JPH0433147B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a color sensor for three-color discrimination of blue, green, and red.

(Prior art) Conventional color sensors generally separate light from an object to be recognized into three color bands of blue, green, and red using a prism or optical filter, and three light receiving sensors are used for each of these three color bands. It was identified as a configuration that corresponds to

In recent years, two-dimensional light receiving sensors such as so-called CCD sensors have been put into practical use, and these include blue, green,
Attempts have been made to construct a two-dimensional color sensor by combining color filter arrays with integrated red pigments.

Such a color sensor combines a color filter that separates target object light and a light-receiving sensor, but the process of creating the color filter is particularly complicated, and the optical connection between the light-receiving sensor and the color filter is extremely complicated. The bonding has drawbacks such as hindering mass production, which requires extremely high precision, and further increasing costs.

(Purpose of the Invention) As a result of numerous tests and studies aimed at solving these drawbacks, the present inventors have discovered that the three primary color filter functions of blue, green, and red can be achieved by using an organic semiconductor using a specific pigment that constitutes the light receiving diode. This can be realized by a laminated combination of thin films, and the above-mentioned cost problem can be solved by eliminating the need for coupling with a color filter by using such a light receiving diode, and it is possible to provide a color sensor that is inexpensive and easy to integrate. This is what led us to discover this and arrive at this invention.

(Structure of the Invention) That is, the present invention provides a heteropn diode or a semiconductor formed by an organic semiconductor thin film having different absorption spectra in the visible region and a semiconductor thin film or metal thin film having a different electrical conductivity type from the organic semiconductor. Blue color with Tsutoki diodes configured on the same substrate.
A color sensor for detecting three colors of green and red, wherein the organic semiconductor thin film is composed of a stack of a merocyanine pigment for blue, a merocyanine pigment for green, and a stack of a phthalocyanine pigment for red and the above pigment. This is a color sensor.

First, it will be explained that filter functions of the three primary colors, that is, blue, green, and red, can be imparted by selecting a semiconductor thin film using dyes (or pigments) and structuring them in layers, which will be described in detail later.

Figure 1 shows the light absorption spectrum in the visible region of organic semiconductor thin films made of merocyanine dyes and phthalocyanine pigments represented by the following formulas (1) to (3) used in the present invention. is the aforementioned merocyanine dye, 2 is the same dye, and 3 is specifically that of magnesium phthalocyanine.

(In the formula, M is Mg, Al, Ga, In, X is Cl, Br, I
) It is known that when these organic semiconductors form a shot barrier diode with a metal, the photosensitivity spectrum matches the light absorption spectrum.

It is clear from FIG. 1 that the merocyanine dye has blue light absorption characteristics, and the dye film alone functions as a blue filter.

Next, the merocyanine dye exhibits light absorption characteristics in both blue and green color bands, but when the dye 21 and the dye 22 are layered and irradiated with white light 20 as shown in FIG. 2a, the filter of the dye 21 As a result of this action, the light absorption spectrum of the dye 22 is shaped into a light absorption spectrum of only a green band, as shown in FIG. 2b.

Furthermore, it is generally known that phthalocyanine-based organic semiconductors exhibit a wide optical absorption spectrum over the green, red, and near-infrared bands, and the optical absorption spectrum of the above-mentioned magnesium phthalocyanine, as an example, is shown in Figure 1.3. ing. Therefore, when the merocyanine dye 21, dye 22, and magnesium phthalocyanine 33 are laminated in the same manner as shown in FIG. 3b and white light 30 is irradiated, the green band component is removed and the red band and near-infrared component are removed as shown in FIG. 3b. It is shaped into an obi. This near-infrared absorption characteristic can be removed by using a filter that is transparent in the visible region and absorbent in the near-infrared.

As detailed above, the merocyanine dye absorbs blue band light, the stack of the merocyanine dye and the dye absorbs green band light, and the stack of these dyes and magnesium phthalocyanine absorbs red band light, respectively. It is clear that color discrimination is possible by creating a layered structure of organic semiconductors.

(Embodiments) Next, the present invention will be specifically explained by embodiments.

FIG. 4 is a cross-sectional view showing the structure of a color sensor according to the present invention, in which a blue photosensitive element 401, a green photosensitive element 402, and a red photosensitive element 403, which will be described later, are provided on a transparent substrate 47 on which a transparent electrode 46 is formed, respectively. It is formed using a thin film formation method using a known vapor deposition method, a photolithography method, a selective etching method, and the like. In the figure, 21 is a pigment, 22 is a pigment, and 3
3 is a phthalocyanine, 44 is a ZnO n-type semiconductor (or Al), 45 is an electrode, 40 is the incident direction of the object light to be recognized, and 48 is a filter that is transparent in the visible region and absorbs near infrared rays. As an example of the filter, a commercially available colored glass filter having light transmission characteristics as shown in FIG. 5 can be used.

