JP2001042456A - Linear light source - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make decreasable the total reflection on the light receiving face and to make increasable the light guide efficiency by forming a lens in the light receiving part of a linear light guide which guides the received light. SOLUTION: The light from a LED 7 as an emission light source is introduced as much as possible to a light guide 11 and is effectively used. A mirror state slope 11b is formed on the end face in the longitudinal direction of the light guide body 11, while a convex lens 11a is formed as the light receiving part on the lower face of the end part along the longitudinal direction of the light guide 11 (made of an acrylic resin having, for example, 1.5 refractive index). The LED 7 housed in a container 12, having an aspheric lens 13 in the upper part is disposed under the light receiving part. The LED is disposed in the bottom of the container 12 and a funnel-like slope 12a is formed in the step 12b where the aspheric lens 13 is to be fixed. The surface of the funnel-like slope is formed into a mirror face so that the light from the LED is reflected and condensed to the aspheric lens 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear light source of a contact-type linear sensor which can be used for a facsimile, a copying machine, a scanner, etc., and reads reflected light from an original by a sensor.

[0002]

2. Description of the Related Art Conventionally, a contact type linear sensor that forms a one-to-one image of a read document using a sensor array and reads the same size as the read document has been used as a document reading device used for facsimile, copier, scanning, and the like. It has been. In the contact-type linear sensor, a sensor chip on which pixels for performing photoelectric conversion are arranged, a sensor substrate on which a protective film for protecting the sensor chip is mounted, irradiation means for irradiating light to the document, and an image of the document. A lens array, which is a lens for forming an image on a pixel of the sensor chip, and a cover glass, which is a document reading surface, are fixed by bonding, press-fitting, fitting, caulking, or the like with one frame as a base. I have.

FIG. 1 shows an example of this kind of close contact type linear sensor.
2 and an exploded perspective view of FIG. Sensor chip 1
And a sensor board 2 for mounting the sensor chip 1,
It comprises a rod array lens 3, illuminating means 8, a cover glass 5, and a base 6 for positioning them. The illuminating means 8 includes an LED 7 as a light source and the light guide 4.

The illuminating means 8 is a linear light source provided with the light guide 4 and the LED 7. The LED 7 serves as a light source, and the light propagating in the light guide 4 in the longitudinal direction is reflected by the light guide 4. -Irradiation part 4b of light guide 4 reflected and diffused by diffusion part 4a
Irradiates the original 9 from outside. The irradiated image of the original 9 is formed by the rod lens array 3 on the pixels arranged on the sensor chip 1, and is photoelectrically converted by the sensor chip 1. That is, the original is scanned by linear illumination, the reflected light is received by the sensor chip 1 serving as a light receiving element, and the density of characters and figures drawn on the original 9 is detected as the intensity of the reflected light, and is converted into an electric signal. It is converted and output as multi-value density information.

[0005] The length of the linear light source varies depending on the size of the document. However, since a portable hand scanner is also required to read B5 or A4, the length of the linear light source is required to be 18 cm or 21 cm.

[0006]

Although the linear light source is long and the light source is located at one end of the linear light source, the light intensity at the irradiation part must be uniform, but adjustment is difficult. there were.

It is desirable that the light from the LED, which is the light emitting source, be guided into the light guide without leaking the light at a maximum and be used effectively. In particular, in a portable device which depends on a battery for its power source, the power consumption is reduced. It is also necessary to increase the light guide efficiency. However, since the light receiving portion of the light guide was a flat surface, light having a large light incident angle was totally reflected and the light guide efficiency was reduced. FIG. 3 is a schematic diagram showing an LED, a light guide, and light guide according to the related art. When the space between the LED and the light guide is air and the light guide is made of an acrylic resin (refractive index: 1.5), when the incident angle is 41 ° or more, the light is totally reflected and cannot enter the light guide. .

[0008]

SUMMARY OF THE INVENTION In a linear light source for guiding and illuminating light received from a light source with a linear light guide, a lens is provided at a light receiving portion of the linear light guide.

In a linear light source for guiding and illuminating light received from a light source with a linear light guide, a concave lens is provided in a light receiving portion of the linear light guide.

In a linear light source for guiding and illuminating light received from a light source with a linear light guide, a convex lens is provided at a light receiving portion of the linear light guide.

[0011]

FIG. 4 shows a first embodiment of the present invention and is a schematic view showing an LED, a light guide and light guide. The end 10a of the light guide 10 has a concave lens shape in which the LED 7 is arranged on the optical axis of the lens. LED
The curvature of the LED 7, the concave lens portion 10a, and the concave lens is considered so that the light irradiated from the lens 7 to the concave lens portion 10a does not undergo total reflection.

The light incident on the light guide is guided in the longitudinal direction of the light guide. The light goes straight in the longitudinal direction from the angle of incidence, the light totally reflects on the surface of the light guide, and the light from the light guide. And irradiate the original. The distribution of the above three types of light can be freely set by the curvature of the LED 7, the concave lens portion 10a and the concave lens, so that the light intensity at the irradiation portion becomes uniform according to the shape of the reflection / diffusion portion provided in the light guide. It should just be arranged.

FIG. 5 shows a second embodiment of the present invention and is a schematic view showing an LED, a light guide, and light guide. A mirror-like inclined surface 11b is provided at the longitudinal end of the light guide 11, and a convex lens 11a is provided on the lower surface of the longitudinal end of the light guide 11 (acrylic resin and has a refractive index of 1.5) to form a light receiving portion. . An LED 7 having an aspheric lens 13 on the upper side and housed in a container 12 is disposed below the light receiving section. The container 12 has an LED disposed at the bottom, and a funnel-shaped slope 12a is formed up to a step 12b for fixing the aspherical lens 13. The funnel-shaped surface is a mirror surface, and the light from the LED 7 is reflected and condensed on the aspheric lens 13. The dimensions in the figures indicate the arrangement of the preferred embodiment.

The aspheric lens 13 has an aspheric coefficient of R1.
K = 0, A1 = −0.22043E-01, A2 = +
0.11998E-01, A3 = + 0.76091E-
02, A4 = -0.33620E-02, and the aspheric coefficient of R2 is K = 0, A1 = + 0.11679E + 0
0, A2 = + 0.26298E + 00, A3 = + 0.3
5399E + 00, A4 = -0.81426E + 00. (K = cone constant, A1 = fourth order aspheric coefficient, A2
= 6th order aspherical coefficient, A3 = 8th order aspherical coefficient, A4 =
10th order aspheric coefficient)

FIG. 6 shows a third embodiment of the present invention and is a schematic diagram showing an LED, a light guide, and light guide. A mirror-shaped inclined surface 14b is provided at the longitudinal end of the light guide 14, and a concave lens 14a is formed on the lower surface of the longitudinal end of the light guide 14.
And a light receiving section. An aspheric lens 15 and an LED 7 are arranged below the light receiving unit.

The light from the LED 7 is condensed by the aspherical lens 15, enters the light guide 14 from the concave lens portion 14 a provided on the light guide 14, is reflected by the slope 14 b, and is guided in the longitudinal direction of the light guide 14. Be lighted. For the above three types of light distribution, the optimal position and curvature can be set by simulating the positional relationship between the light guide, the lens, and the LED and the curvature of the lens.

FIG. 7 shows a fourth embodiment of the present invention and is a schematic diagram showing an LED, a light guide, and light guide. A mirror-shaped inclined surface 16b is provided at a central portion in the longitudinal direction of the light guide 16, and a concave lens 16 is provided on a lower surface of the central portion in the longitudinal direction of the light guide 16.
a is provided as a light receiving section. An aspheric lens 17 and an LED 7 are arranged below the light receiving unit.

The principle is the same, except that the light incident on the light guide 16 is guided half by left and right in the longitudinal direction of the light guide. If the light guide is long or you want to increase the amount of light,
The object can be achieved by providing the light guide at a plurality of locations.

[0019]

By providing a lens on the light receiving portion of the light guide, total reflection on the light receiving surface of the light guide can be reduced, and the efficiency of light guide to the light guide can be increased.

The light guide distribution in the light guide can be adjusted by simulating the positional relationship between the light guide, the lens, and the LED and the curvature of the lens.

If an LED with a condenser lens is used, an aspheric lens can be omitted, and a linear light source with good light guide efficiency can be realized by the curvatures of the LED, the light guide, and the lens provided on the light guide.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a conventional contact-type linear sensor.

FIG. 2 is an exploded perspective view of a contact-type linear sensor according to the related art.

FIG. 3 is a schematic view showing an LED, a light guide, and light guide of light according to a conventional technique.

FIG. 4 is a schematic diagram showing an LED, a light guide, and light guide of the light according to the first embodiment of the present invention.

FIG. 5 is a schematic view showing an LED, a light guide and light guide according to a second embodiment of the present invention.

FIG. 6 is a schematic view showing an LED, a light guide, and light guide of a light according to a third embodiment of the present invention.

FIG. 7 is a schematic view showing an LED, a light guide, and light guide of the light according to a fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sensor chip 2 Sensor board 3 Rod lens array 4 Light guide 4a Reflection / diffusion part 4b Irradiation part 5 Cover glass 6 Base 7 LED 8 Lighting means 9 Document 10 Light guide 10a Concave lens part 11 Light guide 11a Convex lens 11b Slope Reference Signs List 12 container 12a slope 12b step 13 aspherical lens 14 light guide 14a concave lens 14b slope 15 aspherical lens 16 light guide 16a concave lens 16b slope 17 aspherical lens

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F21W 131: 403 F21Y 101: 02

Claims (3)

[Claims] 1. A linear light source for guiding and illuminating light received from a light source with a linear light guide, wherein a lens is provided at a light receiving portion of the linear light guide. . 2. The linear light source according to claim 1, wherein the lens is a concave lens. 3. The linear light source according to claim 1, wherein the lens is a convex lens.