Facsimile and static presentation processing – Facsimile – Picture signal generator
Reexamination Certificate
1998-07-14
2001-03-20
Lee, Cheukfan (Department: 2722)
Facsimile and static presentation processing
Facsimile
Picture signal generator
C358S475000, C358S509000
Reexamination Certificate
active
06204938
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a linear illumination device having a light conducting body and an image reading apparatus using the same.
2. Description of the Related Art
Conventionally, in an illumination device for a facsimile apparatus or an image reading apparatus such as a scanner and a bar code reader, an LED array in which a number of light-emitting devices such as light-emitting diodes are arranged in an array are generally used. (In this application, light-emitting devices such as light-emitting diodes are collectively referred to as LEDs.) In an illumination apparatus with such a structure, a decrease in the number of LEDs to be used in a light source portion causes a decrease and a variation of the illuminance, which makes it difficult to decrease the number of LEDs. Furthermore, since an LED emitting blue light is expensive, it is difficult to reduce fabrication cost.
On the other hand, as a method for decreasing the number of LEDs for the purpose of reducing fabrication cost, a technique of using a light conducting body has been proposed, for example, in Japanese Laid-open Publication No. 8-43633. A structure of an illumination device
100
based on such a conventional technique is shown in FIG.
16
.
In an illumination device
100
shown in
FIG. 16
, one side surface of a bar-shaped light conducting body
101
is provided with a light diffusion portion
102
in parallel with an axis of the light conducting body
101
. Illuminants
103
are formed on both ends of the light conducting body
101
so as to be close to light incident surfaces
104
a
and
104
b.
Light which is incident upon an inside of the light conducting body
101
from the illuminant
103
travels through the light conducting body
101
in accordance with Snell's law. Light which reaches the light diffusion portion
102
on its way is reflected and diffused by the light diffusion portion
102
, and is output from a light-emitting surface
105
opposing the light diffusion portion
102
of the light conducting body
101
.
Furthermore, a structure of an image reading apparatus
200
using a conventional illumination device
210
is shown in FIG.
17
.
In the illumination device
210
of the image reading apparatus
200
shown in
FIG. 17
, LEDs
214
are mounted on a printed wiring board
212
as a light source portion, and the LEDs
214
are sealed with a transparent resin
216
. The illuminance of the LEDs
214
is determined based on a current flowing therethrough. The level of the current is set by a resistance value of a resistor
218
.
Output light
220
from the illumination device
210
passes through a cover glass
222
(which functions as a document table and a cover), is incident upon a surface of an original surface (i.e., a document surface)
224
(subject) to be illuminated, and is reflected from the original surface
224
. Reflected light
226
passes through the cover glass
222
, and is incident upon a rod lens array
230
fixed by a metal frame
228
. An image of the original surface
224
is formed on a photoelectric conversion element
234
mounted on a wiring board
232
by the rod lens array
230
.
Furthermore, the printed wiring board
212
on which the LEDs
214
are mounted and the wiring board
232
on which the photoelectric conversion element
234
is mounted are electrically connected to each other via leads
236
, for example, with a solder
238
.
However, in the above-mentioned conventional illumination device
100
shown in
FIG. 16
, the illuminants
103
as a light source portion are required to be placed on both ends of the light conducting body
101
, which enlarges the size of the device. Therefore, when such an illumination device
100
is used as a contact-type image sensor or the like which is intended to be miniaturized or made compact, inconvenience of enlargement of the entire structure is caused.
Furthermore, the above-mentioned conventional image reading apparatus
200
shown in
FIG. 17
uses the leads
236
for electrically connecting the illumination device
210
to the photoelectric conversion element
234
. Therefore, particularly in a system in which the three LEDs
214
respectively emitting three colors of light (i.e., red, blue, and green) are used as a light source and a colored original (document) is read by switching between the LEDs, the number of the leads
236
increases, causing inconvenience of complicated wiring. In addition, due to the increase in number of the leads
236
, a space for accommodating the wiring therein is required to be enlarged, which hinders miniaturization of an image reading apparatus. Furthermore, when leads with a small diameter are used for the purpose of decreasing an occupied space of the leads
236
, it becomes difficult to attach the leads
236
to the wiring boards
212
and
232
, and the leads
236
become likely to be cut.
SUMMARY OF THE INVENTION
A linear illumination device of the present invention includes: a light conducting body; a light diffusion portion formed at least on one side surface in a longitudinal direction of the light conducting body; a light output portion formed in a portion of the light conducting body opposing the light diffusion portion; a light source portion disposed at a first end of the light conducting body; and a light reflecting layer provided at a second end opposing the first end of the light conducting body.
In one embodiment, the device further includes a non-light diffusion portion provided between the light source portion and the light diffusion portion.
In another embodiment, the device further includes a rough surface for diffusing light, provided in a portion of the light conducting body between the light source portion and the light diffusion portion.
Preferably, at least a portion of a cross-sectional shape perpendicular to the longitudinal direction of the light conducting body has an arch shape. The arch shape may be a portion of a circle, an oval, or a combination thereof.
Preferably, the light conducting body is made of a transparent material, and a size of a diameter of the second end of the light conducting body at which the light reflecting layer is disposed is smaller than a diameter of the first end of the light conducting body at which the light source portion is disposed.
In one embodiment, a triangular wave surface including a plurality of triangular configurations is formed on the light diffusion portion.
In one embodiment, the light source portion contains a light emitting device having at least one luminescent color of red, green, and blue.
In one embodiment, a red light emitting device, a green light emitting device, and a blue light emitting device are disposed in the light source portion along a line substantially parallel to a normal to the triangular wave surface.
The red light emitting device, the green light emitting device, and the blue light emitting device may be controlled in a time-divisional manner.
In one embodiment, the device further includes a light reflecting unit provided around an outer peripheral portion of the light conducting body at least excluding the light output portion.
The light reflecting unit may be a reflecting case, and the light conducting body may be accommodated in the reflecting case.
In one embodiment, the light source portion includes a substrate having a concave portion with a sloped side wall and a light emitting device mounted on a bottom surface of the concave portion of the substrate.
In one embodiment: a surface is provided at a level different from a level of the bottom surface in the concave portion of the substrate; a first conductive pattern is provided on the bottom surface of the concave portion and a second conductive pattern is provided on the surface at the different level; and the light emitting device is mounted on the first conductive pattern and is electrically connected to the second conductive pattern by a metal fine wire.
In one embodiment, the light source portion has a light emitting device which is mounted on a substrate in
Chosa Yoshihiko
Horiuchi Toshiro
Nakamura Tetsuro
Takesako Kohichi
Yamanaka Takashi
Lee Cheukfan
Matsushita Electric - Industrial Co., Ltd.
Ratner & Prestia
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