JP2012186036A - Light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light source device that restrains variations in an initial distribution of light-distributing in spite of repetitive turning-on and off of a light source while permitting thermal expansion of a light guide.SOLUTION: In the light source device including the rod-shaped light guide mounted on a base and a pair of light source parts arranged on both ends of the light guide, an elastic body which pushes from at least one light source part to the other light source part and pushes the pair of light source parts to the light guide is arranged on the base.

Description

  The present invention relates to a light source device used as an illumination light source of an image reading apparatus used for a facsimile, a copying machine, an image scanner, a barcode reader, and the like.

  Conventionally, an image reading apparatus such as a facsimile is known as a light source apparatus described in Patent Document 1.

FIG. 7 is an explanatory diagram of the light source device 101 according to the related art.
Fig.7 (a) is the perspective view which decomposed | disassembled each member. FIG. 7B is a cross-sectional view orthogonal to the longitudinal direction of the light guide 131 in a state where the members of FIG.

The light source device 101 has a cylindrical light guide 131, light sources 121 and 122 opposed to both ends in the longitudinal direction of the light guide 131, and a support for fixing the light sources 121 and 122 and holding the light guide 131. And a body 142.
The light sources 121 and 122 include light emitting diodes.
Light from the light sources 121 and 122 is incident from both ends of the light guide 131 and is sequentially reflected by reflection surfaces provided on the outer surface of the light guide 131. Since this reflection surface is provided along the longitudinal direction of the light guide, the light from the light sources 121 and 122 is sequentially reflected along the longitudinal direction of the light guide 131, and the exit surface of the light guide 131. The linear light is emitted from. On the support 142, the lamp house 111 surrounding the light guide 131 is disposed. The lamp house 111 is provided with an opening 112, and linear light from the light guide 131 is emitted from the opening 112.

JP 09-163079 A

  As in Patent Literature 1, light sources 121 and 122 are provided at both ends of the light guide 101, a light-transmitting resin is used as a member constituting the light guide 101, and light from the light sources 121 and 122 is passed through the light guide 131. If the light sources 121 and 122 are repeatedly turned on and off, the light distribution of the linear light from the light guide 131 may change. Specifically, this will be described with reference to FIG.

FIG. 8 is a diagram showing the process of expansion / contraction of the light guide 131. FIG. 8A shows a state in which the light sources 121 and 122 are turned off, and FIG. Is turned on and the light guide 131 is expanded, and FIG. 8C shows a state where the light sources 121 and 122 are turned off and the light guide 131 contracts.
When the material of the light guide 131 is a translucent resin, the light guide 131 is heated and expanded by absorbing heat radiated from the light sources 121 and 122. Since the support 142 allows the light guide 131 to expand, the support 142 does not have a portion to which the light guide 131 is fixed. When the light guide 131 expands, the portion serving as a fulcrum is the support 142. Not determined against. Therefore, for example, as shown in FIG. 8B, when the fulcrum F1 when the light guide 131 is expanded is located at the center in the longitudinal direction of the light guide 131, the light guide 131 uses the center as a fulcrum. Swells left and right. Next, even when contracting, the portion serving as the fulcrum is not fixed with respect to the support base. For this reason, for example, as shown in FIG. 8C, the fulcrum when the light guide 131 contracts is the end of the light guide 131 in the longitudinal direction (on the left side of the light guide 131 in FIG. 8C). When positioned at the end), the light guide 131 contracts with the end serving as a fulcrum F2. At this time, the fulcrum F1 at the time of expansion and the fulcrum F2 at the time of contraction are different, so that the light guide 131 in FIG. The ratio of the distance L71 to the distance L72 from the other end surface of the light guide 131 to the other light source 122 (L71: L72) after the light guide 131 in FIG. The distance L91 from one end face of the light source to the one light source 121 and the distance L92 from the other end face of the light guide 131 to the other light source 122 (L91: L92) do not match. For this reason, the light source device 101 according to the related art repeatedly expands and contracts by repeatedly turning on and off, and the light distribution changes when the fulcrum during expansion and the fulcrum during contraction do not match. It is presumed that the problem of having occurred.

  In order to prevent the light distribution from changing, it is conceivable to fix both ends of the light guide 131. However, the light guide 131 is not allowed to expand, leading to eccentricity of the light guide 131. .

