JPS6328551B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color separation optical system used in color facsimiles and color graphic reading devices.

In general, drum-scanning type facsimile machines for color photographic electronic transmission and scanners for plate making use a three-color separation system as exemplified in FIG. In Figure 1, a tungsten light bulb 1 and a condenser lens 2
The light beam reflected from the pixel dot 4 on the original surface 3 is directed to the aperture 6 via the objective lens 5.
imaged on top. The aperture 6 has a small hole in the center corresponding to the required resolution, and the light beam passing through the small hole is separated into three primary color components by dichroic mirrors 7 and 8. The dichroic mirror 7 reflects blue light, and the dichroic mirror 8 reflects red light, which pass through a blue shaping filter 9 and a red shaping filter 10, respectively, to the photoelectric converter 1.
1 and 12, a blue signal and a red signal are detected. On the other hand, the green light that has passed through the dichroic mirrors 7 and 8 passes through a green shaping filter 13 and enters a photoelectric converter 14, where a green signal is detected.
Here, the dichroic mirrors 7 and 8 are usually filters with a dielectric multilayer structure to reduce the transmission loss of spectral components, and the shaping filters 9 and 10 are used to improve the blocking characteristics of the dichroic mirrors 7 and 8. Used to trim unnecessary sideband components due to integrity. The above configuration is extremely standard, but dichroic mirrors 7 and 8 are generally expensive, and their wavelength characteristics change depending on the angle of incidence, so it is necessary to shape the incident light beam into a parallel beam. Otherwise, the aperture of the lens system must be narrowed down to reduce angular dispersion. Also, each filter element 9, 10, 13 and photoelectric converter 11, 12, 1 with respect to the optical axis.
It is necessary to pay attention to the accuracy of the arrangement of the parts 4, the structure is complicated, it is not easy to miniaturize, and the overall cost is high.

Furthermore, if a multi-color separation system is constructed using this color separation system, the dichroic mirror must be designed with high precision and low loss, making it complicated and expensive.

The present invention aims to improve the above-mentioned drawbacks and make it simpler and more economical.It is an object of the present invention to provide a color separation head that is particularly suitable for small-sized color facsimile transmitters, multicolor figure reading devices, etc. .

The present invention will be described in detail below based on specific examples.

FIG. 2 is an embodiment showing the basic structure of the present invention. For simplicity, this example exemplifies the case of two-color separation. In FIG. 2, pixel dots 4 on document surface 3 are illuminated by an illumination optical system consisting of a tungsten bulb 21, a condenser lens 22, an aperture 23, and an imaging lens 24. A condenser lens 22 connects the filament image of the tungsten bulb 21 onto the aperture 23 and
The filament image taken out through the small hole in the center becomes a secondary light source and is projected onto the document surface 3 by the imaging lens 24.
A minute spot light is connected to the upper pixel point 4. The small hole of the aperture 23 is determined so that the size of this spot light has a predetermined pixel resolution. On the other hand, the light beam reflected from the pixel point 4 is reflected by the condenser lens 2.
5. The color signal is collected by the photoelectric converter 27 through the color filter 26, and the color signal determined by the spectral transmission characteristics of the color filter 26 is detected. 28, 29,
The other detection system 30 has the same functions as the capacitor 25, the color filter 26, and the photoelectric converter 27, and a color signal in a wavelength band different from that of the color filter 26 is extracted by the color filter 29. When this embodiment is compared with the conventional example shown in FIG. 1, the following structural differences will be apparent. That is, in FIG. 1, the document surface 4 is illuminated from an oblique direction and the reflected light in the vertical direction is detected, whereas in FIG. ing. Next, in Fig. 1, a single light beam that has passed through the aperture 6 is separated in series to obtain a color signal, while in Fig. Color signals are obtained by receiving light beams in parallel with each detection system. Due to the above two basic structural differences, the present invention has the following advantages over the conventional method.

Firstly, it eliminates the need for optical components such as dichroic mirrors or beam splitters used in conventional serial spectroscopy, making it suitable for simplicity and economy.Secondly, the reflection around the vertical axis Thirdly, it is possible to use a wide space to receive light beams and to improve the light collection efficiency.Thus, semiconductor optical sensors can be used as photoelectric converters instead of conventional photomultiplier tubes, and miniaturization is possible. For example, it should be easy.

