JP2009086488A - Linear light source device and image sensor module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a linear light source device capable of uniformly emitting light beams of different wavelengths, respectively, and also, reading contents of a reading object with uniform color tone. <P>SOLUTION: The linear light source device B includes: a light guide body 4 linearly extending as a whole, having a light incident surface disposed at the longitudinal end part thereof, a light reflecting surface 4b extending in the longitudinal direction thereof, for reflecting the light made incident from the light incident surface, and a light emitting surface 4c for emitting the light propagating from the light reflecting surface 4b as linear light extending in the longitudinal direction; and three LED chips 23 disposed rightly facing the light incident surface, for emitting the light beams of different wavelengths. The LED chips 23 are mounted on a rectangular light source substrate 20, and arranged side by side on a straight line extending in a direction z" inclined with respect to either side of the light source substrate 20. Viewed from the longitudinal direction, the direction z" is aligned with an emitting direction z' advancing from the light reflection surface 4b toward the light emitting surface 4c. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a linear light source device used in, for example, a flatbed scanner and an image sensor module.

  7 and 8 show an example of a conventional image sensor module. The image sensor module X shown in the figure includes a substrate 91, a light source module 92, a plurality of sensor IC chips 93, and a light guide 94. The substrate 91 is an insulating substrate, and a plurality of sensor IC chips 93 are arranged in the main scanning direction x. The light source module 92 includes an LED chip 92a that emits red light, green light, and blue light. These LED chips 92a are mounted on the lead frame 92b along the horizontal direction, and are covered with a resin package 92c molded.

  The light guide 94 is a rod having a substantially rectangular cross section extending in the main scanning direction x, and is made of, for example, a transparent acrylic resin. The light guide 94 is formed with a light incident surface 94a, a light reflecting surface 94b, and a light emitting surface 94c. Light emitted from the light source module 92 is incident from the light incident surface 94a. The light reflecting surface 94b is a light scattering surface formed along the main scanning direction x by applying a white paint on a part of the bottom surface. The light exit surface 94c is formed by chamfering the upper corner of the rectangular cross section. The light guide 94 is supported by the case 96 via the reflector 95. The light emitted from the LED chip 92 travels through the light guide 94 through the light incident surface 92, and is reflected toward the light exit surface 94c by the light reflecting surface 94b. Linear light extending in the main scanning direction x is emitted from the light emitting surface 94c. By irradiating the original light Dc (reading object) with the linear light, the reflected light is received by the sensor IC chip 93. As a result, the contents described in the document Dc can be captured as electronic data.

  In general, in the reading process of the image sensor module X, the LED chip 92a of the light source module 92 is caused to emit light sequentially, thereby irradiating the reading object with red light, green light, and blue light that are linear light. In synchronization with this sequential irradiation, the light receiving process by the sensor IC chip 93 is performed three times for one place of the document Dc. By superimposing the three electronic data of red, green, and blue obtained by the three light receiving processes, full-color image data representing the contents described in the document Dc is obtained. In addition, a method is also used in which all the LED chips 92a emit light at the same time to irradiate the original Dc with white light, and the red, green, and blue colors are simultaneously received by the dedicated sensor IC chip 93.

  In the conventional configuration, the emission direction from the light reflection surface 94b toward the light emission surface 94c is inclined, whereas the LED chips 92a are arranged along a horizontal direction different from the inclined emission direction. For this reason, the angle formed by the emission direction and the line segment connecting each LED chip 92a and the light reflecting surface 94c is different for each LED chip 92a, and the red light, the green light from the three LED chips 92a, When blue light is scattered and reflected by the light reflecting surface 94b, the amount of light traveling in the emission direction is slightly different. Thus, the tendency for the difference in the amount of light in the emission direction appears more prominently in the portion closer to the light source module 92. In such a case, when reading the content described in the document Dc by any of the above-described reading methods, the portion closer to the light source module 92 in the main scanning direction x is read with a distorted color tone. was there.

JP 2005-217644 A

  The present invention has been conceived under the above circumstances, and is a linear light source device capable of uniformly emitting light of different wavelengths and reading the content of a reading object with a uniform color tone. An object of the present invention is to provide an image sensor module including the linear light source device.

