WO2022202232A1

WO2022202232A1 - Light guide body, lighting device, image sensor, and reading device

Info

Publication number: WO2022202232A1
Application number: PCT/JP2022/009520
Authority: WO
Inventors: 和敬網干; 和也保科; 剛志石丸; 重雄橘高
Original assignee: 日本板硝子株式会社
Priority date: 2021-03-22
Filing date: 2022-03-04
Publication date: 2022-09-29
Also published as: JPWO2022202232A1; TW202244584A

Abstract

A columnar light guide body 14 includes: a light incident surface provided to a first end surface 14a; a light emission surface 14c provided to a side surface along the longitudinal direction of the light guide body 14; and a first interface 16a, a second interface 16b, and a third interface 16c provided between the light incident surface and the light emission surface 14c.

Description

Light guides, lighting devices, image sensors and reading devices

The present invention relates to a light guide, lighting device, image sensor and reading device.

Conventionally, there is known a lighting device that uses a light guide (also called a light guide) to illuminate an object in a line. Such an illuminating device allows light to enter from the end of a light guide that is long in at least one direction and propagate in the lengthwise direction of the light guide, and linearly along the lengthwise direction from at least one light exit surface. It has the function of irradiating light.

When a lighting device is configured using a long light guide having a light source arranged at at least one end, light emitted from the light source arranged at the end enters the light guide from the end surface and travels along the length of the light guide. Propagate in direction. Part of the light propagating through the light guide is reflected, scattered, or the like by at least one light reflecting surface along the longitudinal direction, and is emitted from the light exit surface facing the light reflecting surface. However, part of the light that has entered the light guide from the end face where the light source is arranged reaches the light exit surface directly without being reflected or scattered by the light reflection surface and exits. Such a phenomenon is occasionally seen in the vicinity of the light source. In such a lighting device, there are cases where the illumination light has a light amount distribution in which the intensity near the light source is high.

In order to obtain a lighting device with a uniform light amount distribution, for example, the pattern of reflection and diffusion of the light reflecting surface of the light guide is optimized.

In Patent Literature 1, an aperture is formed between an end face on which light from a light source is incident and a light emitting surface (light emitting portion) and a light reflecting surface (light reflecting portion) of a light guide. A technique for reducing the amount of light emitted to the light source and making the distribution of the amount of light uniform is described.

JP-A-2000-48616

In the technique disclosed in Patent Document 1, it is necessary to install a surface-treated aperture and a light shielding member constituting the aperture between the light source and the light emitting portion of the light guide, etc., and the need for separate parts. , there are cases where it is not preferable from the viewpoint of an increase in the unit price of the parts, the complexity of the assembly work, the accuracy of the required arrangement, and the like.

The present invention has been made in view of such circumstances, and its object is to provide a light guide body capable of uniforming the light amount distribution with a relatively simple structure, an illumination device using the light guide body, and an image The object is to provide a sensor and a reader.

In order to solve the above-mentioned problems, a light guide according to one aspect of the present invention is a columnar light guide, comprising: a light incident surface provided at or near an end surface of the light guide; and at least one interface provided between the light entrance surface and the light exit surface.

Another aspect of the present invention is also a light guide. The light guide is a columnar light guide, and includes a cavity for accommodating at least part of a light source provided at or near an end face of the light guide, a light incident surface in the cavity, A light exit surface provided on at least a part of a side surface along the longitudinal direction of the light guide, and at least one interface provided between the light entrance surface and the light exit surface.

Another aspect of the present invention is a lighting device comprising the light guide described above and a light source for causing light to enter the light guide from the light incident surface.

Yet another aspect of the present invention comprises the above-described illumination device that linearly illuminates an object, an erecting equal-magnification lens array that collects reflected light from the object, and an erecting equal-magnification lens array. and a light-receiving element that receives the condensed light.

Yet another aspect of the present invention is a reading device comprising the image sensor described above, a driving mechanism for scanning the image sensor, and an image processing section for processing data read by the image sensor.

It should be noted that any combination of the above constituent elements, and any conversion of the expression of the present invention between methods, devices, systems, etc. are also effective as aspects of the present invention. In addition, the amount of light in this specification represents a concept that includes the strength and size of physical quantities such as light power (work rate) and energy unless otherwise specified. , radiant flux, radiant intensity, radiance, irradiance, and radiant energy. shall include notions encompassing physical quantities such as luminous intensity, luminance, and illuminance.

According to the present invention, it is possible to provide a light guide that can uniformize the amount of light with a relatively simple structure, and an illumination device, an image sensor, and a reader using the light guide.

1(a) to 1(d) are schematic diagrams for explaining a lighting device according to an embodiment of the present invention. 4 is a schematic enlarged cross-sectional view of the vicinity of the light source of the lighting device; FIG. It is a figure which shows a light ray when there is no interface between a 1st end surface and a light-projection surface. It is a figure which shows a light ray when there exists an interface by a recessed part between a light-incidence surface and a light-projection surface. It is a figure which shows one pattern of a light reflection surface. FIG. 10 is a diagram showing another pattern of the light reflecting surface; FIG. 10 is a diagram showing still another pattern of the light reflecting surface; FIG. 4A is a schematic cross-sectional view of a portion of a lightguide including a light source and an interface; FIG. 4A is a schematic cross-sectional view of a portion of a lightguide including a light source and an interface; FIG. 4A is a schematic cross-sectional view of a portion of a lightguide including a light source and an interface; FIG. 4A is a schematic cross-sectional view of a portion of a lightguide including a light source and an interface; FIG. 4A is a schematic cross-sectional view of a portion of a lightguide including a light source and an interface; 13(a) to 13(d) are schematic diagrams for explaining a lighting device according to another embodiment of the present invention. 4 is a schematic enlarged cross-sectional view of the vicinity of the light source of the lighting device; FIG. FIG. 4A is a schematic cross-sectional view of a portion of a lightguide including a light source and an interface; FIG. 4A is a schematic cross-sectional view of a portion of a lightguide including a light source and an interface; FIG. 4A is a schematic cross-sectional view of a portion of a lightguide including a light source and an interface; FIG. 4A is a schematic cross-sectional view of a portion of a lightguide including a light source and an interface; FIGS. 19(a) and 19(b) are diagrams showing an example of a light source in which three LED chips are housed in a case. FIGS. 20(a) and 20(b) are diagrams showing an illumination device including a thin circuit board on which a light source is mounted and a flanged light guide with positioning pins. 21(a) to 21(d) are schematic diagrams for explaining the illumination device according to the first example used in the simulation. FIG. 3 is a diagram showing a light amount distribution (irradiance distribution) along the light exit surface of the lighting device according to the first embodiment; 23 is an enlarged view of L=0 to 25 mm in FIG. 22; FIG. FIGS. 24(a) and 24(b) are schematic diagrams for explaining the illumination device according to the second example used in the simulation. FIG. 10 is a diagram showing a light quantity distribution (irradiance distribution) along the light exit surface of the lighting device according to the second embodiment; 26 is an enlarged view of L=0 to 25 mm in FIG. 25; FIG. 27(a) to 27(d) are schematic diagrams for explaining the illumination device according to the third example used in the simulation. FIG. 11 is a diagram showing a light quantity distribution (irradiance distribution) along the light exit surface of the lighting device according to the third embodiment; 29 is an enlarged view of L=0 to 25 mm in FIG. 28; FIG. FIGS. 30(a) to 30(d) are schematic diagrams for explaining the illumination device according to the fourth example used in the simulation. It is a figure which shows the light quantity distribution (irradiance distribution) along the light-projection surface of the illuminating device based on 4th Example. 32 is an enlarged view of L=0 to 25 mm in FIG. 31; FIG. 1 is a schematic cross-sectional view showing a reading device using an illumination device according to this embodiment; FIG.