  As described above, if the light distribution changes when the light guide is repeatedly turned on and off, the illuminance on the reading medium, for example, original paper is partially insufficient, or the color balance during color reading is reduced. The problem of lack of.

  Therefore, an object of the present invention is to provide a light source device that suppresses a change in light distribution at the beginning of lighting even when the light source is repeatedly turned on and off while allowing thermal expansion of the light guide.

A light source device according to a first aspect of the present invention is a light source device including a rod-shaped light guide mounted on a base and a pair of light source units disposed at both ends of the light guide. An elastic body that is pressed from the light source portion toward the other light source portion and presses the pair of light source portions against the light guide is provided on the base.
The light source device according to a second invention is characterized in that, in the first invention, the one light source unit and the base are provided with a guide mechanism for guiding the movement of the light guide in the longitudinal direction. And
A light source device according to a third invention is characterized in that, in the first or second invention, the other light source unit is fixed to the base.
A light source device according to a fourth invention is characterized in that, in the first or second invention, an elastic body that presses from the other light source part toward the one light source part is provided on the base. To do.
A light source device according to a fifth invention is the light source device according to the first or second invention, wherein the pair of light source parts are each a light emitting diode and a reflecting surface for condensing light from the light emitting diode toward the light guide. A cup-shaped member provided on the inner surface of the light-guiding member, wherein the cup-shaped member is brought into contact with the light guide and the light emitting diode is separated from the end surface of the light guide.

The light source device according to the first aspect of the present invention can suppress a change in the light distribution in the longitudinal direction of the light guide body even if the light source unit is repeatedly turned on and off due to the above characteristics.
In the light source device according to the second invention, due to the above characteristics, even when the light source unit is repeatedly turned on and off, the optical axis of the light emitted from one light source unit is the length of the light guide unit when the light guide unit expands. It can suppress shifting with respect to a direction.
In the light source device according to the third invention, due to the above feature, when the light guide body is inflated and contracted, the other light source part serves as a fulcrum, and even if the light source part is repeatedly turned on and off, in the longitudinal direction of the light guide body, Changes in the light distribution can be suppressed.
The light source device according to a fourth aspect of the present invention has an elastic body that presses from one light source unit toward the other light source unit when the light guide body expands and contracts, and one light source unit from the other light source unit. The position where the force with the elastic body that presses toward the balance is a fulcrum, and even if the light source unit is repeatedly turned on and off, changes in the light distribution can be suppressed in the longitudinal direction of the light guide.
The light source device according to the fifth aspect of the present invention can change the light distribution by maintaining the predetermined distance between the light guide and the light emitting diode even if the light source unit is repeatedly turned on and off due to the above characteristics. While suppressing, it can suppress that a light guide is overheated by a light emitting diode.

It is explanatory drawing of the light source device which concerns on a 1st Example. It is explanatory drawing of the light source device which concerns on a 1st Example. It is explanatory drawing of the light source device which concerns on a 2nd Example. It is explanatory drawing of the light source device which concerns on the 3rd and 4th Example. It is explanatory drawing of an experimental result. It is explanatory drawing of an experimental result. It is explanatory drawing of the light source device which concerns on the past. It is explanatory drawing of a subject

FIG. 1 is an explanatory diagram of a light source device 1 according to a first embodiment of the present invention.
1A is a cross-sectional view taken along the longitudinal direction of the light guide 3, and FIG. 1B is a cross-sectional view orthogonal to the longitudinal direction of the light guide 3 (of FIG. 1A). It is AA sectional drawing.

  The light source device 1 includes a rod-shaped light guide 3, a pair of light source portions 2 a and 2 b disposed at both ends of the light guide 3, and extends along the longitudinal direction of the light guide 3 and mounts the light guide 3. The base 5 is provided with an elastic body 7 that presses from the one light source 2a toward the other light source 2b and presses the pair of light sources 2a and 2b against the light guide 3. It is done.

The rod-shaped light guide 3 includes projecting portions 35 projecting toward the light source portions 2a and 2b at both ends, and an annular recess 37 is provided on the periphery of the projecting portion 35. 2b.
Further, the light guide 3 is provided with an emission surface 32 having a semicircular cross section, and the emission surface 32 is provided along the longitudinal direction of the light guide 3.
As the member constituting the light guide 3, a member that transmits visible light is used. For example, acrylic resin, polycarbonate resin, cyclic polyolefin resin such as COC and COP, polyolefin resin such as olefin maleimide copolymer, polyester-based transparent A translucent resin such as a resin is used.

