JPH05122451A - Image scanner - Google Patents

Abstract

PURPOSE:To easily switch the read position or a document whose image is formed on a sensor in the image scanner using a reduction optical system by arranging a light-transmissive member in the optical path between an image forming lens and the image sensor and moving this member to the outside. CONSTITUTION:In the optical system where the light emitted from a light source 1 is reflected from the document surface and is turned back by a mirror 2 and its image is formed on an image sensor 4 by an image forming lens 3, a light-transmissive member 9 is so moved that it can be inserted and removed from between the image forming lens 3 and the sensor 4. Generally, the optical distance is changed by a prescribed extent when a parallel face plate is inserted into a medium whose refractive index is different from that of this plate. Consequently, the light-transmissive member 9 is removed from the optical path to shift the read document position if the light-transmissive member 9 is inserted and the optical system is adjusted in this state to match the read document position to the surface of a platen glass.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image scanner used for image input.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing a conventional flat bed type image scanner main body, and an automatic paper feeder (ADF) for automatically feeding out a read original on the upper part thereof. The operation of reading a document will be described below. The original on the ADF glass 7 is illuminated by the light source 1,
The reflected light from the original is reflected by the mirror 2 and is focused on the one-dimensional image sensor 4 by the imaging lens 3. Since the image of the document read by the image sensor 4 is one-dimensional,
Some mechanical sub-scanning is required to obtain a two-dimensional image of the original. Therefore, when using ADF8, ADF
Reference numeral 8 sequentially sends out the originals to sequentially move the original reading position captured by the image sensor 4. In addition, the document is placed on the platen glass 6 without using the ADF.
When the document is placed on the table, the optical head 5 composed of the light source 1, the mirror 2, the imaging lens 3 and the sensor 4 reads the document while moving in the left-right direction in the figure, and obtains a two-dimensional image of the document. be able to. When such a configuration is adopted, since the common optical head 5 is used for the above-mentioned two types of reading, the original reading surface on the image scanner main body must be at the same height. ADF glass 7 must be on the same surface, and AD
F needs to scoop the original, so the original table glass 6
It has been customary that the ADF glass 7 and the ADF glass 7 are separately configured.

[0003]

As described in the above-mentioned conventional example, in the conventional configuration, the optical head of the image scanner is required to have a constant document surface height at all times. However, there was a problem that there was a large limitation.

[0004]

In order to solve the above-mentioned problems, an image scanner of the present invention comprises a light source for illuminating a document, a one-dimensional image sensor, and an illumination as an optical system for reading an image of the document. In an image scanner equipped with an image forming lens for forming an image of reflected light from the document on the image sensor, a light transmissive member is arranged in an optical path between the image forming lens and the image sensor, and It is characterized in that the light transmitting member can be moved to the outside of the optical path.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, the optical head 5 shows a state in which, for example, a transparent glass plate is inserted as a light transmitting member 9 in the optical path between the imaging lens 3 and the image sensor 4 in addition to the configuration described in the conventional example. In general, when a parallel plane plate (thickness t) having a refractive index n ′ different from the medium is inserted in the optical path of an optical system formed in a medium having a certain refractive index n, t × (1-n The optical distance corresponding to the length of / n ') will change. Therefore, when the optical system is adjusted by aligning the reading document position on the surface of the document table glass 6 with the light transmitting member 9 inserted as shown in FIG. 1, the light transmitting member 9 is moved from the optical path as shown in FIG. By removing it, the position of the read document can be shifted. For example, plate thickness 1 mm,
When a glass having a refractive index of 1.51 is used as the light transmitting member 9, if the lateral magnification of the optical system is 8 times, the longitudinal magnification is 64 times. Therefore, in the state of FIG. 6m
m The document reading position will shift upward. As a method of moving the light transmitting member 9, a method using an actuator such as a solenoid or a motor is considered, and by using such a method, the reading position of the document can be changed by an easy method.

Further, as an application of the present invention, a plurality of parallel plane plates having different thicknesses or refractive indexes are prepared as light transmitting members, and the original reading position is changed by switching using the same actuator as above. It's easy to think of.

FIG. 3 shows an example of the configuration of an image scanner and an ADF using the present invention. Here, since the present invention is used and the document reading position is shifted upward at the time of ADF reading, the ADF glass 7 does not need to be on the same surface as the document table glass, and thus can be configured inside the ADF.

[0008]

By implementing the present invention, it is possible to easily switch the document reading position of the image scanner, and it is possible to dramatically cope with an ADF device or the like.

Further, as a further effect, by shifting the focus at the time of reading a normal document, it is possible to obtain a special effect that moiré at the time of reading a printed matter can be removed.

[Brief description of drawings]

[Figure 1]

FIG. 2 is a configuration diagram of an optical head showing an embodiment of the present invention.

FIG. 3 is a side view showing a configuration example of an image scanner of the present invention.

FIG. 4 is a side view showing a configuration example of a conventional example.

[Explanation of symbols]

 1 Light Source 2 Mirror 3 Imaging Lens 4 Image Sensor 5 Optical Head 6 Original Plate Glass 7 ADF Glass 8 ADF 9 Light Transmission Member

Claims (2)

[Claims] 1. An optical system for reading an image of a document, a light source for illuminating the document, a one-dimensional image sensor, and a connection for forming reflected light from the illuminated document on the image sensor in the previous period. In an image scanner including an image lens, a light-transmissive member is arranged in an optical path between the imaging lens and the image sensor, and the light-transmissive member is movable to the outside of the optical path. Image scanner to do. 2. The light transmissive member includes at least first and second members having different bending rates, and the first and second members have different bending rates.
2. The image scanner according to claim 1, wherein the member is movable so as to be arbitrarily switched with respect to an optical path between the imaging lens and the image sensor.