JPS607213B2 - Color separation light detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color separation light detection device that optically detects each color component of printed materials, cloth, etc., and particularly relates to a color separation light detection device equipped with an illumination light source suitable for color separation signal detection. .

For quality control of color printed matter, for example, equipment that automatically inspects the color balance of color printed matter, or equipment that classifies items and sorts them into good or bad based on the color information of the object, the object to be inspected is irradiated with light. A method is used in which the reflected light is received by a three-color separation receiver and the output of each receiver is compared with a reference value.

Such devices generally use an incandescent lamp as the illumination light source, and add a color filter glass for color separation to a photodiode or photomultiplier tube as a three-color separation receiver, or add a color filter glass to an image pickup tube such as a vidicon. This is achieved using an additional feature. However, this type of conventional device has the following problems.

Namely, (1) unbalance of photocurrent between each band with respect to reference incident light (standard white), (2) low light reception efficiency with respect to total irradiation energy, and (2) decrease in color detection accuracy due to fluctuations in light source color temperature. I will now discuss these issues in some detail. FIG. 1 is a diagram showing the spectral sensitivity of a light receiver, the spectral radiation intensity of an illumination light source, and the spectral transmittance of a color separation filter. In the figure, 11 is the specific spectral sensitivity V(^) of the silicon photodiode, 12 is the specific spectral radiant intensity P (on) of the halogen lamp (considered as A light at rated lighting), and 13, 14, and 15 are R( Spectral transmittance FR (on) of the color filter that determines the red) band, G (green) band, and B (blue) band,
Indicates FG (on) and FB (on). When the standard white signal light (reflected light from the standard white plate) is received by the illumination light source and three-color separation receiver shown in this figure, the resulting signal light currents IR, IG
, ls is IR=K'iriteiR.

(^)・P(^)・FR(in). (V included). d-in IG=
Knoiritei R.

(in>P-in)・FG<^)・V(in)・d in IB=
K'iritei R.

(in), p (^) - FB (^), V (in) - d in.

However, K is a proportional coefficient related to photoelectric conversion, and R is a proportional coefficient related to photoelectric conversion. (on) is the spectral reflectance of the standard white board (ideally Ro (on) = 1
00), P(^), FR(^), FG(in), FB(in), and V(in) are the functions shown in FIG. When calculating the ratio of the three color separation photoelectric signals for the specific example shown in FIG. 1, (lc/IR)xlooo=3.8[%], (
IB/IR)×100=4.2 [%], and IG and IB are about 4% compared to IR. That is, there is a significant imbalance in photocurrent between bands. This is IR S
This means that the S/N of lc and IB is 2 phantom B lower than that of lc and IB, and the total S/N of color separation signals is
Since it is determined by the lowest S/N value of R, IG, and IB, a large imbalance in photocurrent is not preferable from the viewpoint of signal S/N. When color separation signals are obtained as time-series signals from a single photoreceiver by sequentially switching color filters, the unbalance of photocurrent between bands becomes a major obstacle in terms of the dynamic range of amplifiers and A/D converters. Become. Furthermore, if the amount of illumination light is increased in order to sufficiently increase the S/N on the short wavelength side, problems will arise due to heat generation and its cooling. That is, this is the first problem. The second problem is low light receiving efficiency.

With incandescent lamp lighting, most of the radiation is in the infrared region, so the light receiving efficiency is inherently poor, but even for visible wavelengths, it is difficult to implement a color filter that cuts out specific wavelengths within the continuous spectrum. Yes, and absorption by color filters is also significant. Of the total radiant energy that enters the photoreceiver (color filter and photoelectric conversion element), the energy that passes through the color filter and is effectively received is defined as the light receiving efficiency, and is expressed as (enter)-heart)/
('MoriP(^)-d), the 3 shown in Figure 1
For two receivers, B band ratio B = 0.28 [%]
Regarding the G band, G=0.17 [%], and regarding the R band, R=4.2 [%].

The light receiving efficiency on the short wavelength side is extremely poor, and even if the three bands are combined, the light receiving efficiency remains at 4.0 to 5.0%. The third problem is the fluctuation of the detected value due to the fluctuation of the color temperature of the illumination light source.

Color separation detectors have AGC (automatic gain control) added to deal with fluctuations in illumination light intensity and receiver sensitivity, so it is possible to eliminate the effects of these fluctuations, but it is possible to eliminate the effects of these fluctuations. The influence of variations in color temperature (variations in the slope of P(^)) cannot be removed. Even if the color temperature of the light source changes and its relative spectral radiation intensity changes from P(^) to P'(on), K'moxibustion; R.

<^)-P(^)-F(enter)-Vku^). d (in) = K
′′ Moxibustion; R.

(In>-P' (in). F (in). V (^). d In, the AGC circuit only operates so that the difference between P (in) and P' (in) is large. A large deviation appears in the detected color separation signals.

