JPS6096062A - Picture-writing reader - Google Patents

Abstract

PURPOSE:To realize sufficiently and inexpensively suppression of color blurring by forming an triple image of a picture-writing on an image pickup plane of a line image sensor through an inexpensive lens system and filter. CONSTITUTION:Apertures 22, 23, 24- are arranged in a main scanning direction X on the image pickup plane of the image pickup plane of the line image sensor 21 and a three-color separation filter is formed on it as on-chip. A lens system 25 consists of three flat lens arrays 27, 28, 29, which are arranged in three lines in the main scanning direction X with lots of minute convex lenses on a base. The 2nd minute convex lens forms a point image 33 on a scanning line X3-X3' on the aperture 23 for green color as an elected image with unmagnification. Moreover, the point image 33 is formed to the aperture 22 for red color through the 1st minute convex lens and to the aperture 24 for blue color through the 3rd minute convex lens respectively as elected image with unmagnification. In the filter board 26, a red color transmission filter 30 is arranged in parallel with the 1st minute convex lens group of the lens array 29, a green color transmission filter 31 to the 2nd minute convex lens group, and a blue transmission filter 32 is arranged to the 3rd minute convex lens group in parallel.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a calligraphy reading device that separates and reads a calligraphy into three colors.

Structure of a conventional example and its problems FIG. 1 is an arrangement diagram of color separation filters mounted on-chip on the imaging surface of a line image sensor for reading color images.

On the imaging surface, a large number of apertures, three per pixel, are arranged at a pitch of p/3, and on each of these apertures, a red transmission filter R, a green transmission filter G, and a blue transmission filter B are arranged as shown in the figure. They are chipped in order. The image is separated into three colors and captured by these filters.

When such a line image sensor uses an imaging means such as a light-converging rod lens array to form a black and white pattern on its imaging surface, in addition to moiré, color shifts occur in each star, resulting in poor image quality. is known to deteriorate significantly.

FIG. 2 is an explanatory diagram of such a color shift phenomenon.

The line image sensor shown in (b) of the same figure captures a document screen in which the white area (the part marked W) and the black area (the hatched part) are connected in the main scanning direction as shown in (a) of the same figure. When an erect, same-size image is formed on a surface with the positional relationship shown in the figure, the image reproduced from the read output of the line image sensor will have V and white areas (portions marked W) as shown in (C) of the same figure. ) and the black area (hatched area), a one-pixel wide blue area (portion marked B) occurs. This is the aperture 11.12 of the line image sensor corresponding to the black and white boundary of the writing surface.
．． Among 13, the source (white light) enters at open 1.''13
This is because the output of that pixel will be in the same state as when reading blue.

In order to suppress such color shift and moire, in conventional television cameras, etc., a crystal plate is placed in front of the imaging surface of the image sensor, and the birefringence of this crystal plate causes the double axes of the incident image to be The system employs a system in which the image is formed in two directions, or a so-called three-tube system.

However, the former method does not sufficiently suppress color shift due to the significant deterioration in M retention, and is applicable to document and image reading devices such as facsimiles that require reproduction of fine details in hard copies. It is not appropriate to do so.@In the case of a 'dN type document image reading device that forms an erect, same-size image of the screen onto a line image sensor, an extremely large crystal plate corresponding to the maximum reading width is required. A large crystal plate is extremely expensive, making it impossible to create a practical device due to cost considerations.

Also, with the latter method, the number of solid-state image sensors increases, making the device expensive.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional problems, and aims to provide a document and image reading device that can sufficiently suppress color shift and can be realized at low cost.

Structure of the invention.

The present invention forms a triple image of a calligraphic image on the imaging surface of a line image sensor in which a three-color separation filter is arranged in a row using a lens system consisting of a plurality of lens arrays in which microlenses are arranged in three rows in the main scanning direction. In addition, by providing filters that transmit only one color of light corresponding to each optical path of the three colors in the optical path of each image forming the triple image, the above-mentioned objective is achieved. This is what I am trying to do.

Description of examples Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is a schematic perspective view of a document and image reading device according to an embodiment of the present invention. In this figure, 21 is a line image sensor, and an IJ 22 is opened in the main scanning direction X on its imaging surface.
, 23, 24, Yamakawa, etc. are formed in an array, and a three-color separation filter is mounted on the chip as shown in FIG. 25i calligraphy and painting 2 scanning lines x 3-
This is a lens system for forming an erect, equal-magnification triple image of X; 26 is a filter plate.

The lens system 26 is a three-plate lens array 27°28
．． It consists of 29. Lens array 27.28.
29 is made up of a large number of micro convex lenses arranged in three rows in the main scanning direction X on a substrate.