  The linear light source device provided by the first aspect of the present invention extends linearly as a whole, and has a light incident surface provided at an end in the longitudinal direction, the light incident surface that extends in the longitudinal direction, and the light incident surface. A light guide having a light reflecting surface for reflecting the light incident from the light reflecting surface, a light emitting surface for emitting the light traveling from the light reflecting surface as linear light extending in the longitudinal direction, and the light guide A linear light source device provided with a light source module having three LED chips that are provided to face a light incident surface and emit red light, green light, and blue light, the LED chips having two parallel sides Are mounted on a light source substrate having two pairs of sides that are perpendicular to each other, and in an inclined direction inclined with respect to any of the two pairs of sides of the light source substrate in the plane of the light source substrate. Arranged side by side on an extending straight line It is, and the inclined direction, the emission direction toward the light emitting surface from the light-reflecting surface in the light guide body, is characterized in that you have viewed from a direction along said longitudinal direction.

  According to such a configuration, in the normal mounting state, the emission direction defined by the light guide inclined with respect to the vertical direction and the direction in which the LED chips are arranged are aligned. As for the amount of light emitted from the light exit surface after the light emitted from is reflected by the light reflecting surface, the difference is small. Therefore, it is possible to prevent the color tone of the read image from becoming non-uniform due to the non-uniform amounts of the red, green, and blue linear lights.

  In a preferred embodiment of the present invention, each of the LED chips is die-bonded to a single conductive pad formed on the light source substrate. In this case, more preferably, the upper surfaces of the LED chips are connected to conductor parts separated from each other via wires, and the wires extend radially from the LED chips toward the conductor parts. Is provided. According to such a configuration, it is possible to arrange the LED chips as close as possible, which is suitable for making the light amount distribution of the linear light for each color uniform.

  In a preferred embodiment of the present invention, the LED chips are substantially square in plan view, and are arranged so that their diagonals are aligned on the straight line. According to such a configuration, even when the three LED chips are arranged close to each other, the light emitted from the side surface portion of each LED chip is prevented from being absorbed by the adjacent LED chip. Therefore, it is possible to prevent the light emission efficiency of the light source module from being unduly lowered.

  The image sensor module provided by the second aspect of the present invention includes the linear light source device provided by the first aspect of the present invention and the linear light source device arranged along the longitudinal direction and reflected by the reading object. And a light receiving sensor that receives linear light from the linear light source device.

  According to such a configuration, the content of the reading object can be read with a uniform color tone.

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

  Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings.

  1 and 2 show an example of a linear light source device and an image sensor module according to the present invention, and FIGS. 3 and 4 show an example of components of the linear light source device according to the present invention. The image sensor module A of this embodiment includes a substrate 1, a light source module 2, a plurality of sensor IC chips 3, a light guide 4, a lens array 5, and a case 6. As shown in FIG. 2, for example, the image sensor module A reads the description content of the document Dc as image data while being relatively moved in the sub-scanning direction y with respect to the document Dc placed on the document table St. It is configured as. The light source module 2 and the light guide 4 constitute a linear light source device B.

  As shown in FIGS. 1 and 2, the substrate 1 is made of ceramic such as alumina or aluminum nitride, and has a long rectangular shape with the main scanning direction x as the long side direction and the sub-scanning direction y as the short side direction. Yes. The substrate 1 is attached to the lower end of the case 6 and is positioned with respect to the case 6. A plurality of sensor IC chips 3 are mounted on the substrate 1.

  The light source module 2 includes a light source substrate 20, a plurality of terminals 21, a wiring pattern 22, three LED chips 23, a reflector 24, and a translucent member 25. The light source substrate 20 has a rectangular shape, and is made of, for example, ceramic. Alternatively, the light source substrate 20 is made of a composite material of a reinforcing member and a polyimide resin, or a glass epoxy resin. The plurality of terminals 21 are for connecting the light source module 2 to the substrate 1. Each terminal 21 has a clip shape at both ends, and is attached to the light source substrate 20 and the substrate 1 by these clip-shaped portions. The wiring pattern 22 is formed by selectively etching a part of a conductive film made of Cu, for example, and includes a common wiring pattern 22A and a plurality of individual wiring patterns 22B.

  The three LED chips 23 emit red light, green light, and blue light, for example, and are each die-bonded to a single pad 22Aa of the common wiring pattern 22A as shown in FIG. In the present embodiment, as the three LED chips 23, a back anode type is used. According to the backside anode type LED chip 23, it can be expected that the light emission efficiency is increased by the reflection action of the silicon substrate located below the light emitting layer. As shown in FIG. 3, the three LED chips 23 are arranged in series on a straight line L extending in the direction z ″ inclined with respect to any side 20 a to 20 d of the rectangular light source substrate 20. The three LED chips 23 are substantially square in plan view, and are arranged so that their diagonals are aligned on a straight line L. In addition, the three LED chips 23 are connected to the light guide 4. Speaking of the relationship, as shown in FIG. 2, the light guides 4 are arranged so as to be aligned in the emission direction (direction z ′) of the light guide 4 to be described later when viewed from the direction along the main scanning direction x.

  As shown in FIG. 3, the upper surfaces (cathodes) of the three LED chips 23 are connected to the pads 22Ba of the individual wiring patterns 22B via wires W by wire bonding. The three wires W are provided so as to extend radially from the LED chip 23 toward the pad 22Ba. The reflector 24 is made of white resin, for example, and surrounds the three LED chips 23. As shown in FIG. 1, the translucent member 25 is made of, for example, a transparent epoxy resin and covers the three LED chips 23. In addition, in FIG. 3, description of the translucent member 25 is abbreviate | omitted.

  The plurality of sensor IC chips 3 are semiconductor chips each having a rectangular shape in plan view, each having a light receiving portion (not shown), and is an example of a light receiving sensor referred to in the present invention. The plurality of sensor IC chips 3 are mounted on the substrate 1 along the main scanning direction x, and are arranged immediately below the lens array 5 as shown in FIG. The sensor IC chip 3 has a photoelectric conversion function and is configured to output an image signal having an output level corresponding to the amount of received light.

  As shown in FIG. 4, the light guide 4 is a highly transparent member made of an acrylic resin such as PMMA (polymethyl methacrylate), and has a substantially circular cross section. The light guide 4 has a light incident surface 4a (see FIG. 1), a light reflecting surface 4b, and a light emitting surface 4c. As shown in FIG. 1, the light incident surface 4 a is a surface for introducing light from the light source module 2 into the light guide 4, and is configured by one end surface of the light guide 4 in the main scanning direction x. . The light incident surface 4a has a mirror finish in order to prevent light from the light source module 2 from being scattered, and has a gentle convex shape. In the present embodiment, the light guide 4 has a total length of about 230 mm and a diameter of about 4 mm.

  The light reflecting surface 4b directs the light traveling along the main scanning direction x from the light incident surface 4a toward the light emitting surface 4c provided opposite to the light reflecting surface 4b in the direction z ′ (emitting direction). It is a surface for reflecting. As shown in FIG. 4, the light reflecting surface 4 b is provided at the tip of the convex portion 41. The convex portion 41 is a strip having a constant width and a substantially rectangular cross section extending in the main scanning direction x. In the present embodiment, the tip of the convex portion 41 has a flat shape, and the light reflecting surface 4b having a light scattering function is formed by applying white coating to the tip portion. Examples of methods for applying white paint include hot stamping and screen printing. In the present embodiment, the convex portion 41 has a width of about 0.8 mm and a height of about 0.2 mm.

  The light reflecting surface 4b may be formed by forming a fine rough surface instead of the one formed by applying white coating as described above. In this case, the fine rough surface is formed by, for example, forming a part of a mold for forming the light guide 4 by embossing or performing a blasting process on the tip of the convex portion 41 after forming. The In the blast treatment, for example, metal particles having a particle size of about 50 to 200 μm are used.

  The light emitting surface 4c is a surface that emits light toward the document Dc, and extends in the main scanning direction x. From the light emitting surface 4c, linear light extending in the main scanning direction x is emitted. The light guide 4 is attached to the case 6 via a spacer 61. The spacer 61 may be formed integrally with the case 6.