Embodiments of the present invention will be described below. The same or equivalent constituent elements, members, and processes shown in each drawing are denoted by the same reference numerals, and duplication of description will be omitted as appropriate. Moreover, the embodiments are illustrative rather than limiting the invention, and not all features and combinations thereof described in the embodiments are necessarily essential to the invention.

1(a) to 1(d) are four schematic diagrams for explaining a lighting device 10 according to an embodiment of the present invention. FIG. 1(a) is a schematic left side view of the lighting device 10. FIG. FIG. 1B is a schematic plan view of the illumination device 10. FIG. FIG. 1(c) is a schematic AA cross-sectional view of the lighting device 10 shown in FIG. 1(a). FIG. 1D is a schematic bottom view of the illumination device 10. FIG.

The illumination device 10 includes at least a light source 12 and a light guide 14. The light guide 14 is a columnar body extending in the Z direction (also referred to as the longitudinal direction). It includes a light reflecting surface 14b, a light emitting surface 14c that is a side surface along the Z direction of the light guide 14 facing the light reflecting surface 14b, and a second end surface 14d that is the other end surface in the Z direction. In this embodiment, the light source 12 is arranged so that part of the light emitted from the light source 12 travels in the Z direction of the light guide 14, or when the symmetry axis of the light emitted from the light source 12 is the optical axis, the optical axis is arranged on the side of the first end surface 14a so that the Z direction is parallel to the . Light emitted from the light source 12 enters the light guide 14 from the first end surface 14a as a light incident surface, and propagates in the light guide 14 in the Z direction while diffusing. Further, although the light source is arranged only on the side of the first end surface 14a in the drawing, the light source may be arranged on the side of the second end surface 14d at the same time.

FIG. 2 is a schematic enlarged cross-sectional view of the vicinity of the light source 12 of the illumination device 10. FIG. In FIG. 2 , light rays emitted from the light source 12 and incident on the light guide 14 are schematically indicated by arrows.

In this embodiment, the first end face 14a of the light guide 14 is formed with a recess 16 recessed in the Z direction. The recess 16 is formed between the light source 12 and the light exit surface 14c on the first end surface 14a. In this embodiment, the recess 16 is rectangular in cross section and in plan view. A plurality of interfaces (a first interface 16a, a second interface 16b, and a third interface 16c) are formed by the recess 16 between the first end surface 14a as the light incident surface and the light emitting surface 14c. The first interface 16 a is the bottom surface of the recess 16 , the second interface 16 b is the bottom surface of the recess 16 , and the third interface 16 c is the top surface of the recess 16 . Although not particularly shown in FIG. 2, the recess 16 may have a pair of interfaces facing each other in the Y direction, or the recess 16 may penetrate the light guide in the Y direction. This embodiment has a recess 16 recessed in the Z direction or the longitudinal direction from the light incident surface of the light guide 14 .

FIG. 3 shows how part of the light emitted from the light source 12 directly travels to the light exit surface 14c when there is no interface between the first end surface 14a and the light exit surface. For example, such light directly directed to the light exit surface 14 c is closely related to the cause of the biased light intensity distribution in which the light intensity is high in the vicinity of the light source 12 .

FIG. 4 shows the light emitted from the light source 12 when there is an interface formed by the recessed portion 16 between the light incident surface (first end surface 14a) and the light exit surface 14c as a result of having the recessed portion recessed in the Z direction from the light incident surface. It shows how part of the emitted light is refracted by the interface in a direction away from the light source 12 . A light ray that causes an increase in the amount of light near the light source 12 when there is no interface (FIG. 3) is refracted in a direction away from the light source 12 when there is an interface (FIG. 4). The concentration of luminous flux in the vicinity is reduced. As a result, it is possible to make the light amount distribution uniform in the irradiation range.

By providing a concave portion with an interface between the light incident surface or the light source and the light emitting surface 14c in the light guide 14 according to the present embodiment, it is possible to provide an illumination device having a uniform light quantity distribution. In addition, the recess includes the concept of a hole, a groove, a recess, etc., and is not limited to a specific cross-sectional shape or planar view shape. Anything that reduces the concentration of light in the vicinity is sufficient.

The light guide 14 will be described in detail below. The light guide 14 is, for example, in the shape of a rod, a rod (like), or a column elongated in one direction. propagate toward The light guide 14 has a cross section perpendicular to the Z direction of a polygon, a substantially circular shape (including an ellipse), or a combination of these shapes, which may include a curved line. The light guide 14 has a plurality of side surfaces that are flat or curved in the longitudinal direction.

A portion of the light within the light guide 14 propagates in the longitudinal direction while repeating reflections on these side surfaces one or more times. At least one of the side surfaces of the light guide 14 is a light exit surface 14c that linearly emits light. The light guide 14 also includes a light reflection surface 14b that faces the light exit surface 14c and reflects at least part of the light propagating through the light guide 14 toward the light exit surface 14c. In other words, the light emitted from the light source 12 enters the light guide 14 from the first end surface 14a of the light guide 14, and part of the light propagates in the light guide 14 in the longitudinal direction while being reflected. A portion of the light propagating through the light guide 14 reaches the light reflecting surface 14b, and a portion of the light reaches the light emitting surface 14c through the light reflecting surface 14b and is emitted from the light emitting surface 14c. It is possible to realize a lighting device that radiates light linearly along the line. The light guide 14 may be integrally formed including the first end surface 14a, the light emitting surface 14c and the light reflecting surface 14b.