The light receiving mechanism of the present invention will be explained by taking the above-mentioned red photosensitive element 403 as an example. The merocyanine dye 21, the dye 22, and the phthalocyanine layer 33 are all p-type semiconductors, and 44 is an n-type semiconductor made of ZnO. The ZnO semiconductor may be a metal such as Al, but as is known, it is the metal that contributes to the photocurrent.
These are carriers of holes and electrons generated by light absorption near the pn junction or shot barrier.

Therefore, when the 44 is a ZnO semiconductor, since ZnO is transparent in the visible region, it is the carrier generated on the phthalocyanine layer 33 side that contributes to the photocurrent, and the film thickness of the phthalocyanine 43 is If the width of the depletion layer is selected to be approximately the same as the depletion layer width of the region, carriers generated within the dye 22 and the dye 42 will hardly contribute to the photocurrent, and the photocurrent wavelength characteristics will match the light absorption amount characteristics within the phthalocyanine.
Therefore, dye 21 and dye 22 act only as a filter.

Furthermore, when forming a shot barrier using Al or the like as the layer shown in 44 above, it is well known that carriers generated within the depletion layer of the organic semiconductor 33 contribute to the photocurrent. The alternating current wavelength characteristics match the light absorption (optical density) characteristics within the phthalocyanine layer 33.

The blue photosensitive element 401 and the green photosensitive element 4
It is similarly clear that the photocurrent wavelength characteristics of the dyes 02 and 22 correspond to the light absorption (optical density) within the dyes 21 and 22.

From the above, the absorption characteristics of the color sensor according to this embodiment are as shown in FIG.
1 is a blue photosensitive element, 62 is a green photosensitive element, and 63
represent the respective sensitivity characteristics of the red light-sensitive element.

By configuring as in this embodiment, it is possible to configure each photosensitive element for identifying the three primary colors on the same substrate without using an optical filter for separating the three primary colors of blue, green, and red. .

FIG. 7 shows another embodiment, in which the blue, green, and red light-receiving elements described above are arranged two-dimensionally on the same substrate 707 as a set.

Since such a color sensor is constructed of a vapor-deposited film, it has the advantage that a large-area color sensor can be obtained at low cost.

(Effects of the Invention) As described above, the present invention provides an optical system for three primary colors by selecting and using organic semiconductor thin films having the above characteristics constituting a pn junction or a shotgun barrier diode, and by forming a laminated structure combining them. The object light can be equipped with a target filter function, and it is possible to detect the color of the object light without using a conventional color filter. Moreover, according to the configuration of the present invention, it is formed of a vapor-deposited film. It has extremely high industrial effects, such as solving manufacturing problems and making it possible to obtain particularly large-area, highly integrated line or surface sensors at low cost.

[Brief explanation of drawings]

Figure 1 is a diagram of the light absorption characteristics of merocyanine dye and the same dye as well as magnesium phthalocyanine.
Figure 2a is a cross-sectional view of the laminated structure of the same dye and dye, Figure 2b is a light absorption characteristic diagram of the same combination, Figure 3a is a cross-sectional view of the laminated structure of the same dye and magnesium phthalocyanine thin film, Figure 3b 4 is a structural sectional view of an embodiment of the present invention, FIG. 5 is a transmittance characteristic diagram of a commercially available near-infrared cut filter, and FIG. 6 is a photosensitivity characteristic of the color filter of the present invention. 7 are plan views showing other embodiments in which color sensors are two-dimensionally arranged according to the present invention. 21...merocyanine pigment, 22...same pigment, 33...phthalocyanine pigment, 20,30,
40...light, 44...ZnO n-type semiconductor, 45...
...Electrode, 47,707...Transparent substrate, 401,4
02,403...Blue, green, and red photosensitive elements.

Claims (1)

[Claims] 1 A heteropn diode or a Schottky diode formed by an organic semiconductor thin film having different absorption spectra in the visible region and a semiconductor thin film or metal thin film having a different electrical conductivity type from the organic semiconductor is constructed on the same substrate. A color sensor for detecting three colors of blue, green, and red, wherein the organic semiconductor thin film includes: blue: merocyanine dye;
Green: merocyanine pigment and lamination; red: phthalocyanine pigment and the above pigment;
A color sensor composed of laminated layers.