  The lens array 5 is for focusing the light reflected by the document Dc on the plurality of sensor IC chips 3 at the same erect magnification. The lens array 5 includes a block-shaped holder extending in the main scanning direction x and a plurality of lenses arranged along the main scanning direction x. These lenses extend in a direction z whose optical axis is perpendicular to both the main scanning direction x and the sub-scanning direction y.

  The case 6 is made of a synthetic resin and has a substantially block shape extending in the main scanning direction x. The case 6 accommodates the substrate 1, the light source module 2, the plurality of sensor IC chips 3, the light guide 4, and the lens array 5. A rectangular opening 6 a is formed near one end of the case 6 in the main scanning direction x. The reflector 6 of the light source module 2 and a part of the light source substrate 20 are accommodated in the opening 6a. Note that the light source substrate 20 is not limited to the rectangular shape as described above, and for example, a shape having a chamfer at a corner of the rectangle or a shape having a notch in a part of the rectangle is adopted. You can also. In short, it is sufficient that a pair of two parallel sides (20a, 20c, and 20b, 20d) is formed in a substantially rectangular shape including two pairs of sides 20a to 20d that are perpendicular to each other. It can be changed as appropriate for convenience.

  Next, the operation of the linear light source device B and the image sensor module A including the linear light source device B will be described.

  According to this embodiment, the light emitted diagonally downward from the light source module 2 is reflected by the light reflecting surface 4b. In the linear light source device B, the three LED chips 23 are arranged in series along the emission direction (direction z ′) defined by the light guide 4. As a result, red, green, and blue linear light emitted from each of the three LED chips 23 and reflected from the light reflecting surface 4 b and then emitted from the light emitting surface 4 c are located at positions close to the three LEDs 23. Even for the reflected light, the difference in the amount of light is reduced. Therefore, according to the linear light source device B, it is possible to emit red light, green light, and blue light almost uniformly over the entire length region in the main scanning direction x, and the content described in the document Dc can be obtained with a uniform color tone. Can be read.

  With respect to the light source module 2, the sides 20 a to 20 d of the rectangular light source substrate 20 are all along the vertical direction or the horizontal direction when assembled to the case 6. For this reason, when the light source module 2 is assembled as the image sensor module A, the assembling work can be easily performed.

  Three LED chips 23 constituting the light source module 2 are mounted on the wiring pattern 22 of the light source substrate 20. For this reason, the arrangement of the LED chip 23 can be easily changed by changing the shape of the wiring pattern 22. On the other hand, unlike the present invention, for example, in a configuration using a light source module including a resin package molded with a mold, it is necessary to create a new mold in order to change the arrangement of the LED chips. On the other hand, according to the present embodiment, the configuration of the light source module 2 can be easily changed according to the specifications of the scanner in which the image sensor module A is used.

  All of the three LED chips 23 are mounted on a single pad 22Aa, and the wires W connected to the upper surfaces of the LED chips 23 extend radially. According to such a configuration, it is possible to arrange the three LED chips 23 close to each other. As a result, the linear light emitted from the light emitting surface 4c becomes light with a more uniform light amount distribution of red light, green light, and blue light over the entire length region in the main scanning direction x.

  In the present embodiment, the three LED chips 23 having a substantially square shape in plan view are arranged such that their diagonals are aligned on a straight line L. According to this configuration, even if the three LED chips 23 are arranged close to each other, the light emitted from the side surface portion of each LED chip 23 is avoided from being absorbed by the adjacent LED chips 23. Therefore, it is possible to prevent the light emission efficiency of the light source module 2 from being unduly lowered.

  5 and 6 show another example of the light source module constituting the linear light source device according to the present invention. In FIGS. 5 and 6, the same or similar elements as those in the above embodiment are denoted by the same reference numerals as those in the above embodiment, and description thereof will be omitted as appropriate.

  In the light source module 2 ′ shown in FIG. 5, the arrangement posture of the three LED chips 23 is different from the above embodiment. In the present embodiment, the three LED chips 23 are arranged in a posture in which the side surfaces of the adjacent ones face each other. According to such an embodiment, it becomes possible to arrange three LED chips closer together. Therefore, with respect to the linear light emitted from the light emitting surface 4c, the light quantity distribution of red light, green light, and blue light can be made more uniform over the entire length region in the main scanning direction x.

