TW202244584A - Light guide, lighting device, image sensor and reading device - Google Patents

Abstract

This invention relates to a light guide, a lighting device, an image sensor and a reading device. The light guide is cylindrical, and includes a light input surface provided on the first end face, a light output surface provided on a side surface along the longitudinal direction of the light guide, and a first interface, a second interface and a third interface located between the light input surface and the light output surface.

Description

Light guide, lighting device, image sensor and reading device

The invention relates to a light guide, an illuminating device, an image sensor and a reading device.

Conventionally, an illuminating device for linearly illuminating an object using a light guide (also referred to as a light guide) has been known. The function of this type of lighting device is to allow light to enter from one end of the long light guide in at least one direction and propagate in the long side direction in the light guide, and at the same time make the light appear along the long side direction from at least one light exit surface. Linear irradiation.

If the lighting device is constituted by using a long light guide with a light source disposed at at least one end, the light emitted from the light source disposed at the end enters the end surface of the light guide and propagates in the longitudinal direction. A part of the light propagated by the light guide is reflected, scattered, etc. along at least one light reflecting surface in the longitudinal direction, and then emitted from the light emitting surface opposite to the light reflecting surface. However, part of the light that enters the light guide from the end surface where the light source is disposed does not reflect or scatter on the light reflection surface, but directly reaches the light exit surface and is emitted. This phenomenon occasionally occurs near light sources. In this way, the illumination light of the illumination device may have a high-intensity light distribution near the light source.

In order to allow the lighting device to have an even light distribution, some measures will be taken, such as optimizing the reflection and diffusion pattern of the light reflection surface of the light guide body.

According to the description of cited document 1, small holes (apertures) are formed between the end face where the light of the light source enters, and the light exit surface (light exit portion) and the light reflection surface (light reflection portion) of the light guide. ), to reduce the amount of light emitted directly from the light source, in an attempt to average the light distribution through this technique.

[Citation Document 1] Japanese Patent Publication No. 2000-48616

If the technology disclosed in Citation 1 is adopted, the small holes that have undergone surface treatment and other measures, and the shading members that constitute them must be arranged between the light source and the light emitting part of the light guide, so additional parts are required. Disadvantages such as high unit price of parts, cumbersome assembly work, and high configuration accuracy requirements may not meet the needs.

In view of this situation, the present invention aims to provide a light guide with a relatively simple structure that can average light distribution, and an illumination device, an image sensor, and a reading device using the light guide.

In order to solve the above-mentioned problems, a light guide of an aspect of the present invention is a columnar light guide, including a light incident surface arranged at or near the end face of the light guide, and a light-incident surface arranged along the long side of the light guide. The light exit surface on at least a part of the side of the direction, 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 columnar light guide body of the light guide system includes: a groove that accommodates at least a part of the light source on or near the end surface of the light guide body; a light incident surface in the groove; The light exit surface on at least a part of the side of the direction; and at least one interface provided between the light entrance surface and the light exit surface.

Still another aspect of the present invention is a lighting device, which includes the above-mentioned light guide, and a light source for injecting light into the light guide from the light incident surface.

Another aspect of the present invention is an image sensor, which includes: the above-mentioned lighting device that illuminates the object in a straight line, an upright equal-magnification lens array that collects reflected light from the object, and an upright equal-magnification lens array that receives A light receiving element that magnifies the light collected by the lens array.

Another aspect of the present invention is a reading device, which includes: the above-mentioned image sensor, a driving mechanism for scanning the image sensor, and an image processing unit that processes data read by the image sensor.

In addition, arbitrary combinations of the above constituent elements, or conversion of the expression of the present invention among methods, devices, systems, etc., are effective aspects of the present invention. In addition, the amount of light in this specification refers to the concept of the power (operating rate) and energy of light, including the intensity and size of physical quantities, if it is not specifically stated; in addition, for example, the amount of radiation includes: radiant flux (power, radiant flux), radiation intensity (radiant intensity), radiance (radiance), irradiance (irradiance), radiant energy (radiant energy) and other concepts including physical quantities; photometry includes beam/luminous flux (luminous flux), luminous intensity (luminous intensity) ), brightness (luminance), illuminance (illuminance) and other concepts that include physical quantities.

[Advantages of the Invention] The present invention can provide a light guide that averages the amount of light with a relatively simple structure, and an illumination device, an image sensor, and a reading device using the light guide.

Embodiments of the present invention will be described below. The same or equivalent constituent elements, members, and processes shown in the drawings are denoted by the same symbols, and repeated explanations are appropriately omitted. In addition, the implementation forms are only examples, not intended to limit the invention, and all the features and combinations described in the implementation forms do not necessarily represent the essence of the invention.

Fig. 1(a)-(d) are schematic diagrams illustrating four sides of an illumination device 10 according to an embodiment of the present invention. Fig. 1 (a) is the schematic view of the left side of the lighting device 10; Fig. 1 (b) is the schematic plan view of the lighting device 10; Fig. 1 (c) is the section along the line A-A in the lighting device 10 shown in Fig. A schematic diagram; FIG. 1(d) is a schematic diagram below the lighting device 10.

The lighting device 10 has at least one light source 12 and a light guide 14 . The light guide 14 is a columnar body extending along the Z direction (also referred to as the long side direction), including: a first end face 14a, which is the end face at one end of the Z direction; a light reflection surface 14b, which is the light guide 14 At least one side along the Z direction; the light emitting surface 14c is opposite to the light reflecting surface 14b and is the side of the light guide body 14 along the Z direction; the second end surface 14d is the end surface at the other end of the Z direction. In this embodiment, the light source 12 is arranged on the first end surface 14a side, so that a part of the light emitted from the light source 12 advances toward the Z direction of the light guide body 14, or, if the symmetry axis of the light emitted by the light source 12 is used as Optical axis, which can make the optical axis parallel to the Z direction. The light emitted from the light source 12 enters the light guide body 14 from the first end surface 14 a as the light incident surface, diffuses, and propagates in the Z direction in the light guide body 14 . In addition, although the light source is arranged only on the side of the first end surface 14a in the drawing, the light source may also be arranged on the side of the second end surface 14d at the same time.

FIG. 2 is an enlarged schematic cross-sectional view of the lighting device 10 near the light source 12 . In FIG. 2 , light rays emitted from the light source 12 and entered into the light guide 14 are typically indicated by arrows.