For example, when a circumscribed circle is assumed for the cross-sectional shape of the light guide 14 perpendicular to the Z direction, the diameter of the circumscribed circle may be 1 mm to 30 mm, and the length in the longitudinal direction may be 50 mm to 1200 mm. . For example, when the lighting device 10 is used in a whiteboard reading device, the effective length in the longitudinal direction may reach about 1000 mm, and the lighting device 10 may be used in a reading device mounted on a multifunction printer or the like. If used, it may reach an effective longitudinal length of 100 mm to 330 mm.

The light guide 14 is mounted on at least one side of the light guide 14 for the purpose of mounting to a housing or the like, mounting the light source 12 or a circuit board on which the light source 12 is mounted, or mounting other parts. A collar-like flange may be included near the end (for example, the first end surface 14a). For example, the flange may have a surface perpendicular to the longitudinal direction (Z direction) of the light guide 14, and has ancillary structures such as positioning pins and notches for the purpose of improving positioning accuracy with other parts. may be

When the light source 12 or the circuit board on which the light source 12 is mounted is attached near the first end surface 14 a of the light guide 14 , a cavity (recess) is formed in the first end surface 14 a of the light guide 14 so as to include part or all of the light source 12 . or a kind of hollow) may be provided. When the light guide 14 and the light source 12 (for example, a light emitting element) are integrated, the light source 12 main body or part thereof is housed inside the light guide and substantially sealed, so that the delicate part of the light source 12 is protected from the outside air. Since the probability of being exposed to disturbance is reduced, the service life of the parts can be extended, and this is also preferable from the viewpoint of space saving. In the case where the light guide 14 has a cavity for accommodating the light source, the light emitting surface of the light source 12 is substantially perpendicular to the longitudinal direction (Z direction) of the light guide 14, or the optical axis of the light source 12 is aligned with the light guide 12. When the light source 12 is mounted parallel to the longitudinal direction (Z direction) of the cavity, the longitudinal bottom surface of the light guide 14 of the cavity may be the light incident surface. When the surface of the light source 12 from which light is emitted is defined as a light emitting surface, the distance between the light emitting surface of the light source and the light incident surface of the light guide is 0 to 5 mm, and the distance is 0 to 3 mm (excluding 0 mm). ). The interval of 0 mm means that the light emitting surface of the light source and the light incident surface of the light guide are in contact with each other. If the light exit surface of the light source and the light entrance surface of the light guide are separated even by a small amount, the light is refracted by the light entrance surface of the light guide, which can reduce the concentration of the luminous flux near the light source. have a nature.

In addition, from the viewpoint of propagation efficiency and illumination efficiency, it is desirable that the light guide 14 be transparent to the light of the wavelength contained in the illumination light, and that the light absorption by the material constituting the light guide 14 be small. For example, the internal transmittance of the light guide 14 having a thickness of 10 mm at a wavelength of 550 nm may be 90% or more, preferably 95% or more, more preferably 98% or more. Internal transmittance is the transmittance excluding surface reflectance at the entrance and exit surfaces.

The light guide 14 may be made of resin from the requirements of workability and low cost. When the light guide 14 is made of resin, the productivity can be improved by means such as injection molding or cast molding. Moreover, the light guide 14 may be formed by combining resin with metal, ceramics, glass, or the like. For example, the long portion of the light guide 14 is made of transparent resin or glass, and the flange (for attachment to a housing or the like or attachment of the light source 12 or circuit board) is made of metal, ceramics, or non-transparent resin. may Also, when a high-intensity LED or the like is used as the light source 12, ceramics such as alumina having a high heat dissipation property may be used as a material forming the vicinity of the light source 12 because the amount of heat generated is large.

Transparent resins such as cycloolefin-based resins, acrylic-based resins, vinyl chloride-based resins, epoxy-based resins, PET-based resins, PC-based resins, and GPPS-based resins can be used as materials for forming the light guide 14 . . As a method for producing the light guide 14, an injection molding method, an insert molding method, a blow molding method, an extrusion molding method, or the like can be used. Further, the light guide 14 may be produced by combining a metal such as aluminum or duralumin, a ceramic material such as alumina or zirconia, or the like, with the above transparent resin.

Next, the light exit surface 14c of the light guide 14 will be described in detail. The light exit surface 14c is a surface that is provided on at least a part of the side surface of the light guide 14 along the longitudinal direction and emits light from the inside of the light guide 14 to the outside. The light exit surface 14c may have a smooth and flat surface, or may partially include a curved surface depending on the external shape of the object. Further, when the spread of the emitted light is desired, a so-called diffusion surface may be obtained by providing a plurality of minute irregularities on the surface of the light emitting surface 14c, frosting, rubbing, or the like. In addition, the light emitting surface 14c may have an antireflection film or a reflection reducing film formed thereon in order to improve the light transmission efficiency. Anti-reflection coatings and anti-reflection coatings are formed by forming a dielectric multilayer film by sputtering, vacuum deposition, etc., applying a coating with a low refractive index material, or applying a coating with a low refractive index material containing hollow particles or solid particles. can be formed by Further, a light absorption film or a light reflection film may be formed on the light exit surface 14c in order to suppress the emission of light in a part of the wavelength range. The light absorption film may be formed, for example, by coating the light exit surface 14c with a resin containing fine particles or a pigment that absorbs light in a specific wavelength range. The light reflecting film may be a dielectric multilayer film formed by a sputtering method, a vacuum deposition method, or the like.

Next, the light reflecting surface 14b of the light guide 14 will be described in detail. The light reflecting surface 14b is provided with a pattern for appropriately reflecting or diffusing light. The mode of the pattern is not limited to these, but a rough surface is formed in a pattern, a printed pattern such as white or silver that reflects light, a crater with a diameter of about several μm to several mm, or a part of a spherical surface. (visually visible as a polka-dot pattern in a plan view), conversely, convex portions are formed, column-shaped solids such as cylinders, cone-shaped solids, and frustum-shaped solids whose side surfaces are illuminated. A pattern formed in a concave shape over the width of the reflective surface, a convex shape, or a combination thereof may be formed. The pattern on the light reflecting surface 14b may be formed in consideration of the desired light intensity distribution of the illumination light, the length and size of the lighting device, the shape of the light guide 14, the light distribution of the light source 12 used, and the like. Also, for the light reflecting surface 14b, an antireflection film, a reflection reducing film, a light absorbing film, and a light reflecting film can be formed in the same manner as for the light emitting surface 14c, depending on the purpose and intended performance. .

