JPS59152455A - Color separating method - Google Patents

Abstract

PURPOSE:To reduce a loss in the quantity of light and to increase reading speed by allowing a maximum reflection wavelength and a maximum transmission wavelength for color separation to coincide with the middle wavelength at which the maximum light emitting energy is generated in each wavelength region of a light source. CONSTITUTION:A fluorescent lamp 3 contains a fluorescent substance suitable for light emission in three wavelength regions B, G, R to form specified wavelength regions B, G, R. Peak wavelengths (b), (g), (r) each showing the maximum light emitting energy are measured in the wavelength regions. A minimum transmission wavelength Mb close to the maximum reflection wavelength of a mirror 11 and the maximum transmission wavelength Fb of a filter 15 are allowed to coicide with the wavelength (b). A minimum transmission wavelength Mr close to the maximum reflection wavelength of a mirror 12 and the maximum transmission wavelength Fr of a filter 17 are allowed to coincide with the wavelength (r). The maximum transmission wavelength Fg of a filter 16 is allowed to coincide with the wavelength (g). As a result, light in the wavelength regions reflected from an original is subjected to efficient color separation with the matched mirrors and filters. When such a color separating method is applied to a reading device, the quantity of light reaching the photoelectric conversion part is increased, and the reading speed can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a method of separating document information into optical information according to a plurality of wavelength ranges, and particularly relates to a method of color separation using mirrors or filters.

(Prior art) Conventionally, color faxes, color copying machines, etc. use document reading devices to decompose document information into optical information in multiple wavelength ranges, and guide each of them to a photoelectric conversion section to convert them into image signals. Alternatively, it can be guided directly to a photoreceptor to form a color image. How is the document reading device used? A method is adopted in which the document is irradiated with a light source, the reflected light from the document is guided to a mirror or a filter, and color image information is separated into a plurality of wavelength ranges. However, in conventional color fax machines, a halogen lamp or fluorescent lamp is used as a light source, and the reflected light from the document is separated into three primary colors using mirrors or filters. In this case, for example, the wavelength range of a fluorescent lamp has a gentle emission distribution in the visible range as shown in Figure 1, but in contrast,
The amount of light for each of the primary colors is greatly reduced because a large amount is absorbed by mirrors and filters. In order to prevent this decrease in light intensity after color separation, a brighter light source is required.
This results in an increase in power consumption. Moreover, fluorescent lamps emit light in wavelength ranges other than the reflection wavelength range or transmission wavelength range of mirrors and filters, consuming energy, and since this emitted energy is not used for color separation, it is a waste of energy. It has become. Furthermore, when the conventional color separation method is used in a reading device, the reading speed tends to decrease due to a decrease in the amount of light, creating a problem in increasing the speed of the device.

(Objective of the Invention) An object of the present invention is to provide a method that can efficiently utilize the emission energy of a light source and separate document information into colors.

(Structure of the Invention) The method of the present invention uses each of a plurality of wavelength ranges possessed by a light source.
Find the center wavelength, match the maximum reflection wavelength and maximum transmission wavelength that the color separation optical system performs color separation processing to each of these center wavelengths, and use these to decompose the document information into optical information according to multiple wavelength ranges. It is characterized by

The method of the present invention will be explained below with reference to Examples.

First, a case will be described in which document information is decomposed into optical information for each of the three primary colors of blue, green, and red using the method of the present invention. In this case, a fluorescent lamp with a light emission distribution as shown in FIG. 2 is used as a light source for the document illumination device, and a color separation optical system is formed of two mirrors, each mirror having a light emission distribution as shown in FIG. 3. It shall exhibit the following spectral characteristics.

That is, the fluorescent lamp used here is formed to exhibit luminance several times (here, two to three times) higher than in other regions in three wavelength ranges B, G, and R corresponding to the three primary colors. In other words, this fluorescent lamp has three wavelength ranges B as a fluorescent material coated on its inner wall.

Many phosphors adapted to emit only G and R are used,
This precludes the use of phosphors suitable for flat luminescence distribution as in the past. In addition to this, a fluorescent lamp with a multilayer coating on the inner wall can also be used. Furthermore, “
1981 National Conference of the Institute of Electronics and Communication Engineers, 1125, Fakumiri illumination light source using slit type hot cathode fluorescent tube,
It is also possible to use a hot cathode fluorescent tube as seen in the article "(Ota, Kansaki)". In any of these cases, specific wavelength ranges B, G', and R corresponding to the three monochromatic lights of blue, green, and red are formed, and from this, the three central wavelengths h++7+ r, that is,
The peak wavelength that can exhibit the maximum emission energy is determined for each wavelength range.

Next, the spectral characteristics of the two mirrors (see Figure 4) are set based on the three center wavelengths h+, q+, and r of the fluorescent lamp.