In this embodiment, on the first end surface 14 a of the light guide body 14 , a concave portion 16 is formed that is concave toward the Z direction. The concave portion 16 is formed on the first end surface 14a between the light source 12 and the light emitting surface 14c. In this embodiment, the concave portion 16 is rectangular in section or plan view. Through the arrangement of the concave portion 16 , a plurality of interfaces (first interface 16 a , second interface 16 b , third interface 16 c ) are formed between the first end surface 14 a as the light incident surface and the light exit surface 14 c. The first interface 16 a is the lower side of the recess 16 , the second interface 16 b is the bottom of the recess 16 , and the third interface 16 c is the upper side of the recess 16 . Although not particularly shown in FIG. 2 , the concave portion 16 may have a pair of interfaces facing each other in the Y direction, or the concave portion 16 may penetrate the light guide in the Y direction. The light guide 14 of this embodiment has a recess 16 that is recessed from the light incident surface toward the Z direction or the longitudinal direction.

FIG. 3 is a schematic diagram of a part of the light emitted from the light source 12 going directly to the light emitting surface 14c when there is no interface between the first end surface 14a and the light emitting surface. For example, the light directly going to the light emitting surface 14 c as mentioned above is closely related to the reason why the light intensity becomes high near the light source 12 and causes the light intensity distribution to be biased.

Fig. 4 shows the result that the light incident surface has a concave portion that is sunken in the Z direction. When there is an interface through the concave portion 16 between the light incident surface (first end surface 14a) and the light emitting surface 14c, a part of the light emitted from the light source 12 The light will pass through the interface and be refracted in a direction farther away from the light source 12 . When the interface does not exist ( FIG. 3 ), the light that is one of the reasons for the increase in light intensity near the light source 12 will be refracted in a direction farther away from the light source 12 when the interface exists ( FIG. 4 ), reducing the concentration of light beams near the light source 12 . Therefore, it is possible to achieve the goal of averaging the light distribution in the irradiated area.

In the light guide 14 of this embodiment, since a concave portion with an interface is provided on the light incident surface or between the light source and the light exit surface 14c, an illuminating device that distributes the light quantity uniformly can be provided. In addition, the so-called concave portion includes concepts such as holes, grooves, and grooves, and does not limit specific cross-sectional shapes or top-view shapes, as long as it can play a role through several interfaces constituting the concave portion to reduce the concentration of light beams near the light source.

The light guide 14 will be described in detail below. The light guide body 14 can be, for example, a unidirectional long rod, rod (shaped) body or column, and transmits the light entering the light guide body 14 from the first end surface 14 a to the longitudinal direction inside the light guide body 14 . The vertical section of the light guide 14 in the Z direction is polygonal, slightly circular (including ellipse), or a combination of the above-mentioned shapes, or even includes a part of a curve. The light guide body 14 has a plurality of side surfaces extending in the longitudinal direction and composed of flat or curved surfaces.

A part of the light is repeatedly reflected one or more times on the aforementioned side surfaces in the light guide 14 and propagates in the longitudinal direction. At least one of the side surfaces of the light guide body 14 is a light emitting surface 14 c that emits light in a straight line. Furthermore, the light guide body 14 includes a light reflection surface 14b opposite to the light exit surface 14c, which reflects at least a part of the light propagating in the light guide body 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 14 a of the light guide 14 , and part of the light is reflected in the light guide 14 while propagating in the longitudinal direction. The light guide body 14 transmits a part of the light to the light reflection surface 14b, passes through the light reflection surface 14b and then makes a part of the light reach the light exit surface 14c, and then emits from the light exit surface 14c, so that the light can be routed in a straight line along the longitudinal direction. A lighting device 10 that emits light. The light guide body 14 includes a first end surface 14a, a light exit surface 14c, and a light reflection surface 14b, and these may be integrally formed.

Assuming that the vertical cross-sectional shape of the light guide 14 in the Z direction is set as a circumscribed circle, 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, if the lighting device 10 is used in a whiteboard reading device, the effective length in the long direction can reach about 1000 mm; It can reach 100mm ~ 330mm.

If the light guide 14 is assembled in components such as housings, for the purpose of assembling the light source 12 or the circuit board on which the light source 12 is mounted, or for the purpose of assembling other parts, at least one end of the light guide 14 can be (for example, the first end surface 14 a ) is provided with a collar-shaped flange. For example, the flange can be a right-angled surface of the light guide body 14 in the long side direction (Z direction), or it can have additional structures such as positioning pins or notches to improve the positioning accuracy with other parts.

If the light source 12 or the circuit board carrying the light source 12 is assembled near the first end surface 14a of the light guide body 14, a groove (recess or cavity or the like) can be set on the first end surface 14a of the light guide body 14, so that it contains A part or the whole of the light source 12. If the light guide 14 and the light source 12 (such as a light-emitting element) are integrally formed, the body of the light source 12 or a part of it can be stored inside the light guide and roughly sealed to reduce the exposure of the vulnerable part of the light source 12 to the outside air or external interference Possibility to prolong the life of the parts, but also has the advantage of saving space. If the light guide 14 has a groove for accommodating the light source, the light emitting surface of the light source 12 can be slightly at right angles to the long side direction (Z direction) of the light guide 14, or when the light source 12 is assembled, the light from the light source 12 The axis is parallel to the long side direction (Z direction) of the light guide body 14 , so that the bottom surface of the groove in the long side direction of the light guide body 14 becomes the light incident surface. If the surface from which the light from the light source 12 exits is regarded as the light exit surface, the distance between the light exit surface of the light source and the light entrance surface of the light guide is 0-5mm, and the distance is 0-3mm (except 0mm) also can. When the distance is 0 mm, it 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. As long as the light emitting surface of the light source is slightly separated from the light incident surface of the light guide, since the light incident surface of the light guide also plays the role of refracting light, it is possible to reduce the concentration of light beams near the light source to some extent.

Also, from the viewpoint of transmission efficiency and illumination efficiency, it is preferable that the light guide 14 is transparent to the wavelength light contained in the illumination light, and the material constituting the light guide 14 absorbs as little light as possible. For example, the internal transmittance of the light guide body 14 with a thickness of 10 mm at a wavelength of 550 nm may be above 90%, preferably above 95%, and more preferably above 98%. Internal transmittance refers to the transmittance of the incident and outgoing surfaces except for the surface reflectance.

The light guide 14 can be made of resin to meet the requirements of its processability and low cost. If the light guide body 14 is made of resin, methods such as injection molding or casting can be used to improve production efficiency. In addition, the light guide body 14 may be formed by combining materials such as resin and metal, ceramics, and glass. For example, the long side of the light guide body 14 is formed with transparent resin or glass, and the flange (used to assemble to components such as the housing or to assemble the light source 12 and the circuit board) and other parts can be made of metal, ceramics or non-transparent. resin to form. In addition, if a high-intensity LED or other light source is used as the light source 12, ceramics such as alumina with high heat dissipation properties can be used as the material near the light source 12 because of its high calorific value.