2 completed + + 28. +29. is the first row of micro convex lenses -272, 2821292 is the second row of micro convex lenses,
273.28. ．． 293 is a third row of micro convex lenses. The second row micro convex lenses on the lens arrays 27, 28, and 29 are arranged so that the optical axes of the corresponding ones coincide, and the point images 33 on the scanning lines x, -x, and ' are aligned with the corresponding pixels of the line image sensor 21. An erect, same-magnification image is formed in an aperture 23 around the edge of the lens.

The minute convex lenses in the second and third rows are arranged so that the lenses on at least one of the lens arrays are relatively shifted by p/3 in opposite directions in the main scanning direction X with respect to the lenses on the other lens arrays. so that the point image 33 is formed into an erect, equal-magnification image through the first row of minute convex lenses to the red aperture 22 adjacent to the aperture 23, and through the third row of minute convex lenses to the blue aperture 24. It has become.

The filter plate 26 includes a red transmission filter 30 arranged parallel to the first row micro convex lens group of the lens array 29, and a second red transmission filter 30.
Green transmission filter 3 arranged parallel to the column micro convex lens group
A blue transmission filter 32 is provided parallel to the micro convex lens group 1- and the third lens group 1-1.

According to such a configuration, occurrence of color misregistration can be suppressed. For example, a document surface in which a black area (hatched area) and a white area (ES portion marked W) are connected in the main scanning direction X as shown in FIG. When an image is formed in the positional relationship shown on the image pickup surface of the line image sensor 21 shown in FIG. Since only light of the same color is incident, the output is black. Further, since the color source that passes through the filters provided therein enters the openings 43 to 46, the output thereof becomes a white state. Therefore.

The image reproduced from the output of the line image sensor is shown in (C) of the same figure, and is the black and white boundary of the writing surface? The conventional blue portion does not appear in τμ.

This effect is not limited to the example shown above, but also applies to a writing surface with an arbitrary pattern and arbitrary color distribution, and the three adjacent red, blue, and green colors on the imaging surface of the line image sensor. Since the open r:J outputs a signal that is a three-color image of the same point on the document surface, it can achieve the same color shift suppression effect as a three-front type blurry camera.

Note that the lens arrays 27, 28, and 29 mentioned above are as follows.

By using a negative type of minute convex lens group, it can be manufactured at low cost and with a high sheath using general plastic molding technology. Alternatively, it can be made by fixing a separately manufactured micro-convex lens body to a large number of micro-apertures formed in the substrate. However, the former method is generally more advantageous in terms of increasing the fineness and density of microconvex lenses and reducing manufacturing costs.

Further, although the lens system 25 in this embodiment is composed of three lens arrays, the number of lens arrays may be two or four or more. however.

A configuration with three or more lenses can reduce aberrations and object-to-image distance.

FIG. 5 is a schematic perspective view of a document and image reading device according to another embodiment of the present invention. In this embodiment, a large number of minutely distributed refractive index lenses 5o having a convex lens effect are arranged in three rows in the main scanning direction X by diffusing media with different refractive indexes from the surface of the flat glass substrate. A lens system 25 is constructed using four completely planar lens arrays 51 to 54 formed by the following methods. In addition, filters 31 to 32
It is closely attached to the lower surface of the Id lens array 64 and is vignetted.

Other configurations - and lens system 26 and filter 30 -
The operation of 32 is the same as that of the above embodiments. The purpose is to prevent image deterioration (flare) caused by the source passing through the white light source, the slit member provided between the lens system and the writing surface, and the gap between the lens groups of the lens array, and to make the image intensity distribution uniform. There is an aperture stop installed in the lens system.

Effects of the Invention The present invention provides triple images of a line image sensor through an inexpensive lens system and filter.
As mentioned above, this configuration sufficiently suppresses color shift by focusing the image on s (H
! Since it does not require an increase in the number of image sensors like the i method, it is possible to achieve the effect of realizing a document and image reading device with less color shift at a low cost.Q

[Brief explanation of drawings]

FIG. 1 is an arrangement diagram of a three-color separation filter of a line image sensor, FIG. 2 is an explanatory diagram of the color shift phenomenon, FIG. 3 is a schematic perspective view of a document reading device according to an embodiment of the present invention, and FIG. FIG. 5 is a schematic perspective view of a document image reading device according to another embodiment of the present invention. 021 . . . line image sensor, 25
... Lens system, 27-29.51-54...
...Lens array-3o to 32...Filter. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 3 Figure 4rIA Figure 5

Claims (1)

[Claims] It has a line image sensor in which three-color separation filters are arranged in the main scanning direction corresponding to the pixels on the imaging surface, and a plurality of lens arrays in which many microlenses are arranged in three rows in the main scanning direction. a lens system for forming a calligraphic triple image relatively displaced by a predetermined amount in the scanning direction on the imaging surface; and an optical path of the first, second, and third rows of microlenses on the lens array. The first . Second
and first, second, and third filters that transmit only light of a third color.