JPH06303392A - Image scanner - Google Patents

Abstract

PURPOSE:To enable highly accurate positioning at the time of switching the plural kinds of lenses by a simple structure and to prevent an entire scanner from being enlarged by supporting the respective lenses by a base rotatable with a pivot. CONSTITUTION:A lens unit 6 is provided with the pivot 10a at a center part and the vicinity of a peripheral part 10b is freely slidably supported by a rail 18 in a circular-arc shape. Thus, a sectorial base 10 rotatable within a surface parallel to an original table, three lenses 11-13 whose magnifications are mutually different respectively arranged on the base 10 so as to make the center of an optical axis coincide at the time of switching the lenses and a driving unit 14 composed of a wire 15 engaged with the peripheral part 10b so as to drive by wire the base 10 within the above-mentioned surface, a pair of pulley 16 and a motor 17 are provided. By controlling the motor 17 by a controller in a prescribed procedure, the respective lenses 11-13 are selectively arranged between the mirror of a mirror unit and an image receiving element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image scanner, and more particularly to an image scanner capable of converting a read line density and the like by switching a lens.

[0002]

2. Description of the Related Art The resolution required for an image scanner is 400 for reading a sketch image such as A3.
600 dpi, which is frequently used as a simple print document for scanning A4 size documents (dpi (dots per inch))
i 12 for reading transparent documents up to 4 x 5 inches
It is considered to change depending on the original, such as 00 dpi.

In order to change the linear density in an image scanner in response to such a demand, it has been conventionally practiced to selectively use a plurality of types of lenses having different magnifications. As a lens switching structure in such an image scanner, for example, each lens is mounted on a slider movable on a rail and each lens is selectively driven by a CCD (Charge-Coupled) by driving the slider with a motor.
-Device) or other image receiving element, or hold each lens in a rotatable disc-shaped holder and drive this holder by a motor to selectively move each lens in front of the image receiving element. The structure which arranges was general.

However, the lens as described above is
Since the optical positional relationship requires a high degree of accuracy, for example, in the case where the slider holding each lens moves linearly on the rail, the rail is installed to a certain extent over the entire moving range of the slider. Of precision, and the assembling work tends to be troublesome. Further, in the image scanner as described above, the scanning unit normally scans along a horizontal document table, the image received by the mirror is reflected in parallel with the document table, and the image is received by the image receiving element. Therefore, from the viewpoint of operability, it is desired to reduce the bulk in the height direction of the image scanner, that is, the direction perpendicular to the original table surface, but it is of a type in which the disc-shaped holder for holding each lens is rotated. In this case, since the disk-shaped holder is rotated in a plane perpendicular to the optical path, the holder protrudes in the height direction, the image scanner becomes large in size, and the operability thereof deteriorates.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the problems of the prior art as described above, and its main purpose is to provide a simple structure with high accuracy when switching a plurality of types of lenses. An object of the present invention is to provide an image scanner that can be positioned and does not increase the size of the entire apparatus.

[0006]

According to the present invention, the above-mentioned object is to relatively scan the table on which the object is placed and the table surface in order to capture the image of the object by the image receiving element. And an image scanner having a plurality of types of lenses that can be switched and used, and a scanning unit for scanning, a reflection optical system that deflects light forming an image from the scanning unit toward an image receiving element in parallel with the table. , So that the optical axes of the respective lenses are located on the same plane and intersect the pivots on a base rotatable about a pivot provided on the optical path of the light in a plane parallel to the table surface. In favor of
This is achieved by providing an image scanner characterized in that the lens used can be selected by rotating the base.

[0007]

As described above, by supporting each lens on the base that can be pivoted about a pivot, the positioning accuracy of each lens can be secured if only the accuracy of the pivot is secured. Further, since the rotating direction of the base is parallel to the original table surface, the bulkiness in the height direction is about the same as that of the single lens.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing a schematic configuration of an image scanner to which the present invention is applied. Casing 1
A document table 2 is provided on the upper surface of the. A reflection lamp 3a and a mirror 3b are provided on the lower surface side of the document table 2.
The scanning unit 3 is provided, and the transmissive lamp 4 interlocking with the scanning unit 3 is provided on the upper surface side. Further, a movable mirror unit 5 composed of a pair of mirrors 5a and 5b for reflecting the light from the scanning unit 3 toward an image receiving element 7 described later in parallel with the document table 2 faces the mirror 3b of the scanning unit 3. It is provided at the position where Here, the scanning unit 3, the transmissive lamp 4, and the movable mirror unit 5 are configured to move and scan in parallel with the document table 2, and in particular, the mirror unit 5 is interlocked with the scanning unit 3 to move a half distance thereof. However, the distance between the document table 2 and the image receiving element 7 is always the same.

