Facsimile and static presentation processing – Facsimile – Picture signal generator
Reexamination Certificate
1999-03-10
2003-09-30
Grant, II, Jerome (Department: 2722)
Facsimile and static presentation processing
Facsimile
Picture signal generator
C358S475000
Reexamination Certificate
active
06628431
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an image reader and a method for controlling the image reader. More particularly, the invention relates to an image reader capable of reading an image and a translucent original such as photographic film at high quality through self-advancement of a read unit provided with a reducing optical system employing an image-forming lens, as well as to a method for controlling the image reader.
BACKGROUND ART
Conventionally, a flat-bed-type image (or original) reader for reading an image through self-advancement of a read unit provided with a reducing optical system employing an image-forming lens is known as an image reader or an original reader (i.e., scanner) for reading, as image information, character information and graphic information present on a medium such as paper.
FIG. 18
shows a conventional flat-bed-type image reader. As shown in
FIGS. 18A and 18B
, the flat-bed-type image reader is composed of a flat bed unit
151
and a read unit
152
.
The flat bed unit
151
has an original bed
161
for placement of an original, a guide rail
162
, and a reference shaft
171
. The read unit
152
has a reducing optical system and a contact member
153
. The reducing optical system includes a fight source
175
, reflecting mirrors
176
, an image-forming lens
177
, and a CCD
178
. The contact member
153
includes a sliding member or a rolling member displaced so as to face the guide rail
162
.
When an original is scanned, the read unit
152
is driven by an unillustrated driving belt and caused to travel on the reference shaft
171
. A side of the read unit
152
which faces the guide rail
162
slides on a surface of the guide rail
162
. The surface of the guide rail
162
is finished to a high degree of flatness.
Accordingly, in the conventional image reader of
FIG. 18
, a positional error S may arise between the original bed
161
and the read unit
152
, as shown in
FIG. 18C
, due to various factors, such as the flatness and attachment accuracy of the guide rail
162
and the distortion of the entire image reader, including the flat bed unit
151
and the read unit
152
. When the error &dgr; arises, the optical path length between the original bed
161
and the CCD
178
becomes unstable.
Meanwhile, in recent image readers, the read unit
152
provided with a reducing optical system employing an image-forming lens has implemented higher resolution. In order to implement higher resolution, as shown in
FIG. 19
, the image-forming lens is forced to employ a shallow depth of field and a shallow depth of focus.
Accordingly, the conventional image reader involves the following problems.
(1) An unstable optical path length causes impairment in reading accuracy.
(2) Defocus results from a failure of an image to fall within the depth of field.
(3) Distortion of the entire image reader brings about a positional shift (skew) between a read start position and a read end position.
In an image reader (scanner) having a function to read a translucent original made of, for example, a transparent film, a light source for irradiating an original with light and a light-receiving sensor for receiving image-representing light which has passed through the original are moved in a mutually facing manner, thereby reading image information from the original. In order to read image information of the translucent original at high quality, an appropriate positional relation must be maintained between the light source for irradiating the original with light and the light-receiving sensor for receiving image-representing light which has passed through the original.
FIG. 20
shows a conventional flat-bed-type image reader capable of reading a translucent original
201
. As shown in
FIG. 20
, the image reader is composed of a reader body
260
and a freely-openable original cover
252
attached to the reader body
260
.
The reader body
260
includes a read unit
262
provided with reflecting mirrors
263
, an image-forming lens
264
, and a CCD
265
. The read unit
262
is driven by an unillustrated driving belt and caused to travel on a reference shaft
266
in a subscanning direction. The reader body
260
also includes an original bed
261
for placing a translucent original
201
thereon.
The original cover
252
is configured such that a light source unit
254
having a light source
253
is driven by an unillustrated driving element and caused to travel synchronously with the travel of the read unit
262
. The original cover
252
also includes a diffusion plate
255
. The diffusion plate
255
is disposed so as to face the original bed
261
and is adapted to diffuse light from the light source
253
to thereby absorb a positional deviation of the light source
253
from the reflecting mirrors
263
.
When the translucent original
201
is to be read, the translucent original
201
is placed on the original bed
261
, and then the original cover
252
is closed. Subsequently, the translucent original
201
is irradiated with light from the light source
253
. The light passes through the original bed
261
and reaches the CCD
265
via the reflecting mirrors
263
and the image-forming lens
264
, to thereby form an image on the CCD
265
. The thus-formed image of the translucent original
201
is converted to image data by the CCD
265
.
FIG. 21
shows a detailed structure of the original cover
252
. The original cover
252
has a guide rail
280
extending in the subscanning direction and serving as a driving element for driving the light source unit
254
. A rack
281
is formed at one side of the guide rail
280
. To a unit frame
279
of the light source unit
254
are attached the light source
253
and driving elements for the light source unit
254
, such as a pulse motor
287
and gears
283
and
284
. Further, the light source unit
254
has a pinion
282
serving as its driving element. The pinion
282
is journaled to be meshed with the rack
281
. The pinion
282
is driven by the pulse motor
287
via the gears
283
and
284
.
Two slide shoes
285
are provided on the light source unit
254
such that the slide shoes
285
are located on one side of the guide rail
280
opposite the rack-formed side thereof. The slide shoes
285
are pressed by means of pressing elements
286
so that the slide shoes
285
come in contact with the guide rail
280
at two positions located on opposite sides with respect to the meshing position between the rack
281
and the pinion
282
. Thus, the two slide shoes
285
define the orientation of the light source unit
254
.
Contact members
278
each formed of, for example, a sliding member are provided on opposite sides of the unit frame
279
of the light source unit
254
such that they abut the original cover
252
. One contact member
278
presses a cover frame
256
of the original cover
252
via a pressing element
286
. Thus, the light source unit
254
travels on the basis of the cover frame
256
. The diffusion plate
255
is fixed on the cover frame
256
by means of, for example, screws.
The translucent original
201
to be scanned by the flatbed-type image reader assumes the following forms: a naked film
201
a
as shown in
FIG. 22A
; and the film
201
a
accommodated in a film folder or case
201
b
as shown in FIG.
22
B. The film
201
a
is about 0.2 to 0.3 mm thick, and the film folder
201
b
is about 2 to 3 mm thick.
When the above-mentioned translucent original
201
placed on the original bed
261
is thick, the original cover
252
may be unable to be closed to a predetermined position. By contrast, when the translucent original
201
is thin, an improper assembling accuracy of an attachment portion of the original cover
252
may cause a failure to establish contact between the original cover
252
and the translucent original
201
in the vicinity of the attachment portion. In these cases, the distance between the light source
253
and the translucent original
201
varies along a main scanning direction. Also, when the original cover
252
is distorted in the Z direct
Masuda Minoru
Matsumoto Masashi
Miyauchi Yasunori
Sunasaki Tomohiro
Grant II Jerome
PFU Limited
LandOfFree
Picture readers and method for controlling the same does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Picture readers and method for controlling the same, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Picture readers and method for controlling the same will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3055359