5 to 7 show several patterns of the light reflecting surface 14b. The pattern of the light reflecting surface 14b provided on the light guide 14 is not limited to these, and these patterns may be combined as appropriate.

In FIG. 5, a plurality of substantially circular structures 18 having various sizes in plan view are formed. The substantially circular structure 18 may be concave or convex. As shown in FIG. 5, the structure 18 may have a plurality of concave shapes such as a part of a spherical surface with a diameter of several μm to several mm or a curved surface. The size of the substantially circular structures 18 may vary, for example, as the distance from the light source 12 increases, or they may be arranged at random.

In FIG. 6, a plurality of groove-shaped or ridge-shaped structures 20 are formed in a direction perpendicular to the Z direction. Let grooves be concave and ridges be convex. The grooves and ridges may be formed in a direction perpendicular to the Z direction as shown in FIG. These structures 20 may also vary in pitch or size, or may be arranged at random, for example, as they move away from the light source 12 . For example, groove-shaped or ridge-shaped structures 20 formed far from the light source 12 may have a smaller arrangement pitch than those formed near the light source 12 .

In FIG. 7, the reflective pattern 22 is formed on the light reflecting surface by printing or the like. The individual reflection patterns 22 are, for example, white or silver with high reflectance, and may change color such as brightness and color according to the distance from the light source 12. For example, reflection patterns formed far from the light source 12 The reflectance of 22 may be higher than that formed near the light source 12 . Also, for example, the area of the reflection pattern 22 formed far from the light source 12 may be larger than that of the reflection pattern 22 formed near the light source 12 .

Next, a cover (not shown) that covers the light guide 14 will be described. The illumination device 10 may include a cover that covers at least the rod-shaped portion or the effective range (the range where light is irradiated) of the light guide 14 . The light that has entered the light guide 14 is repeatedly reflected by the side surfaces of the light guide 14 and propagates in the longitudinal direction (Z direction) of the light guide 14 . may be emitted. Since the light emitted from the surfaces other than the light emitting surface 14c becomes a loss, the light emitted from the surface other than the light emitting surface 14c is re-reflected in the light guide 14 and returned to the light guide 14 side. can be considered. The cover may have a structure that has a shape along the shape of the side surface of the light guide 14 on the inside. should be white or silver.

On the contrary, the illumination device 10 can also be considered to have no cover. While the cover is expected to perform its function, it increases the cost of the illumination device 10 and the reading device using it. Therefore, depending on the demand for low cost, it is fully conceivable to propose a lighting device 10 that does not have a cover (coverless). A low cost lighting device 10 can be a selling point. When light propagates through the light guide 14, the function of total reflection by multiple side surfaces is exhibited. Since total reflection or high reflectance appears when the angle of incidence to the surface increases, the rod portion of the light guide 14 is made thinner (the diameter of the circumscribed circle of the cross-sectional shape of the light guide 14 is reduced); By fabricating the light guide 14 from a material having a large refractive index, it is possible to reduce the emission of light from the side surfaces other than the light emitting surface 14c and improve the propagation properties. The effective length of the light guide 14 is a length that can irradiate at least the desired range of the object (specific length of one side of the object) and that can ensure the desired uniformity of light intensity. you can Alternatively, the effective length of the light guide 14 may be 85% to 100% of the total length of the long bar-shaped portion of the light guide 14 . Further, the surface of the light guide 14 other than the light exit surface may be partially or wholly colored with a color such as white or silver that can be expected to improve light reflectivity, although not limited thereto.

Further, when the light guide 14 is fixed to a housing or the like, as will be described later, the structure of the housing is such that it has a surface facing the side surface other than the light emitting surface 14c of the light guide 14, and the surface is made of a reflective material such as white or silver. By having a high percentage color, the function of the cover described above can be compensated.

Next, the interface formed by the concave portion 16 will be described in detail. The light guide 14 according to this embodiment has at least one interface between the light incident surface and the light exit surface 14c. Alternatively, at least one interface is provided on the optical path of light from the light incident surface to the light exit surface 14c. It is a conventional problem of the light guide 14 that the amount of light in the vicinity of the light source 12 is higher than that in other parts (brightness in the vicinity of the light source 12 is brighter than other parts), and the present inventors are working to solve this problem. Among them, the idea is reached that the amount of light in the vicinity of the light source 12 can be reduced by providing an interface between the light source 12 and the light emitting surface 14c that can refract or scatter part of the light emitted from the light source 12. did.

An LED, which is often used as the light source 12, generally has a Lambertian light distribution and emits light up to an angle of 70° or 80°. When such an LED is arranged near the first end face 14a of the light guide 14, part of the light does not propagate in the longitudinal direction of the light guide 14 and directly reaches the light exit surface 14c to be emitted. Since a large number of light rays following the optical path are generated in the vicinity of the light source 12, the amount of light in the vicinity thereof increases. By providing an interface between the light incident surface and the light emitting surface 14c, the light directly directed to the light emitting surface 14c is reflected, refracted, or diffused in a direction away from the light source at the interface between the light guide 14 and the air. , the amount of light in the vicinity of the light source 12 is reduced.

8-12 are schematic cross-sectional views of a portion of a light guide 14 including a light source 12 and an interface, in which the light source 12 is positioned at the end of the light guide and the first end face 14a of the light guide. is the light incident surface.

In FIG. 8, by providing the concave portion 16 in the Z direction from the first end face 14a, the surface (lower side surface) of the concave portion 16 closer to the light reflecting surface is used as the first interface 16a, and the surface of the concave portion 16 recessed in the Z direction. The light guide 14 is shown with the (bottom surface) as the second interface 16b and the surface (upper surface) closer to the light exit surface of the recess 16 as the third interface 16c. The light rays emitted from the light source 12 are refracted in a direction away from the light source 12 by the occurrence of two or three interfaces on the optical path of the light that is emitted from the light source 12 and directed to the light emission surface 14c, so that the light rays are directed to the light emission surface 14c that is closer to the light source 12. can be reduced, thereby reducing the amount of light emitted from the light emitting surface 14c near the light source 12. FIG.

9 and 10 show a light guide 14 in which a plurality of interfaces are formed by providing a so-called wedge-shaped recess 16 in the Z direction from the first end surface 14a. In the light guide 14 shown in FIGS. 9 and 10, the obliquely inclined interface 16d tends to have a critical angle or an angle close to it in relation to the light beam directed from the light source 12 toward the light exit surface 14c. It is possible to increase the number of refracted light rays, and to more effectively reduce the amount of light emitted from the light emission surface 14c closer to the light source 12 .