As a material for forming the light guide body 14, transparent resins such as cycloolefin-based resins, acrylic resins, vinyl chloride-based resins, epoxy-based resins, PET-based resins, PC-based resins, and GPPS-based resins can be used. As a method of manufacturing the light guide 14, methods such as injection molding, insert molding, blow molding, and extrusion molding can be used. In addition, the light guide 14 can be made by combining metals such as aluminum and duralumin or ceramic materials such as alumina and zirconia with the above-mentioned transparent resin.

Next, the light exit surface 14 c of the light guide body 14 will be described in detail. The light emitting surface 14 c is provided on at least a part of side surfaces along the longitudinal direction of the light guide body 14 , and emits light from the inside of the light guide body 14 . The light exit surface 14c may have a smooth and flat surface, or may include a part of a curved surface according to the shape of the object. In addition, if it is necessary to diffuse the emitted light, a plurality of micro-concave-convex portions can be provided on the surface of the light-exiting surface 14c, and it can be processed into a so-called diffusing surface by applying frosting or polishing. Furthermore, in order to increase light transmittance, an anti-reflection film or an anti-reflection film may be formed on the surface of the light exit surface 14c. Anti-reflection film and anti-reflection film can form dielectric multilayer film by sputtering method and vacuum evaporation method, or use low refractive index material as coating film, by containing hollow particles or solid particles with low refractive index material to apply the coating film. In addition, in order to suppress the emission of light in a part of the wavelength range, a light-absorbing film or a light-reflecting film may be formed on the light-emitting surface 14c. For example, the light-absorbing film can be formed by coating the light-emitting surface 14 c with a resin film containing particles or pigments that can absorb light in a specific wavelength range. The light reflective film can be formed by sputtering, vacuum evaporation and other methods to form a dielectric multilayer film.

Next, the light reflection surface 14 b of the light guide body 14 will be described in detail. The light-reflecting surface 14b is suitably provided with textures that reflect or diffuse light, including but not limited to the following: textured surfaces, printed textures such as white or silver that reflect light, and a diameter range of several μm ~ A few millimeters or so, such as a pit or a part of a spherical surface with multiple concave parts (looking like a water drop pattern when viewed from above), or a texture formed into a convex part in reverse, three-dimensional columnar or three-dimensional cone-shaped, three-dimensional prisms such as cylinders A pattern whose side faces are concave across the width of the light-reflecting surface, or a pattern that is conversely formed into a convex shape, or a combination of the above-mentioned textures. Conditions such as the intensity distribution of the required illumination light, the length and size of the illumination device, the shape of the light guide body 14, and the light distribution of the light source 12 used can also be considered to form lines on the light reflection surface 14b. In addition, antireflection film, antireflection film, light absorption film, and light reflection film may be formed on the light reflection surface 14b in the same manner as the light exit surface 14c according to the purpose and required performance.

5 to 7 show several textures of the light reflection surface 14b. The texture of the light reflecting surface 14b of the light guide body 14 is not limited thereto, and these textures can be properly combined.

Fig. 5 shows that a plurality of structures 18 are formed on the light reflecting surface, and they are approximately circular shapes of various sizes when viewed from above. The slightly circular structure 18 can be concave or convex. As shown in FIG. 5 , the structure 18 may exhibit a plurality of concave shapes with a diameter ranging from several μm to several mm, such as a part of a spherical surface or a curved surface. The size of the roughly circular structures 18 , for example, can vary in spacing or size as the distance from the light source 12 increases, and can also be arranged randomly.

FIG. 6 shows that a plurality of groove-like or ridge-like structures 20 are formed on the light-reflecting surface in a direction perpendicular to the Z direction. Grooves represent depressions and ridges represent protrusions. Grooves or ridges may be formed in a direction at right angles to the Z direction as shown in FIG. 6 . The structure 20 can change its pitch or size as it gets farther away from the light source 12 , and can also be randomly arranged. For example, the groove-shaped or ridge-shaped structures 20 formed farther away from the light source 12 may be arranged at a smaller pitch than the structures 20 formed near the light source 12 .

FIG. 7 shows reflective textures 22 formed on the light reflective surface by printing or the like. Each reflective texture 22 can be, for example, white or silver with high reflectivity, and its coloring such as brightness or hue can be changed according to the distance between it and the light source 12. For example, the reflective texture 22 formed farther away from the light source 12 can be The reflectivity can be higher than that of the reflection lines 22 formed near the light source 12 ; or, the area of the reflection lines 22 formed farther away from the light source 12 can be larger than that of the reflection lines 22 formed near the light source 12 .

Next, the cover (not shown) covering the light guide body 14 will be described. The illuminating device 10 may include a cover to cover at least a rod-shaped portion or an effective range (range irradiated with light) of the light guide body 14 . The light incident into the light guide 14 is reflected back and forth on the side of the light guide 14 and travels in the longitudinal direction (Z direction) of the light guide 14 , but part of the light may exit from the side of the light guide 14 . If the light exits from the surface other than the light exit surface 14c, it will cause loss. Therefore, an additional function can be considered to allow the light emitted from the surface other than the light exit surface 14c to be reflected again in the light guide body 14 and return to the light guide body 14 side. The inner structure of the cover can be designed to match the shape of the side surface of the light guide 14, and in order to improve the reflectivity inside the cover, at least the inner side opposite or in contact with the light guide 14 is preferably white or silver.

On the contrary, it is also conceivable to adopt an aspect in which the lighting device 10 does not have a cover. Although there is a cover, it can be expected to function, but it also increases the cost of elements such as the lighting device 10 and the reading device using it. Therefore, if there is a demand for cost reduction, a coverless illuminating device 10 should also be considered. The low-cost lighting device 10 can be used as a marketing bonus. When the light propagates in the light guide body 14, it can pass through multiple side surfaces to perform the function of total reflection. Because the phenomenon of total reflection or high reflectivity occurs when the incident angle of light relative to the surface becomes larger, when making the light guide 14, if the rod part of the light guide 14 is thinned (the cross-sectional shape of the light guide 14 The diameter of the circumscribed circle becomes smaller), and the light guide body 14 is made of a material with a large refractive index, which can reduce the situation of light exiting from the side other than the light exit surface 14c, thereby improving the transmission rate. The effective length of the light guide body 14 is at least the length that can illuminate the required range of the object (the length of a specific side of the object), or the length that can ensure the uniformity of the required light intensity. In addition, the effective length of the light guide body 14 may be 85% to 100% of the total length of the long rod-shaped portion of the light guide body 14 . In addition, the surface of the light guide body 14 other than the light exiting surface may be partially or entirely colored in a color that is expected to improve light reflectivity, such as white or silver, but is not limited thereto.

