Facsimile and static presentation processing – Facsimile – Picture signal generator
Reexamination Certificate
1999-02-24
2002-12-17
Lee, Cheukfan (Department: 2722)
Facsimile and static presentation processing
Facsimile
Picture signal generator
C358S483000
Reexamination Certificate
active
06496285
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image reading apparatus incorporated in a facsimile machine, a scanner and the like.
2. Description of the Related Art
As is well known, a conventional image reading apparatus includes a light source for irradiating a document brought to an image reading section, and a plurality of light receiving elements mounted on a printed circuit board. The light receiving elements are arranged to receive light reflected at the image reading section and output image signals (which are relatively weak) in accordance with the received light. These image signals are sent to a predetermined position via a wiring pattern formed on the printed circuit board. The light source and the printed circuit board are accommodated in a suitable container.
The conventional image reading apparatus have been found disadvantageous in the following points.
It is assumed that a cold-cathode tube is used for the light source of the image reading apparatus. For actuating the cold-cathode tube, high-voltage and high-frequency driving power needs to be supplied to the cold-cathode tube. To this end, typically, use is made of an inverter connected to the cold-cathode tube via a connection cable.
In the above arrangement, due to the use of the high-voltage and high-frequency driving power, electrical noises may be generated at the inverter or the connection cable or the cold-cathode tube. The occurrence of electrical noises is unfavorable since the electrical noises tend to adversely influence the relatively weak image signals supplied by the light receiving elements.
The above problem may seem to be solved by using a light-emitting diode (which does not need high-voltage and high-frequency driving power) for the light source instead of the cold-cathode tube. However, when the image reading apparatus is incorporated in e.g. a facsimile machine, electrical noises may well be generated at some of the components or elements contained in the facsimile machine.
Turning back to an instance where a cold-cathode tube is used for the light source, the conventional image reading apparatus also suffers from the following problem.
As shown in
FIG. 22
of the accompanying drawings, a conventional cold-cathode tube has an elongated, straight configuration. Specifically, the conventional cold-cathode tube has two longitudinal ends
39
and an intermediate portion
3
e
located between the ends
39
. As illustrated, the cold-cathode tube has a length which is generally equal to the width L
1
of a document
90
to be read out. Such an arrangement has the following disadvantage.
Reference is now made to
FIG. 23
which shows the relationship between relative luminosity of the conventional cold-cathode tube and longitudinal positions of the cold-cathode tube. As can be seen, the relative luminosity at the ends
39
of the cold-cathode tube (indicated by reference character C) is unduly smaller by about 20-30% than that in the intermediate portion
3
e
. Thus, when the length of the cold-cathode tube is equal to the width L
1
of the document (FIG.
22
), the cold-cathode tube will fail to properly irradiate the end portions of the document corresponding in position to the ends
39
of the cold-cathode tube.
In order to overcome the above problem, an arrangement shown in
FIG. 24
may be adopted. According to the illustrated arrangement, the length L
2
of the cold-cathode tube is rendered greater than the width L
1
of the document
90
. In this manner, every portion of the document
90
can be irradiated with an equal amount of light emitted from the intermediate portion of the cold-cathode tube.
However, with the arrangement shown in
FIG. 24
, the ends
38
of the cold-cathode tube are located outside of the document
90
as viewed in the primary scanning direction. Clearly, this arrangement is disadvantageous since the size of the image reading apparatus is unfavorably made larger due to the increased length of the cold-cathode tube.
Further, a certain amount of light is emitted from the ends
38
of the cold-cathode tube. However, in the arrangement shown in
FIG. 24
, the light from the ends
38
will simply be wasted without being used to irradiate the document
90
.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention is to provide an image reading apparatus which eliminates or reduces the above-described problems.
According to a first aspect of the present invention, there is provided an image reading apparatus comprising:
a cold-cathode tube for irradiating a linearly extending image reading section, the cold-cathode tube including a first end portion, a second end portion, and an intermediate portion arranged between the first end portion and the second end portion; and
a plurality of light receiving elements for receiving light reflected at the image reading section;
wherein at least one of the first and the second end portions extends in a direction differing from another direction in which the intermediate portion extends.
With such an arrangement, a document to be read out is advantageously irradiated since the first or second end portion extends from the intermediate portion at a certain angle (90 degrees for example). Further, with the above arrangement, the longitudinal dimension of the cold-cathode tube can be reduced. Thus, the image reading apparatus incorporating the cold-cathode tube can be reduced in size.
According to a preferred embodiment, each of the first and the second end portions extends in a direction differing from said another direction.
The image reading apparatus further comprises a lens array for focusing the reflected light onto the light receiving elements, wherein the lens array is disposed in a region defined by the first end portion, the second end portion and the intermediate portion.
With such an arrangement, the lens array and the cold-cathode tube are compactly held in place.
The image reading apparatus may further comprise an inverter for supplying power to the cold-cathode tube, wherein the lens array is disposed between the inverter and the intermediate portion.
According to a second aspect of the present invention, there is provided a cold-cathode tube for irradiating an image reading section of an image reading apparatus comprising:
a first end portion provided with an electrode;
a second end portion provided with another electrode; and
an intermediate portion arranged between the first end portion and the second end portion;
wherein at least one of the first and the second end portions extends in a direction differing from another direction in which the intermediate portion extends.
According to a third aspect of the present invention, there is provided an image reading apparatus comprising:
a light source for irradiating an image reading section;
a plurality of light receiving elements for receiving light reflected at the image reading section;
a printed circuit board having an upper surface for mounting the light receiving elements and a lower surface opposite to the upper surface;
a container for accommodating the light source and the printed circuit board;
an outer shield member which is grounded and externally attached to the container; and
an inner shield member which is accommodated in the container and electrically connected to the outer shield member.
With such an arrangement, electrical noises can be shielded by the outer and the inner shield members, so that the relatively weak image signals supplied from the light receiving elements will not be adversely influenced by the noises.
The light source may comprise a cold-cathode tube, the inner shield member being arranged between the cold-cathode tube and the printed circuit board.
According to a preferred embodiment, the image reading apparatus further comprises a reflector for supporting the cold-cathode tube, wherein the inner shield member defines a groove for accommodating the reflector.
The container may be formed with a first hollow portion for accommodating the inner shield member.
The image reading a
Fujimoto Hisayoshi
Onishi Hiroaki
Takakura Toshihiko
Lee Cheukfan
Merchant & Gould P.C.
Rohm & Co., Ltd.
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