Here, a first mirror receives the light flux that is reflected light from the original, a second mirror receives the light flux that has passed through the first mirror, and the light flux that has passed through the second mirror is colored so that it is in the green wavelength range G. A resolving optical system is used. The first mirror is set to have a maximum reflection wavelength that is close to the minimum transmission wavelength Mh so as to coincide with one center wavelength of the fluorescent lamp, and as shown by the solid line in Figure 3, the minimum transmission wavelength Mh is set as the bottom. Transmits light in the visible range (red and green range) other than those in the visible range (red and green range) to a base with high transmittance. Furthermore, the maximum reflection wavelength of the second mirror is set to be similar to the minimum transmission wavelength Mr so as to coincide with the other center wavelength r of the fluorescent Nago, and the minimum transmission wavelength Mr is set as shown by the broken line in FIG. The bottom is used to transmit light in the other visible regions (blue and green regions) with high transmittance. The first mirror and the second mirror are each half mirrors, and the spectral characteristics of each can be adjusted depending on the material, thickness, and number of deposited films.Using these as parameters, the above-mentioned spectral characteristics can be adjusted to an appropriate state. It is set to .

When a fluorescent lamp as described above and two mirrors forming a color separation optical system are used as a set, a reading device 1 shown in FIG. 4 can be formed. This reading device 1 has a glass original placing table 2 on which a color original (not shown) is placed, and the above-mentioned fluorescent lamp 3 as a document illuminating device is arranged below the original placing table 2. Furthermore, an imaging optical system 8 is arranged to image the reflected light from the original onto the three light receiving surfaces 5, 6, and 7 of the photoelectric conversion section 4. This imaging optical system 8 directs the reflected light from the document to a mirror 9.
and the imaging lens 10 to each light receiving surface 5, 6.7, and the above-mentioned first and second mirrors as a color separation optical system are installed between the imaging lens 10 and each light receiving surface 5, 6.7. 11,
This is a configuration in which 12 units are arranged. Here, the mirror 9 used has a flat reflectance over the entire visible range. The photoelectric conversion unit 4 is formed of a solid-state image sensor in which photoelectric conversion elements such as photodiodes and CCDs are arranged in an array in one direction, and this is arranged so as to form three light receiving surfaces 5, 6.7. Accordingly, document information corresponding to each wavelength range is read separately.

When the reading device 1 shown in FIG. 4 operates, a long slit light perpendicular to the paper surface is irradiated onto a color original from the fluorescent pair 3, and the slit-shaped imaging light flux, which is the light reflected from the original, is mirrored. 9 and the imaging lens 10, the first mirror 1
1.

Three wavelength ranges B corresponding to three center wavelengths h+ q+ r
, G, and R are incident on the first mirror 11, only the light beam in the wavelength range B around the center wavelength is reflected, and the light beam in other regions is transmitted.

The light beam transmitted through the first mirror has two center wavelengths g.

It mainly maintains two wavelength ranges G and R corresponding to γ, and the second mirror 12 reflects only the light beam in the wavelength range R at the center wavelength r, and reflects the light beam in other regions, that is, the light beam at the center wavelength g. The light beam in area G is transmitted. As a result, monochromatic blue light in the wavelength range B enters the light receiving surface 5 of the photoelectric conversion unit 4, monochromatic green light in the wavelength range G enters the light receiving surface 6, and the light receiving surface 7
Red monochromatic light in the wavelength range R is incident on the . Based on the above-mentioned conditions, the document receives long slit light in the main scanning direction (perpendicular to the paper surface) and is also scanned by the slit light in the sub-scanning direction. ．． The light is guided to the photoelectric conversion unit 4 via the second mirror 11, 12, and is read and processed separately as information on three monochromatic lights of blue, green, and red.

In addition, when color document information is accurately decomposed into three monochromatic colors of blue, green, and red, and assuming that the optical paths toward the three light receiving surfaces 5 and 6.7 are under similar conditions, the emission energy of the three monochromatic lights generated by the light source is It is necessary that the values are substantially the same, so that each monochromatic light under the same conditions is incident on each light receiving surface. However, here, the emission energy of fluorescent pair 3 is green.
Red>blue (see Figure 2), and fluorescent pairs that maintain this state are common. However, since the light intensity of each monochromatic light decreases the same each time it passes through the same medium, here, the first mirror 11 and the second mirror 12 form a color separation optical system, and blue, which has a small emission energy, is The configuration is such that the red light is reflected by the mirror 11, the red light is then reflected by the second mirror 12, and the green light, which has the highest light emitted energy, is taken out after passing through the two mirrors, and the intensity of the light emitted energy is corrected. That is, here, the surface reflectance of the first mirror 11 is R1, the transmittance including the internal partial transmittance of the mirror material is TI, and similarly the second mirror 1 is
2 to R2, T2. When the light source light intensity is IO, the light intensity In of the light receiving surface 5 that receives monochromatic light in the blue wavelength range is In-lo
XR1, similarly the amount of light on the light receiving surface 7 11. Hako. -IOX
T, X R2, similarly light receiving surface 60 light amount■. Hako. −
IOX T, X'r2. In general, reflectance is higher than transmittance < (R+, >'h.