At a position facing the mirror 5b of the mirror unit 5, there are three image receiving elements 7 having different magnifications, which are CCDs for receiving the image of the document placed on the document table 2 from the scanning unit 3. It is provided via a lens unit 6 capable of switching lenses. The output line of the image receiving element 7 is connected to the image processor unit 8,
The image received by the image receiving element 7 from the original table 2 via the scanning unit 3, the mirror unit 5, and the lens unit 6 is subjected to the processing described below by the image processor unit 8 and output to the outside.

The scanning unit 3, the transmissive lamp 4, the movable mirror unit 5, and the lens unit 6 are driven and controlled by the controller 9, and the processing of the image processor unit 8 is also controlled by the controller 9.

The lens unit 6 has a pivot 10a at the center thereof.
And a fan-shaped base 10 which is rotatable in a plane parallel to the original table 2 by being slidably supported by an arc-shaped rail 18 in the vicinity of the peripheral edge 10b, and a lens on the base 10. Three lenses 11 having different magnifications, which are arranged so that the centers of the optical axes coincide with each other at the time of switching.
˜13, a wire 15, a pair of pulleys 1 engaged with the peripheral portion 10b to drive the base 10 in the plane by the wire.
6 and a drive unit 14 including a motor 17. By controlling the motor 17 by the controller 9 in the procedure described later, the lenses 11 to 13 are selectively arranged between the mirror 5b of the mirror unit 5 and the image receiving element 7. The drive unit 14 is provided on the side of the pivot 10a with respect to the peripheral portion 10b, and the base 1
When the wire 15 is wound so as to surround 0, no extra space is required for installing the drive unit, and the overall size is reduced.

On the other hand, in FIG. 1, at a standby position of the scanning unit 3, that is, at a proper position outside the scanning range of the document table 2, any one of the lenses 11 to 13 of the lens unit 6 is a mirror 5b.
Reference pattern 1 for inspecting whether it is arranged between the image receiving element 7 and the image receiving element 7, or whether its optical axis matches the optical path.
9 is provided downward. The reference pattern 19 is formed by drawing two white strips on a black background at a predetermined interval. Therefore, when the scanning unit 3 is in the standby position, the reference pattern 19 is read, the positions and the intervals of the two white belts are measured, and it is checked whether or not the conditions given in advance are met to check each lens. Which one of 11 to 13 is arranged between the mirror 5b and the image receiving element 7,
Further, by measuring the displacement of the position of the white band, it is possible to inspect whether the optical axis matches the optical path without using a limit switch or a proximity sensor.
Needless to say, as shown in FIGS. 3 (a) to 3 (h), the reference pattern may actually have one strip or a black strip on a white background. Absent. The result detected in this way is determined based on the final output of the detection optical system, and therefore includes all errors in the middle.

If it is determined based on this inspection result that the suitable lens is not arranged, the motor 17 is driven to wind the wire 15 in the clockwise or counterclockwise direction, and the lenses 11 to 13 are wound. A desired lens is selected from among these and is arranged between the mirror 5b of the mirror unit 5 and the image receiving element 7, and the lens is finely positioned so that the received reference pattern does not shift. At that time, since the fan-shaped base 10 is structured to rotate about the pivot 10a, radial displacement does not occur, and positional displacement in the rotational direction can be eliminated by feedback control. Therefore, high accuracy can be easily obtained. The image receiving element 7 can be provided at an appropriate position on the optical path downstream of the mirror 5b, and may be located at the position of the pivot 10a, for example.

FIG. 4 is a block diagram schematically showing the processing procedure of the image scanner. First, the manuscript table 2
The image is received by the image receiving element 7 via the scanning unit 3, the mirror unit 5, and the lens unit 6. The CCD element 7 outputs an RGB signal corresponding to the image receiving screen to the image processor unit 8. The image processor unit 8 converts each of the received analog RGB signals into a digital signal. By this A / D conversion, the subsequent signal processing can be performed by digital calculation. Image processor unit 8
Performs shading processing, gradation conversion (γ correction) on the digital RGB signal, and linear density conversion if necessary.

Although the scale of digital calculation depends on the number of bits of A / D conversion, in this embodiment, since it is as large as 12 bits for each channel, a LUT (look-up table) used in a conventional image scanner. The shading correction method based on this method is not preferable because it requires an excessive amount of memory. Further, it has been difficult to improve the accuracy of linear density conversion.

The image processor unit 8 further applies an MTF (Modulation Transfer Fu
correction, color correction, and output to the outside through the interface. Then, it is subjected to image processing by a computer or the like (not shown) and output to an output device such as a plotter. Here, each of the above-mentioned lenses is selected according to the linear density required by the processing device side. In the present embodiment, the base 10 is rotated by the wire 15, but as a means for rotating the base 10 in the plane, for example, a method using a gear,
A method of directly connecting to the motor shaft can be used.

Further, in this embodiment, the table on which the object is placed is stationary and the scanning means and the reflection optical system having the mirror are moved, but the scanning means and the reflection optical system are stationary and the table is May be configured to move.

The scanner to which the present invention is applied can automatically or manually switch the optical lens according to the document size to change the resolution without deterioration of the image. FIG. 5 is a diagram showing an example of the relationship between the resolution and the document.

For example, an A3 size original is 297 mm long and fits between the lines l1 and l7, but it is preferable to read an image at a resolution of 400 dpi.
It is preferable to read the image at a resolution of 600 dpi, which fits between the lines 12 and 16 at 10 mm. Further, in a so-called 4 × 5 inch format (101.6 mm, width 127 mm) that fits between the lines 13 and 15 (101.6 mm), it is preferable to read an image at a resolution of 1200 dpi.

When the user places a document of size l3 to l5 on the document surface of the scanner, the scanner determines that a resolution of 1200 dpi is suitable from the size of the document, and
Switch to the 00 dpi lens and the original will automatically change to 1
It is read at 200 dpi. Also, there is a photograph etc. in a part of the A4 size document, and only that part has resolution 1
If you want to read at 200 dpi, select the relevant part from l3 to l
By installing in 5 parts, manually selecting 1200 dpi, and setting it, it is possible to read an image at 1200 dpi even for a document of a size not specified.
The lens can be determined according to the operator's selection.

[0022]

As is apparent from the above description, according to the image scanner of the present invention, by supporting each lens on the base which is rotatable about the pivot, if only the pivot is assembled with high precision, a plurality of lenses can be assembled. High positioning accuracy is ensured during switching. Further, since the rotation direction of the base is along the document table surface, the bulkiness in the height direction is about the same as that of the single lens, and the entire apparatus is not enlarged.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an image scanner to which the present invention is applied.

FIG. 2 is a plan view of the lens unit shown in FIG.

3 (a) and 3 (b) are front views of the reference pattern of FIG.

FIG. 4 is a block diagram showing an operating procedure of the image scanner of the present embodiment.

FIG. 5 is a diagram showing a relationship between a document size and a desired resolution.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 casing 2 original table 3 scanning unit 3a reflection lamp 3b mirror 4 transmission lamp 5 movable mirror unit 5a, 5b mirror 6 lens unit 7 image receiving element 8 image processor unit 9 controller 10 base 10a axis 10b peripheral portion 11 to 13 lens 14 Drive unit 15 Wire 16 Pulley 17 Motor 18 Rail 19 Reference pattern

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[Procedure amendment]

[Submission date] March 25, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an image scanner to which the present invention is applied.

FIG. 2 is a plan view of the lens unit shown in FIG.

3 (a) to ( h ) are front views of the reference pattern of FIG.

FIG. 4 is a block diagram showing an operating procedure of the image scanner of the present embodiment.

FIG. 5 is a diagram showing a relationship between a document size and a desired resolution.

[Description of Reference Signs] 1 casing 2 original table 3 scanning unit 3a reflection lamp 3b mirror 4 transmission lamp 5 movable mirror unit 5a, 5b mirror 6 lens unit 7 image receiving element 8 image processor unit 9 controller 10 base 10a axis 10b peripheral portion 11 to 13 lens 14 drive unit 15 wire 16 pulley 17 motor 18 rail 19 reference pattern

Claims (1)

[Claims] 1. A table on which the object is arranged, scanning means for relatively scanning the table surface, and an image from the scanning means are formed in order to capture an image of the object with an image receiving element. An image scanner having a reflection optical system that deflects light toward an image receiving element in parallel with the table, and a plurality of types of lenses that can be switched and used, wherein an image scanner is provided around a pivot provided on an optical path of the light. Each lens is supported by a base that is rotatable in a plane parallel to the table surface such that its optical axes are located on the same plane and intersects with the pivot axis, and the base is used for rotation. An image scanner featuring a selectable lens.