JP2016015240A - Linear light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an efficient linear light source device in which a dead space does not occur in the longitudinal direction of a light guide body and in which an effective light emitting region is long, in the linear light source device including the light guide body and an LED element for introducing light in incident end surfaces on both ends of the light guide body.SOLUTION: A light guide body comprises a plurality of light guide rods arranged in a linear manner at an interval with each other, and each of the opposing end surfaces of the adjacent light guide rods configures an incident end surface. At the gap between each light guide rod, an LED element is arranged toward a direction orthogonal to the light guide rod, and at the gap, a light-transmitting diffusion member is arranged so as to oppose to a body to be irradiated. The light from the LED element is diffused by the diffusion member and enters the light guide rods on both sides, and the light which has transmitted the diffusion member is radiated toward the body to be irradiated.

Description

  The present invention relates to a linear light source device, and more particularly to a linear light source device for an image reading device used for a facsimile, a copying machine, an image scanner, a barcode reader, and the like.

In recent years, in the above-described image reading apparatus, a linear light source device using a small and low power consumption LED element is improved due to an improvement in output of an LED element (light emitting diode) and an increase in sensitivity of a CCD sensor as a light receiving element. For example, Japanese Patent Application Laid-Open No. 2011-124063 (Patent Document 1) discloses the technique.
FIG. 10 shows a schematic structure of this conventional linear light source device 20.
In FIG. 10A, an LED element 22 is disposed on one end face of a translucent rod-shaped light guide 21, and light from the LED element 22 is introduced from the end face into the light guide 21 and directed upward. Are emitted.
Thus, this type of linear light source device is required to be further reduced in size as the installation space on the image reading device side is made smaller.
However, in the linear light source device 20, due to the configuration in which the LED elements 22 are disposed opposite to the end face of the light guide 21, dead space D is inevitably generated at the end of the light guide, and the effective light emitting area is wide. There was a problem that could not be taken.
Further, as shown in FIG. 10B, when the LED elements 22 are arranged on both end faces of the light guide 21 in order to obtain a high amount of light, a dead space D is generated at both ends, and the above problem is further increased. It has become.

On the other hand, as shown in FIG. 11, in order to eliminate uneven brightness and color unevenness when using a plurality of LEDs, an LED element 32 is arranged in the center of the light guide member 31 and above it. Japanese Patent Application Laid-Open No. 2000-184135 (Patent Document 2) discloses a configuration in which the reflection member 33 is provided to reflect and direct light on both sides of the light guide member 31.
However, in such a complicated device form, it is difficult to uniformly spread the light guided from the LED element 32 to the left and right of the light guide member 31, and the structure of the central portion of the light guide member 31 has a complicated shape. In addition, it is difficult to obtain accurate reflection characteristics, and it cannot be said that it is preferable in terms of cost in manufacturing the apparatus.

JP 2011-124063 A JP 2000-184135 A

  In view of the above-described problems of the prior art, the present invention includes a light guide and an LED element that introduces light into an incident end face of the light guide, and emits light from the light guide to an irradiated body. In the linear light source device to irradiate, an efficient linear light source device having a long effective light emitting region is provided without causing a dead space in the longitudinal direction of the light guide.

  In order to solve the above-described problems, in the linear light source device according to the present invention, the light guide body includes a plurality of light guide bars arranged linearly with a gap between each other, and Each facing end surface constitutes an incident end surface, and faces the gap between the light guide bars, and the LED elements are arranged in a direction perpendicular to the light guide bars. A translucent diffusing member is disposed so as to face each other, and the light from the LED element is diffused by the inner surface of the diffusing member and is incident on the light guide rods on both sides and is transmitted through the diffusing member. The irradiated light is irradiated toward the irradiated object.

The diffusing member also serves as a connecting member for connecting and supporting a light guide bar arranged with a gap.
Further, the LED element is disposed at a position retracted from the gap between the light guide bars and facing the gap.
Further, the diffusing member is constituted by a diffusing portion on the irradiated body side and a light shielding portion on the LED element side.
Further, three or more light guide bars are provided, and LED elements are disposed in any gaps between the light guide bars.