A diffusion sheet 4 extending along the longitudinal direction of the light guide 3 is disposed on the opposite side of the light guide 3 from the emission surface 32.
A base 5 is disposed on the back side of the diffusion sheet 4, and the diffusion sheet 4 is sandwiched between the light guide 3 and the base 5.

The base 5 extends along the longitudinal direction of the light guide 3, includes a bowl-shaped surface 51 on which the diffusion sheet 4 is placed, and places the light guide 3 through the diffusion sheet 4.
The light guide 3 includes a holding projection 36 between the emission surface 32 and a surface placed on the bowl-shaped surface 51 of the base 5, and the holding projection 36 is a longitudinal portion of the light guide 3. It is provided extending along the direction.
The base 5 includes a holding projection 52 that contacts the holding projection 36 of the light guide 3, and the holding projection 36 of the light guide 3 and the holding projection 52 of the base 5 are, for example, The light guide 3 is clamped by a light guide holding spring 6 such as a leaf spring, and the light guide 3 is restrained from moving and rotating in the orthogonal direction in the longitudinal direction.

The base 5 is longer than the light guide 3, and places one light source unit 2 a at one end in the longitudinal direction, and in the longitudinal direction behind the one light source unit 2 a. An end wall portion 53 extending vertically is provided. Further, the end wall portion 53 of the base 5 includes, for example, a columnar guide protrusion 531 that protrudes toward the one light source portion 2 a and extends along the longitudinal direction of the light guide 3.
The base 5 fixes the other light source part 2b at the other end in the longitudinal direction via a fixing means (not shown).
As the members constituting the base 5, resin members such as engineer plastics such as PC, PBT, PPS and super engineer plastics are used, and Al, Mg, Al, Mg, Si, Al, Cu are used. Metal members such as aluminum extruded materials and cast materials are used. In particular, in order to cool the light guide 3 and reduce the expansion amount of the light guide 3, it is preferable to employ a metal member for the portion of the base 5 on which the light guide 3 is placed.

The pair of light source units 2 a and 2 b surrounds the light emitting diode 21 provided on the substrate 22, a hemispherical sealing body 23 that seals the light emitting diode 21, and the periphery of the sealing body 23 and the substrate 22. And an annular cup-shaped member 24 provided on the top.
The cup-shaped member 24 is provided with a reflection surface 241 that reflects light from the light-emitting diode 21 on its inner surface and makes it incident on the end surface of the light guide 3. Further, the front end portion of the cup-shaped member 24 is in contact with the concave portion 37 of the light guide 3 so that the light emitting diode 21 and the end surface of the light guide 3 are separated by a predetermined distance. Note that the cup-shaped member 24 may have a reflecting surface 241 formed on the inner surface, or may be a member that reflects light, such as white resin, and cools the light guide 3. From the viewpoint, it is preferable to use a metal member such as aluminum whose inner surface is mirror-finished.
A heat radiator (also referred to as a heat sink) 25 for cooling the light emitting diode 21 is provided on the back surface of the substrate 22.
In one light source unit 2 a, for example, a cylindrical guide hole 252 extending along the longitudinal direction of the light guide 3 is provided behind the radiator 25, and a predetermined distance is provided in the guide hole 252. With the guide gap 255 formed, the guide protrusion 531 provided on the base 5 is inserted.

  An elastic body 7 is provided between the heat radiating body 25 of one light source unit 2a and the end wall portion 53 of the base 5, and one end of the elastic body 7 is fixed to the end wall portion 53. The other end is inserted into an elastic body insertion hole 251 provided in the heat dissipating body 25 of one light source unit 2a, and is pressed from one light source unit 2a toward the other light source unit 2b.

In the light source device 1 shown in FIG. 1, the case where the light sources 2a and 2b are repeatedly turned on and off will be described with reference to FIG.
2A is an explanatory diagram of the light source device 1 when the light guide 3 is not expanded when the light is off, and FIG. 2B shows the light source units 2a and 2b of FIG. It is explanatory drawing of the light source device 1 which was made to light and the light guide 3 expanded.
In FIG. 2, the same components as those shown in FIG.