  In the light source module 2 ″ shown in FIG. 6, the three LED chips 23 ″ are of the back cathode type and are mounted on the pads 22Ba of the individual wiring pattern 22B. The upper surfaces (anodes) of the three LED chips 23 ″ are respectively connected to a single pad 22Aa of the common wiring pattern 22A via wires W. When the back surface cathode type LED chip 23 ″ is employed, Compared to the above embodiment, it is possible to cope with the problem by changing the shape of the wiring pattern 22 as necessary and changing the direction of the power source.

  The linear light source device and the image sensor module according to the present invention are not limited to the above-described embodiments. The specific configuration of each part of the linear light source device and the image sensor module according to the present invention can be modified in various ways.

  In the above embodiment, the convex portion provided with the light reflecting surface has a constant width. Instead, the convex portion has a region where the width of the convex portion continuously or stepwise increases as the distance from the light incident surface increases. It is good also as a structure. The amount of light that enters from the light incident surface and reaches various places in the light guide tends to decrease as the distance from the light incident surface increases. According to the above configuration, the amount of light in various places of linear light emitted from the light emitting surface. It is suitable for achieving uniformization.

It is principal part sectional drawing which shows an example of the image sensor module which concerns on this invention. It is sectional drawing which follows the II-II line | wire of FIG. It is a front view which shows an example of the light source module which comprises the linear light source device which concerns on this invention. It is principal part sectional drawing which shows an example of the light guide which comprises the linear light source device which concerns on this invention. It is a front view which shows the other example of the light source module which comprises the linear light source device which concerns on this invention. It is a front view which shows the other example of the light source module which comprises the linear light source device which concerns on this invention. It is a principal part disassembled perspective view which shows an example of the conventional image sensor module. It is principal part sectional drawing which shows an example of the conventional image sensor module.

Explanation of symbols

A Image sensor module B Linear light source device Dc Document (reading object)
L straight line St document table W wire x main scanning direction (longitudinal direction)
y Sub-scanning direction z direction z 'direction (outgoing direction)
z "direction (tilt direction)
1 Substrate 2 Light source module 3 Sensor IC chip (light receiving sensor)
4 Light guide 5 Lens array 6 Case 20 Light source substrate 21 Terminal 22 Wiring pattern 22Aa (Single) pad 22Ba Pad (conductor portion)
23 LED chip 24 Reflector 25 Translucent member 41 Convex part 4a Light incident surface 4b Light reflecting surface 4c Light emitting surface

Claims (5)

A light incident surface provided at a longitudinal end, a light reflection surface that extends in the longitudinal direction and reflects light incident from the light incident surface, and a light reflection surface that extends linearly as a whole. A light guide having a light emitting surface for emitting the traveling light as linear light extending in the longitudinal direction;
A light source module having three LED chips provided facing the light incident surface of the light guide and emitting red light, green light, and blue light;
A linear light source device comprising:
The LED chip is mounted on a light source substrate having two pairs of sides in which pairs of two parallel sides are perpendicular to each other, and any of the two pairs of sides of the light source substrate in the plane of the light source substrate. Are arranged side by side on a straight line extending in the inclined direction inclined with respect to
The linear light source device according to claim 1, wherein the inclined direction and the emission direction from the light reflecting surface toward the light emitting surface of the light guide are aligned as viewed from a direction along the longitudinal direction.   2. The linear light source device according to claim 1, wherein each of the LED chips is die-bonded to a single conductive pad formed on the light source substrate. The upper surface of each LED chip is connected to conductor parts separated from each other via wires,
The linear light source device according to claim 2, wherein the wire is provided so as to extend radially from the LED chip toward the conductor portion.   4. The linear light source device according to claim 2, wherein the LED chips are substantially square in a plan view and are arranged so that diagonals thereof are aligned on the straight line. A linear light source device according to any one of claims 1 to 4, a light receiving sensor arranged along the longitudinal direction and receiving linear light from the linear light source device reflected by a reading object,
An image sensor module comprising:

Images