In addition, if the light guide body 14 is fixed to the casing as described later, the casing has a surface opposite to the side surface of the light guide body 14 except the light exit surface 14c in structure, then this surface can be designed as a white or silver reflective surface. A high rate of color to complement the above-mentioned function of the lid.

Next, the interface formed by the concave portion 16 will be described in detail. In the light guide 14 of this embodiment, there is at least one interface between the light incident surface and the light exit surface 14c. In addition, there is at least one interface on the light path from the light incident surface to the light exit surface 14c. The amount of light near the light source 12 is higher than other parts (the brightness near the light source 12 is brighter than other parts) is a problem that has always existed in the light guide body 14. The inventor of the present invention got the following inspiration when trying to solve this problem: as long as the light source An interface is provided between 12 and the light emitting surface 14c to refract or scatter part of the light emitted from the light source 12, thereby reducing the amount of light in the vicinity of the light source 12.

LEDs, which are often used as the light source 12, generally have a Lambertian distribution, allowing light to be emitted at an angle of 70° or 80°. If the aforementioned LEDs are disposed near the first end surface 14 a of the light guide 14 , part of the light does not propagate toward the long side of the light guide 14 , but directly reaches the light exit surface 14 c and is emitted. The light rays following this light path are generated particularly in large quantities near the light source 12 to increase the amount of light around it. Through the interface between the light incident surface and the light exit surface 14c, the light originally directed toward the light exit surface 14c is reflected, refracted, Diffusion or the like acts to reduce the amount of light in the vicinity of the light source 12 .

8 to 12 are partial cross-sectional schematic views of the light guide 14 including the light source 12 and the interface. The light source 12 in each figure is arranged at the end of the light guide 14, and the first end surface 14a of the light guide 14 is taken as light incident surface.

As shown in FIG. 8, the light guide 14 is provided with a concave portion 16 from the first end surface 14a toward the Z direction. The surface (lower side) of the concave portion 16 close to the light reflection surface is the first interface 16a, and the concave portion 16 is located on the deep surface of the Z direction. The (bottom surface) is the second interface 16b, and the surface (upper side) of the concave portion 16 close to the light exit surface is the third interface 16c. The light emitted from the light source 12 has two or three interfaces on the light path going to the light exit surface 14c, so that the light is refracted in a direction farther away from the light source, reducing the light going to the light exit surface 14c near the light source 12 Therefore, the amount of light emitted from the light emitting surface 14c near the light source 12 can be reduced.

9 and 10 show that the light guide 14 has a so-called wedge-shaped concave portion 16 from the first end surface 14a toward the Z direction, and forms a plurality of interfaces. In the light guide 14 shown in FIG. 9 and FIG. 10 , especially the obliquely inclined interface 16 d tends to have a critical angle or an angle close to the critical angle with the light rays advancing from the light source 12 to the light exit surface 14 c, which can The light refracted at the interface is increased, so the amount of light emitted from the light emitting surface 14c near the light source 12 can be reduced more effectively.

FIG. 11 shows that a plurality of concave portions 16 are arranged in a row in the X direction of the light guide body 14 . Through the light guide body 14 shown in FIG. 11 , the interface can be increased so that the light emitted from the light source 12 and progressing toward the light exit surface 14c can be refracted, so the amount of light emitted from the light exit surface 14c near the light source 12 can be effectively reduced.

FIG. 12 shows that a portion of the light guide 14 near the light source 12 forms an inclined surface 16e. The light guide body 14 shown in FIG. 12 is the same as the light guide body 14 shown in FIG. 9 and FIG. Angle can increase the light refracted at the interface, so it can effectively reduce the amount of light emitted from the light emitting surface 14c near the light source 12 .

The concave portion 16 containing a plurality of interfaces can have a cross-section parallel to the X direction (perpendicular to the Z direction) that can be polygonal such as a triangle or a quadrangle, or can be wedge-shaped or stepped. In addition, the interface constituting the concave portion 16 may be a concave-convex surface.

The concave portion 16 formed on the first end surface 14a in the long side direction of the light guide body 14 can be filled with black or white resin, or a black or white coating film can be formed on the surface constituting the concave portion 16 .

13(a) to 13(d) are schematic diagrams illustrating an illumination device 30 of another embodiment of the present invention. FIG. 13( a ) is a schematic left side view of the lighting device 30 . FIG. 13( b ) is a schematic plan view of the lighting device 30 . Fig. 13(c) is a schematic cross-sectional view of the illuminating device 30 shown in Fig. 13(a) along the line B-B. FIG. 13( d ) is a schematic bottom view of the lighting device 30 . FIG. 14 is an enlarged schematic cross-sectional view of the lighting device 30 in the vicinity of the light source 12 .

In this embodiment, a groove 32 is formed on the first end surface 14 a of the light guide body 14 . If the light source 12 is disposed on or near the end surface of the light guide body 14 , it is more advantageous to provide a groove 32 for accommodating the light source on the end surface of the light guide body 14 . When the light source 12 such as an LED element is accommodated in the groove 32 , it is easier to seal the area near the light source 12 to achieve the purpose of protecting the light source 12 from external interference.

In this embodiment, the concave portion 16 including a plurality of interfaces (the first interface 16a, the second interface 16b, and the third interface 16c) is from the first end surface 14a of the light guide body 14 to the long side direction of the light guide body 14 formed, and protrude further inward than the bottom surface 32 a of the groove 32 . The surface of the light source 12 opposite to the bottom surface 32 a of the groove 32 is the emitting surface of the light source 12 . Also, please note that in the lighting device 30 of this embodiment, the light guide 14 has a flange 34, which includes a surface at a right angle to the Z direction near the first end surface 14a. Even in this embodiment, the first end surface 14a of the light guide body 14 is provided with a groove 32 for accommodating the light source, its functions and effects are the same as those without the groove 32 (please refer to FIG. 1 ). In this embodiment, when the light source 12 emits light around the Z direction, the bottom surface 32a of the groove 32 is the light incident surface, which is easy to understand. The distance between the light emitting surface of the light source 12 and the light incident surface (of the light guide) may be 0-5 mm, or 0-3 mm (except 0 mm).

15 to 18 are schematic partial cross-sectional views of the light guide body 14, which has the light source 12 accommodated in the groove and the concave portion including the interface.