As shown in FIG. 2A, when the light source sections 2a and 2b are turned off and the light guide 3 is not heated, the light guide 3 is not expanded.
In the light source device 1 of the present invention, the elastic body 7 fixed to the base 5 is pressed from the one light source part 2a toward the other light source part 2b in a state where the other light source part 2b is fixed to the base 5. is doing. A light source gap 54 is provided between the cup-shaped member 24 of the one light source unit 2a and the base 5, so that the cup-shaped member 24 of the one light source unit 2a is guided by the pressing of the elastic body 7. The light emitting diode 21 of the one light source unit 2 a is pressed against the concave portion 37 of the body 3 and is separated from the one end surface 33 of the light guide 3 by a predetermined distance. Further, the light guide 3 receives a pressure from the elastic body 7 via the one light source 2a and is pressed toward the other light source 2b. As a result, the cup-shaped member 24 of the other light source unit 2 b is pressed against the concave portion 37 of the elastic body 7, and the light emitting diode 21 of the other light source unit 2 b is separated from the other end surface 34 of the light guide 3 by a predetermined distance. Separated.

When the light source units 2a and 2b are turned on by a power source (not shown), light enters from both ends of the light guide 3 from the pair of light source units 2a and 2b, and the incident light enters the light guide 3 inside. Light is guided, reflected by the diffusion sheet 4 and emitted from the emission surface 32, and linear light along the longitudinal direction of the light guide 3 is obtained.
The light guide 3 is heated and expanded by heat from the pair of light source parts 2a and 2b. In the light source device 1 according to the first embodiment, since the other light source part 2b is fixed to the base 5, the light guide 3 expands with the other light source part 2b as a fulcrum. Specifically, the light guide 3 expands toward the one light source unit 2a with the concave portion 37 in contact with the other light source unit 2b as a base point. At this time, as shown in FIG. 1B, the light guide 3 is fixed to the base 5 with the peripheral surface excluding the emission surface 32, so that the light guide 3 is orthogonal to the longitudinal direction of the light guide 3 (see FIG. 1B). In a state in which movement in the direction 1 (b) is restricted in the Y direction or the Z direction, the slider 5 moves toward the one light source 2 a while sliding with respect to the holding projection 52 of the base 5 and the diffusion sheet 4.

One light source part 2a receives the expansion of the light guide 3 and moves toward an end wall part 53 provided behind one light source part 2a. At this time, one of the light source portions 2a is slid by the columnar guide hole portion 252 with respect to the columnar guide projection portion 531 so that the guide gap 255 which is a predetermined distance when the light source is turned off is reduced. As a result, the movement of the light guide 3 in the direction perpendicular to the longitudinal direction (the Y direction and the Z direction in FIG. 2) is restricted, and the movement of the light source 3 in the longitudinal direction of the light guide 3 is guided. The
The elastic body 7 is reduced by the movement of the one light source unit 2a while being pressed from the one light source unit 2a toward the other light source unit 2b. One light source unit 2a and the other light source unit 2b continue to be pressed against the concave portion 37 of the light guide 3 by receiving the pressure applied by the elastic body 7 even when the light guide 3 is expanded. The state where one light source unit 2a and the other light source unit 2b are separated by a predetermined distance is maintained.

If it demonstrates using a specific numerical example, the light guide 3 will be formed, for example with an acrylic resin, the full length will be 340 mm, and when it will be heated to 60 degreeC with the heat from the light source parts 2a and 2b, the expansion | swelling will be carried out. The amount L2 is 1 to 2 mm.
For example, if the base 5 does not expand due to the heat from the light source units 2a and 2b, the elastic body 7 receives the expansion of the light guide 3 from the length L1 when extinguished, and the length L3 is 48 to 49 mm (L1-L2).

  Then, when the light sources 2a and 2b are turned off, the light guide 3 is cooled, and the state shown in FIG. 2B returns to the state shown in FIG. That is, even if the light sources 2a and 2b are repeatedly turned on and off, the state of FIG. 2B and the state of FIG. 2A are repeated, so that the light guide 3 expands no matter how many times it is turned on. The light distribution of the linear light obtained in the state hardly changes.

  Thus, the light source device 1 according to the first embodiment is an elastic body that presses from the one light source part 2a toward the other light source part 2b in a state where the other light source part 2b is fixed to the base 5. 7 is provided on the base 5, when the light sources 2 a and 2 b are turned on, the light guide 3 expands in the direction of the one light source 2 a using the other light source 2 b as a fulcrum, and the elastic body 7 By reducing the size, the light guide 3 is allowed to expand, and it is possible to prevent the position of the light guide 3 from changing when the light sources 2a and 2b are turned on any number of times. Even when the light source units 2a and 2b are turned on, the elastic body 7 presses the light source unit 2a from the one light source unit 2a toward the other light source unit 2b, so that the pair of light source units 2a and 2b acts on the light guide 3. No matter how many times the light source units 2a and 2b are turned on, the light emitting diode 21 of the light source units 2a and 2b and the light guide 3 are maintained at a predetermined distance. Accordingly, the light source device 1 according to the first embodiment can suppress the change in the light distribution even when the light guide 3 is expanded even when the light source device 1 is repeatedly turned on and off.

  Further, the light source device 1 according to the first embodiment includes a guide mechanism including a guide hole 252 of one light source unit 2 a and a guide protrusion 531 provided on the base 5. When the light guide 3 is expanded, the guide mechanism guides the movement of the one light source part 2 a to move in the longitudinal direction of the light guide 3, and the one light source part 2 a is guided with respect to the longitudinal direction of the light guide 3. The light source 3a is prevented from shifting to an undesired position, and the longitudinal direction of the light guide 3 expanded with the optical axis of the light source 2a. Can be prevented from shifting and the light distribution of the light guide 3 can be prevented from changing.

In the light source device 1 according to the first embodiment, since the light guide 3 is restricted from moving in the direction perpendicular to the longitudinal direction, when the light guide 3 expands, the light guide device 1 is turned off. It is expanded along the longitudinal direction of the light body 3, the light guide body 3 is suppressed from being eccentrically decentered, and the light distribution of the light guide body 3 can be prevented from changing.
That is, the holding projection 52 of the base 5, the holding projection 36 of the light guide 3, and the light guide holding spring 6 change the expansion direction of the light guide 3 in the longitudinal direction of the light guide 3. It can be made to function as a guide mechanism for the light guide 3 that guides in the direction.

  Further, in the light source device 1 according to the first embodiment, the cup-shaped member 24 of the pair of light source units 2 a and 2 b and the light guide 3 come into contact with each other, and the light emitting diode 21 is separated from the end face of the light guide 3. Thereby, when the output of the light emitting diode 21 is large, the light guide 3 can be prevented from being excessively heated by the light emitting diode 21, and the end surface of the light guide 3 can be prevented from being deformed.

  As described above, in the first embodiment, the other light source unit 2b is fixed to the base 5. However, in the second embodiment, the other light source unit 2b is fixed to the base 5. This will be explained with an example that does not.

FIG. 3 is an explanatory view of the light source device 1 according to the second embodiment of the present invention, and is a cross-sectional view along the longitudinal direction of the light guide 3.
In FIG. 3, the same components as those shown in FIGS. 1 and 2 are denoted by the same reference numerals.

3 shows that the other light source 2b is not fixed to the base 5, the elastic body 7 is provided behind the other light source 2b, and the other light source 2b and the base 5 are also provided. It differs from FIGS. 1 and 2 in that a guide mechanism is provided.
As a description of the second embodiment of FIG. 3, the description of the parts common to those in FIGS. 1 and 2 will be omitted, and the different parts will be described.

As shown in FIG. 3, one light source unit 2a has the configuration described in FIG. 1, and the other light source unit 2b has the same configuration as the one light source unit 2a.
Thereby, the 1st elastic body 7 is provided behind one light source part 2a, and the 2nd elastic body 7 is provided behind the other light source part 2b.
In the case of the configuration as in the second embodiment, when the light sources 2a and 2b are turned on, the fulcrum of expansion of the light guide 3 is a position where the forces of the first and second elastic bodies 7 are balanced, For example, when the pressing forces of the two elastic bodies 7 are equal, the center of the light guide 3 is the fulcrum. For this reason, also in the second embodiment, since the fulcrum of the light guide 3 is determined at a predetermined position, even when the light sources 2a and 2b are repeatedly turned on and off, the position when the light guide 3 is expanded changes. This can be suppressed. And while pressing the 1st and 2nd elastic body 7 toward the other light source part 2b from one light source part 2a, by pressing toward the one light source part 2a from the other light source part 2b, A pair of light source units 2a and 2b are pressed against the light guide 3, and the light emitting diode 21 and the light guide 3 of the light source units 2a and 2b are separated from each other by a predetermined distance no matter how many times the light sources 2a and 2b are turned on. The maintained state is maintained. Accordingly, the light source device 1 according to the second embodiment can suppress the change in the light distribution even when the light guide 3 is expanded even when the light source device 1 is repeatedly turned on and off.

  The light source device 1 according to the second embodiment is guided so that the movement of one light source unit 2a is moved in the longitudinal direction of the light guide 3 by providing a guide mechanism in one light source unit 2a. The light source part 2a can be prevented from moving in a direction perpendicular to the longitudinal direction of the light guide 3, and the other light source part 2b is provided with a guide mechanism, so that the other light source part 2b moves. Is guided to move in the longitudinal direction of the light guide 3, and the other light source part 2 b can be prevented from moving in a direction orthogonal to the longitudinal direction of the light guide 3. Thus, the optical axis of one light source unit 2a and the longitudinal direction of the expanded light guide 3 are suppressed from shifting, and the optical axis of the other light source unit 2b and the length of the expanded light guide 3 are suppressed. It is possible to suppress the deviation from the direction, and to prevent the light distribution of the light guide 3 from changing.

  The guide mechanism is not limited to the one shown in FIGS. 1 to 3 as long as it can guide in the longitudinal direction of the light guide 3, and may be the one shown in FIG. 4, for example.

  FIGS. 4A and 4B are explanatory views of the light source device 1 according to the third embodiment, and the same components as those shown in FIGS. 1 and 2 are denoted by the same reference numerals. .

  4 (a) and 4 (b) show that the guide protrusion 531 is not provided on the end wall 53, the guide protrusion 531 has a T-shape, and a guide hole. 1 and FIG. 2 in that the shape of the portion 252 is T-shaped, but the guide mechanism including the guide protrusion 531 and the guide hole 252 is provided when the light source portions 2a and 2b move. The movement of the light guide 3 in the direction perpendicular to the longitudinal direction can be restricted, and the movement of the light guide 3 in the longitudinal direction can be guided. As described above, the guide mechanism applied to the present invention can regulate the movement of the light guide 3 in the longitudinal direction and can guide the movement of the light guide 3 in the longitudinal direction. If there are, various changes can be made to the shape and position.

  FIG. 4C is an explanatory diagram of the light source device 1 according to the fourth embodiment, and the same components as those shown in FIGS. 1 and 2 are denoted by the same reference numerals.

  FIG. 4C is different from FIGS. 1 and 2 in that the light source portions 2a and 2b are provided with guide protrusions 255 and the base 5 is provided with guide holes 532. However, the guide mechanism composed of the guide protrusion 255 and the guide hole 532 can regulate the movement of the light guide 3 in the direction orthogonal to the longitudinal direction when the light source portions 2a and 2b move, and The movement of the light guide 3 in the longitudinal direction can be guided. As described above, if the light guide 3 can be controlled to move in the direction perpendicular to the longitudinal direction and can guide the movement of the light guide 3 in the longitudinal direction, the light source units 2a and 2b and the base can be used. Various changes can be made to the relationship between the protrusion and the hole of the guide mechanism of the base 5.

An experiment was conducted to confirm the effect of the present invention.
In the experiment, the light source device 1 shown in FIG. 1 as the present invention and the light source device 101 shown in FIG. 7 as a comparative example were prepared.
The specifications of the light source devices 1 and 101 are shown below.

As the light emitting diodes provided in the light source units 2a and 2b, those emitting white light were adopted, and a copper substrate was used as a substrate on which the light emitting diodes 21 were provided.
The light guides 3 and 131 are made of acrylic resin as a material, the diameter of the cylindrical portion is φ6 mm, and the length in the longitudinal direction is 340 mm.
The diffusion sheet 4 is made of PET resin, and this PET resin is provided with a diffuse reflection surface using a light stabilizer TiO ₂ on the surface in contact with the light guides 3 and 131. The diffusion sheet 4 has a length of 335 mm and a thickness of 0.2 mm.
The material of the base 5 is polycarbonate.

