Optical: systems and elements – Single channel simultaneously to or from plural channels – By surface composed of lenticular elements
Reexamination Certificate
2003-01-30
2004-04-06
Dang, Hung X. (Department: 2873)
Optical: systems and elements
Single channel simultaneously to or from plural channels
By surface composed of lenticular elements
C359S621000
Reexamination Certificate
active
06717734
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an image-forming lens unit for use in an image reading apparatus for example. The present invention also relates to an image reading apparatus incorporating such a lens unit.
BACKGROUND ART
Conventionally, various types of image reading apparatus are used for reading an image carried on a document. For example, there exists an image reading apparatus which reads an image of a document line by line (each line extending in the primary scanning direction). This type of image reading apparatus includes a plurality of light receiving elements arranged in a row. Accordingly, for forming an image of a document on these light receiving elements, a lens unit (lens array) need be used which includes a plurality of lenses arranged in a row extending in the primary scanning direction.
FIG. 42
illustrates an example of prior art image reading apparatus. The image reading apparatus includes a case
100
having a hollow portion, and a transparent plate
101
fitted in an upper portion of the case. The transparent plate
101
contacts a document D which is pressed against the plate by a platen roller
102
. By the rotation of the platen roller
102
, the document D is transferred in a direction indicated by an arrow Td (which is perpendicular to the primary scanning direction). The transparent plate
101
has an upper surface which includes a linear image read area Sa extending in the primary scanning direction. For irradiating the image read area Sa with light, a light source
103
is provided in the case
100
. A lens array
104
is provided below the image reading area Sa. The lens array
104
includes a plurality of lenses
105
arranged in a row extending in the primary scanning direction. As shown in
FIG. 42
, light from the image read area Sa is collected by the lenses
105
to be received by a plurality of light receiving elements
106
provided thereunder. Similarly to the lenses
105
, the plurality of light receiving elements
106
are arranged in a row extending in the primary scanning direction.
FIG. 43
is a perspective view showing the entirety of the lens array
104
. As shown in this figure, the plurality of lenses
105
are held by an elongated holder portion
104
a.
Each lens
105
is a columnar self focusing lens (selfoc lens) the refractive index of which varies depending on the distance from the central axis. Therefore, as shown in
FIG. 44
, light traveling within the lens
105
follows a tortuously bent path. By using such a lens, an object a-b and its image a′-b′ become equal in orientation and size.
In a prior art method for making the lens array
104
, prior to the formation of the holder
104
a
, lenses
105
are formed. Thereafter, the holder
104
a
are so formed by resin molding (insert molding) as to embed the lenses
105
. Thus, in the prior art method, the formation of the plurality of lenses
105
and the molding of the holder
104
are performed in separate process steps. This method is disadvantageous because the lens array
104
cannot be made efficiently.
The above-described problem becomes more serious due to the fact that a large number of lenses
105
are necessary for making a lens array
104
and that each lens
105
is very small. That is, each lens
105
needs to be precisely positioned relative to the holder
104
a
. For the lens array
104
which deals with a large number of small lenses, it is clearly very difficult to perform such positioning precisely and efficiently.
The image reading apparatus as shown in
FIG. 42
also has the following problems.
For reading an image at a high resolution, a document image need be formed by the lenses
105
without blurring. For this purpose, it is necessary to precisely set a distance La between the upper surface
105
a
of each lens
105
and the document G to a predetermined value. However, in an actual image reading process, the document G may rise from the transparent plate
101
so that the distance La may become longer than the predetermined length. Such a problem occurs more often in a hand-held scanner type image reading apparatus which does not include a platen roller.
In the prior art apparatus, therefore, the focal depth of each lens
105
is set large so that the image reading can be performed at a high resolution even when the distance La becomes slightly longer than the focal distance.
However, for making the focal depth of the lenses
105
large, the distance La need be set long. Further, when the focal depth is made large, the focal distance of each lens
105
becomes longer, so that a distance Lb (the distance between the lower surface
105
b
of each lens
105
and each light receiving element
106
) need be made longer. As a result, in the prior art image reading apparatus, the distance between the transparent plate
101
and the light receiving elements
94
becomes long, which increases the size of the image reading apparatus.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a lens unit which is capable of eliminating or at least lessening the above-described problems.
Another object of the present invention is to provide an image reading apparatus utilizing such a lens unit. A lens array which is provided in accordance with a first aspect of the present invention comprises: a body including a plurality of lenses and a holder portion for holding the lenses; and separating means for optically separating the plurality of lenses from each other; wherein the plurality of lenses and the holder portion are formed of a light-permeable resin and integral with each other.
In a preferred embodiment, the body includes an upper surface, and a lower surface opposite to the upper surface, and at least one of the upper and the lower surfaces is provided with a plurality of projections or recesses corresponding to the plurality of lenses.
Preferably, the separating means includes light-shielding portions for absorbing light.
In a preferred embodiment, the body includes a plurality of hollows provided adjacent to the plurality of lenses. The light-shielding portions include a dark-colored coating applied to wall surfaces of the body which define the hollows. Herein, the dark color may preferably be black. However, the present invention is not limited thereto, and any other color may be applicable if only it blocks or absorbs light.
Instead of the dark-colored coating, the light-shielding portions may be formed by inserting dark-colored members into the hollows.
In a preferred embodiment, the hollows are so provided as not to penetrate through the body.
In another preferred embodiment, the hollows are so provided as to penetrate through the body.
The hollows may be arranged in a row. In this case, each of the hollows may extend linearly in a direction intersecting the row.
The plurality of hollows may be generally cylindrical for surrounding the plurality of lenses, respectively.
The plurality of hollows may be so formed as to make the plurality of lenses tapered.
In a preferred embodiment, the light-shielding portions include dark-colored members embedded in the body.
In a preferred embodiment, the light-shielding portions include portions of the body which are dark-colored.
Preferably, the lens array of the present invention further includes a light-shielding member for covering an outer surface of the holder portion.
In a preferred embodiment, the plurality of lenses are arranged in a matrix, and the body is in the form of a plate.
In accordance with a second aspect of the present invention, there is provided a lens array comprising: a plurality of lenses; and a holder portion for holding the plurality of lenses; the lens array further including a plurality of hollows located adjacent the plurality of lenses; wherein the plurality of lenses and the holder portion are formed of a light-permeable synthetic resin and integral with each other.
In accordance with a third aspect of the present invention, there is provided a lens unit comprising: a first lens array including a plurality of first lenses, a first hold
Dang Hung X.
Martinez Joseph
Merchant & Gould P.C.
Rohm & Co., Ltd.
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