JPH0477471B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color sensor using an amorphous semiconductor as a photoactive layer.

Color sensors using single crystal silicon for the photoactive layer are already known. Its basic configuration is the first
As shown in the figure, a plurality of photodiode regions 2, 3, and 4 are provided on the surface of a single-crystal silicon substrate 1, and different color filters, such as a red filter 5, a green filter 6, and a blue filter 7, are arranged on each of these regions. , furthermore there is an infrared cut filter 8.
In such a sensor, when visible light enters the substrate 1 through each filter, it is sent to the diode region 2 if it is red, and to the diode region 3 if it is green, depending on the color of the incident visible light. , and if it is blue, signals are output to the diode region 4, respectively.

The photosensitivity characteristic of single crystal silicon itself exhibits a peak in the infrared region, as shown by curve A in FIG. On the other hand, although the red filter 5 exhibits a transmittance peak in the red band, the spread of its band characteristics is generally attenuated, but extends into the infrared region.
Therefore, when using single crystal silicon for the photoactive layer,
If the photodiode region 2 is simply passed through a red filter, the photodiode region 2 will be strongly sensitive to the incident infrared light, although it is attenuated, depending on the photosensitivity characteristics of the single crystal silicon itself, and accurate color information cannot be detected. The infrared cut filter 8 in the conventional color sensor described above is provided to remove such incident infrared light, and is indispensable.

However, the presence of such an infrared cut filter not only complicates the configuration of the sensor, but also has the disadvantage that the process of superimposing the filter on the silicon substrate during manufacturing tends to damage the fragile silicon substrate. bring.

The present invention has been made in view of the above points, and will be described below with reference to Examples.

FIG. 3 shows a color sensor 10 sensitive to red, green, and blue colors according to this embodiment. This color sensor 10 has a first,
Second and third thin film photosensitive elements 12R, 12G, 1
Contains 2B. Each of these photosensitive elements is attached to one of the substrates 11.
A color filter film unique to each element provided on the main surface,
That is, the red filter film 1 is provided on the first photosensitive element 12R.
3R, a green filter film 1 is provided on the second photosensitive element 12G.
3G, a blue filter film 1 is provided on the third photosensitive element 12B.
It has 3B. As each filter membrane, WRATTEN manufactured by Eastman Kodatsu Co., Ltd.
GELATEN FILTER is suitable, and its No. 25 is the red filter film 13R, and the green filter film 1 is
The product number 3G is No. 58, and the blue filter film 13B is No. 47B, and these are fixed onto the substrate 11 with a transparent resin adhesive such as Canada Balsan.

Each of the first to third photosensitive elements 12R, 12G, and 12B further includes a first electrode film 14, a photoactive layer 15, and a second electrode film 16 provided on the other main surface of the substrate 11.
The photosensitive element is provided with a laminate body, and these laminate bodies are individually opposed to the filter films of the respective photosensitive elements.

The first electrode film 14 is made of a transparent conductive material such as tin oxide or indium/tin oxide, and the second electrode film 1
6 is made of aluminum or the like.

The photoactive layer 15 is made of an amorphous silicon semiconductor with a thickness of about 1 μm, and its details are shown in FIG. To explain this in more detail along with the manufacturing method, the substrate 11 on which only the first electrode 14 of each element 12R, 12G, and 12B has been formed is placed in a reaction chamber, and a glow discharge is performed in an atmosphere containing silane gas or impurity gas. A P-type layer 15a made of amorphous silicon and an I-type layer 1 are provided on the first electrode 14.
5b and an N-type layer 15c are sequentially deposited to form a photoactive layer 1.
5 is formed. The deposition area can be limited to a predetermined portion by using a mask. The formation of an amorphous silicon diode by glow discharge itself is well known as disclosed in Japanese Patent Publication No. 53-37718.

Each photosensitive element 12R, 12G, 12B is arranged in a smaller area than each color filter 13R, 13G, 13B so as to be located inside thereof.

By the way, now each photosensitive element 12R, 12G, 1
If 2B has the same area as each color filter 13R, 13G, 13B, the following problem will occur.

That is, since the transparent substrate 10 exists between each photosensitive element 12R, 12G, 12B and each color filter 13R, 13G, 13B, for example, the color filter 13R is irradiated obliquely near the boundary with the color filter 13G. The resulting light is incident on the photosensitive element 12G facing the color filter 13G, which causes so-called crosstalk. Therefore, the photosensitive element 12G receives not only the light that has passed through the color filter 13G, but also the light that has passed through the color filter 13G.
Since the light transmitted through the color filter 13R is also detected, accurate signals cannot be obtained.

In contrast, in the present invention, each photosensitive element 12R, 1
2G, 12B are the respective color filters 13R, 13G,
For example, even if light is obliquely irradiated near the boundary between the color filter 13R and the color filter 13G, the photosensitive element 12G has a smaller area than the color filter 13B and is located inside the color filter 13B. This element 12
It will not be incident on G. Therefore, accurate color detection can be obtained.