In the experiment, a driving current within the maximum rated range is supplied to the light emitting diode 21, and the light guide 3 absorbs heat from the light sources 2a and 2b, and the light is turned on for about 30 minutes until the expansion of the light guide 3 is saturated. The light distribution was measured when the expansion of the light guide 3 was saturated (first measurement).
After the measurement, the light sources 2a and 2b were turned off for about 30 minutes until the light guide 3 was contracted to the original length of 340 mm.
After the light guide 3 contracted, the light sources 2a and 2b were turned on again for 30 minutes, and the light distribution was measured when the expansion of the light guide 3 was saturated (second measurement).
In the comparative example, after the light guide 3 contracts after the second measurement, the light sources 2a and 2b are turned on again for 30 minutes, and the light distribution is measured when the expansion of the light guide 3 is saturated. (3rd measurement).

For the measurement, the light receiving part of the illuminometer is arranged at a position 8 mm above the emission surface 32 of the light guide 3 (position equivalent to the original document surface of the actual machine), and a glass with a thickness of 3 mm is attached to the lower part of the illuminometer. Using the center of the light guide 3 in the longitudinal direction as a reference, the measurement was performed within a total range of 400 mm, that is, 200 mm toward the one end surface 33 and 200 mm toward the other end surface 34.
In this measurement range of 400 mm, the diffusion sheet 4 is disposed on the back side of the light exit surface 32 of the light guide 3.

  FIG. 5 is a measurement result of the comparative example, and the light distribution is not consistent in any of the first to third measurement results, and the light guide is used for the second and third measurements. The light distribution that is line-symmetric with respect to the center of 131 has been lost.

FIG. 6 shows the measurement results of the present invention. Both the first and second measurement results have substantially the same light distribution, and both are line-symmetric with respect to the center of the light guide 3. A light distribution is obtained.
This is because, in the light source device 1 according to the present invention, in addition to the fulcrum when the light guide 3 is expanded, the elastic body 7 that presses from one light source part 2a toward the other light source part 2b is provided. This is because the base 5 is provided. That is, in the light source device 1 according to the present invention, the fulcrum at the time of expansion of the light guide 3 is determined, and the expansion is allowed by the elastic body 7, so that the light source units 2a and 2b can be repeatedly turned on and off. It is possible to suppress the change of the position at the time of expansion. Further, when the elastic body 7 is pressed from one light source part 2a toward the other light source part 2b, the pair of light source parts 2a and 2b are pressed against the light guide 3, and the light source parts 2a and 2b are turned on / off. Even if the above is repeated, the distance between the light emitting diode 21 and the light guide 3 when the light source units 2a and 2b are turned on can be kept at a predetermined distance. Accordingly, it is considered that the light source device 1 according to the present invention can suppress the change in the light distribution even when the light source units 2a and 2b are repeatedly turned on and off.

DESCRIPTION OF SYMBOLS 1 Light source device 2a One light source part 2b The other light source part 21 Light emitting diode 22 Board | substrate 23 Sealing body 24 Cup-shaped member 241 Reflecting surface 25 Radiator 251 Elastic body insertion hole 252 Guide hole 254 Guide gap 255 Guide Protruding portion 3 Light guide 32 Emission surface 33 One end surface 34 Other end surface 35 Protruding portion 36 Retaining portion 37 Recessing portion 4 Diffusion sheet 5 Base 51 Gutter-like surface 52 Retaining portion 53 End wall portion 531 Guide protrusion 532 Guide hole 54 Light source gap 6 Light guide holding spring 7 Elastic body

Claims (5)

In a light source device comprising a rod-shaped light guide placed on a base, and a pair of light source portions disposed at both ends of the light guide,
An elastic body that is pressed from at least one light source section toward the other light source section and presses the pair of light source sections against the light guide is provided on the base. The light source device according to claim 1, wherein a guide mechanism that guides movement of the light guide body in a longitudinal direction is provided on the one light source unit and the base. The light source device according to claim 1, wherein the other light source unit is fixed to the base. The light source device according to claim 1, wherein an elastic body that presses toward the one light source unit from the other light source unit is provided on the base. Each of the pair of light source units includes a light emitting diode, and a cup-shaped member provided on its inner surface with a reflection surface that condenses light from the light emitting diode toward the light guide,
The light source device according to claim 1, wherein the cup-shaped member is in contact with the light guide, and the light emitting diode is separated from an end surface of the light guide.

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