TWI394920B - Light guide and linear light source device - Google Patents

Description

Light guide body and linear light source device

The present invention relates to a light guide for use in an image reading device for a facsimile machine, a photocopier, a scanner, a bar code reader, and the like, and a light guide plate provided with a liquid crystal panel. The light source for the edge illumination for the back light source.

In the image reading device such as a personal facsimile machine, LEDs (hereinafter referred to as LEDs) have high output and high sensitivity of CCD sensors as light-receiving elements, and small-sized and low-power LEDs have been It is used as a light source for reading a light source device. A conventional linear light source device using such an LED as a light source is known, and a light guide body is used for the purpose of reducing the number of light sources and obtaining uniform illumination intensity, and light emitted from the light source is incident on the light guide body. Let the light be guided in the direction of the desired direction.

Fig. 8 is a view showing a configuration of a linear light source device disclosed in Japanese Laid-Open Patent Publication No. Hei 9-163080.

The linear light source device includes a light guide 1 made of a transparent resin or the like, and a light source 2 made of an LED. The light guide 1 is provided with a light take-in portion 3 at one end in the axial direction, and a smooth surface 4 on which a reflective film is formed at the other end. The light source 2 is disposed to face the light taking-in portion 3. Further, an embossed groove 5 extending in the axial direction is provided on the outer peripheral surface on the side opposite to the irradiation direction of the light guide 1. The embossed groove 5 has a cutting direction perpendicular to the axial direction, and a cross section along the axial direction is a two-sided triangular shape.

The light emitted from the light source 2 enters the inside of the light guide 1 from the light taking portion 3, is reflected and reflected in the light guide 1, and is reflected to the reflecting surface 6 of the embossed groove 5, and then guided at a predetermined angle. The light body 1 is emitted.

Among the light emitted from the light source 2, the light α1 having a large incident angle with respect to the light taking-in portion 3 is reflected by the reflecting surface 6 of the embossing groove 5 close to the light taking-in portion 3 (light α 2 ). The light α 1 having a large incident angle with respect to the light taking-in portion 3 is small in the incident angle to the reflecting surface 6 of the embossing groove 5 (light α 2 ), so that it can be nearly vertical (slopewise toward the smooth surface 4) The exit angle is emitted from the light guide 1 (light α 3).

On the other hand, among the light emitted from the light source 2, the light β1 having a small incident angle with respect to the light taking-in portion 3 enters along the axial direction of the light guide 1, and is moved away from the light take-in portion 3 but is close to smooth. The reflecting surface 6 of the embossed groove 5 of the surface 4 is reflected (light β 2). The light β 1 having a small incident angle with respect to the light taking-in portion 3 has a large incident angle (light β 2 ) with respect to the reflecting surface 6 of the embossed groove 5, so that the light is guided at an angle inclined toward the smooth surface 4 Body 1 is emitted (light β 3).

[Patent Document 1] Japanese Patent Laid-Open Publication No. Hei 9-163080

However, since the linear light source device shown in Fig. 8 emits light β 3 having an angle inclined toward the smooth surface 4, black streaks may occur in the read image. Fig. 9 is a partial cross-sectional view showing the image reading device for reading the object 42 and the light for explaining the shadow 44.

The image reading device is provided with a mounting surface 41 which is formed of a light-transmitting member on the light-emitting surface 9 of the linear light source device, and the reading object 42 in which the image to be taken in is placed is placed. The mounting surface 41 is used. The light emitted from the light exit surface 9 of the light guide 1 is irradiated to the mounting surface 41, and the projected image of the read target 42 is used as a read image.

When a reading object 42 having a thickness such as a book is used, a thickness is generated between the light irradiation surface of the reading object 42 and the document cover 43. Since the light does not pass through the reading object 42, the light β 3a that illuminates the end portion of the reading object 42 does not illuminate the document cover 43. The light β 3a irradiated from the end portion of the object 42 to be irradiated slightly deviates from the irradiated light β 3b in the axial direction, and the document cover 43 is irradiated, but since it has an angle, it is offset from the end of the reading object 42 in the axial direction. Irradiation. Therefore, between the light β 3a and the light β 3b, the shadow 44 is not generated by the light, and the black image is displayed when the image is read.

