JPH0262922A - Optical sensor - Google Patents

Abstract

PURPOSE:To output signals equal in sensitivity from respective photoconductive areas with simple structure by setting a conductive film to specific area so that the quantities of light which are incident through color filters of red, green, and blue are corrected among respective photoconductive areas. CONSTITUTION:The photoconductive areas R, G, and B are formed on a transparent substrate 1 corresponding to the color filters 5R, 5G, and 5B. In the area R (G and B), conductive films 4Ra and 4Rb are formed on an amorphous semiconductor layer 3 of P-I-N junction in specific shapes at a specific interval. When the conductive films 4Ra and 4Rb are applied with bias voltages and irradiated with light through the filter 5R from the side of the substrate 1, a current between the conductive films 4Ra and 4Rb varies and they operates as an optical sensor. At such a time, the conductive films 4Ra and 4Ba are made about 4.7 and 2.5 times as large as the film 4Ga so as to equalize the product of the intensity of spectral sensitivity, the light transmissivity of a color filter, and the area of the conductive film to that of the area G, thereby equalizing the relative intensity of a light current among the areas R, G, and B.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical sensor having color filters of different colors.

[Background of the invention]

The present inventor has discovered that on a transparent substrate on which a transparent conductive film has been previously deposited,
We have proposed an optical sensor constructed by forming a plurality of laminates consisting of P-1-N bonded amorphous semiconductor layers and metal electrodes (Japanese Patent Application No. 62-331620). Figure 5(a),
(b) is a sectional view and a plan view showing the structure of the optical sensor.

The transparent substrate 51 is made of glass, translucent ceramic, or the like, and a transparent conductive film 52 is adhered to one main surface of the transparent substrate 51 .

The transparent conductive film 52 is formed of a metal oxide film such as tin oxide, indium oxide, indium/tin oxide, etc.
(Both are formed so that they are a common film to the laminates x and y.)

The amorphous semiconductor layer 53 has at least metal electrodes 54x, 5
A P-I-N junction is formed in the X+7 portion of the stacked body where 4y is formed.

The metal electrodes 54x, 54y are formed on the amorphous semiconductor layer 53 in a rectangular shape and spaced apart from each other by a predetermined distance. A constant bias voltage is applied between the metal electrodes 54x and 54y from an external circuit (not shown).

The optical sensor having the above-mentioned structure has a structure in which diodes, which are P-1-N junction laminated bodies x and y, are tied together.

Now, if a + bias voltage is applied to the metal electrode 54x of the laminate X and a - bias voltage is applied to the metal electrode 54y of the laminate y, the laminate
A reverse bias is applied to the y side of the stack, and a forward bias is applied to the y side of the stack.

The current due to the bias application is applied to the metal electrode 54x of the laminate X.
- 8 layers of amorphous semiconductor layer 53N-I layer 531-2 layer 53
P--transparent conductive film 52--two layers of amorphous semiconductor layer 53P--I layer 53I--NFt 53N--metal electrode 54y of laminate y. That is, the resistance between the metal electrodes 54x and 54y is the sum of the reverse resistance of the laminate X and the forward resistance of the laminate y,
In the bright state, a photovoltaic force is generated in the laminated body X and the laminated body y, but since they are at opposite potentials, they cancel each other out. Since a bias voltage of - is applied, a reverse photocurrent (bright current) is generated in the stack X, and a change in the reverse photocurrent of the stack
Light current) as Hataraku. Therefore, the resistance of the entire optical sensor appears to decrease due to light irradiation, and it functions like a photoconductive sensor. This makes the illuminance-resistance value characteristic linear.

Recently, there has been an increasing demand for optical sensors that can detect not only the intensity of incident light but also the spectral intensity of wavelengths of light, that is, color sensors.

FIG. 6 is a sectional view of a conventional color sensor.

In the conventional color sensor, a pair of opposing electrodes 65.65'' corresponding to each pixel are formed on the support 62 so as to sandwich a photoconductive layer 63 made of an amorphous semiconductor layer. , R (red), G (green), and B (blue) color filters 64 are deposited on the photoconductive layer 63 (see Japanese Patent Laid-Open No. 141956/1983).

Then, when light is irradiated from the light-receiving surface side of the sensor,
A photocurrent corresponding to the intensity of light of a predetermined wavelength is output to the photoconductive layer 63 through the color filter 64 .