FIG. 11 shows a light guide 14 in which a plurality of concave portions 16 are arranged in the X direction. According to the light guide 14 shown in FIG. 11, it is possible to increase the number of interfaces that refract the light emitted from the light source 12 toward the light exit surface 14c. It is possible to reduce the amount of emitted light.

FIG. 12 shows a light guide 14 having an inclined surface 16e formed in a portion near the light source 12. FIG. According to the light guide 14 shown in FIG. 12, similarly to the one shown in FIG. 9 and FIG. It is possible to increase the number of light rays refracted at the interface, and it is possible to effectively reduce the amount of light emitted from the light emitting surface 14c near the light source 12. FIG.

The recessed portion 16 including a plurality of interfaces may have a cross section parallel to the X direction (perpendicular to the Z direction) of a polygonal shape such as a triangle or quadrilateral, or may be wedge-shaped or step-shaped. Further, the interface forming the concave portion 16 may be a sliding surface.

A concave portion 16 formed in the longitudinal direction of the light guide 14 from the first end surface 14a may be filled with a black or white resin, or a black or white coating film may be formed on the surface forming the concave portion 16. may

13(a) to 13(d) are schematic diagrams for explaining a lighting device 30 according to another embodiment of the present invention. FIG. 13(a) is a schematic left side view of the illumination device 30. FIG. FIG. 13B is a schematic plan view of the illumination device 30. FIG. FIG. 13(c) is a schematic BB cross-sectional view of the illumination device 30 shown in FIG. 13(a). FIG. 13D is a schematic bottom view of the illumination device 30. FIG. FIG. 14 is a schematic enlarged cross-sectional view of the vicinity of the light source 12 of the illumination device 30. As shown in FIG.

In this embodiment, a cavity 32 is formed in the first end face 14a of the light guide 14. As shown in FIG. If the light source 12 is arranged at or near the end face of the light guide 14, it may be advantageous to provide the end face of the light guide 14 with a cavity 32 for housing the light source. This is because when the light source 12 such as an LED element is housed in the cavity 32, it becomes easy to seal the area near the light source 12 for the purpose of protecting the light source 12 from disturbance.

Also in this embodiment, the recess 16 including a plurality of interfaces (first interface 16a, second interface 16b, third interface 16c) extends from the first end surface 14a of the light guide 14 in the longitudinal direction of the light guide 14, Moreover, it is formed so as to overhang the bottom surface 32a of the cavity 32 . A surface of the light source 12 that faces the bottom surface 32 a of the cavity 32 is an emission surface of the light source 12 . Also, in the illumination device 30 according to this embodiment, it should be noted that the light guide body 14 has a flange 34 including a plane perpendicular to the Z direction in the vicinity of the first end surface 14a. Even when the cavity 32 for housing the light source is provided in the first end surface 14a of the light guide 14 as in the present embodiment, the action and effect are the same as those of the mode in which the cavity 32 is not provided (see FIG. 1). . It can be easily understood that in this embodiment, when light is emitted from the light source 12 centering on the Z direction, the bottom surface 32a of the cavity 32 serves as the light incident surface. The distance between the light exit surface of the light source 12 and the light entrance surface (of the light guide) may be 0 to 5 mm, or may be 0 to 3 mm (excluding 0 mm).

15 to 18 are schematic cross-sectional views of part of a light guide 14 comprising a light source 12 housed in a cavity and a recess containing an interface.

FIG. 15 shows a light guide 14 in which a plurality of interfaces are formed by providing a so-called wedge-shaped recess 16 in the Z direction from the first end surface 14a. In the light guide 14 shown in FIG. 15, the obliquely inclined interface 16d tends to have a critical angle or an angle close to the critical angle in relation to the light beam directed from the light source 12 toward the light exit surface 14c, and the light beam refracted at the interface can be increased, and the amount of light in the vicinity of the light source 12 can be reduced more effectively.

FIG. 16 shows a light guide 14 in which a plurality of concave portions 16 are arranged in the X direction. According to the light guide 14 shown in FIG. 16, it is possible to increase the interface that refracts the light emitted from the light source 12 and directed to the light emitting surface 14c, thereby effectively reducing the amount of light in the vicinity of the light source 12. be able to.

17 and 18 show the light guide 14 provided with the concave portion 16 extending from the bottom surface 32a (light incident surface) of the cavity 32 in the Z direction. Concave portions 16 including interfaces such as these can similarly reduce the amount of light in the vicinity of light source 12 .

Next, the light source 12 will be described in detail. The light source 12 is arranged so that the light emitted from the light source 12 enters the light guide with the end surface of the rod-shaped light guide 14 (or the bottom surface 32a of the cavity 32 for housing the light source, if any) as the light incident surface. It is arranged near the end face of the light guide 14 . The light source 12 may be arranged on or near one end surface (e.g., first end surface 14a) of the light guide 14, or on or near both end surfaces (first end surface 14a and second end surface 14d) of the light guide 14. .

As the light source 12, a light-emitting diode (LED) or a light source (such as a light bulb) that emits light by energizing a filament or the like can be used. In particular, LEDs are particularly effective because they are small, have a low power consumption, emit a large amount of light, and are capable of reproducing various colors. When an LED is employed as the light source 12, for example, it may be a plurality of LEDs including at least three chips that emit light of wavelengths belonging to R (red), G (green), and B (blue). By appropriately tuning the wavelength and intensity, it is possible to emit visually white light, which is suitable as a light source for image sensors and reading devices.

FIGS. 19(a) and 19(b) show an example of the light source 12 in which three LED chips 40 are accommodated within the case 42. FIG. FIG. 19(a) is a schematic front view of the light source 12, and FIG. 19(b) is a schematic CC cross-sectional view of the light source 12 shown in FIG. 19(a). Further, the inside of the case 42 in which the LED chip 40 is arranged may be filled with a transparent resin. The light source 12 made up of such an LED can be regarded as having a light exit surface 42 a on the end face of the case 42 .

As described above, a white LED in which LED chips that emit light of three colors of RGB are integrated may be used as the light source 12 . In addition, by making one or two of the RGB LED chips inactive (do not emit light), one of the three colors other than white or a color obtained by mixing these colors can be emitted. It can also be emitted. In addition, since the light intensity of each RGB LED chip is not constant, considering the strength and weakness, we optimized the arrangement parameters such as the relative position and phase with the light guide according to the performance required of the lighting device. may

Furthermore, as the LED that emits white light, a single-chip type LED containing a blue LED and a resin containing a yellow phosphor, or a single-chip type LED containing a blue LED and a resin containing red/green phosphors, or the like is used. be able to.

