JPS5868364A - Reader - Google Patents

Abstract

PURPOSE:To obtain a small-sized reader by providing an optical means of reflecting a part of incident light and transmitting the remainder in an image forming lens, reflecting and transmitting the transmitted light through another optical means, and reading multicolor information through a lens with short optical path length. CONSTITUTION:At the internal center part of an image forming lens 131, a dichroic mirror 132 which transmits a part of light incident to the lens and reflect the remainder is provided. This mirror 132 reflects light with a long wavelength range including red light and transmits light including blue light and green light. The transmitted light is guided to a dichroic mirror 133 to reflect light with a wavelength range including blue light and also to transmit light with a wavelength range including green light. Thus, the dichroic mirror 132 is incorporated in the image forming lens 131 in one body to allow the use of a lens with short focal length, thereby shortening the length of an optical path.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reading device, and more particularly to a reading device that illuminates a document and uses an imaging lens to form an image of the reflected light on a light receiving element to read image information on the document. be.

To read the image of a multicolor original, the original placed on a document table is illuminated by a light source such as a Hagen lamp and entered into a color separation means such as a light detector, and the color separation means separates the light into multiple wavelength ranges. An image is formed on a light-receiving element such as a one-dimensional image sensor. In such a reading device, the document is fixed and a light source or a reflective spot is moved to scan an area of the document, or the document is scanned by moving the document.

FIG. 1 shows an example of the configuration of such a conventional reading device, where l is a document table glass on which a document is placed, c is a rod-shaped light source such as a gas lamp or a fluorescent lamp, and a reflective shade J is used. Install it inside. 4' s j $ 4 is the first reflection mirror, and the first reflection mirror scans the document surface (sub-scanning) while moving in the entrance direction along a guide rail (not shown) together with the light source. )do. The third mirror element and the third mirror element are integrated by a support (not shown), and the third mirror element is integrated with the third mirror element by a support (not shown).
In the same direction B as Erazan, the moving speed of the first mirror-tei is -
move on the aforementioned guide rail at a speed of . Further, 7 is an imaging lens, and j is a color separation means using a dichroic pickup, etc. In this example, light in a long wavelength region including red light is reflected and sent to a -dimensional solid-state image sensor, for example, C0DIG. form an image. Note that the CCDs 9 and 10 have a predetermined number of light receiving elements in the direction perpendicular to the drawing, and each CCD 9 and 10 reads the same position on the original. In addition,
// is the national polity that houses these parts.

In such a reading device, a light source 4, a first mirror 4
! The positions of the first mirror 6 and the third mirror 6 are respectively indicated by dotted lines in the figure. It moves to f' and 6', but at this time, from the document table l to mirror 4' e
! *The optical path length through A to lens 7 is always kept constant. Therefore, if the signals from the cent and lO light receiving elements are read out in order during sub-scanning (main scanning), sequential signals obtained by raster scanning the document surface can be obtained.

In addition, Figure 1 shows another example of this conventional reading device, in which the original is moved to continue capturing images, and the image information is color-separated into three colors: red, blue, and a. Here, ko l is a document transporter, and the document n is transported by this holder J/,
The image fails to be read at position P on document reading glass n. That is, the light from the light source is reflected at the position P and is made to enter the imaging lens via the ray/l ray. Further, the dichroic mirror decomposes the light into red light, blue light, and green light, and the transmitted light is input to a dichroic mirror. Dike mirror reflects blue light and transmits green light. Therefore, red light is received by the light receiving element 3°, blue light is received by the light receiving element 3°, and green light is received by the light receiving element J/.

Note that J is a holding plate that allows the original to be well focused on the bin F.

However, in such conventional reading devices,
Since the imaging lens 7 and the color separation means t are arranged separately, a lens with a long focal length is required, and there is a limit to miniaturization of the apparatus. If it is necessary to separate into three or more colors, there is a limit to miniaturization, and the device becomes large.

SUMMARY OF THE INVENTION An object of the present invention is to provide a reading device that is miniaturized in order to eliminate such conventional drawbacks.

Hereinafter, the present invention will be described in detail based on the drawings, but the same reference numerals are given to FIG. 1 and the same parts as in FIG.

FIG. 3 shows an example of the reading device of the present invention, and corresponds to the conventional example shown in FIG. Here, /J/ is an imaging lens, and an optical means, for example, a seventh dichroic mirror lJ, that transmits part of the light incident on the lens and reflects part of it, is installed inside the center of the imaging lens.
There will be a This 1st Dyke P Ikshiller/3 pieces is
First light in a long wavelength range including red light is reflected, and first light including blue light and green light is transmitted. Also, /J'
Reference numeral J designates a second Kodich mirror that reflects third light in a wavelength range including blue light and transmits first light in a wavelength range including green light. Therefore, the first light is the light receiving element isa, the third light is the light receiving element /Jl, and the first light is the light receiving element /Jl.
The light is received by J4. Recording can be performed using the signals from these elements /3 to /34 using well-known techniques. By integrating the dichroic mirror /, 7J into the imaging lens /J/ in this way, a lens with a short focal length can be used, and the optical path length can therefore be shortened.

Further, FIG. 1 shows another example of the present invention, which corresponds to the conventional example shown in #IJ. Here, 44/ is an imaging lens, and the half-R radar as the optical means described above is provided inside the center thereof. Furthermore, a half cellar 4t3 is provided to reflect part of the light that has passed through the half mirror and to transmit a part, and a total reflection mirror is provided to reflect the light that has passed through the half mirror. on the other hand,
The 7th filter allows only red light to pass through the optical path of the reflected light from the bar 7 mirror! The seventh filter allows only blue light to pass through the optical path of the reflected light from the half mirror! of,
A third filter 417 that allows only green light to pass is provided in the optical path of the reflected light from the mirror. Therefore, the plum light-receiving element receives red light, the light-receiving element 30 receives blue light, and the light-receiving element J/ receives green light. Image signals taken out from each of these elements 31 are processed by a well-known signal processing circuit (not shown) to obtain desired image information, and based on this information, for example, an inkjet head is driven to record on recording paper. .

The flat dichroic mirrors shown in Figures 3 and 3 can be easily constructed, and the mirror and the imaging lens can be integrated very easily.

As described above, according to the present invention, it is possible to shorten the optical path length of a reading device that can read originals in one or more colors, contributing to miniaturization of the device.

[Brief explanation of the drawing]

1 and 1 are block diagrams each showing an example of a conventional reading device, and FIG. 3 and FIG.
Ge C! T! 'tAy&'...Mirror, Ri...Imaging lens, t...Dichroic mirror, Te, 10
...light receiving element, // river body, edge...fourth,
Engineering...manuscript...manuscript table glass, review...
・Light source, co-mirror, m-imaging lens,
279 Ko...Dichroic mirror, Ko? , 3o
, J/...light receiving element, 3 pieces...holding plate, /
3/...imaging lens, 13 pieces,/? J... Dike mirror, /J4' t /Jj t /J4・
...Light receiving element, nail...imaging lens, dakotN--half mirror-1e-mirror, DaS~Da7...filter. Patent applicant: Canon Co., Ltd.

Claims (1)

[Claims] In a reading device that irradiates a document with light and images the reflected light on a light-receiving element for each of a plurality of colors via an imaging lens to read image information on the document, the image is formed within the imaging lens. a first optical means that is disposed integrally with the lens and transmits a part of the reflected light and reflects a part of the reflected light; and a first optical means that is disposed outside the imaging lens and transmits the light from the first optical means. and at least one second optical means that transmits a part and reflects a part, and reads a plurality of color information with the light receiving element via the first optical means and the second optical means. A reading device characterized by: