Optical: systems and elements – Lens – With support
Reexamination Certificate
1998-03-09
2001-02-06
Epps, Georgia (Department: 2873)
Optical: systems and elements
Lens
With support
C359S819000, C250S201700
Reexamination Certificate
active
06185053
ABSTRACT:
FIELD OF THE INVENTION
The present invention is related to a resolution adjusting device, and more particularly to a device for adjusting a resolution of an image scanning apparatus in horizontal and vertical directions.
BACKGROUND OF THE INVENTION
At the present time, a ruler
11
with a pattern of vertical lines
12
(having a certain line pairs per minimeter, lp/min) is often used as a target to adjust the focus of the lens in the scanner as shown in FIG.
1
. However, there is a higher resolution in the horizontal direction but a lower resoluion in the vertical direction resulting from using the pattern of vertical lines of the ruler
11
.
Please refer to
FIG. 2
showing a theoretical diagram of the characteristic of a general lens. X specifies the resolution in the horizontal direction and Y specifies the resolution in the vertical direction. The ruler
11
provides an image to be received by a charge coupled device (CCD) for adjusting the focus of the lens in the scanner. During the process of adjusting the lens, the resolution of the image in the horizontal direction is not in accordance with that in the vertical direction. As shown in
FIG. 2
, the point A is the best point of the horizontal resolution. The modulation transport function (MTF) of the horizontal direction is about 0.35 but that of the vertical direction is only 0.04 (the MTF is proportional to the resolution). On the other hand, the point E is the preferable point of the vertical resolution, wherein the MTF in the horizontal direction is about 0.24 but that in the vertical direction is only 0.1. However, the desired point should be the point B rather than the extreme point A or E. The resolution of the lens is often focused on the point A by using the ruler
11
with a pattern of vertical lines.
FIG. 3
is a real diagram showing the characteristic of the lens. T specifies the best point
31
of the vertical resolution of the image of the subject P after providing an optical signal transmitted through the lens
30
, C specifies the best point
32
of the vertical and horizontal resolutions, and S specifies the best point
33
of the horizontal resolution. If the ruler
11
with a pattern of the vertical lines is used as a target, only the horizontal resolution can be adjusted such that the resolution is usually adjusted on the point
33
. Therefore, the horizontal resolution of the image is clear but the vertical resolution of the image is vague. The deviation of the horizontal resolution can be calibrated by taking advantage of the pattern of the vertical line so that the horizontal resolution can be adjusted in the best condition. However, the deviation of the vertical direction can not be calibrated. It seems impossible to adjust the resolution on the best point B as shown in FIG.
2
.
In order to overcome this defect, the present invention provides a device for adjusting a resolution of an image-pickup apparatus. The focus of the lens can be fastly and exactly adjusted in the range between point C and D according to the characteristic of the lens as shown in
FIG. 2
to obtain the best resolution (the point B). Thus, the efficiency for calibrating the optical apparatus can be improved to meet the requirements of high yield rate and low cost.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a device for adjusting a resolution of an image scanning apparatus in horizontal and vertical directions.
According to the present invention, the resolution adjusting device includes a diagonal pattern for providing an image to be received by the photoelectric conversion device of the image scanning apparatus to obtain an adjusted resolution by adjusting a position of the focusing device of the image scanning apparatus according to the image.
In accordance with one aspect of the present invention, the diagonal pattern is formed by a plurality of oblique blocks in different colors.
In accordance with another aspect of the present invention, the plurality of oblique blocks have spaced black and white colors in between.
In accordance with another aspect of the present invention, the diagonal pattern has a plurality of oblique lines therein.
In accordance with another aspect of the present invention, each of the oblique lines and a horizontal line have an included angle ranged from 15° to 85°.
In accordance with another aspect of the present invention, the focusing device includes a lens.
In accordance with another aspect of the present invention, the phtoelectric conversion device includes a charge coupled device (CCD).
The present invention may best be understood through the following description with reference to the accompanying drawings, in which:
REFERENCES:
patent: 4560864 (1985-12-01), Kinoshita et al.
patent: 5969346 (1999-10-01), Nagasaka et al.
Alston & Bird LLP
Epps Georgia
Mustek Systems Inc.
Thompson Timothy
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