In addition, although the mounting type of the LED is not limited to these, a substrate type LED or PLCC (Plastic Leaded Chip Carrier) type LED, which is thin and can be surface mounted, can be used.

The light source 12 made up of these LEDs and the like may be formed on a substrate (circuit board) on which a circuit for driving is formed. The circuit board may be a rigid board or a flexible board. A rigid substrate is suitable for a structure that requires strength because it is rigid. A flexible substrate is thin and inexpensive, and its low rigidity may be overcome by fixing and integrating it with the light guide. Substrate materials include phenolic resins, epoxy resins, polyimide resins, fluorine resins, PRO resins, polyimide films, PET films, etc. In addition, composite substrates containing paper, glass fiber, cloth, etc. may

FIGS. 20(a) and 20(b) show a lighting device 50 comprising a thin circuit board 51 on which a light source 12 is mounted, and a light guide 14 with a flange 34 having positioning pins 52. FIG. FIG. 20(a) is a schematic left side view of the illumination device 50. FIG. FIG. 20(b) is a schematic DD sectional view of the illumination device 50 shown in FIG. 20(a). In the illumination device 50 , a positioning pin 52 protrudes from the flange 34 . A hole 53 through which the positioning pin 52 is inserted is formed in the circuit board 51 , and the light source 12 is arranged in advance at a fixed position with respect to the hole 53 . By using the positioning pin 52 and the hole 53 as described above, the light source 12 can be accurately positioned with respect to the light guide 14 .

The circuit board 51 may include an electrode 54 for power supply for driving the light source. Furthermore, if the circuit board 51 is flexible, it becomes easy to attach it to a housing that constitutes the contact image sensor, to connect and fix it to other circuit boards, and to package it.

Specific examples of the present invention will be described below.

<First embodiment>
By using the light guide 14 having at least one interface between the light incident surface and the light exit surface 14c, how does the variation in the light amount distribution in the Z direction (longitudinal direction of the light guide 14) of the illumination device change? A simulation was conducted to see if there would be any improvement.

FIGS. 21(a) to 21(d) are schematic diagrams for explaining the illumination device 60 according to the first example used in the simulation. FIG. 21(a) is a schematic left side view of the lighting device 60 according to the first embodiment. FIG. 21(b) is a schematic plan view of the illumination device 60 according to the first example. FIG. 21(c) is a schematic EE cross-sectional view of the lighting device 60 according to the first embodiment shown in FIG. 21(a). FIG. 21(d) is a schematic bottom view of the illumination device 60 according to the first example.

It is assumed that the light guide 14 has a quadrangular prism shape extending in the Z direction and has an end face parallel to the XY plane and four side faces perpendicular to the end face. The upper side surface parallel to the YZ plane was used as the light emitting surface 14c, and the opposite lower side surface was used as the light reflecting surface 14b. The material of the light guide 14 has a refractive index of 1.49 at the wavelength used and no absorption. The air around the illumination device 60 has a refractive index of 1. The end face of the light guide 14 is parallel to the XY plane, wg=hg=3.0 mm, the total length Lg=227.5 mm, and the effective length Lef at the light exit surface 14c=225.5 mm.

As shown in FIG. 21, the light guide 14 has a concave portion 16 between the portion of the first end surface 14a where the light source 12 is arranged and the light exit surface 14c. The concave portion 16 has a substantially rectangular parallelepiped shape having two interfaces perpendicular to the X direction and facing each other, one interface perpendicular to the Z direction, and two interfaces perpendicular to the Y direction and facing each other. The concave portion 16 has a dimension hc=0.5 mm in the X direction and a dimension wc=2.4 mm in the Y direction. dc is the maximum distance (depth or overhang amount) in the Z direction of the concave portion 16 from the light incident surface (that is, the first end surface 14a) of the light guide 14, and the value of dc is changed as a parameter described later. I did a simulation.

The light reflecting surface 14b of the light guide 14 has a plurality of concave grooves 62 having a triangular cross section perpendicular to the Z direction arranged in the Z direction. Roughly speaking, the arrangement pitch is large in the area near the light source 12 and the arrangement pitch is small in the area far from the light source 12 . The side surfaces (including the light exit surface 14c) other than the light reflection surface 14b are flat.

On all surfaces of the light guide 14, it was assumed that Snell's law was strictly satisfied at the point where the light rays reached, and that there was substantially no scattering or absorption.

The light source 12 is assumed to be an LED, the light emission surface of the light source 12 is parallel to the XY plane, ws = hs = 1.5 mm, and emits light having a Lambertian light distribution axially symmetric in one direction. shall be. The light source 12 is arranged so that the optical axis is parallel to the Z direction and coincides with the central axis passing through the central portion of the light guide 14 when the axis along which the light distribution is symmetrical is taken as the optical axis. It is arranged on the first end face 14 a of the light guide 14 .

The simulation used TracePro (Ver. 20.4), lighting design, analysis and optimization software from Lambda Research Corporation. The light source 12 emitted a total of 1×10 ⁶ light beams having a wavelength of 550 nm and having the above light distribution. Further, the number of light rays incident on a unit area at a position spaced 4.78 mm in the X direction from the light exit surface 14c of the light guide was counted to obtain the irradiance. These models are intended to show the effectiveness of the recess (interface), and are optimized according to the specifications, including the shape of the light guide and the mode of the light reflecting surface, when mounted on the actual equipment. Note that it should

The light amount distribution of the illumination device 60 according to the first embodiment was evaluated as the irradiance distribution along the light exit surface 14c. 22 and 23, the horizontal axis represents the irradiance at a certain position as the average value of the irradiance over the entire effective length, with the lower limit of the effective length Lef of the light guide 14 on the light source side being 0 and the distance in the Z direction. The divided irradiance ratio is plotted. In this embodiment, the irradiance ratio is preferably 10 or less over the entire effective length, more preferably 6 or less, and even more preferably 4 or less. FIG. 23 is an enlarged view of L=0 to 25 mm in FIG. 22 and 23 show the irradiance ratio of the comparative example without the recess 16 (interface), the irradiance ratio when dc = 0.60 mm, the irradiance ratio when dc = 1.30 mm, and dc = The irradiance ratio at 2.00 mm is shown.