In the color sensor 10, each color filter 1
Due to the presence of 3R, 13G, and 13B, if the light incident from the filter side contains red color, it enters the first photosensitive element 12R via the red filter 13R and the substrate 11, and enters the first photosensitive element 12R mainly into I-type light in the element. Free carriers are generated in layer 15b. These free carriers are collected at the first and second electrodes 14, 16, and a voltage is generated between the electrodes. Similarly, when the incident light contains green color or blue color, a voltage is generated between the first and second electrodes 14 and 16 in the second photosensitive element 12G and the third photosensitive element 12B, respectively. Therefore, by detecting these voltages, the color of the incident light can be detected.

As shown by curve B in FIG. 2, the photosensitivity characteristics of an amorphous semiconductor have a band that is almost within the visible light region. Therefore, in the color sensor 10 of this embodiment, even if infrared light enters through the red filter 13R, it is hardly detected, and therefore accurate color information can be detected without using the infrared cut filter that was conventionally required. can do. Furthermore, in the color sensor 10 of this embodiment, each color filter 13R, 13G, 13B is attached to the surface of the substrate opposite to the photoactive layer 15, so that the photoactive layer 15 is not damaged when attached. Nor.

The embodiment of the present invention is such an excellent color sensor 10.
The purpose of this invention is to further improve the accuracy of color detection. In other words, although the photosensitivity characteristics of amorphous semiconductors have a band within the visible light range as described in Figure 2, it is not flat and has a range of approximately
It has a peak around 550nm. Further, the transmittance of each color filter film 13R, 13G, and 13B is not the same as shown by curves 17R, 17G, and 17B in FIG. 5, and in particular, that of the red filter film 13R is the highest. Therefore, the first to third photosensitive elements 12R, 1
The photosensitivity of 2G and 12B is also different, and even if the incident intensity is the same, different detection outputs will be generated.

The most significant feature of the embodiment of the present invention is that the light-receiving area of each element 12R, 12G, and 12B differs according to the photosensitivity of each element, and the light-receiving area of the element with the highest photosensitivity is the smallest. ing. More specifically, the ratio of the light-receiving areas of the first, second, and third photosensitive elements 12R, 12G, and 12B is set at a ratio of approximately 2:3:5, thereby increasing the photosensitivity of each element. (Output voltage/incident light intensity) is almost the same, and color detection is performed with good accuracy.

In the above embodiment, each element 12R, 12G, 12
The photoactive layer 15 in B was a photovoltaic type including a PIN junction, but it can also be changed to a photoconductive type by forming only I-type amorphous silicon with a thickness of about 5 μm, for example. . In this case, as shown in FIG. 6, on the surface of the photoactive layer 15, a pair of electrodes 16a,
16b may be applied.

In the above embodiment, both the photoactive layer 15 and the first and second electrode films 14 and 16 are separated for each element.

In particular, the photoactive layer 15 is patterned to separate each photosensitive element. This is the same reason as the reason why accurate color detection was achieved by arranging each photosensitive element 12R, 12G, 12B in a smaller area than each color filter 13R, 13G, 13B so as to be located inside it. This is due to

That is, if the photoactive layer 15 is formed so as to extend between each photosensitive element, the photoactive layer 15 between the elements will be irradiated with light incident obliquely from near the boundaries of each color filter, which may cause errors. This is because the ivy color information will be included.

Further, instead of the amorphous silicon used for the photoactive layer 15 in the above embodiment, other materials such as amorphous silicon carbide may be used, and even 1
It is also possible to mix polycrystals or microcrystals into the part.

Further, the number of photosensitive elements can be increased or decreased as necessary.

As is clear from the above description, according to the present invention, it is possible to realize a color sensor that eliminates the need for an infrared cut filter and allows easy attachment of other color filters.
Moreover, the color detection accuracy can be improved.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the conventional example, Fig. 2 is a photosensitive characteristic diagram, Fig. 3A is a plan view of the embodiment of the present invention, Fig. 3B is a sectional view taken along line BB, and Fig. 3C is the same. 4 is an enlarged sectional view of a main part, FIG. 5 is a transmission characteristic diagram, and FIG. 6 is a sectional view of a main part of another embodiment. DESCRIPTION OF SYMBOLS 11...Substrate, 12A, 12B, 12C...1st, 2nd, 3rd photosensitive element, 15... Photoactive layer.

Claims (1)

[Claims] 1 includes a plurality of thin-film photosensitive elements provided on a light-transmitting substrate, each of which includes a color filter film unique to each element provided on one main surface of the substrate, and a color filter film unique to each element provided on one main surface of the substrate; Each of the elements comprises a photoactive layer mainly made of an amorphous semiconductor having photosensitivity characteristics in the visible light region provided on the surface, and a laminate of electrode films individually facing each of the color filter films, and each of the above elements includes: The light-receiving area is patterned to be smaller than the color filter film, and the light-receiving area is arranged inwardly from the color filter film, and the light-receiving area is different depending on the photosensitivity of each element. A color sensor that is characterized by its color.