JPH11136468A - Image scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce manufacturing cost of an image scanner by easily and simply correcting position deviation with respect to an optical lens, shortening required time further and reducing the number of processes. SOLUTION: For this image scanner B, a glass plate 5, an optical lens 3 and a photodetector 2 are successively disposed along the optical axis of the optical lens 3, wherein an original 4 is irradiated by a light source, and the reflected light is converged through the glass plate 5 and the optical lens 3 to the photodetector 2. Further, the glass plate 5 is used for correcting the position deviation of the optical lens 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a computer scanner, a digital copier, and an image scanner used for a facsimile.

[0002]

2. Description of the Related Art In recent years, communication technology has progressed remarkably, and devices for transmitting and collecting information of various specifications for that purpose have been developed.
The development of image scanners used in digital copiers and the like has been remarkably advanced.

FIG. 4 is a principle diagram of the image scanner A. 1 is a circuit board, 2 is a light receiving element disposed on the circuit board 1, 3 is an optical lens, 4 is a document, and irradiates the document 4 with a light source, and reflected light from the document 4 is optical. The light is condensed by the lens 3 and received by the light receiving element 2. According to the image scanner A using the optical lens 3 as described above, light is received by the small light receiving element 2 with respect to the reading range a of the document 4. In this optical system, the location of the optical lens 3 must be accurately determined between the original 4 and the light receiving element 2 by design.

[0004]

According to the image scanner A having the above-described structure, a reading error occurs when the position of the optical lens 3 is shifted from the designed reference position in the optical axis direction. .

[0005] This problem will be described with reference to FIGS. 5 and 6.
FIG. 5 shows a case where the position of the optical lens 3 is shifted from the design reference position to the light receiving element 2 side in the optical axis direction. A wide range b was read. Also, as shown in FIG. 6, if the position of the optical lens 3 is shifted from the design reference position toward the original 4 in the optical axis direction, the reading range a of the original 4 is narrower than the original reading range a. Was reading.

When the position of the optical lens 3 deviates from the designed reference position in the optical axis direction, the reading range a changes to the range b or the range c, thereby causing a magnification error. . Therefore, the position of the optical lens 3 is adjusted by moving the optical lens 3 in the optical axis direction.

However, such position adjustment is performed by fixing the optical lens with screws or the like. However, this requires a very complicated operation, increases the number of steps, and causes a positional shift during the fixing. However, it is difficult to perform the adjustment with high accuracy, and as a result, the time required for the position adjustment is increased, and the manufacturing cost is increased.

Accordingly, the present invention has been completed in view of the above-mentioned problems, and an object of the present invention is to make it easy and simple to correct a positional shift with respect to an optical lens, to further shorten the required time and reduce the number of steps. It is another object of the present invention to provide an image scanner with reduced manufacturing cost.

[0009]

In the image scanner of the present invention, an optical lens and a light receiving element are arranged along the optical axis of the optical lens, a light source irradiates an object to be detected, and the reflected light passes through the optical lens. The light-collecting device is configured to condense light on a light-receiving element, and a light-transmitting glass plate for correcting a displacement of the optical lens is disposed between the optical lens and the detection object.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image scanner according to the present invention will be described with reference to FIGS. FIG. 1 is a principle view of an image scanner B of the present invention, FIG. 2 is a principle view of another image scanner C of the present invention, and FIG. 3 is an enlarged view of a main part of the image scanners B and C of the present invention. . In these figures, the same parts as those of the conventional image scanner A are denoted by the same reference numerals.

According to the image scanner B shown in FIG. 1, a document 4, which is an object to be detected, an optical lens 3, and a CCD
The light receiving elements 2 are sequentially arranged along the optical axis of the optical lens 3, and the light receiving elements 2 are disposed on a circuit board 1 formed of a glass epoxy substrate. A translucent glass plate 5 is provided between the original 4 and the optical lens 3 having the optical axis.
Is used for correcting the position shift.

In the image scanner C shown in FIG. 2, an infrared absorbing film 6 is formed on the glass plate 5, and the other structure is the same as that of the image scanner B shown in FIG. The infrared absorbing film 6 is for absorbing infrared light that becomes optically noise, and is called an IR cut filter 7 in combination with the glass plate 5.
In the IR cut filter 7, since the thickness of the infrared absorbing film 6 is 1/1000 or less of the thickness of the glass plate 5,
The refractive index of the IR cut filter 7 substantially corresponds to the refractive index of the glass plate 5. Although the infrared absorbing film 6 is provided on the glass plate 5 on the optical lens 3 side, it may be provided on the document 4 side.

FIGS. 1 and 2 show a case where the position of the optical lens 3 is shifted from the design reference position toward the light receiving element 2 in the optical axis direction, and if the glass plate 5 or the IR cut filter 7 is used. Otherwise, the document 4 is read in the reading range d. However, the range d is larger than the original reading range a. Therefore, in order to accurately read the reading range a,
The glass plate 5 and the IR cut filter 7 are arranged and adjusted.