However, general light irradiated from the light-receiving surface side contains light of all wavelengths, and according to the spectral sensitivity of the amorphous semiconductor layer, there is a peak around 550 nm, so color filters with the same sensitivity If you use , only green will have high sensitivity. For this reason, in conventional color sensors, the spectral sensitivity distribution and sensitivity of color filters are arbitrarily controlled to control the amount of light incident on the amorphous semiconductor layer through each filter.

That is, in order to control the spectral sensitivity distribution and sensitivity of the color filter, complicated selections such as filter component materials and optical characteristics have been made.

Furthermore, since each color filter corresponds one-to-one to a photoconductive region, the number of terminals and conductors from which output signals from the photoconductive regions are derived increases, making the detection circuitry for processing the output signals complex.

[Object of the present invention]

The present invention has been devised in view of the background of the above-mentioned optical sensor, and its purpose is to provide a diode-tied structure which has an extremely simple structure and can output an output signal of equal sensitivity from the photoconductive region corresponding to each color filter. It provides an optical sensor.

[Specific means for solving the problem] According to the present invention, in order to achieve the above-mentioned object, a transparent conductive film, a P-I-N bonded amorphous semiconductor layer, and a P-I-N bonded amorphous semiconductor layer are provided on a transparent substrate. In an optical sensor in which a plurality of photoconductive regions made of two conductive films for applying a bias voltage are formed, and different color filters are formed in the photoconductive regions, P -I-N bonded amorphous semiconductor layers are arranged in opposite directions, and one of the conductive films is set to a predetermined area between each photoconductive region so as to correct the amount of light incident through a color filter. provided.

〔Example〕

Hereinafter, the optical sensor of the present invention will be explained in detail based on the drawings.

FIG. 1(a) is a plan view showing the structure of the optical sensor according to the present invention, and FIG. 1(b) is a cross-sectional structural view taken along line X--X of FIG. 1(a).

The optical sensor of the present invention has three photoconductive conductors formed on a transparent substrate 1 to correspond to color filters 5R, 5C, and 5B of different colors, for example, red (R), green (G), and blue (B). Regions R, G, and B are formed.

One photoconductive region R that constitutes photoconductive regions R, G, and B
, a transparent conductive film 2R is deposited on a color filter 5R on a transparent substrate l, and a P-I film is further applied on the transparent conductive film 2R.
-N junction amorphous semiconductor layer 3 is deposited, and P
Conductive films 4Ra and 4Rb to which a bias voltage is applied are formed on the -IN junction amorphous semiconductor layer 3.

The other photoconductive regions G and B have similar structures, but
The amorphous semiconductor layer 3 deposited on the transparent conductive films 2G and 2B is formed as a film common to each of the photoconductive regions R, G, and B.

The transparent substrate 1 is made of glass, translucent ceramic, etc.
Color filters 5R and 5G are provided on the entire surface of the transparent substrate 1.
, 5B are the respective photoconductive regions R,G.

They are applied independently in correspondence to B.

The color filters 5R, 5G, and 5B are made by coloring organic resin such as gelatin or polyimide resin on a transparent substrate 1 with a predetermined colorant. For example, Acid Red 25 is used for red.
7. Solvent Yellow 77 and Acid Blue are used for green, and Solvent Blue 42 is used for blue. In addition, those using pigments and interference filters can also be used.

Incidentally, after the organic resin is colored with a predetermined colorant, the whole may be covered with a protective film (not shown) such as silicon oxide or silicon nitride in order to improve heat resistance and prevent the colorant from flowing out.

The transparent conductive films 2R, 2G, and 2B are formed of metal oxide films such as tin oxide, indium oxide, and indium tin oxide, and each color filter 5R is formed on the entire surface of the transparent substrate 1.
, 5G, and 5B, respectively. Specifically, after attaching a mask on the entire surface of the transparent substrate 1, the above-mentioned metal oxide film is deposited, or after depositing a metal oxide film on the entire surface of the insulating substrate 1, a resist film is applied. It is formed into a predetermined shape by machining and cutting.

The amorphous semiconductor layer 3 is formed continuously in each of the photoconductive regions R, G, and B, and connects the first conductivity type, the second conductivity type, and the third conductivity type from the substrate side, that is, P- An I-N junction is formed. Specifically, the amorphous semiconductor layer 3 is made of amorphous silicon deposited by a plasma CVD method or a photo CVD method in which silicon compound gas such as silane or disilane is decomposed by glow discharge. IJ'5 is formed using a reactive gas containing silane gas mixed with a P-type doping gas such as diporane, and IJ'5 is formed using a reactive gas containing silane gas mixed with an N-type doping gas such as phosphine.NF4 is formed using a reactive gas containing silane gas mixed with an N-type doping gas such as phosphine.

