JPS62224161A - Picture reader - Google Patents

Abstract

PURPOSE:To attain the lighting of an original with high uniformity by providing a light diffusion means to the lighting means side of a picture original so as to reduce the effect of a foreign material in the lighting light path and to correct the shading. CONSTITUTION:The picture original 3 being a color photographic film, e.g., after development processing is clipped by flat plates 4a, 4b. The luminous flux 10 from a white light source 1 is focused by a condenser lens 2, is transmitted through the flat plate 4a, projected to the picture original 3 and the input picture is formed on a photographic element 7 by a projecting lens 6 via the flat plate 4b and R, G, B filters 5 capable of replacement. The flat plate 4b is a transparent parallel flat plate, the flat plate 4a is a translucent parallel flat plate having the light diffusion performance and the flat plate 4a is made of opal glass or frosted glass or the like. Thus, the image of a foreign material such as dust or dirt in the light path from the light source 1 to the flat plate 4a is diffused and the lighting luminous quantity is averaged.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image reading device, and more particularly to an image reading device that converts an analog image into a read digital image signal and outputs the signal.

[Conventional technology]

In recent years, methods have been developed in which analog images such as characters, figures, and patterns are read, digital electrical signals are obtained, and the digitized image signals are changed into desired images by electrical processing. Image signals are frequently used for transmission.

Image reading devices used for such purposes generally include a light source for illuminating an analog image (input image), a condenser lens for guiding light from the light source to the input image, an input image holding means, and an imaging device. and a projection lens that forms the input image onto the image sensor.

[Problem 3 to be solved by the invention In an image reading device, ideally, when reading a standard image with uniform density over the entire surface, the outputs of all the light receiving elements of the image sensor should be the same. In image reading devices, in reality, the illumination light source is not a perfect point light source or a perfect uniform light source, so the illumination light distribution on the document surface is uneven (shading). There was a problem with getting the output.

In addition, in conventional image reading devices, images due to dust, dirt, scratches, etc. attached to both sides of the condenser lens constituting the illumination means are not projected onto the image document, and the input image is not uniformly illuminated. First, there is a problem in that it is difficult to read images accurately.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an image reading device that can reduce the influence of foreign substances such as dust and dirt in an illumination optical path and can correct shading.

[Means for solving problems]

According to the present invention, in order to solve the problems of the prior art as described above and achieve the above object, there is provided a means for illuminating an image original having image information, and a means for illuminating an image original having image information; and an imaging means having a plurality of light-receiving elements for converting the image into an image signal, the light diffusing means being disposed on the illumination means side of the image original and at a position close to the image original. An image reading device is provided, the image reading device having the following features.

〔Example〕

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a plan view schematically showing the structure of an embodiment of the apparatus of the present invention, and FIG. 2 is a partial perspective view thereof.

In FIG. 1, 1 is a light source for illumination, and 9 is a white light source. 2 is a condenser lens, which together with the light source 1 constitutes illumination means. 3 is an image original having image information, and the image information is color image information formed by a spectral transmittance distribution. The image original 3 is, for example, a developed color photographic film. 4a.

Reference numeral 4b denotes a pair of flat plates constituting a holding means for the image original 3, and the image original 3 is held between the pair of flat plates 4a and 4b. 5 is a filter, and the filter is, for example, a red transmission filter (R filter), a green transmission filter (G filter), and a back color transmission filter (B filter). 6 is a projection lens υ,
For example, it consists of a convex spherical lens. Reference numeral 7 denotes an image sensor having a plurality of light-receiving elements, and this element is, for example, a CCD solid-state image sensor.

In FIG. 1, the condenser lens 2 and the projection lens 6 are arranged coaxially, and 8 is the optical axis of these lenses. The light source 1 is arranged on the optical axis 8.

In the apparatus of this embodiment, the light beam from the light source 1 is focused by the condenser lens 2, passes through the flat plate 4a, enters the image original 3, and illuminates the original.

In FIG. 2, lO indicates the illumination light flux.