Further, similarly, the reading object 42 also has a step of a zigzag line or the like.

The present invention has been made in view of the above problems, and an object thereof is to provide a light guiding body and a linear light source device capable of not forming a black streak in a read image even when a reading object has a thickness or a step. Radiated light.

According to a first aspect of the invention, the light guide body is a rod-shaped light guide body, and one end portion in the axial direction is a light take-in portion, and an embossed groove extending in the axial direction is formed on the side surface, and is characterized in that: The embossed groove has a plurality of groove portions, and a side surface of the groove portion on the light-receiving portion side serves as a reflection surface, and the groove portion The reflection surface of at least one of the grooves is composed of a primary reflection surface and a secondary reflection surface.

According to a second aspect of the present invention, in the first aspect of the present invention, the secondary reflection surface is formed at an axial end portion of the primary reflection surface, and an inclination angle of the secondary reflection surface is larger than an inclination angle of the primary reflection surface. .

According to a third aspect of the invention, the groove portion is configured by the reflection surface, the flat surface, and the light transmission surface, and has the reflection surface including the primary reflection surface and the secondary reflection surface. The light transmitting surface of the groove portion is composed of a primary light transmitting surface and a secondary light transmitting surface.

According to a third aspect of the present invention, in the third aspect of the present invention, the primary light-transmissive surface is formed at an end portion of the secondary light-transmissive surface in the axial direction, and the oblique angle of the secondary light-transmissive surface is larger than the primary light-transmitting surface. The angle of inclination is large.

According to a fifth aspect of the invention, the groove portion is configured by the reflection surface, the flat surface, and the light transmission surface, wherein the flat surface is inclined counterclockwise from the axial direction.

According to a sixth aspect of the invention, there is provided a linear light source device, comprising: the light guide according to any one of items 1 to 5, and the light-collecting surface facing the light guide; The light source into the department.

According to the light guide and the linear light source device of the present invention, since the reflecting surface of the groove portion of the embossed groove is constituted by the primary reflecting surface and the secondary reflecting surface, the linear light source device can be emitted toward the reading target in the axial direction. Light with different angle components, so even if the reading object has thickness or step difference In the case of the original cover, there will be no black lines on the read image.

A first embodiment of the present invention will be described. Fig. 1 is a perspective view showing the structure of a linear light source device of the present invention.

The linear light source device includes a light guide 2 made of a transparent resin or the like, and a light source 2 composed of an LED. The light guide body 1 is a cylindrical member, and the light take-in portion 3 is provided at one end in the axial direction, and the other end is a smooth surface 4. An embossed groove 5 extending in the axial direction is provided on the outer peripheral surface which is the side surface of the light guide 1, and the position of the opposing surface to the embossed groove 5 is the light exit surface 9. The embossed groove 5 is formed in a plurality of grooves 7 having a cutting direction perpendicular to the axial direction of the light guiding body 1.

The light source 2 is disposed inside the package box made of, for example, a resin, and is arranged with a plurality of blue LED elements, and the blue LED protection is fixed by the molding material to block the external air, and the phosphor layer will come from the blue The blue light of the color LED is converted into white light. Further, in general, the LED elements are different in light output. However, when the light source 2 is provided with a plurality of LED elements, the light output of the light source 2 does not affect the light output of each LED element, and a certain light output can be ensured. The light source 2 is disposed opposite to the light taking portion 3.