Fluctuations in the color temperature of this type of light source are unavoidable to some extent, and therefore there are restrictions on the detection accuracy of color separation signals. Thus, there are three major problems with conventional devices. The present invention has been made in view of these points,
By providing a fluorescent lamp for illumination that passes through color separation signal detection as a light source for illumination, the above problems can be eliminated.
It is an object of the present invention to provide a color separation photodetection device that can obtain excellent color separation detection performance.

That is, the present invention coats the tube wall of a lighting poppy or a light lamp with a plurality of types of poppies and luminous bodies, and matches the light emission peak wavelength of each poppy or luminous body with the sensitivity peak wavelength of a color separation receiver to receive light. In addition to improving efficiency and reducing the influence of color temperature fluctuations of the light source on the detection signal accuracy, the mixing ratio of multiple types of poppies and light bodies has been improved so that the amount of light emitted by each poppy and light body can be adjusted using a color separation receiver. By mixing the photocurrents in inverse proportion to the sensitivity of the color separation receivers, it is possible to eliminate the imbalance of photocurrents between the color separation receivers.

The present invention will be described in detail below with reference to the drawings. FIG. 2 is a diagram showing an embodiment of the configuration of the discriminating device of the present invention. In this figure, 25-1, 25-2, 25-3, 25-4 are conveyor belts, 26-1, 26-2, 26-3, 26-4
is a rotating roller for driving each belt, and the paper-like object 27 is conveyed in the direction of arrow 28 while being sandwiched between belts 25-1, 25-2 and belts 25-3, 25-4.
An illumination unit 32 composed of an illumination light source 29, a condensing lens 30, and a transparent guide 31 functioning as a slit uniformly illuminates a predetermined area in the width direction of the paper-like object 27 being conveyed. The light receiving unit 33 is composed of a diffusion plate/guide plate 34 and a plurality of photodetectors 35-1, 35-2, 35-3, etc., and the light transmitted through the paper-like object 27 is transmitted to the plurality of photodetectors 35. -1, 35-2, 35-3, etc. are uniformly received. Here, each photodetector has a different wavelength sensitivity and receives transmitted light in multiple bands. The electrical signals obtained by the photodetectors 35-1, 35-2, 35-3, etc. are respectively guided to the signal processing device 36, and are processed, for example, by the front layer amplifiers 37-1, 37-2, 37-3. The signal is then amplified by integrating circuits 38-1, 38-2, and 38-3 for a predetermined conveyance period of the paper-like object, and then sent to a discrimination circuit 39, where it is compared with a reference signal and its color component is detected. be done. The illumination light source 29 has a tube wall coated with a plurality of types of poppies and light bodies, and the emission peak wavelengths of the individual poppies and light bodies and the color separation receivers 35-1, 35-2, 35-3... The sensitivity peak wavelength of . . Regarding the mixing ratio of the plurality of types of poppies and light bodies, the amount of light emitted by each poppy and light body is
-3... are selected so as to be inversely proportional to the sensitivity of the color separation receivers 35-1, 35-2, 35-3, .
．． - Considered to eliminate mutual photocurrent imbalance. Next, this fluorescent lamp will be specifically explained using examples.

[Example 1] 41% by weight of europium-activated strontium pyrophosphate poppy light (Sr2P207:Eu), europium and manganese-activated barium aluminate (string AI, 20,
9: Eu, Mn) 4 base weight%, manganese activated magnesium fluorogermanate (3.8Mg0, 0.9Mg
F2.Ce02:Mn) 1% by weight of each poppy and light material were thoroughly mixed, mixed with a butyl acetate/nitrocellulose binder, and coated on a glass cylinder.

Next, the poppy and light lamps were manufactured by baking, evacuation, filling with mercury and inert gas, and attaching filaments according to the conventional method for manufacturing poppy and light lamps. This poppy, this light lamp,
When lit, visible part mercury discharge wire and poppy/light body emit light,
It appeared to be a white light source with a slight bluish tinge. Figure 3 shows the luminous energy distribution of this poppy and the light body. Using this poppy lamp as a light source, a white standard paper was irradiated with light, and the reflected light was detected through the R, G, and B band filters described above.

The resulting photocurrent ratio is (IG/IR)=88.4%, (
IB no IR) = 85.2%, and the light receiving efficiency is B =
13.2%, R G = 6.7%, R R = 5.7%. It is clear that the imbalance between each current value is significantly improved compared to when an incandescent lamp is used as a light source. In addition, the light reception efficiency is about 6" tones compared to B band, G
Approximately 40 times that of the band' and approximately 1.3 times that of the R band.
It has been improved twice. The portions of the poppy, the light emission energy distribution of the light lamp, and the portions of the light body involved in light emission did not substantially change even at an outer wall temperature of 100°C. However, because the output ratio of the visible mercury discharge line (43 nodes m, 547 nm) changes somewhat, lo/IR and IB/IR change somewhat, but the variation is less than 10% between 20qo and 10000. there were. On the other hand, in conventional incandescent light bulbs, the visible light emission energy distribution shifts due to slight variations in input voltage, and this appears as large variations in IG/IR and IB/IR. The phosphor is not limited to the above examples, but generally includes europium-activated strontium pyrophosphate, europium-activated strontium/magnesium pyrophosphate, europium-activated strontium orthophosphate, and tin-activated strontium pyrophosphate. and at least one of manganese-activated magnesium gallate, manganese-activated zinc walnate, europium and manganese-activated barium aluminate, antimony and manganese-activated calcium halophosphate, manganese-activated magnesium fluorogermanate, and iron. It may be a mixture of at least one type of activated lithium metaaluminate.