FIG. 15 shows that the light guide 14 has a so-called wedge-shaped concave portion 16 in the Z direction on the first end surface 14a, forming a plurality of interfaces. In the light guide 14 shown in FIG. 15 , especially the obliquely inclined interface 16d, it tends to have a critical angle or an angle close to the critical angle with the light rays advancing from the light source 12 to the light exit surface 14c, which can increase the The refracted light thus reduces the amount of light in the vicinity of the light source 12 more effectively.

FIG. 16 shows that a plurality of concave portions 16 are arranged in a line in the X direction of the light guide body 14 . Through the light guide 14 shown in FIG. 16 , the interface can be increased so that the light emitted from the light source 12 and going toward the light exit surface 14 c can be refracted, so that the amount of light near the light source 12 can be effectively reduced.

17 and 18 show that the light guide body 14 is provided with an extended concave portion 16 from the bottom surface 32 a (light incident surface) of the groove 32 toward the Z direction. The concave portion 16 including the interface can also reduce the amount of light near the light source 12 as mentioned above.

Next, the light source 12 will be described in detail. The light source 12 is arranged near the end face of the light guide body 14, so that the light emitted from the light source 12 enters as light from the end face of the rod-shaped light guide body 14 (if the groove 32 for accommodating the light source is provided, the bottom face 32a). into the light guide. The light source 12 can be arranged on or near one end surface of the light guide body 14 (such as the first end surface 14 a ), or can be arranged on or near the end surfaces (first end surface 14 a and second end surface 14 d ) of the light guide body 14 .

The light source 12 can be a light source (for example, a light bulb) that allows components such as a light emitting diode (LED) and a filament to emit light when energized. LEDs, in particular, are particularly effective because of their small size, low power consumption, large light volume, and ability to reproduce various colors. If an LED is used as the light source 12, for example, a plurality of LEDs that emit light of wavelengths R (red), G (green), and B (blue) and include at least three chips can be used. In this case, by Moderately adjusting the wavelength and intensity can emit white light by visual recognition, which is suitable as a light source for image sensors and reading devices.

FIG. 19( a ) and FIG. 19( b ) are schematic diagrams of one example of the light source 12 , which accommodates three LED chips 40 in a box 42 . Fig. 19(a) is a front schematic diagram of the light source 12; Fig. 19(b) is a schematic cross-sectional diagram of the light source 12 shown in Fig. 19(a) along the line C-C. Moreover, the inside of the case 42 where the LED chip 40 is disposed may also be filled with a transparent resin. The light source 12 constituted by the aforementioned LED can be regarded as having a light emitting surface 42 a on the end surface of the box body 42 .

In this way, it is also possible to integrate the LED chips that respectively emit RGB three-color light into a white LED to be used as the light source 12 . In addition, if one or both of the RGB LED chips are made inert (non-luminous), any one of the three colors other than white can be emitted, or light of the color obtained by mixing these colors. Moreover, because the light intensity of each RGB LED chip is different, its strength can be considered, and the relative position and position between it and the light guide body can be optimized according to the required performance of the lighting device.

Furthermore, as the LED emitting white light, a single-chip type LED containing a resin containing a blue LED and a yellow phosphor, or a single-chip type LED containing a resin containing a blue LED and a red or green phosphor can be used.

In addition, regarding the actual mounting type of the LED, a substrate-type LED or a PLCC (Plastic Leaded Chip Carrier) type LED that is thin and can be actually mounted on the surface can be used, but is not limited thereto.

The light source 12 composed of the aforementioned LED and the like can be formed on a substrate (circuit substrate) provided with a driving circuit. The circuit substrate can be a rigid substrate or a flexible substrate. Rigid substrates are suitable for structures that require strength due to their rigidity. The flexible substrate is thin and cheap, and the problem of low rigidity can be solved as long as it is fixed to the light guide body and integrally formed. The substrate can be made of phenolic resin, epoxy resin, polyimide resin, fluorine resin, PRO resin, polyimide film, PET film and other materials, or it can be made of paper or glass fiber, cloth and other materials. Composite substrates are formed.

Fig. 20 (a) and Fig. 20 (b) are the schematic diagrams of illuminating device 50, and this illuminating device 50 comprises the thin circuit board 51 that actually installs light source 12 and the light guide body 14 with flange 34, and this flange 34 has Locating pin 52. FIG. 20( a ) is a schematic left side view of the lighting device 50 . Fig. 20(b) is a schematic cross-sectional view of the lighting device 50 shown in Fig. 20(a) along line D-D. Protruding positioning pins 52 are provided on the flange 34 of the lighting device 50 . Furthermore, 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 a predetermined position with respect to the hole 53 . As long as the positioning pin 52 and the hole 53 are used as described above, the correct position of the light source 12 relative to the light guide 14 can be determined.

The circuit board 51 may include a power supply electrode 54 for driving the light source. If the flexible circuit substrate 51 is used, it can be easily assembled into the housing of the contact image sensor, or connected, fixed and packaged to other circuit substrates.

Specific embodiments of the present invention will be described below.

<First Embodiment> This embodiment uses the light guide body 14 with at least one interface between the light incident surface and the light exit surface 14c, and simulates how to improve the lighting device in the Z direction (the longitudinal direction of the light guide body 14). ) on the deviation of light distribution.

21(a) to 21(d) are schematic diagrams illustrating an illumination device 60 for simulating the first embodiment. Fig. 21(a) is a schematic view of the left side of the lighting device 60 of the first embodiment. Fig. 21(b) is a schematic plan view of the lighting device 60 of the first embodiment. Fig. 21(c) is a schematic cross-sectional view of the lighting device 60 of the first embodiment shown in Fig. 21(a) along line E-E. Fig. 21(d) is a schematic bottom view of the lighting device 60 of the first embodiment.

Assume that the light guide 14 is a quadrangular column extending in the Z direction, has an end surface parallel to the X-Y plane, and four side surfaces at right angles to the end surface. The upper side parallel to the Y-Z plane is the light exit surface 14c, and the lower side opposite thereto is the light reflection surface 14b. The material of the light guide 14 does not absorb light, and the refractive index of the used wavelength is 1.49. The periphery of the lighting device 60 is air, and its refractive index is 1. The end face of the light guide 14 is parallel to the X-Y plane, wg=hg=3.0mm, the total length Lg=227.5mm, and the effective length on the light exit surface 14c is Lef=225.5mm.

As shown in FIG. 21 , the light guide 14 has a concave portion 16 between a portion where the light source 12 is arranged on the first end surface 14 a and the light exit surface 14 c. The concave portion 16 has a substantially rectangular parallelepiped shape, and has two interfaces at right angles to the X direction, one interface at right angles to the Z direction, and two interfaces at right angles to the Y direction. The dimension of the recess 16 in the X direction is hc=0.5mm, and the dimension in the Y direction is wc=2.4mm. dc is the longest distance (depth or extension) from the light incident surface of the light guide 14 (that is, the first end surface 14 a ) to the recess 16 in the Z direction, and the change of the dc value will be used as a parameter for the simulation described later.

