting diode element is laid out so as to be located in a gap between the long side portion and the reflector, and a bonding wire connecting the light emitting diode element and the wiring land straddles the reflector. A light-emitting diode light source unit.   A reflector reference hole is provided in the frame of the reflector unit, and a substrate reference hole is provided in the printed wiring board. The reflector is configured to emit light by aligning the reflector reference hole with the substrate reference hole. The light-emitting diode light source unit according to claim 1, wherein the light-emitting diode light source unit is positioned with respect to the diode array. Emitting diode light source unit according to claim 1 or 2, wherein the reflector is made of liquid crystalline polymer.

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