The light source is a fluorescent lamp made by combining various types of poppies and light bodies, and it is irradiated onto a white standard paper, and the reflected light is
, obtained when detected through a B-band filter (
The measured values of IB/IR), (IG/IR), RiB, Katana G, and RiR are shown in Table 1.

Further, the emission energy distribution of the poppy and light lamps of each example in Table 1 is shown in FIGS. 4 to 8. Table 1 There are many possible combinations of poppies and light bodies other than those shown in Table 1, but as mentioned above, (IB/IR), (lc
/IR) that are far apart from each other by more than 100%, the object of the present invention cannot be achieved.

That is, the unbalance of current values in each band when an incandescent lamp is used must be improved. (I
If the values of B/IR) and (IG/IR) are less than 10%, the effect will be smaller than when using an incandescent lamp. Similarly 900
% or more, unbalance in the opposite direction will occur, making it unsuitable. Furthermore, there is no point in improving unless the light receiving efficiency is also improved compared to when using an incandescent lamp. The conversion efficiency of the light source from electrical energy to light is about 4 times that of an incandescent lamp or a light lamp, so the light reception efficiency of the three bands combined for a light source is 2.
When it is 0% or more, the efficiency of light reception output from electrical input becomes higher than that of a device using an incandescent lamp as a light source. More preferably, in order to avoid imbalance in signal output between each band, the amount of light transmitted through the filter of each band is
It is desirable that the spectral sensitivity be proportional to the reciprocal of the spectral sensitivity. For these reasons, it is necessary that the light receiving efficiency is 3% or more. In addition, the spectral transmittance curve of the filter can be changed depending on the combination of filters, but in order to separate blue, green, and red as a color separation device, it is necessary to It is clear that a band-transmissive filter that transmits only red to near-infrared light from 440 m to 58 m, green from 440 to 58 m, and blue light from 360 to 52 m is more convenient for improving separation performance. .

The detector may be of any type as long as it has a photoelectric conversion chamber, but silicon photodiodes, silicon photodiode arrays, and CCDs are preferable when particularly fast time response is required.

As detailed above, the disadvantages of conventional color separation detection devices that use an incandescent lamp as a light source and combine color separation filters and detectors are that This can be greatly improved by using a lamp as a light source.

Furthermore, the drawbacks of incandescent lamps, such as their short lifespan and large amount of heat, can be overcome by replacing them with light lamps.

[Brief explanation of the drawing]

Figure 1 shows the spectral transmittance curve of a filter used in a conventional photolysis detection device, the spectral sensitivity of a silicon photodiode, and the emission energy distribution of an incandescent lamp.
The figure shows the configuration of a color-separated light detection device according to an embodiment of the present invention, and FIGS. 3 to 8 show the luminous energy distributions of poppies and light lamps of Embodiments 1 to 6 used in the device of the present invention, respectively. It is a diagram. 25... Conveyor belt, 26... Rotating roller, 27...
...Paper-like object, 29...Light source for illumination, 30...
- Condensing lens, 35... Light receiver, 36... Signal processing device. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8

Claims (1)

[Scope of Claims] 1. A fluorescent lamp light source that irradiates a color detection target object, and light in different predetermined wavelength ranges among the light reflected or transmitted from the color detection target object by this fluorescent lamp light source. The fluorescent lamp light source is equipped with a plurality of color separation filters for transmitting and extracting the light, and a photodetector for converting the light transmitted through the color separation filters into electrical signals, and the fluorescent lamp light source is configured such that the amount of light transmitted through each of the color separation filters is A color separation photodetection device characterized in that the light emission energy distribution is 3% or more of the total light emission amount, and the ratio of the output of the photodetector corresponding to each color separation filter is 10% to 90%. 2. The fluorescent lamp light source contains at least one of europium-activated strontium pyrophosphate, europium-activated strontium/magnesium pyrophosphate, europium-activated strontium orthophosphate, tin-activated strontium pyrophosphate, and manganese-activated gallium acid. magnesium,
At least one of manganese-activated zinc silicate, europium and manganese-activated barium aluminate, antimony and manganese-activated calcium halophosphate, manganese-activated magnesium fluorogermanate, and iron-activated lithium metaaluminate. 2. A color-separated light detection device according to claim 1, wherein the device is a fluorescent lamp tube whose tube wall is coated with a phosphor made of a mixture of two types of phosphors. 3. The color separation photodetection device according to claim 1, wherein the photodetector has the spectral sensitivity of a silicon photodiode.