The light reflective surface 14b of the light guide 14 has a plurality of concave grooves 62 perpendicular to the Z direction and having a triangular cross-section arranged in a row along the Z direction. Roughly speaking, the arrangement pitch is larger in the area close to the light source 12 , and the arrangement pitch is smaller in the area far from the light source 12 . Side surfaces (including the light exit surface 14 c ) other than the light reflection surface 14 b are flat surfaces.

As long as the light reaches points on all surfaces of the light guide body 14, Snell's law of refraction is strictly established, and virtually no light is scattered or absorbed.

Assuming that the light source 12 is an LED, the light emitting surface of the light source 12 is parallel to the X-Y plane, ws = hs = 1.5mm, and the light with symmetrical optical axis and Lambertian distribution is emitted in one direction. When the light distribution takes the axis of symmetry as the optical axis, the light source 12 is arranged on the first end surface 14 a of the light guide 14 so that the optical axis is parallel to the Z direction and consistent with the central axis passing through the central part of the light guide 14 .

TracePro (Ver.20.4), which is lighting design, analysis, and optimization software from Lambda Research Corporation, was used in the simulation. The light rays emitted from the light source 12 have a wavelength of 550 nm, a total of 1×10 ⁶ rays, and have the above-mentioned light distribution. Furthermore, calculate the number of light rays per unit area incident from the light exiting surface 14c of the light guide body at a distance of 4.78mm in the X direction, as the irradiance. It should be noted that the purpose of the above example is to show the effectiveness of the concave part (interface). When actually mounted on the machine, it needs to be optimized according to the specifications including the shape of the light guide and the shape of the light reflection surface.

The light intensity distribution of the lighting device 60 of the first embodiment was evaluated as the irradiance distribution along the light exit surface 14c. Fig. 22 and Fig. 23 are diagrams of irradiance ratio, the horizontal axis is the distance in the Z direction when the effective length Lef of the light guide body 14 is 0 at the light source side, and the irradiance ratio is divided by the irradiance at a certain position The average value of irradiance over the entire effective length is obtained. In this embodiment, the irradiance ratio is preferably 10 or less, more preferably 6 or less, and more preferably 4 or less over the entire effective length. Fig. 23 is an enlarged view of L=0～25mm in Fig. 22. Figure 22 and Figure 23 show the irradiance ratio of the comparative example when there is no concave portion 16 (interface), the irradiance ratio when dc = 0.60mm, the irradiance ratio when dc = 1.30mm, and the irradiance when dc = 2.00mm Compare.

As can be seen from FIG. 22 and FIG. 23 , the Z value of the irradiance ratio is almost always in a range exceeding about 12.5 mm, similar to each protrusion amount (dc). On the other hand, when the Z value is in the range of 12.5mm or less, the concave portion 16 of the interface is not provided, or dc is too large, the irradiance ratio will become larger, but when dc = 0.6mm, the irradiance ratio is 6 or less, and it can be expected It has lighting characteristics with good irradiance distribution (light distribution). When the amount of protrusion (dc) is in an appropriate range, the bottom surface (second interface 16b) of the concave portion 16 deep in the Z direction will refract part of the light in a direction farther from the light exit surface 14c, so that the light reaching the vicinity of the light source 12 It can be speculated that the irradiance of the exit surface is no longer increased but suppressed. At this time, the projection amount (depth) dc of the concave portion relative to the light incident surface is 0.1 mm, preferably 0.3 mm, and more preferably 0.4 mm. In addition, the dc system is 1.0 mm or less, preferably 0.9 mm or less, more preferably 0.8 mm or less.

<Second Embodiment> FIG. 24(a) and FIG. 24(b) are schematic diagrams illustrating a lighting device 70 for simulating the second embodiment. Fig. 24(a) is a schematic view of the left side of the lighting device 70 of the second embodiment. Fig. 24(b) is a schematic cross-sectional view of the illuminating device 70 of the second embodiment shown in Fig. 24(a) along the line F-F.

The lighting device 70 of the second embodiment is different from the lighting device 60 of the first embodiment except that the concave portion 16 of the light guide body 14 is wedge-shaped in the Z direction. All are the same as the first embodiment.

The light intensity distribution of the lighting device 70 of the second embodiment was evaluated as the irradiance distribution along the light exit surface 14c. Fig. 25 and Fig. 26 are diagrams of irradiance ratio, the horizontal axis is the distance in the Z direction when the effective length Lef of the light guide body 14 is 0 at the light source side, and the irradiance ratio is divided by the irradiance at a certain position The average value of irradiance over the entire effective length is obtained. In this embodiment, the irradiance ratio is preferably 10 or less, more preferably 6 or less, and more preferably 4 or less over the entire effective length. Figure 26 is an enlarged view of L=0～25mm in Figure 25. Figure 25 and Figure 26 show the irradiance ratio of the comparative example when there is no recess (interface), and the irradiance ratio of the following cases: assuming that the protrusion of the recess in the Z direction is dc, the wedge-shaped end angle of the end of the recess (The angle between the Y-Z plane and the inclined plane) is θc, which respectively represent the irradiance ratio when (dc, θc) = (2.00mm, 30°), (1.50mm, 30°), (1.50mm, 19°).

It can be seen from Fig. 25 and Fig. 26 that, as with each extension (dc), the relative irradiance ratio Z value will almost certainly be in the range exceeding 12.5 mm. On the other hand, when the Z value is below 12.5mm and the concave portion 16 of the interface is not provided, the light intensity will increase, but the extension (dc) is 1.50mm or the end angle (θc) is 30° or At a smaller angle (19°), the irradiance ratio does not increase but is suppressed, and it is expected to obtain lighting characteristics with a good irradiance distribution (light distribution). In the second embodiment, because the shape of the end portion of the recess 16 deep in the Z direction is wedge-shaped, the light will reach the oblique interface with respect to the Z direction at a large incident angle, and by increasing the reflectivity of the interface, the light source will It can be speculated that the relative irradiance of the rays near 12 traveling directly toward the light exit surface 14c will have a reduced effect. θc is preferably not more than 26°, more preferably not more than 22°. Also, θc is preferably at least 15°, more preferably at least 16°.

<Third Embodiment> FIGS. 27(a) to 27(d) are schematic diagrams illustrating an illuminating device 80, which is used to simulate the third embodiment. Fig. 27(a) is a schematic view of the left side of the lighting device 80 of the third embodiment. Fig. 27(b) is a schematic plan view of the lighting device 80 of the third embodiment. Fig. 27(c) is a schematic cross-sectional view of the illuminating device 80 of the third embodiment shown in Fig. 27(a) along line G-G. Fig. 27(d) is a schematic bottom view of the lighting device 80 of the third embodiment.

The lighting device 80 of the third embodiment has a flange 34 near the first end surface 14 a of the light guide body 14 . The size of the flange surface parallel to the X-Y plane is wf = hf = 3.50mm, and the thickness of the flange in the Z direction is tf = 2.90mm. Furthermore, the lighting device 80 of the third embodiment has a groove 32 on the first end surface 14 a of the light guide body 14 , and the light emitting surface of the light source 12 is accommodated in the groove 32 . The distance between the light emitting surface of the light source 12 and the light incident surface of the light guide 14 (ie, the bottom surface of the groove 32 ) is 0.10 mm.

The light intensity distribution of the lighting device 80 of the third embodiment was evaluated as the irradiance distribution along the light exit surface 14c. Fig. 28 and Fig. 29 are diagrams of irradiance ratio, the horizontal axis is the distance in the Z direction when the effective length Lef of the light guide body 14 is 0 at the light source side, and the irradiance ratio is divided by the irradiance at a certain position The average value of irradiance over the entire effective length is obtained. In this embodiment, the irradiance ratio is preferably 10 or less, more preferably 6 or less, and more preferably 4 or less over the entire effective length. Fig. 29 is an enlarged view of L=0～25mm in Fig. 28. Fig. 28 and Fig. 29 show the irradiance ratio of the comparative example when there is no concave portion (interface), and the irradiance ratio of the following situation: assuming the maximum distance in the Z direction from the light incident surface of the light guide body 14 to the concave portion 16 (Depth or extension) is dc, and dc is the irradiance ratio at 2.00mm, 1.30mm, and 0.60mm respectively.

It can be seen from FIG. 28 and FIG. 29 that, similar to the protrusion amount (dc), the Z value of the irradiance ratio is almost always in a range exceeding about 12.5 mm. On the other hand, when the Z value is in the range of 12.5mm or less, the irradiance ratio of each example is less than 6, and the maximum irradiance ratio is also 1 when the overhang (dc) is 1.30mm and 2.00mm. Left and right, lighting characteristics with better irradiance distribution (light distribution).

In the third embodiment, the flange 34 or its vicinity, especially the vicinity of the junction between the flange 34 and the rod-shaped portion extending toward the long side of the light guide 14, there is light emitted and reaching the effective lighting range. So the result tends to be different from the flangeless first or second embodiment. When the amount of extension is 1.30mm or 2.00mm, it can be inferred that between Z ranges from 0 to 12.5mm, it is sometimes difficult to obtain the irradiance for providing illumination, but for example, as long as the light exits the surface 14c of its effective length When the starting point moves about 10mm in the Z direction, the entire effective length of the light exit surface 14c can obtain an average irradiance distribution (light distribution), which can also be inferred.

<Fourth Embodiment> FIGS. 30(a) to 30(d) are schematic diagrams illustrating an illumination device 90 for simulating the fourth embodiment. Fig. 30(a) is a schematic view of the left side of the lighting device 90 of the fourth embodiment. Fig. 30(b) is a schematic plan view of the lighting device 90 of the fourth embodiment. Fig. 30(c) is a schematic cross-sectional view of the lighting device 90 of the fourth embodiment shown in Fig. 30(a) along the line H-H. Fig. 30(d) is a schematic bottom view of the lighting device 90 of the fourth embodiment.

The lighting device 90 of the fourth embodiment is different from the third embodiment except that the end portion of the concave portion 16 deep in the Z direction is wedge-shaped, and other points are the same as the third embodiment.

The light intensity distribution of the lighting device 90 of the fourth embodiment was evaluated as the irradiance distribution along the light exit surface 14c. Fig. 31 and Fig. 32 are diagrams of irradiance ratio, the horizontal axis is the distance in the Z direction when the effective length Lef of the light guide body 14 is 0 at the light source side, and the irradiance ratio is divided by the irradiance at a certain position The average value of irradiance over the entire effective length is obtained. In this embodiment, the irradiance ratio is preferably 10 or less, more preferably 6 or less, and more preferably 4 or less over the entire effective length. Fig. 32 is the enlarged view of L=0～25mm in Fig. 31. Figure 31 and Figure 32 show the irradiance ratio of the comparative example when there is no recess (interface), and the irradiance ratio of the following cases: Assuming that the protrusion of the recess in the Z direction is dc, the wedge-shaped end angle of the end of the recess (The angle between the Y-Z plane and the inclined plane) is θc, which respectively represent the irradiance ratio when (dc, θc) = (2.00mm, 30°), (1.50mm, 30°), (1.50mm, 19°).

As can be seen from FIG. 31 and FIG. 32 , the Z value of the irradiance ratio is almost always in a range exceeding about 12.5 mm, similarly to each protrusion amount (dc). On the other hand, when the Z value is below 12.5mm and the concave portion 16 of the interface is not provided, the irradiance ratio will become larger, but the extension (dc) is 1.50mm or the end angle (θc) is 30° or smaller angle (19°), the irradiance ratio does not increase but is suppressed, and it is expected to obtain lighting characteristics with good irradiance distribution (light distribution). In the fourth embodiment, because the shape of the end portion of the recess 16 deep in the Z direction is wedge-shaped, the light will reach the interface oblique to the Z direction at a large incident angle, and by increasing the reflectivity of the interface, the light source will It can be speculated that the relative irradiance of the rays near 12 traveling directly toward the light exit surface 14c will have a reduced effect.

FIG. 33 is a schematic cross-sectional view of a reading device 100 using the lighting device 10 of this embodiment. The reading device 100 includes: a touch plate 102 on which an object to be read (original) 120 is placed, an image sensor (adhesive image sensor) 104, a drive mechanism 116 for scanning the image sensor 104, and a processing through An image processing unit 118 for the data read by the image sensor 104 . The reading device 100 uses the driving mechanism 116 to move the image sensor 104 in a direction parallel to the contact plate 102 , so as to scan a part or the whole of the document 120 to read the information of the document 120 .

The image sensor 104 includes an illumination device 106 that illuminates the original 120 linearly (perpendicular to the long direction of the paper surface), and an upright constant magnification lens array 108 that collects the light reflected from the original 120 by an upright constant magnification optical system. , the light-receiving elements 110 arranged in an array to receive the collected light, the circuit board 112 on which the light-receiving elements 110 are mounted, the lighting device 106, and the upright equal magnification lens array 108 and the light-receiving elements 110 are accommodated and fixed in a specific arrangement. The housing 114.