As shown in FIGS. 1 and 2, the image original (9 is a 3b size color film) held between the flat plates 4& and 4b constituting the image original holding means is fed by a feeding means 9 (not shown). The optical axis 8 is moved intermittently in steps in a direction perpendicular to the optical axis 8. The step movement may be performed for only the film original 3 with the flat plates 4m and 4b fixed, or both the film original 3 and the flat plates 4a and 4b may be moved. In this way, image information of a desired frame can be appropriately positioned in the portion held between the pair of flat plates 4a and 4b.

In this embodiment, of the pair of flat plates constituting the image original holding means, the flat plate 4b on the filter 5 side is a normal transparent parallel flat plate, while the flat plate 4a on the condenser lens 2 side It is a translucent parallel plane plate with diffusive properties. Is this kind of flat plate 4a just in case? - Can be formed from glass, ground glass, etc.

Although one filter 5 is shown in FIG. 1, in this embodiment, the filter 5 can be replaced by means not shown. In this embodiment, an R filter, a G filter, and a B filter are provided.
Any one of these filters is placed at the position of the filter 5 shown in FIG. 1 at any time by means (not shown). (may be located).

Thus, in this embodiment, first, with the R filter positioned as the filter 5, only the red component of the color image of the image original 3 is read by the image sensor 7 υ, and then the filter is read by the filter exchanging means as the filter 5. Only the green component is read with the G filter positioned, and then only the background color component is read in the same manner with the B filter positioned as filter 5. This completes the reading of one color image information.

In this embodiment as described above, since a material having light diffusivity is used as the flat plate 4a on the illumination light source side constituting the image original holding means, there is a light beam in the optical path from the light source 1 to the flat plate 4a. Foreign matter such as certain dust or dirt (for example, dust or dirt that adheres to the surface of the flat plate 4a, the surface of the condenser lens 2, or the surface of optical parts such as optionally interposed filters, or even scratches on the surfaces of these optical parts) etc.) is diffused when it is projected onto the image original 3 (that is, the illumination light amount distribution is averaged), making it possible to obtain a better illumination state. Similarly, in this embodiment, since a material having light diffusing properties is used as the flat plate 4a, it is possible to reduce illumination unevenness due to non-uniformity of the light source 1.

In the above-mentioned embodiment, a case is exemplified in which the flat plate 4a constituting the image original holding means also serves as a light diffusion means, but the present invention is not limited to this, and for example, the condenser lens 2 and the image original It also includes those in which a light diffusing means is arranged between 3 and 3.

Further, in the embodiment described above, a case is shown in which the film image original 3 is held between the flat plates 4a and 4b, and according to this, the curling of the film original 3 is corrected and the film original 3 is maintained in a flat shape. Although high-resolution reading is possible, the present invention is not limited to this, and also includes a method in which an image original other than a film is held by an appropriate holding means.

In the above embodiments, the case where the image information is color image information is shown, but it goes without saying that the present invention can also be applied to reading monochrome image information.

〔Effect of the invention〕

According to the present invention as described above, it is possible to achieve highly uniform illumination of an image original by reducing the influence of foreign objects in the illumination optical path and correcting shading with a simple configuration, thus achieving a more accurate image reading system. It becomes possible.

[Brief explanation of drawings]

FIG. 1 is a plan view showing the structure of the apparatus of the present invention, and FIG. 2 is a partial perspective view thereof. 1: Light, 2: Condenser lens, 3: Image original, 4a
, 4b: Plane plate, 5: Filter, 6: Projection lens, 7:
Image sensor. Figure 2

Claims (4)

[Claims] (1) An image reading device having means for illuminating an image original having image information, and an imaging means having a plurality of light-receiving elements for receiving a luminous flux transmitted through the image original and converting the image information into an image signal. An image reading device characterized in that the image reading device further comprises a light diffusing means disposed on the illumination means side of the image original and at a position close to the image original. (2) The illumination means includes a light source and a condenser lens that focuses light from the light source and guides it to the image original, and a light diffusion means is disposed between the condenser lens and the image original. , an image reading device according to claim 1. (3) Image document holding means includes a pair of optically transparent or translucent plate-like bodies that hold both sides of the image document, and of the plate-like bodies, the plate-like body on the illumination means side is The image reading device according to claim 1, which is also the light diffusing means. (4) The image reading device according to claim 1, further comprising a projection optical system that guides a light beam from the image original to the imaging means.