According to the linear light source device of the present invention, the light guide is constituted by a plurality of light guide bars arranged in a straight line with a gap, and the LED elements are arranged in the gap. The dead space in the longitudinal direction can be made as small as possible, and the linear light source device can be made compact.
In addition, since the diffusing member is disposed facing the LED element, the light from the LED element is diffused and incident on the light guide rods on both sides, so that the light can be used effectively and one of the light from the LED element can be used. Since the portion to be transmitted is irradiated to the irradiated object, a drop in illuminance at a position corresponding to the gap between the light guide bars can be eliminated, and a uniform illuminance distribution can be obtained.
In addition, since the diffusing member also serves as a connecting member for the light guide rod, the number of parts can be reduced and the structure is simplified.

The perspective view of the linear light source device of Example 1 of this invention. FIG. 2 is a side sectional view (A) of FIG. 1 and a transverse sectional view (B) thereof. The side sectional view (A) and the transverse sectional view (B) of Example 2. Explanatory drawing of the countermeasure against the malfunction of Example 2. FIG. FIG. 6 is a side sectional view of Example 3. Side sectional view (A), top view (B), and transverse sectional view (C) of Example 4. The cross-sectional view (A) of Example 5 and the cross-sectional view (B) of Example 6. Schematic which shows an experiment example. The graph showing the effect of this invention. Conventional linear light source device. Another conventional linear light source device.

FIG. 1 is a perspective view showing a linear light source device of the present invention, FIG. 2 (A) is a side sectional view thereof, and FIG. 2 (B) is a transverse sectional view thereof.
As shown in FIG. 1 and FIG. 2A, the light guide 2 in the linear light source device 1 is divided into a first light guide rod 3 and a second light guide formed in the length direction. It consists of a rod 4 and is supported on a support base 15 so as to be arranged linearly as a whole.
As shown in FIG. 2A, the first and second light guide bars 3 and 4 are arranged in a straight line with a gap S, and a diffusion member 11 is arranged in the gap. . The diffusing member 11 is made of a translucent material such as white polycarbonate, for example, and reflects part of the light from the LED element 10 on its inner surface and transmits the other part.
In this embodiment, the diffusing member 11 also serves as a connecting member for connecting and supporting the first light guide rod 3 and the second light guide rod 4. May be a separate member.

An LED element 10 is disposed in the gap S between the light guide bars 3 and 4. In this embodiment, the LED element 10 is arranged in the same direction as the light emitting direction of the light guide 2, that is, so as to face the irradiated body.
The light from the LED element 10 is directly incident on the light guide rods 3 and 4 from the incident end surfaces 3a and 4a of the first light guide rod 3 and the second light guide rod 4 facing each other. , Toward the diffusion member (cum connecting member) 11. A part of the light traveling from the LED element 10 toward the diffusing member 11 is diffusely reflected on the inner surface to become diffused light, and enters the light guide bars 3 and 4 from the incident end surfaces 3a and 3b. The part passes through the diffusing member 11 and is irradiated toward the irradiated object.
Then, the light that is diffusely reflected from the LED element 10 and diffused and reflected from the diffusion member 11 and enters the light guide rods 3 and 4 travels through the light guide rods 3 and 4 and is reflected by the reflecting portions 3d and 4d. Then, the light exits from the light exit surfaces 3e and 4e toward the irradiated body.

FIG. 3 shows another embodiment 2. In this embodiment 2, the LED element 10 is slightly retracted from the gap S between the incident end surfaces 3a and 4a of the light guide bars 3 and 4, that is, The light guide rods 3 and 4 are disposed so as to face the gap S at positions shifted in the radial direction.
That is, the diffusing member (connecting member) 11 is formed with a housing portion 12c through a main opening 12a formed in the gap S and a communication opening 12b communicating with the main opening 12a. The LED element 10 is arranged.
The light from the LED element 10 reaches the main opening 12a through the communication opening 12b, and enters the light guide bars 3 and 4 from the incident end faces 3a and 4a. Further, the light directed toward the diffusing member 11 is partly diffusely reflected and is incident on the light guide rods 3 and 4, and part of the light is transmitted and directed toward the irradiated object, similarly to the embodiment of FIG. 2. .
With such an arrangement, it is not necessary to provide a space for directly installing the LED element 10 in the gap S between the light guide bars 3 and 4, and a design that makes the gap S smaller is possible.

In Example 2, as shown in FIG. 3B, the diffusing member (connecting member) 11 has an upper portion (illuminated side) as a light transmissive diffusing portion 11a and a lower portion (LED element side). ) May be used as the light shielding portion 11b. The diffuse light transmissive part 11a is made of a light transmissive material such as white polycarbonate, and the light shield part 11b is made of a light transmissive material such as polycarbonate coated with an aluminum plate or black paint.
As shown in FIG. 4A, when the LED element 10 is in a position retracted from the incident end face 3a of the light guide bar 3, a part of the light from the LED element 10 enters from the incident end face 3a of the light guide bar 3. Instead, the light is directly incident on the end portion of the light guide bar 3 from below and is directly emitted, and the illuminance is remarkably increased in the vicinity of the end portion, making it difficult to obtain uniform light distribution characteristics.
As shown in FIG. 4 (B), the light from the LED element 10 can be prevented from being directly transmitted from below the light guide bar 3 by making a part of the diffusion member 11 on the LED element side a light shielding portion 11b. .

In said Example 1, 2, although the light guide which consists of two light guide bars was shown, it is not restricted to this, The number of installation can be increased according to a desired irradiation width. For example, FIG. 5 shows a third embodiment provided with three light guide bars. The third embodiment includes first, second, and third light guide rods 3, 4, and 5, and an LED element 10 and a diffusing member (connection member) 11 are provided in the gaps between the light guide rods. Is provided.
In this arrangement, since light is introduced from the LED elements on both end faces into the second light guide bar 4 located in the center, it is longer than the first and third light guide bars 3 and 5 on both sides. It is a measure.
Of course, it is possible to use three or more light guide bars.

FIG. 6 shows a fourth embodiment in which the linear light source devices of the first to third embodiments are arranged in a planar shape.
As shown in FIGS. 6B and 6C, a plurality of linear light source devices 1 are arranged in parallel. In the fourth embodiment, the diffusing member 11 can be a member common to each linear light source device. In this embodiment as well, an example in which the diffusing member 11 includes a light transmissive diffusing portion 11a and a light shielding portion 11b is shown.
With such an arrangement, substantially parallel light can be emitted in a planar shape, and can be used, for example, for surface inspection of a workpiece (irradiated body).

  Further, FIG. 7 shows other embodiments 5 and 6. In the above-described embodiments 1 to 4 of FIGS. 1 to 6, the LED element 10 has the same light emitting direction as the light guide 2. Although it arrange | positions so that it may face to a to-be-irradiated body and face in the space | gap S toward the direction, in Example 5 shown to FIG. 7 (A), with respect to the emission direction of the light from the light guide 2. The LED elements 10 are arranged in the orthogonal direction. Further, in Example 6 shown in FIG. 7B, the LED elements 10 and 10 are arranged on both sides in the direction orthogonal to the light emitting direction.

An experiment was conducted to demonstrate the effect of the present invention.
<Invention>
As shown in FIG. 8 (A), the light guide rods 3 and 4 each having a length of 39 mm and a diameter of φ5 mm are arranged so as to have a gap S: 2 mm to have a total length of 80 mm. The LED element 10 was disposed so as to face. The LED element 10 is disposed at a position retracted by 6 mm from the center of the light guide rods 3 and 4.
In the gap, a diffusing member (connecting member) 11 having a light emitting side as a diffusing portion having a light transmitting function and an LED element side as a light shielding portion is disposed. The width of the light guide rods 3 and 4 is 1 mm at the end thereof inserted into the diffusion member 11, and the light emission length of the light guide rods 3 and 4 is 38 mm.
<Conventional example>
As shown in FIG. 8 (B), a light guide having a length of 80 mm and a diameter φ of 5 mm and an LED element facing each other is prepared.
<Comparative example>
As a comparative example, in the structure of the present invention shown in FIG. 8A described above, a structure in which all the diffusion members in the gap between the light guide rods are replaced with a non-light-transmissive light shielding member (not shown) is prepared.

These were measured by measuring the illuminance by placing a light receiver of the illuminometer at a position 5 mm from the light exit surface of the light guide bar.

The result is shown in FIG.
A comparison of the illuminance light distribution between the present invention and the conventional example is shown in FIG. 9A, and the present invention is compared with the decrease in illuminance on the left side (−40 mm side) showing the LED element arrangement side in the conventional example. Then, the illuminance drop in that portion is clearly reduced, and the influence of dead space is clear in the conventional example.
In addition, a comparison of the illuminance light distribution between the present invention and the comparative example is shown in FIG. 9B, and in the present invention provided with the diffusing member, there is no decrease in illuminance at the central portion in the longitudinal direction. On the other hand, in the comparative example which does not have a diffusion member, it turns out that the illumination fall in the said site | part is large.

  As described above, in the present invention, in the linear light source device including the rod-shaped light guide and the LED element that introduces light into the incident end surface of the light guide, the light guides are spaced from each other. A plurality of light guide rods arranged in a straight line, and facing the gap between the incident end faces of the adjacent light guide rods, the LED element is arranged in a direction perpendicular to the light guide rod, and the gap Includes a translucent diffusion member disposed so as to face the LED element, and the light from the LED element is diffused by the inner surface of the diffusion member and is incident on the light guide rods on both sides. At the same time, the light transmitted through the diffusing member is irradiated toward the irradiated object, so that the light can be effectively used, the dead space in the longitudinal direction of the light guide is reduced, and effective. It can provide an efficient linear light source device with a long light emitting area. That.

DESCRIPTION OF SYMBOLS 1 Linear light source device 2 Light guide 3 1st light guide rod 3a Incident end surface 3d Reflection part 3e Light output surface 4 Second light guide rod 4a Incident end surface 4d Free end surface 4e Light output surface 5 3rd light guide rod DESCRIPTION OF SYMBOLS 10 LED element 11 Diffusion member 11a Diffusion part 11b Light-shielding part 12 Opening part 12a Main opening part 12b Communication opening part 12c Storage part 15 Support stand S Gap

Claims (5)

In a linear light source device that includes a light-transmitting rod-shaped light guide and an LED element that introduces light into an incident end face of the light guide, and irradiates an irradiated body with light emitted from the light guide.
The light guide comprises a plurality of light guide bars arranged in a straight line with a gap between each other,
Each facing end surface of the adjacent light guide rod constitutes an incident end surface, facing the gap between the light guide rods, the LED element is arranged in a direction orthogonal to the light guide rod,
In the gap, a translucent diffusion member is disposed so as to face the irradiated body,
The light from the LED element is diffused by the inner surface of the diffusing member and incident on the light guide rods on both sides, and the light transmitted through the diffusing member is irradiated toward the irradiated body. A characteristic linear light source device.   The linear light source device according to claim 1, wherein the diffusing member also serves as a connection member that connects and supports a light guide bar disposed with a gap.   The linear light source device according to claim 1, wherein the LED element is disposed at a position retracted from a gap between the light guide bars and facing the gap.   The linear light source device according to claim 3, wherein the diffusing member includes a diffusing portion on the irradiated body side and a light shielding portion on the LED element side. The linear light source device according to claim 1, wherein three or more light guide bars are provided, and LED elements are disposed in any gaps between the light guide bars.

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