FIG. 3a shows another embodiment in which a multicolor separation system is constructed by arranging a large number of detection systems. 31, 32, 33
and 34 are the same as the tungsten light bulb 21, condenser lens 22, aperture 23, and imaging lens 24 in FIG.
A minute spot light is connected to the picture element point 4 above. The reflected light from pixel point 4 is diffused around the vertical axis. Therefore, if a large number of detection systems consisting of a condenser lens 35, a color filter 36, and a photoelectric converter 37 are arranged in a ring shape around an axis as shown in the figure,
Reflected light can be received by multiple channels at the same time. The condenser lens 35, color filter 36, and photoelectric converter 37 have the same functions as the condenser lens 25, color filter 26, and photoelectric converter 27 shown in FIG. 2, and the spectral characteristics of each channel depend on the characteristics of the color filter 36. Determined. In this example, the case where the spectrum is divided into 6 channels CH ₁ to CH ₆ is exemplified, and if a band-pass filter as shown in FIG. It can be separated into 6 colors instead of 3.

Figures 4a and 4b are examples of structural diagrams of a specific color separation head using the color separation optical system shown in Figure 3.
The components indicated by 41 to 47 are respectively 3 in Fig. 3.
It corresponds to 1 to 37. tungsten light bulb 4
1. Micro spot light irradiation optical components consisting of a condenser lens 42, an aperture 43, and an imaging lens 44 are mounted in a lens barrel 48 to constitute an illumination system, while a condenser lens 45, a color filter 46, and a photoelectric converter 47 form a set of color light detection units, and a plurality of color light detection units are mounted in a ring shape as shown in the figure on a donut-shaped hat-shaped holder 49 to constitute a multi-channel detection system. Each detection unit is attached so that its optical axis forms a conical shape with the irradiation point 4 of the document 3 as the apex, and the inclination angle is set so that all the optical axes intersect at one point at the irradiation point 4.

Such a multicolor separation system can be applied to automatic pattern separation processing for electronic printing plate making, textiles, dyeing, etc., and can also be used as a multicolor separation system, as well as for recognizing the surface of a colored object and reading multicolor figures. is also valid.

In the above-mentioned embodiment, the case where reflected light from the surface of the document is detected is exemplified, but the present invention can be applied in a similar way to the case where the document is a transparent original such as a photographic film. In this case, the detection system is placed on the opposite side of the illumination system across the document, and receives transmitted light diffusely distributed around the vertical transmission axis in the same way as in the case of reflection. However, in the case of a film original with good transparency, the diffusion property is weaker than that of a reflective original, so in such a case, a diffusion sheet or the like may be placed on the back side of the film original.

As described above, the present invention irradiates minute spot light from a direction perpendicular to the document surface, and detects reflected or transmitted light from the document surface using a plurality of photodetectors arranged around the vertical axis of the document surface. With a color separation head configured to receive light, a color separation system with a simple configuration, high light utilization efficiency, and high sensitivity can be realized. Furthermore, a compact multicolor separation system can be constructed using a light receiving element such as a semiconductor optical sensor, and is suitable for realizing an inexpensive and small color image reading device or color facsimile.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing a configuration example of a conventional three-color separation optical system, FIG. 2 is a system diagram showing an example of a two-color separation system showing the basic structure of a color separation optical system according to the present invention, and FIG. Figure a is a perspective view showing an embodiment of the color separation optical system according to the present invention suitable for multicolor separation;
Figure b is a diagram showing an example of the characteristics of the spectral color filter used in figure a, and Figures 4a and b are a plan view and a cross section showing an example of a color separation head using the color separation optical system according to the present invention. FIG. 3...Document surface, 4...Picture element point, 21, 31, 4
1...Tungsten light bulb, 22, 32, 42...
Condenser lens, 23, 33, 43...Aperture, 24, 34, 44...Imaging lens, 25,
28, 35, 45... condenser lens, 26,
29, 36, 46...color filter, 27, 3
0, 37, 47...Photoelectric converter, 48... Lens barrel,
49...Kasagata holder.

Claims (1)

[Scope of Claims] 1. An illumination optical system that irradiates minute spot light from a direction perpendicular to the document surface, and an illumination optical system that is arranged around the vertical axis of the document surface and that emits reflected light or transmitted light of the spot light from the document surface. a plurality of photodetector groups that receive light, and a color filter group that is attached to the front surface of each of the photodetector groups and extracts a desired spectral component of the reflected light or transmitted light, A color separation optical system characterized by color-separating and detecting density color information into a plurality of spectral components. 2. The color separation optical system according to claim 1, wherein the photodetector group and the color filter group are each arranged annularly on a suitable circumference around the vertical axis.