As the lighting device 106, the lighting devices described in the above-mentioned embodiments can be used. A high-quality reading device 100 can be realized by using an illumination device capable of averaging the light distribution as in the above-mentioned embodiment.

The above is the relevant description for the implementation of the present invention. As long as those skilled in the art can understand, the above-mentioned implementation forms are only examples, and various changes can be made in the combination of each component element and each treatment process, and each change form is included in the protection scope of the present invention.

10, 30, 50, 60, 70, 80, 90: Lighting device 12: Light source 14: Light guide 14a: first end face 14b: light reflective surface 14c: Light exit surface 14d: Second end face 16: Concave 16a: The first interface 16b: The second interface 16c: The third interface 16d: interface 18: Constructs 100: reading device 102: Contact plate 104: Image sensor 106: lighting device 108: Upright equal magnification lens array 110: Light receiving element 112: circuit substrate 114: Shell 116: Driving mechanism 118: Image processing department 120: Original 20: Constructs 22: Reflection type 32: Groove 32a: bottom surface 34: Flange 40:LED chip 42: Box 42a: light exit surface 51: Circuit board 52: Locating pin 53: hole 54: electrode 62: concave groove

1 (a) to (d) are schematic diagrams illustrating an illumination device according to an embodiment of the present invention. Fig. 2 is an enlarged schematic cross-sectional view of the lighting device near its light source. Fig. 3 is a schematic diagram of light rays when there is no interface between the first end surface and the light exit surface. Fig. 4 is a schematic diagram of light rays when there is an interface between the light incident surface and the light exit surface through a concave portion. Fig. 5 is a schematic diagram of one kind of texture on the light reflecting surface. Fig. 6 is a schematic diagram of another texture on the light reflecting surface. Fig. 7 is a schematic diagram of other textures on the light reflecting surface. Fig. 8 is a partial cross-sectional schematic diagram of a light guide including a light source and an interface. Fig. 9 is a partial cross-sectional schematic diagram of a light guide including a light source and an interface. Fig. 10 is a partial cross-sectional schematic diagram of a light guide including a light source and an interface. Fig. 11 is a partial cross-sectional schematic diagram of a light guide including a light source and an interface. Fig. 12 is a partial cross-sectional schematic diagram of a light guide including a light source and an interface. 13(a) to (d) are schematic diagrams illustrating lighting devices of other embodiments of the present invention. Fig. 14 is an enlarged schematic cross-sectional view of the lighting device near its light source. Fig. 15 is a partial cross-sectional schematic diagram of a light guide including a light source and an interface. Fig. 16 is a partial cross-sectional schematic diagram of a light guide including a light source and an interface. Fig. 17 is a partial cross-sectional schematic diagram of a light guide including a light source and an interface. Fig. 18 is a partial cross-sectional schematic diagram of a light guide including a light source and an interface. Fig. 19(a) and (b) are schematic diagrams of one example of a light source containing three LED chips in a box. Fig. 20 (a) and (b) are schematic diagrams of an illuminating device, which includes a thin circuit board on which a light source is actually installed and a light guide with a flange, and the flange has a positioning pin. 21 (a) to (d) are schematic diagrams illustrating an illumination device used to simulate the first embodiment. Fig. 22 is a diagram showing light distribution (irradiance distribution) along the light exit surface of the lighting device of the first embodiment. Fig. 23 is an enlarged view of L=0～25mm in Fig. 22. Fig. 24(a) and (b) are schematic diagrams illustrating a lighting device for simulating the second embodiment. Fig. 25 is a diagram showing the light quantity distribution (irradiance distribution) along the light exit surface of the lighting device of the second embodiment. Figure 26 is an enlarged view of L=0～25mm in Figure 25. 27( a ) to ( d ) are schematic diagrams illustrating a lighting device for simulating the third embodiment. Fig. 28 is a diagram showing the light quantity distribution (irradiance distribution) along the light exit surface of the lighting device of the third embodiment. Fig. 29 is an enlarged view of L=0～25mm in Fig. 28. 30(a) to (d) are schematic diagrams illustrating an illumination device used to simulate the fourth embodiment. Fig. 31 is a diagram showing light intensity distribution (irradiance distribution) along the light exit surface of the lighting device of the fourth embodiment. Fig. 32 is the enlarged view of L=0～25mm in Fig. 31. Fig. 33 is a schematic cross-sectional view of a reading device using the lighting device of this embodiment.

10: Lighting device

12: Light source

14: Light guide

14a: first end face

14b: light reflective surface

14c: Light exit surface

16: Concave

16a: The first interface

16b: The second interface

16c: The third interface

Claims (12)

A columnar light guide comprising: a light incident surface, which is provided at or near an end surface of the light guide; a light exit surface provided on at least a part of the side along the long side of the light guide; and At least one interface is arranged between the light incident surface and the light exit surface. According to claim 1, the light guide body has at least one light reflection surface on the side surface along the longitudinal direction of the light guide body, and the light reflection surface is provided at a portion opposite to the light exit surface. The light guide according to claim 1 or 2, which has a concave portion that is depressed from the end surface toward the long side of the light guide, and the surface included in the concave portion is provided with the interface. In the light guide according to Claim 3, the cross section of the recess perpendicular to the long side direction of the light guide has a polygonal shape. In the light guide according to claim 3, the cross section of the concave portion perpendicular to the long side direction of the light guide has a wedge shape. The light guide according to claim 3, which has a plurality of the concave portions on the end surface. The light guide according to claim 1 or 2, which has a groove on the end surface for accommodating at least a part of the light source. A columnar light guide comprising: a groove, which is arranged on or near an end surface of the light guide, and accommodates at least a part of the light source; a light incident surface, which is fastened in the groove; a light exit surface provided on at least a part of the side along the long side of the light guide; and At least one interface is arranged between the light incident surface and the light exit surface. The light guide as claimed in claim 1, 2 or 8 has a flange formed near the end surface. A lighting device comprising: A light guide, which is as described in claim 1, 2 or 8; and A light source injects light into the light guide body from the light incident surface. An image sensor comprising: A lighting device, which is as described in claim 10, and illuminates the object in a straight line; an array of vertical equal magnification lenses that collect reflected light from objects; and A light-receiving element receives the light collected by the upright equal-magnification lens array. A reading device comprising: An image sensor, which is as described in claim 11; a drive mechanism that scans the image sensor; and An image processing unit processes the data read by the image sensor.

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