The light emitted from the light source 2 is a light distribution having a completely diffused surface light source, and is irradiated toward the light guide 1. When the emitted light from the light source 2 is incident on a highly tortuous medium, it is a light having a small meander angle according to the reflection rule. For example, when the light emitted from the light source 2 is incident on the light guide 1 having a tortuosity of n=1.49 through the air, the incident surface is for the light guide 1. When the central axis is a vertical surface, even if the incident angle is light of 89°, the incident angle of the 42° oblique light to the axis of the light guide 1 , that is, the side surface (outer peripheral surface) of the light guide 1 is 48°, exceeding Critical angle. Therefore, when the side surface of the light guide body is parallel to the axis by the mirror surface, the light incident on the light guide body 1 can be totally reflected and totally guided without loss.

Fig. 2 is an enlarged cross-sectional view showing the linear light source device of the present invention cut in the axial direction X.

The embossed groove 5 is perpendicular to the axial direction X of the light guide body, and is provided with a plurality of groove portions 7 cut in the radial direction Y from the embossed groove 5 toward the light exit surface 9, and a flat surface 8 is formed on the top of each groove portion 7. . Since the amount of light guided in the light guide 1 decreases as it goes away from the light taking portion 3, the length of the flat surface 8 in the axial direction X becomes shorter as it goes away from the light taking portion 3, and is embossed. The amount of light reflected by the groove 5 can be uniform across the entire axis. Further, in order to make the amount of light more uniform, the length of the radial direction Y of each of the groove portions 7 is gradually increased from the vicinity of the smoothing surface 4 from the vicinity of the light taking portion 3, and the width of the groove portion 7 is gradually increased.

The light incident from the light source 2 reflects the inner wall of the light guide 1 and reaches the embossed groove 5, and when the incident angle of the reflecting surface 6 exceeds the critical angle, the total reflection enters the light exit surface 9 and is guided by the light. Body 1 is shot toward the outside. The light A1 having a large incident angle with respect to the light taking-in portion 3 is reflected by the reflecting surface 6 of the embossed groove 5 close to the light taking portion 3. Since the incident light A1 has a small incident angle with respect to the reflecting surface 6 of the embossed groove 5, it is totally reflected to the light emitting surface 9 in the vertical direction. The light B1 having a small incident angle with respect to the light taking-in portion 3 is advanced along the axial direction X of the light guide 1, and is far away. The light taking-in portion 3 is reflected by the reflecting surface 6 of the embossed groove 5 close to the smooth surface 4. Since the incident light B1 has a large incident angle with respect to the reflecting surface 6 of the embossed groove 5, it is reflected by an angle having an inclination in the axial direction X from the light taking-in portion 3 toward the smooth surface 4.

Fig. 3 is a projection view showing the light guide 1 of the present invention taken along the line A-A' shown in Fig. 2 in the radial direction Y. The solid line is the shape of the light guide 1 of the display line A-A', and the broken line is the groove portion 7 showing the embossed groove 5.

The cross section of the light guide 1 in the radial direction is not completely circular, and a part of the light guide 1 is provided with a straight portion. When viewed from the entire light guide body 1, a horizontal plane extending in the axial direction is provided on the outer peripheral surface. The embossed groove 5 is located at this level. Because the horizontal plane can easily perform high-precision groove processing.

The embossed groove 5 is formed into a groove portion 7 that is cut into the radial direction Y in the width direction Z and cut at the same length. In the projection view of the plane in the radial direction Y and the width direction Z, the groove portion 7 has a trapezoidal shape.

Fig. 4 is an enlarged cross-sectional view showing each of the groove portions 7 in which the embossed grooves 5 of the light guide of the present invention are cut in the axial direction X.

The side surface on the light-receiving portion 3 side of each of the groove portions 7 serves as the reflecting surface 6, and the side surface on the smooth surface 4 side serves as the light-transmitting surface 10. The reflecting surface 6 is composed of a primary reflecting surface 11 and a secondary reflecting surface 12, and a secondary reflecting surface 12 is formed at an end portion of the primary reflecting surface 11 in the axial direction X. The groove portion 7 is formed in the axial direction X of the smooth surface 4 from the light taking-in portion 3, and forms a primary reflecting surface 11 that is immersed in the radial direction Y. The primary reflecting surface 11 continues to form the secondary reflecting surface 12, and the secondary reflecting surface 12 is continued. The surface 12 forms a flat surface 8, and the continuous flat surface 8 forms a light-transmissive surface 10 that protrudes in the opposite direction of the radial direction Y. That is, the groove portion 7 is oriented toward the axis The primary reflecting surface 11, the secondary reflecting surface 12, the flat surface 8, and the light transmitting surface 10 are sequentially formed in the order of X.