Next, an embodiment of the image scanner C will be described. The distance between the document 4 and the light receiving element 2 was 490 mm, the light receiving element 2 having a light receiving range of 50.266 mm was mounted, the original reading range a of the document 4 was 304 mm, and the maximum angle of view was 19.92 degrees. In the image scanner C, using a light source (xenon tube) having a wavelength of 546 nm,
An IR cut filter 7 having a refractive index of 1.5187 (glass plate 5: BK7) was provided.

Regarding the IR cut filter 7,
Two types of thickness t of 3 mm or 4 mm were prepared, and each was evaluated with a magnification error ΔS. The evaluation based on the magnification error ΔS will be described with reference to FIG. 3, which shows an optical system in which the IR cut filter 7 (thickness: t, refractive index: n) is arranged, and also shows a change in the optical path at the maximum angle of view.
The incident angle θi of the light with respect to the IR cut filter 7 becomes the same as the emission angle therefrom, and the magnification error ΔS is shown in Expression 1. In the drawing, the refraction angle is indicated by θr, and the amount of change in the reading width is indicated by Δl.

[0016]

(Equation 1)

Thus, when the IR cut filter 7 was not provided, the magnification error ΔS was + 0.64%, whereas the thickness t of the IR cut filter 7 was 3 mm.
, The magnification error ΔS is −0.06%, and when the thickness t is 4 mm, the magnification error ΔS is −0.06%.
29%. Therefore, according to this optical system, I
The thickness t of the R cut filter 7 is 5
By preparing about 6 types and appropriately using them, the magnification error ΔS could be kept within ± 0.15%. By the way, if this adjustment is performed by adjusting the position of the optical lens 3 only,
Adjustment in units of about 0.07 mm is required.

As described above, in the present invention, in order to actually manufacture the image scanner C, first, the optical lens 3 is adjusted and fixed, the magnification is measured, and the IR cut filter 7 having a thickness corresponding to the magnification error is used. Adjust the precise magnification. That is, it is sufficient to prepare with IR cut filters 7 having different thicknesses and select them as appropriate.
In short, the position can be roughly adjusted. For example, a positioning block is provided on a core base for fixing an optical lens,
It is only necessary to press and fix the optical lens against this positioning block. As a result, precise position adjustment is no longer required, and the time required for the adjustment is reduced.
Only the installation time and the measurement time (the measurement time is about 3 seconds). Therefore, precise magnification adjustment can be stably performed in a short time.

In the image sensor according to the present invention, the factors that determine the thickness of the glass plate 5 and the IR cut filter 7 include the maximum angle of view, the refractive index of the glass, the reading width of the original, and the amount of magnification adjustment. It has been found that the angle of view is the most important factor, and that if the thickness is 25 mm or less, it can be advantageously designed.

It should be noted that the present invention is not limited to the above embodiment, and various changes and improvements may be made without departing from the scope of the present invention. For example, in this example, various types were prepared with the thickness of the glass plate 5 (IR cut filter 7), but by changing the refractive index, both the refractive index and the thickness were changed. You may.

[0021]

As described above, according to the image sensor of the present invention, a translucent glass plate is disposed between the object to be detected and the optical lens, and this glass plate is used for correcting the positional deviation of the optical lens. By preparing a plurality of glass plates having different thicknesses and disposing them as appropriate, the displacement can be corrected without displacing the optical lens. As a result, the required time is shortened, the number of steps is reduced, and as a result, the manufacturing cost can be reduced.

Further, in the image sensor according to the present invention, since the positional deviation is corrected without displacing the optical lens, it is not necessary to fix the optical lens again with a screw or the like, thereby preventing a decrease in accuracy due to this. I was able to.

[Brief description of the drawings]

FIG. 1 is a principle diagram of an image scanner of the present invention.

FIG. 2 is a principle view of another image scanner according to the present invention.

FIG. 3 is an enlarged view of a main part of the image scanner of the present invention.

FIG. 4 is a diagram illustrating the principle of a conventional image scanner.

FIG. 5 is an explanatory diagram showing a state of displacement of an optical lens in a conventional image scanner.

FIG. 6 is an explanatory diagram showing a state of displacement of an optical lens in a conventional image scanner.

[Explanation of symbols]

 A, B, C Image scanner 1 Circuit board 2 Light receiving element 3 Optical lens 4 Document 5 Glass plate 6 Infrared absorbing film 7 IR cut filter

Claims (1)

[Claims] 1. An image scanner comprising: an optical lens and a light receiving element arranged along an optical axis of the optical lens; a light source irradiating an object to be detected; and light reflected from the object through the optical lens to the light receiving element. An image scanner, wherein a translucent glass plate for correcting a displacement of the optical lens is disposed between the optical lens and the detection object.