JPH05276315A - Optical system for picture reader - Google Patents

Abstract

PURPOSE:To inexpensively form an optical system of the picture reader reading an original with a wide width at a high density with simple adjustment. CONSTITUTION:A lens 17, a half mirror 19 whose reflectance is 50% and whose transmittivity is 50% and two CCDs 18a, 18b are arranged as optical elements within a wide read width, a light passing through the lens 17 and transmitting a half of one side of the half mirror 19 is formed to the CCD 18a, and the light reflected in the other half of the half mirror 19 is formed to the CCD 18b. A Dach mirror whose reflecting face is formed at a right angle may be employed in place of the half mirror. In this case, a half of the light through the lens and reaching the Dach mirror is reflected in one reflecting face of the Dach mirror and formed to one CCD, and the light of the other half is reflected in the other reflecting face and formed to the other CCD.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical system for a full-color image reading device having a wide A3 size or more and a high density of 600 dpj or more.

[0002]

2. Description of the Related Art Digital PPC copiers, electronic files,
An image reading device is used for CAD and the like. Although the A3 size is the mainstream for electronic file systems, it has become particularly popular in recent years, and the demand for high quality and high functionality is increasing accordingly. Among them, 600 dpj or more,
For example, high density and full color of 800 dpj and 1200 dpj are particularly important items. Incidentally, for colorization, a solid-state image pickup device (hereinafter referred to as CCD) having 1 chip and 3 lines forms the mainstream of color separation and image forming systems.

However, it is the current situation that the device technology cannot keep up with the demands of the market. Monochrome, A3 size, 600dpj image with 1 CCD
What is imaged in is currently under development. On the other hand, a full-color, A3 size, 600 dpj density image formed by one CCD is not in the examination stage at present. Further, in order to cope with the high density of the CCD, the number of individual image forming elements increases, and as a result, the variation among the individual image forming elements increases, and finally the image quality is affected.

A conventional image reading apparatus will be described with reference to the drawings.

An image reading apparatus 1 whose external view is shown in FIG. 7 includes a light source 3, mirrors 4, 5, 6 and a lens 7 below a document glass 2 on which a document is to be placed, as shown in FIG. An optical scanning unit that has, and a CCD 8 that converts an optical image into an electric signal
Is equipped with. In the illustrated device, the light source 3 and the mirror 4,
As is well known, the reference numerals 5 and 6 move from the solid line position to the broken line position for scanning the document placed on the document glass 2.

In such an image reading apparatus 1, when the number of effective pixels of the CCD 8 is equal to or has a margin with respect to the reading width, one lens 7 is provided as shown in FIGS. 9 and 10.
And one CCD 8 are arranged optically. h is the reading width.

However, in order to meet the market demands for wide width, high density, and full color as described above, as shown in FIGS. 11 and 12, for the wide reading width H, two lenses 7a are used. , 7b and two CCDs 8a,
It is general practice to divide one line into images using 8b (see, for example, Japanese Patent Laid-Open No. 56-98075).

[0008]

However, in the image forming method using the above-mentioned two lenses and two CCDs, the number of parts increases and the cost increases, and since two lens systems are used, the lens In addition to the variation, the peripheral portion of the lens is used to form the joint portion, so that the deterioration of the image in the joint portion of the line cannot be avoided. Further, since the optical adjustment requires two steps, it takes time. Especially, the deterioration of the image at the joint portion makes the adjustment extremely difficult, and sometimes the adjustment cannot be completed.

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art.

[0010]

According to the present invention, in the optical system of a wide-color and high-density full-color image reading apparatus, one object and a half mirror having a reflectance of 50% and a transmittance of 50% are provided. Two solid-state image pickup devices are provided, and among them, light transmitted from one half of the half mirror among lights from the lens forms an image on one solid-state image pickup device, and the other one side of the half mirror. It is solved by arranging the light reflected by half to form an image on another solid-state imaging device.

Further, in order to solve the above-mentioned problems, the present invention provides an optical system of a wide-color and high-density full-color image reading apparatus, in which one lens, a roof mirror whose reflection surface is at a right angle, and two solid-state image pickup devices. Of the light from the lens, the light reflected by one reflecting surface of the roof mirror is focused on one solid-state image sensor, and reflected by the other reflecting surface of the roof mirror. It is proposed that the light is arranged so as to form an image on another solid-state image sensor.

[0012]

With respect to a wide reading width, one lens and one half mirror having a reflectance of 50% and a transmittance of 50% are provided.
Two CCDs are optically arranged, and the light transmitted through one half of the half mirror through the lens is imaged on one CCD, and the light reflected by the other half of the half mirror is imaged on the other CCD. .. This structure is inexpensive and the optical adjustment is easy.

Instead of the half mirror, it is possible to use a roof mirror whose reflection surface has a right angle. At this time, one half of the light passing through the lens and reaching the Dach mirror is
The light is reflected by one reflecting surface of the roof mirror and forms an image on one CCD, and the light of the other half on one side is reflected by the other reflecting surface and forms an image on another CCD. This structure is suitable for a high-speed reading device because the light amount does not decrease.

[0014]

The present invention will be described below with reference to the embodiments shown in the drawings.

In the first invention shown in FIGS. 1, 2 and 3, one lens 17 is provided for a wide reading width H, and
One half mirror 19 and two CCDs 18a, 18
b and are provided. The light passing through the lens 17 passes through the half mirror 19 by 50%, and the half mirror 19 causes 50% of the light.
% Reflected. The light transmitted through one half of the half mirror 19 is imaged on the CCD 18a, and the light reflected by one half of the half mirror 19 is imaged on the CCD 18b. Thereby, a wide and high-density image can be read.

Further, since the optical arrangement according to the first invention described above splits the light emitted from the lens, the position adjustment of the lens is performed by the conventional optical arrangement using a single lens shown in FIG. You can do it on the same level as you do.
Further, since the positional relationship between the two CCDs has an inclination of 45 °, it is determined by the precision of the parts supporting the lens and the CCD. Adjustment of the CCD is also very easy as compared with the optical arrangement using two lenses and two CCDs shown in FIG.

The optical arrangement of the second invention shown in FIGS. 4, 5 and 6 is different from the optical arrangement of the first invention described above in that a Dach mirror whose reflection surface has a right angle is used instead of the half mirror. It is that you are.

That is, in FIGS. 4, 5 and 6, the light passing through the lens 27 reaches the roof mirror 29.
The Dach mirror 29 is arranged so that its apex is located at the center of the lens 27, and passes through the lens 27 so that the Dach mirror 2
One half of the light reaching 9 is reflected by one reflecting surface of the roof mirror 29 to form an image on the CCD 28a, and the other half of light is reflected on the other reflecting surface to form an image on the CCD 28b. This makes it possible to read a wide and high-density image.

The arrangement of the lens 27, the roof mirror 29, and the CCDs 28a and 28b in the second aspect of the invention is determined by the precision of the components that support them, so fine adjustment is not necessary and the precision of the components is not extremely severe.

[0020]

According to the first aspect of the present invention, one lens, one half mirror, and two CCDs are used, and the light after passing through the lens is divided into two by the half mirror. As a result, the number of lens systems is one, and since the joint portion is adjusted at the lens center portion (most dominant portion), optical adjustment can be performed easily and inexpensively, and it is effective for a device that reads a wide original at high density.

According to the second aspect of the present invention, since the roof mirror is used instead of the half mirror in the first aspect, the light passing through the lens can be equally divided without reducing the light amount. Therefore, a wide original can be read at high density and at high speed, which is suitable for a high-speed reading device that requires a light amount. .

[Brief description of drawings]

FIG. 1 is a plan view of an optical arrangement of the first invention.

FIG. 2 is a side view thereof.

FIG. 3 is a perspective view showing a main part of the optical arrangement of the first invention.

FIG. 4 is a plan view of the optical arrangement of the second invention.

FIG. 5 is a side view thereof.

FIG. 6 is a perspective view showing a main part of the optical arrangement of the second invention.

FIG. 7 is a perspective view showing the outer appearance of the image reading apparatus.

FIG. 8 is a schematic sectional view thereof.

FIG. 9 is a plan view of a conventional optical arrangement in the image reading apparatus.

FIG. 10 is a side view thereof.

FIG. 11 is a plan view of another conventional optical arrangement in a wide and high density image reading apparatus.

FIG. 12 is a plan view thereof.

[Explanation of symbols]

 1 Image Reading Device 17, 27 Lens 18a, 18b CCD (Solid-State Image Sensor) 19 Half Mirror 28a, 28b CCD (Solid-State Image Sensor) 29 Dach Mirror

Claims (2)

[Claims] 1. An optical system of a wide-color and high-density full-color image reading apparatus, which includes one lens, a half mirror having a reflectance of 50% and a transmittance of 50%, and two solid-state image pickup elements. Of the light from the lens, the light transmitted through one half of the half mirror forms an image on one solid-state imaging device, and the light reflected by the other half of the half mirror is coupled to another solid-state imaging device. An optical system characterized by being arranged so as to form an image. 2. An optical system of a wide-width and high-density full-color image reading apparatus, which is provided with one lens, a roof mirror having a reflecting surface at a right angle, and two solid-state image pickup elements, and these are arranged so that Of the light, one of the roof mirrors
It is arranged such that the light reflected by one reflecting surface forms an image on one solid-state image sensor and the light reflected by the other reflecting surface of the roof mirror forms an image on another solid-state image sensor. And optical system.