θ 1 is an angle indicating a counterclockwise rotation from the axial direction X to the primary reflection surface 11 , and θ 2 is an angle indicating a clockwise rotation from the opposite direction of the axial direction X to the light transmission surface 10 . θ 3 is an angle indicating a counterclockwise rotation from the axial direction X to the secondary reflection surface 12 .

In order to allow at least half or more of the light from the light source 2 to be totally reflected by the light guide 1, it is necessary to make the light emitted from the light source 2 at 45° even if it is 28° to the axis of the light guide 1 in the light guide 1. The slanted light is totally reflected. Therefore, the inclination angle θ 1 of the primary reflecting surface 11 is 20° in the vicinity of the light taking-in portion 3. Further, the inclination angle θ 2 of the light transmitting surface 10 is not 28° or more in contact with light having a 28° inclination.

The inclination angle θ 3 of the secondary reflection surface 12 is larger than the inclination angle θ 1 of the primary reflection surface 11 . Therefore, the light reflected by the primary reflecting surface 11 is reflected again to the secondary reflecting surface 12.

The light A1 incident on the primary reflecting surface 11 located away from the secondary reflecting surface 12 is reflected as light A2 having an angle inclined in the axial direction X. On the other hand, the light B1 incident on the primary reflecting surface 11 in the vicinity of the secondary reflecting surface 12 is again reflected by the secondary reflecting surface 12, and is reflected as the light B2 having an angle inclined in the opposite direction to the axial direction X. . When the inclination angle θ 3 is 75° to 90°, the emitted light B2 advances in a preferable direction.

Since the reflecting surface 6 is composed of the primary reflecting surface 11 and the secondary reflecting surface 12, the light A1 traveling in a single direction from the light source toward the inside of the light guiding body Even if B1 is guided, B1 is reflected by the reflecting surface 6 and becomes light A2 and B2 that advance in two directions. In order to make the light amount of the light A2 and the light B2 have an appropriate ratio, the adjustment can be suitably performed, but the height of the secondary reflecting surface 12 is such that half of the light having an inclination of 15 to 20 degrees can collide with the second reflection. Face 12 is preferred.

Fig. 5 is a partial cross-sectional view showing the image reading device in a state in which the light beams A2 and B2 are irradiated onto the reading target 42.

As shown in Fig. 4, the lights A2 and B2 reflected by the reflecting surface 6 are emitted to the outside of the light guiding body 1 through the light emitting surface 9, and the reading target 42 shown in Fig. 5 is irradiated. The image reading device is provided with a mounting surface 41 which is formed of a light-transmitting member on the light-emitting surface 9 of the linear light source device, and the reading object 42 in which the image to be taken in is placed is placed. The mounting surface 41 is used. The light emitted from the light exit surface 9 of the light guide 1 is irradiated to the mounting surface 41. In the image reading device, the reading target 42 on which the image to be taken in is described is placed on the mounting surface 41, and the projection image of the reading target 42 placed on the mounting surface 41 is detected as a read image.

When a reading object 42 having a thickness such as a book is used, a thickness is generated between the light irradiation surface of the reading object 42 and the document cover 43. Since the light does not pass through the reading target 42, the light A2 having the angular component inclined in the axial direction X illuminates the end of the reading target 42 without illuminating the original cover 43. However, the light B2 having the angular component inclined in the opposite direction to the axial direction X can be irradiated to a position where the light A2 cannot be irradiated to the document cover 43, so that the light is not irradiated.

Similarly, when the reading object 42 has a step of a meander line or the like, Be applicable.

Therefore, since the reflecting surface 6 of the groove portion 7 of the embossed groove 5 is composed of the primary reflecting surface 11 and the secondary reflecting surface 12, it is possible to obtain light having two different angular components in the axial direction X from the linear light source device. Since the reading object 42 is emitted, even if the reading object 42 has a thickness or a step, the original cover 43 does not appear, and black streaks do not appear in the read image.

A second embodiment of the present invention will be described. Fig. 6 is an enlarged cross-sectional view showing each groove portion 7 of the embossed groove 5 of the light guide of the present invention.

In the second embodiment, the shape of the groove portion 7 of the embossed groove 5 is changed in the linear light source device of the first embodiment. The groove portion 7a formed with the reflecting surface 6 formed of one surface and the groove portion 7b formed with the reflecting surface 6 composed of the primary reflecting surface 11 and the secondary reflecting surface 12 are alternately formed. The groove portion 7b is a rectangular groove that is immersed in the radial direction Y from the flat surface 8 of the groove portion 7a. The secondary reflection surface 12 formed in the groove portion 7b has a smaller immersion length in the radial direction Y than the secondary reflection surface 12 of the first embodiment, and the surface area thereof also increases. Further, the light transmitting surface 10 formed in the groove portion 7b is also composed of the primary light transmitting surface 13 and the secondary light transmitting surface 14. The inclination angle θ 4 of the primary light transmission surface 13 is an angle indicating a clockwise rotation from the opposite direction of the axial direction X to the primary light transmission surface 13 , and an inclination angle θ 2 with respect to the light transmission surface 10 of the groove portion 7 a. Slightly the same. The secondary light-transmissive surface 14 is a phase-to-surface secondary surface 12. The inclination angle θ 5 of the secondary light-transmissive surface 14 is a smooth direction from the opposite direction of the axial direction X to the secondary light-transmissive surface 14 The angle at which the hour hand rotates is larger than the inclination angle θ 4 of the primary light transmission surface 13 .

The groove portion 7a is formed with a reflection surface 6 that is immersed in the radial direction Y in the axial direction X, and the continuous reflection surface 6 forms a flat surface 8, and the continuous flat surface 8 forms a light-transmissive surface 10 that protrudes in the opposite direction to the radial direction Y. In other words, the groove portion 7a sequentially forms the reflecting surface 6, the flat surface 8, and the light transmitting surface 10 in the axial direction X.

On the other hand, the groove portion 7b is formed with the primary reflection surface 11 that is immersed in the radial direction Y in the axial direction X, and the secondary reflection surface 11 is formed by the primary reflection surface 11 to continue the secondary reflection surface 12, and the secondary reflection surface 12 is continued to form the flat surface 8 The continuation of the flat surface 8 forms the secondary light-transmissive surface 14 that protrudes in the opposite direction to the radial direction Y, and the secondary light-transmissive surface 14 continues to form the primary light-transmissive surface 13 twice. In other words, the groove portion 7b sequentially forms the primary reflecting surface 11, the secondary reflecting surface 12, the flat surface 8, the secondary light transmitting surface 14, and the primary light transmitting surface 13 in the axial direction X.

The light A1 incident on the reflecting surface 6 of the groove portion 7a is reflected as light A2 having an angle inclined in the axial direction X. On the other hand, the light B1 incident on the primary reflecting surface 11 of the groove portion 7b is incident on the primary reflecting surface 11 irrespective of the length (height) in which the second reflecting surface 12 is immersed in the radial direction Y. The angle or the incident position is substantially reflected again, and the light B2 having an angle inclined in the opposite direction to the axial direction X is reflected. The height at which the light A1 enters the reflecting surface 6 and the height at which the light B1 enters the primary reflecting surface 11 are slightly the same, but the reflected light A2, B2 advances in different directions.

