JPS59228466A - Color original reader - Google Patents

Abstract

PURPOSE:To attain the miniaturization and light weight of the device by using a fluorescent display tube as a light source for lighting a color original reader. CONSTITUTION:The fluorescent display tube 20 is used as the light source for lighting an original 5 placed on a contact glass 12. The display tube 20 is constituted by providing an electrode board 22 on a glass base plate 21, phosphors 23G, 23B and 23R irradiating three colors of R, G and B are laminated thereupon fitting a filament 24 on said phosphors. A reflected light from the original is transmitted through a cover glass 25 and the base plate 21 and the image is formed on an image sensor 7 via a coupling optical system 27.

Description

[Detailed description of the invention] Technical field The present invention relates to a color document reading device.

Conventional technology A color original reading device used as an input device for a color facsimile, a color copier, an office computer, a personal computer, etc. has conventionally illuminated the original with one white light, and after passing through a color separation filter, each color component was separated. A color image reading method using an image sensor is well known, but this method has drawbacks such as poor color reproducibility, expensive optical equipment, and difficult adjustment.

Fl, f: For example, as an improvement, JP-A-55-3
No. 0215 discloses that a manuscript is produced by using a plurality of light sources that emit light of different colors, for example, red, green, and blue (hereinafter abbreviated as R, G, and B), which are complementary colors to each other, with their emission times staggered at regular intervals. The color of the illumination light is sequentially irradiated line by line in the scanning direction, and the reflected light is received by a single image sensor, which then transmits image information in synchronization with the blinking of the multiple light sources mentioned above. A color document reading method has been disclosed in which color information of the document is obtained by reading the document.

As shown in FIG. 1, an apparatus for carrying out this method includes four fluorescent pairs 1, 2, and 3 arranged parallel to each other.
．． It has been proposed that a point Pi on the document 5 is irradiated with a light source consisting of a light source 4, and the reflected light is received by an image sensor 7 via an imaging lens 6. In the figure, fluorescent pairs 3 and 4 are of the same color because the angle of the original illumination direction with respect to the original surface is lower than that of fluorescent pairs 1.2 and the illuminance is lower. , the other two fluorescent pairs are 1
Each book has a different color, and one set of fluorescent pairs 3 and 4 and the fluorescent pair 11' 2 k are sequentially staggered and flashed. The color of the light of each fluorescent pair is, for example, 3, 4 and '(5G, l is R, 2 is B
shall be. Note that the symbols 8, 9, to, and 11 are reflective plates.

Now, as shown in FIG. 2, the angle of the two tangents drawn from point P to the outer circle of the fluorescent pair G with respect to the original surface is 01. θ2
and the similar angle for the R and B fluorescent pair 1.2 is 03
．． θ4, the luminance of the fluorescent pair k LF, the illuminance IP (G) by the fluorescent pair 3 or 4 at point P, the fluorescent pair l
The illuminance "P(RorB)" according to 2 or 2 is as follows.

Ip(c) = LF −π(cosθ1−CD5
θ2)”P(RorB)””LF” π(co
! lIθ3−cQSθ4) Therefore, if the luminance of the fluorescent pair is the same, the arrangement angle of the fluorescent pair with respect to the original (θ1+θ
2)/2 or (θ3+04)/2'ff: It is necessary to increase it, or it is necessary to increase the inclusive angle (θ2-θ, ) or (θ4-3)k. This 1. If the arrangement of the four fluorescent pairs is determined in consideration of these conditions, the shape of the light source section for document illumination becomes large, which has the drawback of increasing the size of the device in the case of a moving light source scanning type device.

Purpose The present invention has been made in view of the above-mentioned drawbacks of the conventional color document reading device using a fluorescent pair, which sequentially irradiates the document line by line with light sources of different colors.
It is an object of the present invention to provide a color document reading device that is lightweight and can be miniaturized.

Configuration The present invention will be described in detail below based on embodiments shown in the drawings.

FIG. 3 is a diagram showing an embodiment of the present invention. In this embodiment, instead of the conventional four fluorescent pairs, one fluorescent display tube 20 is used as a light source for illuminating the document 5 placed on the contact glass 12 at point P. It's cold.

As shown in detail in FIGS. 4(a) and 4(b), this fluorescent display tube 20 has an electrode plate 22 provided on a glass substrate 21, and a fluorescent display tube 20 that emits three colors of light, R, G, and B, respectively. Light body 23G,
23B and 23R are laminated and arranged parallel to the main scanning direction of the original, a filament 24 is attached above the filament 24, and the whole is covered with a cover glass 25 for protection.

Note that, like the conventional device, two phosphors 23G that emit G color are provided on both outer sides, and B and R phosphors 23B are provided on the inner side.
23R is provided with one row each. Further, an appropriate gap is provided between the B and R phosphors, and an annocuture 26 is provided below the gap through which the electrode plate 21VC1rl can pass. When the hot cathode rays generated by applying a voltage to the filament 24 are attracted to the electrode plate 22, the fluorescent bodies 23G, 23B, and 23R are excited by the hot cathode rays and emit fluorescent lights of colors G, B, and R, respectively. Light is emitted, passes through the cover glass 25, and illuminates the original 5 at point P, and the reflected light is transmitted through the cover glass 5 and the aperture 26 of the electrode plate 22.
, passes through the glass substrate 21, and is imaged on the image sensor 7 via an imaging optical system (for example, a roof mirror lens array) 27.

Now, by a lighting circuit (not shown), each of the R, G, and H phosphors 23R,
By sequentially switching on and off the electrode plates 22 and filaments 24 corresponding to 23G and 23B, R
, G, B, R, G, B, R, G, B, and so on.

The color document reading device of the present invention uses the integrated and elegant fluorescent display tube having the above structure as an illumination light source, so that it is smaller and lighter than the conventional device. In this case, the width t of the phosphors of each color may be determined by taking into consideration the spectral emission energy of each phosphor, the spectral sensitivity of the image sensor, the comprehensive angle from the irradiation point P on the document surface, etc. Generally, B is emitted twice because the emission energy of B and the spectral sensitivity of the image sensor are low.
, R may emit one light, and the widths of the phosphors of father and B may be increased.

Effects As described above, according to the present invention, the illumination section can be made smaller compared to the conventional light source for reading color originals that uses a plurality of fluorescent lamps, and the level of the output signal of the image sensor can be reduced. Each color can be easily made uniform.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a conventional device, FIG. 2 is a schematic diagram for explaining the illuminance of an original by each light source, FIG. 3 is a sectional view showing an embodiment of the present invention, and FIG. 4 (,) (b)
1A and 1B are a cross-sectional view and a plan view, respectively, of a fluorescent display tube in this embodiment. 5...Document 7...Image sensor 20
...Fluorescent display tubes 23R, 23G, 23B...Each color band 7-

Claims (2)

[Claims] (1) The light emission times of multiple light emitters of different colors are shifted at regular intervals, and the color of the irradiation light is switched line-by-line on the document in the main scanning direction, line by line, and the reflected light is simply A color image reading device that receives light with one image sensor, characterized in that the light source for illuminating the document is a fluorescent display tube in which phosphors having a plurality of different emission colors are arranged side by side. (2) The color image reading device according to claim 1, wherein the widths of the respective color phosphors of the fluorescent display tube are mutually varied so that the image sensor output is uniform.