As can be seen from FIGS. 22 and 23, for each overhang amount (dc), the irradiance ratio is substantially constant within a range where the value of Z exceeds approximately 12.5 mm. On the other hand, in the range where the value of Z is 12.5 mm or less, the irradiance ratio is large for those without the concave portion 16 with the interface and for those with excessively large dc, but for those with dc = 0.6 mm The irradiance ratio becomes 6 or less, and lighting characteristics having a good irradiance distribution (light amount distribution) can be expected. When the overhang amount (dc) is within the proper range, part of the light ray is refracted in a direction away from the light exit surface 14c by the bottom surface (second interface 16b) of the recess 16 recessed in the Z direction, and the light ray near the light source 12 is refracted. It is presumed that the increase in irradiance reaching the light exit surface of is suppressed. An overhang amount (depth) dc of the concave portion with respect to the light incident surface is 0.1 mm, preferably 0.3 mm, and more preferably 0.4 mm. Also, dc is 1.0 mm or less, preferably 0.9 mm or less, and more preferably 0.8 mm or less.

<Second embodiment>
24(a) and 24(b) are schematic diagrams for explaining the illumination device 70 according to the second example used in the simulation. FIG. 24(a) is a schematic left side view of a lighting device 70 according to the second embodiment. FIG. 24(b) is a schematic FF sectional view of the illumination device 70 according to the second embodiment shown in FIG. 24(a).

The illuminating device 70 according to the second embodiment differs from the illuminating device 60 according to the first embodiment in that the tip of the concave portion 16 of the light guide 14 in the Z direction is wedge-shaped. etc., including the simulation conditions and method, are the same as those in the first embodiment.

The light quantity distribution of the illumination device 70 according to the second example was evaluated as the irradiance distribution along the light exit surface 14c. 25 and 26, the horizontal axis represents the irradiance at a certain position as the average value of the irradiance over the entire effective length, with the lower limit on the light source side of the effective length Lef of the light guide 14 being 0 and the distance in the Z direction. The divided irradiance ratio is plotted. In this embodiment, the irradiance ratio is preferably 10 or less over the entire effective length, more preferably 6 or less, and even more preferably 4 or less. FIG. 26 is an enlarged view of L=0 to 25 mm in FIG. 25 and 26 show the irradiance ratio of a comparative example without a concave portion (interface), the overhang amount in the Z direction of the concave portion as dc, and the wedge-shaped tip angle at the tip of the concave portion (between the YZ plane and the slope). When the angle) is θc, the irradiance ratio in each case of (dc, θc) = (2.00 mm, 30°), (1.50 mm, 30°), (1.50 mm, 19°) is show.

As can be seen from FIGS. 25 and 26, for each overhang amount (dc), the relative irradiance ratio is substantially constant in the range where the value of Z exceeds approximately 12.5 mm. On the other hand, in the range where the value of Z is 12.5 mm or less, the light intensity increases for those without the concave portion 16 with the interface, but the overhang amount (dc) is 1.50 mm or the tip angle (θc) is 30°, and when it is a smaller angle (19°), an increase in the irradiance ratio is suppressed, and illumination characteristics having a good irradiance distribution (light amount distribution) can be expected. In the second embodiment, when the tip of the concave portion 16 recessed in the Z direction has a wedge shape, the light ray reaches the interface oblique to the Z direction at a large incident angle. It is presumed that the reflectance due to the light source 12 increases, and the irradiance associated with the light rays directly directed to the light exit surface 14c near the light source 12 decreases. θc is 26° or less, preferably 22° or less. θc is 15° or more, preferably 16° or more.

<Third embodiment>
27(a) to 27(d) are schematic diagrams for explaining the illumination device 80 according to the third example used in the simulation. FIG. 27(a) is a schematic left side view of a lighting device 80 according to the third embodiment. FIG. 27(b) is a schematic plan view of a lighting device 80 according to the third embodiment. FIG. 27(c) is a schematic GG sectional view of the illumination device 80 according to the third embodiment shown in FIG. 27(a). FIG. 27(d) is a schematic bottom view of the lighting device 80 according to the third embodiment.

The illumination device 80 according to the third embodiment has a flange 34 near the first end face 14a of the light guide 14. As shown in FIG. The dimension of the flange face parallel to the XY plane is wf=hf=3.50 mm, and the thickness of the flange in the Z direction is tf=2.90 mm. Furthermore, the illumination device 80 according to the third embodiment has a cavity 32 at the first end face 14a of the light guide 14, and the light exit surface of the light source 12 is accommodated in the cavity 32. As shown in FIG. The distance between the light exit surface of the light source 12 and the light entrance surface of the light guide 14 (that is, the bottom surface of the cavity 32) was set to 0.10 mm.

The light amount distribution of the illumination device 80 according to the third example was evaluated as the irradiance distribution along the light exit surface 14c. 28 and 29, the horizontal axis represents the irradiance per unit area at a certain position as the distance in the Z direction with the lower limit of the effective length Lef of the light guide 14 on the light source side being 0, and the irradiance over the entire effective length. is a plot of the irradiance ratio divided by the mean of . In this embodiment, the irradiance ratio is preferably 10 or less over the entire effective length, more preferably 6 or less, and even more preferably 4 or less. FIG. 29 is an enlarged view of L=0 to 25 mm in FIG. 28 and 29 show the irradiance ratio of a comparative example without a recess (interface) and the maximum distance (depth or overhang amount) dc in the Z direction of the recess 16 from the light incident surface of the light guide 14. The respective irradiance ratios are shown for 2.00 mm, 1.30 mm, and 0.60 mm.

As can be seen from FIGS. 28 and 29, for each overhang amount (dc), the irradiance ratio is substantially constant within a range where the value of Z exceeds approximately 12.5 mm. On the other hand, in the range where the value of Z is 12.5 mm or less, each example has an irradiance ratio of less than 6, which is relatively good, and the overhang amount (dc) of 1.30 mm and 2.00 mm is the maximum. The irradiance ratio is also around 1, and it has lighting characteristics with an even better irradiance distribution (light amount distribution).

In the third embodiment, there is a light ray emitted from the flange 34 or its vicinity, particularly near the boundary between the flange 34 and the rod-shaped portion extending in the longitudinal direction of the light guide, and reaching the effective illumination area. A result of a tendency different from that of the first embodiment or the second embodiment, which does not have the When the overhang amount is 1.30 mm or 2.00 mm, it is presumed that it may be difficult to obtain the irradiance for illumination in the range of Z from 0 to 12.5 mm. For example, by shifting the starting point of the effective length of the light exit surface 14c by about 10 mm in the Z direction, it is presumed that a uniform irradiance distribution (light amount distribution) can be obtained over the effective length of the light exit surface 14c.