Further, the light C1 irradiated to the groove portion 7b from a position higher than the lights A1 and B1 is incident on the secondary reflecting surface 12. Since the inclination angle of the secondary reflection surface 12 is large, the incident angle of the light C1 is smaller than the critical angle, and the light C1 passes through the secondary reflection surface 12. The transmitted light of the light C1 is re-entered from the secondary transmission surface 14 The light is incident on the inside of the light guide body, and becomes light C2 that is guided in the axial direction X.

In this manner, the groove portion 7a formed with the reflection surface 6 formed of one surface and the groove portion 7b formed with the reflection surface 6 composed of the primary reflection surface 11 and the secondary reflection surface 12 are alternately formed, even from the light source toward the light guide. The light A1, B1 traveling in a single direction inside the body is guided, and the light A2 reflected by the reflecting surface 6 of the groove portion 7a and the light reflected by the primary reflecting surface 11 and the secondary reflecting surface 12 of the groove portion 7b are still visible. B2, that is, light A2, B2 having an angular component having two different directions in the axial direction X is emitted toward the reading target 42. In addition, since the light C1 that has passed through the secondary reflecting surface 12 is again incident on the inside of the light guiding body and becomes the light C2 that is guided in the axial direction X, the light can be efficiently utilized.

Further, the formation interval between the groove portion 7a of the reflection surface 6 formed of one surface and the groove portion 7b formed with the reflection surface 6 composed of the primary reflection surface 11 and the secondary reflection surface 12 may not be formed alternately. The embossed groove 5 in which the number of the groove portions 7b formed by the primary reflecting surface 11 and the secondary reflecting surface 12 is formed by appropriately inserting the groove portion 7a formed of the reflecting surface 6 formed of one surface may be used. . And, on the contrary, it is possible.

In the groove portion 7 of the embossed groove 5 on the smooth surface side in the axial direction X of the light guide body, the original cover has the primary reflection surface 11 formed thereon, and the original cover has a shadow on the end portion of the reading target. The groove portion 7b of the reflecting surface 6 formed by the secondary reflecting surface 12 may be used.

Description will be given of the third embodiment of the present invention. Fig. 7 is a partially enlarged cross-sectional view showing the groove portion 7 of the embossed groove 5 of the light guide of the present invention. Fig. 7(a) is a view showing the flat surface 8 from the axial direction of the groove portion 7a as shown in Fig. 6. When the X is inclined counterclockwise, FIG. 7(b) shows a case where the inclination angles of the secondary reflection surface 12 and the secondary transmission surface 14 of the groove portion 7b shown in Fig. 6 are 90 or less.

As shown in Fig. 7(a), in the third embodiment, the linear light source device of the second embodiment is formed by inclining the flat surface 8 of the groove portion 7a counterclockwise from the axial direction X. The flat surface 8 is formed in a state in which the contact with the reflecting surface 6 is slightly rotated counterclockwise from the axial direction X as a fulcrum. When the light A1 is incident on the flat surface 8, the incident angle θ a becomes smaller than when the flat surface 8 is parallel to the axial direction X. The light A1 is totally reflected by the angle corresponding to the incident angle θ a on the flat surface 8 to become the light A2. The angle θ b of the light A2 with respect to the axial direction X is larger than the case where the flat surface 8 is parallel to the axial direction X, and the light A2 is an angular component which can increase the radial direction Y.

As shown in Fig. 7(b), in the linear light source device of the second embodiment, the angle of inclination of the secondary reflecting surface 12 and the secondary reflecting surface 14 of the groove portion 7b is 90 or less. When the inclination angle θ 3 of the secondary reflecting surface 12 is 90° or less, when the light B1 is reflected to the primary reflecting surface 11 and is incident on the secondary reflecting surface 12, the incident angle θ d of the secondary reflecting surface 12 is twice. The inclination angle θ 3 of the reflecting surface 12 is larger than that in the case of 90°. Since the emission light B2 of the secondary reflecting surface 12 corresponds to the incident angle θ d as well, the angle θ e with respect to the radial direction Y becomes small. In the light B2, the angular component in the opposite direction to the axial direction X is smaller than the case where the inclination angle θ 3 is 90°, and the angular component in the radial direction Y is increased, so that the light B2 advances in the direction close to the radial direction Y.

1‧‧‧Light guide

2‧‧‧Light source

3‧‧‧Light intake department

4‧‧‧ Smooth surface

5‧‧‧ embossed ditch

6‧‧‧reflecting surface

7‧‧‧Ditch Department

7a‧‧‧Ditch

7b‧‧‧Ditch Department

8‧‧‧flat surface

9‧‧‧Light shot

10‧‧‧Transparent surface

11‧‧1 times reflective surface

12‧‧‧2 reflection surfaces

13‧‧1 times light transmission surface

14‧‧‧2 times translucent surface

41‧‧‧Loading surface

42‧‧‧Reading objects

43‧‧‧Document cover

44‧‧‧ Shadow

1 is a perspective view showing a configuration of a linear light source device according to the present invention. [Fig. 2] An enlarged cross-sectional view of a linear light source device according to the present invention. [Fig. 3] The light guide of the present invention is cut in a radial direction. [Fig. 4] An enlarged cross-sectional view of each groove portion of the embossed groove of the light guide of the present invention [Fig. 5] A partial cross-sectional view of the image reading device in which light is irradiated onto the object to be read [Fig. 6] An enlarged cross-sectional view of each groove portion of the embossed groove of the light guide of the present invention [Fig. 7 (a) (b)] A partially enlarged cross-sectional view of the groove portion of the embossed groove of the light guide of the present invention [Fig. 8] Sectional view of a structure of a conventional linear light source device [Fig. 9] A partial cross-sectional view of an image reading device in which light is irradiated on a state to be read

6‧‧‧reflecting surface

7‧‧‧Ditch Department

8‧‧‧flat surface

10‧‧‧Transparent surface

11‧‧1 times reflective surface

12‧‧‧2 reflection surfaces

Claims (4)

A light guide body is a rod-shaped light guide body used for an illumination light source of an image reading device, and one end portion in the axial direction is a light take-in portion, and an embossed groove extending in the axial direction is formed on the side surface. The embossed groove has a plurality of groove portions whose cutting direction is perpendicular to the axial direction of the light guide body, and a side surface on the light-receiving portion side of the groove portion is a reflection surface, and at least one groove portion of the groove portion is reflected. The surface is composed of a primary reflection surface and a secondary reflection surface, and the secondary reflection surface is formed at an end portion of the primary reflection surface in the axial direction, and the inclination angle of the secondary reflection surface is larger than the primary reflection surface. An inclination angle; at least a part of the light having an angle inclined to the axial direction is reflected by the primary reflection surface, and is reflected again by the secondary reflection surface, and reflects light having an angle oblique to the opposite direction of the axial direction, from The light guide body emits light having an angle inclined in the axial direction and light having an angle inclined in the opposite direction to the axial direction toward the reading target. The light guide according to the first aspect of the invention, wherein the groove portion is formed by the reflection surface, the flat surface, and the light transmission surface in the axial direction, and has the primary reflection surface and the secondary reflection. In the groove portion of the reflecting surface formed by the surface, the light transmitting surface of the groove portion is composed of a primary light transmitting surface and a secondary light transmitting surface; and the axial end portion of the secondary light transmitting surface is formed once. The translucent surface, the inclination angle of the aforementioned two translucent surfaces is a ratio The inclination angle of the first light transmission surface is large. The light guide according to the first aspect of the invention, wherein the groove portion is formed by the reflection surface, the flat surface, and the light transmission surface in the axial direction, and the flat surface is inclined from the axial direction in a counterclockwise direction. A linear light source device comprising: a light guide body according to any one of claims 1 to 3; and a light source facing the light take-in portion provided in the light guide body.