R2>T2), and as a result, the light amount loss is ■. >bt)
'I.

becomes. This result cancels out the strength of the emitted light energy of the fluorescent pair 3, that is, green>red>blue, and each light receiving surface 5
, 6.7 can each receive monochromatic light similar to that emitted based on approximately the same luminous energy.

In the above, two first and second color separation optical systems are used as the color separation optical system. Second mirror 1.1. '12 has been described, but instead of this, as shown in FIG. 14 is used to divide it into three parts, and three filters 15, 16, and 17 are placed on the three optical paths.
It may be arranged such that the light beams in each wavelength range separated by these filters are imaged on the respective light receiving surfaces 5, 6.degree.7, and the document is read as information of three monochromatic lights of blue, green, and red. In addition to this, the means for dividing the imaging light beam into three light beams may be a well-known means in which a half mirror is used to divide the imaging light beam into three light beams of equal light quantity. The spectral characteristics of the filters 1, 5, 16, and 17 used in these cases are, for example, as shown in FIG. Things are adopted and used. That is, the filter 15 can mainly transmit light in the wavelength range B, and in particular, a filter having a maximum transmission wavelength Fb that is the same wavelength as the center wavelength of one of the fluorescent pairs is used. The filter] 6 can mainly transmit light in the wavelength range G, and in particular, a filter having a maximum transmission wavelength F, 7 which is the same wavelength as the center wavelength q of one of the fluorescent pairs is adopted. Similarly filter 17
can mainly transmit light in the wavelength range R, and in particular, one having a very thick transmission wavelength Fr that is the same wavelength as one center wavelength r of the fluorescent lamp is used.

Although each of the two series of color separation methods t has been described for color separation of three primary colors, separation of a plurality of other desired colors can be performed in the same manner.

(Effect of the invention) As described above, according to the color separation method of the present invention,
It separates colors as a phosphor in a fluorescent lamp, which is a light source.
Select and employ a device that can particularly enhance the emission energy in the wavelength range corresponding to the two wavelength ranges. As a result, the light source does not waste energy in emitting light in unnecessary wavelength ranges, making it economical. Furthermore, among the three center wavelengths b+(1+r) that generate the maximum emission energy in each of the three wavelength ranges of the fluorescent lamp, the center wavelength and the minimum transmission wavelength y1b that approximate the maximum reflection wavelength of the first mirror 11 are selected. Or maximum transmission wavelength Fh of filter 15
are set to the same wavelength, the center wavelength r and the minimum transmission wavelength Mr that approximates the very thick reflection wavelength of the second mirror 2 or the maximum transmission wavelength Fr of the filter 17 are set to the same wavelength, and the center wavelength g and the filter 17 are set to the same wavelength. The maximum transmission wavelength Fg of 16 was set to be the same wavelength. As a result, the light in each wavelength range included in the imaging light flux, which is the reflected light from the original, is efficiently color-separated by matching mirrors and filters, and the loss of light amount here is reduced compared to conventional methods. The emitted energy of the light source can be used without wasting it. Moreover, if such a color separation method is applied to a reading device, the amount of light reaching the photoelectric conversion section will increase, and the reading speed can be increased.

[Brief explanation of the drawing]

Fig. 1 is a light emission distribution characteristic diagram of a conventional fluorescent lamp, Fig. 2 is a light emission distribution characteristic diagram of a fluorescent lamp used in the method of the present invention, and Figure 3 is a spectral distribution characteristic diagram of a mirror used in the method of the present invention. FIG. 4 is a schematic diagram of a reading device to which the method of the present invention is applied, and FIG.
The spectral distribution characteristics of the filter shown in the figure are shown, and FIG. 6 is a schematic diagram of a reading device used in place of the reading device shown in FIG. 4. 3 ・Fluorescent lamp, 1.1. 1.2 Mirror,
15. ]'6゜17・Filter, B, G, R-wavelength range, 62g, r center wavelength, Mh, Mg, M
'r Minimum transmission wavelength, Fh, Fg, Fr Extremely thick transmission wavelength. r Deputy Director [? lπ〕 Pot D 圀

Claims (1)

[Claims] (1) A method of illuminating a document with a light source and guiding light reflected from the document to a color separation optical system consisting of mirrors or filters to separate document information into optical information classified by a plurality of wavelength ranges. ,
Then, from each of the plurality of wavelength ranges possessed by the light source, the center wavelength at which the maximum luminous energy is generated is determined for each of these wavelength ranges, and the maximum light emission energy for which the color separation optical system performs color separation processing is determined at each of these center wavelengths. A color separation method characterized by matching reflection wavelengths or thick transmission wavelengths. 2. The color separation according to claim 1, characterized in that a fluorescent lamp is used as the light source, and the emission energy of a plurality of wavelength ranges of the fluorescent lamp is enhanced compared to other wavelength ranges. Method.