<Fourth embodiment>
FIGS. 30(a) to 30(d) are schematic diagrams for explaining the illumination device 90 according to the fourth example used in the simulation. FIG. 30(a) is a schematic left side view of a lighting device 90 according to the fourth embodiment. FIG. 30(b) is a schematic plan view of a lighting device 90 according to the fourth embodiment. FIG. 30(c) is a schematic HH sectional view of the illumination device 90 according to the fourth embodiment shown in FIG. 30(a). FIG. 30(d) is a schematic bottom view of the lighting device 90 according to the fourth embodiment.

The illumination device 90 according to the fourth embodiment differs from the third embodiment in that the shape of the tip of the concave portion 16 recessed in the Z direction is wedge-shaped, but other points are the same as in the third embodiment. is.

The light amount distribution of the illumination device 90 according to the fourth example was evaluated as the irradiance distribution along the light exit surface 14c. 31 and 32, the horizontal axis represents the irradiance at a certain position as the average value of the irradiance over the entire effective length, with the lower limit on the light source side of the effective length Lef of the light guide 14 being 0 and the distance in the Z direction. The divided irradiance ratio is plotted. In this embodiment, the irradiance ratio is preferably 10 or less over the entire effective length, more preferably 6 or less, and even more preferably 4 or less. FIG. 32 is an enlarged view of L=0 to 25 mm in FIG. 31 and 32 show the irradiance ratio of a comparative example without a concave portion (interface), the overhang amount in the Z direction of the concave portion as dc, and the tip angle of the wedge shape at the tip of the concave portion (between the YZ plane and the slope). When the angle) is θc, the irradiance ratio in each case of (dc, θc) = (2.00 mm, 30°), (1.50 mm, 30°), (1.50 mm, 19°) is show.

As can be seen from FIGS. 31 and 32, for each overhang amount (dc), the irradiance ratio is substantially constant within a range where the value of Z exceeds approximately 12.5 mm. On the other hand, in the range where the value of Z is 12.5 mm or less, the irradiance ratio is large for those without the concave portion 16 with the interface, but the overhang amount (dc) is 1.50 mm or the tip angle (θc ) is 30° or smaller (19°), the increase in the irradiance ratio is suppressed, and illumination characteristics having a good irradiance distribution (light amount distribution) can be expected. In the fourth embodiment, when the tip of the concave portion 16 recessed in the Z direction has a wedge shape, the light ray reaches the interface oblique to the Z direction at a large angle of incidence. It is presumed that the reflectance due to the light source 12 increases, and the effect of reducing the irradiance associated with the light rays directly directed to the light exit surface 14c in the vicinity of the light source 12 is presumed.

FIG. 33 is a schematic cross-sectional view showing a reading device 100 using the illumination device 10 according to this embodiment. The reading device 100 includes a contact plate 102 on which an object (original) 120 to be read is placed, an image sensor (contact image sensor) 104, a drive mechanism 116 for scanning the image sensor 104, and an image read by the image sensor 104. and an image processing unit 118 that processes data. The reading device 100 can scan part or all of the document 120 to read information on the document 120 by moving the image sensor 104 in a direction parallel to the contact plate 102 using the drive mechanism 116 .

The image sensor 104 includes an illumination device 106 that illuminates the document 120 in a line (long in the direction perpendicular to the paper surface), and an erecting equal-magnification system that collects reflected light from the document 120 with an erecting equal-magnification system. Lens array 108 , light receiving elements 110 arranged in an array for receiving the condensed light, circuit board 112 on which light receiving elements 110 are mounted, illumination device 106 , erect equal-magnification lens array 108 and light receiving elements 110 and a housing 114 that accommodates and fixes the in a predetermined arrangement.

As the lighting device 106, the devices of the above-described embodiments can be used. By using the illumination device according to the above-described embodiment with the uniform light quantity distribution, the reading device 100 with high image quality can be realized.

The present invention has been described above based on the embodiment. It should be understood by those skilled in the art that this embodiment is merely an example, and that various modifications can be made to combinations of each component and each treatment process, and that such modifications are within the scope of the present invention. be.

The present invention can be used for lighting devices, image sensors, and reading devices that use light guides.

12 light source, 10, 30, 50, 60, 70, 80, 90 illumination device, 14 light guide, 16 recess, 32 cavity, 34 flange, 51 circuit board, 52 positioning pin, 53 hole, 100 reader, 104 image Sensor, 110 light receiving element, 106 illumination device, 108 erect equal-magnification lens array, 120 manuscript, 102 contact plate.

Claims

A columnar light guide,
a light incident surface provided at or near an end surface of the light guide;
a light exit surface provided on at least part of a side surface along the longitudinal direction of the light guide;
at least one interface provided between the light incident surface and the light exit surface;
A light guide, comprising:
2. The light guide according to claim 1, further comprising a light reflection surface provided on at least a portion of a side surface along the longitudinal direction of the light guide that faces the light exit surface.
A recess recessed in the longitudinal direction of the light guide from the end face,
3. The light guide according to claim 1, wherein the interface is provided by a surface included in the recess.
The light guide according to claim 3, wherein the recess has a polygonal cross section perpendicular to the longitudinal direction of the light guide.
The light guide according to claim 3, wherein the recess has a wedge-shaped cross section perpendicular to the longitudinal direction of the light guide.
The light guide according to any one of claims 3 to 5, wherein the end face is provided with a plurality of recesses.
The light guide according to any one of claims 1 to 6, characterized in that the end face is provided with a cavity for accommodating at least part of the light source.
A columnar light guide,
a cavity at or near an end face of the light guide for containing at least a portion of the light source;
a light incident surface within the cavity;
a light exit surface provided on at least part of a side surface along the longitudinal direction of the light guide;
at least one interface provided between the light incident surface and the light exit surface;
A light guide, comprising:
The light guide according to any one of claims 1 to 8, further comprising a flange formed in the vicinity of said end face.
a light guide according to any one of claims 1 to 9;
a light source for causing light to enter the interior of the light guide from the light incident surface;
A lighting device comprising:
11. The lighting device according to claim 10, which illuminates the object in a line;
an erecting equal-magnification lens array that collects reflected light from an object;
a light receiving element for receiving light condensed by the erecting equal-magnification lens array;
An image sensor comprising:
an image sensor according to claim 11;
a driving mechanism for scanning the image sensor;
an image processing unit that processes data read by the image sensor;
A reading device comprising: