Linear light source

Abstract

It is an object of the present invention to offer a linear light source, which can realize a document read apparatus, in which there is little illuminance differences in a depth direction with respect to a document arrangement glass, in which even if the height of the document that serves as an object to be read is different, there is no big difference between the contrast of a copied image and the original document. A linear light source, in which an LED is arranged at an end portion of an approximately cylindrical light guiding member configured so that an upper portion, which has an approximately circular portion and which includes a light emitting face, a flat lower portion, which includes a light reflection face formed so as to face the upper portion, and side portions which connect the upper portion and the lower portion to each other, are arranged to extend in a longitudinal direction, respectively, and a light diffusion and reflection member provided outside of the light guiding member.

Description

technical field [0001] The present invention relates to a linear light source used in a document illuminating device, in particular to a linear light source in which LEDs are arranged at the end of a light guide. Background technique [0002] Conventionally, a technology using a light emitting diode (LED) as a light source of a document lighting device is known. This technology is divided into the following two types: an array type in which a plurality of LEDs are arranged across the width direction of the document surface; The type of light delivered to the light guide. Recently, with the increase in output of LEDs, the type using a light guide has attracted attention. [0003] As a linear light source using a light guide, Japanese Patent No. 2900799 is included, for example. This publication discloses the following configuration: arrange the LED at the end of the light guide, make the radiated light from the LED enter the light guide, transmit it inside the light guide,...

AI Technical Summary

Problems solved by technology

Therefore, the illuminance distribution greatly differs depending on the position in the X direction and the position in the Y direction, so there is a problem that accurate copying cannot be performed in the reading area of ​​the original.

[0013] In other words, in the reading area of ​​the glass where the originals to be copied are arranged, since the difference in illuminance in the Y direction (also called the depth direction) is large, the contrast of the reproduced image changes depending on the height of the originals, and accurate copying cannot be performed. manuscript problem

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