Conductive film 4Ra, 4Ga, 4Ba, 4Rb, 4Gb, 4B
b are formed on the amorphous semiconductor layer 3 in a predetermined shape and at predetermined intervals. That is, conductive films 4Ra and 4Rb are formed on the amorphous semiconductor layer 3 corresponding to the transparent conductive and conductive film 2R of the photoconductive region R.
are formed, conductive films 4Ga and 4Gb are formed on the amorphous semiconductor layer 3 corresponding to the transparent conductive IPA2G of the photoconductive region G, and the amorphous semiconductor layer corresponding to the transparent conductive film 2B of the photoconductive region B is formed. 3, conductive films 4Ba and 4Bb are formed. Specifically, the conductive films 4Ra, 4Ga, 4Ba, 4
For Rb, 4Gb, and 4Bb, a mask is attached on the amorphous semiconductor layer 3, and then a metal such as nickel, aluminum, titanium, or chromium is deposited on the amorphous semiconductor layer 3, or a metal such as nickel, aluminum, titanium, or After depositing a metal film such as chromium, it is formed into a predetermined pattern by resist etching treatment, laser fusing treatment using a YAG laser, or the like.

The optical sensor configured as described above includes each photoconductive region R2G,
Laminate Ra-Rb, Ga-
It has a structure in which GbXBa-Bb diodes are tied together in opposite directions.

The operation will be explained using the photoconductive region R shown in FIG. 1(b).

Isometrically, between the conductive film 4Ra and the conductive film 4Rb,
A resistor R1 of the laminate Ra and a resistor R2 of the laminate Rb are connected in series, and a resistance between the laminates Ra and Rb is connected in parallel to the combined resistance of the resistors R1 and R2. This means that the resistor R3 in the crystalline semiconductor layer 3 is connected.

Now, if a + bias voltage is applied to the conductive film 4Ra of the laminate Ra and a - bias voltage is applied to the conductive film 4Rb of the laminate Rb, the laminate R
A reverse bias is applied to the amorphous semiconductor M 3 Ra on the a side, and a forward bias is applied to the amorphous semiconductor Ff3Rb on the side of the stack.

In the dark state, the resistance between the conductive films 4Ra and 4Rb is the reverse resistance R1 of the laminate Ra and the forward resistance R2 of the laminate Rb.
The current flowing between the conductive films 4Ra and 4Rb is
This corresponds to the resistance (R1+R2). In the bright state in which light is irradiated from the transparent substrate 1 side of the above-mentioned optical sensor through the color filter 5R, photovoltaic force is generated in the laminate Ra and the laminate Rb, but since they are at opposite potentials, they cancel each other out and actually Although no photovoltaic current flows, since a bias voltage is applied to the conductive film 4Ra and - to the conductive film 4Rb,
A reverse photocurrent is generated in the stacked body Ra. In addition, the laminate R
h is a resistor consisting of a forward resistance of a diode.

The current between the two conductive films 4Ra and ARb is vi,
Conductive film 4Ra of carcass Ra - N layer of amorphous semiconductor layer 3a -
The flow flows from layer 1 to layer 2 to transparent conductive film 2 to layer 2 of the amorphous semiconductor layer 3b of the laminate Rb, layer 1, layer N, and conductive film 4Rb.

Here, the resistance in the photoconductive region R appears to be reduced by the light irradiation, and it functions like a photoconductive type sensor. As a result, the illuminance resistance value characteristic becomes linear, and the γ value becomes approximately 1.

That is, the two conductive films 4., 4., 4., 4., 4., 4., 4., 4., 4., 4., 4. The current between Ra and ARb changes and acts as a light sensor.

This also applies to the other photoconductive regions G and B.

Here, since the amorphous silicon used for the above-mentioned amorphous semiconductor layer 3 has an optical forbidden band width of about 1.8 eV, the spectral sensitivity is 700 nm with a peak of 550 nm as shown in FIG.
nm is the limiting wavelength. At this time, blue (B) 450n
m, green (G) 550nm, red (R) 650nm
The intensities of are approximately 50χ, 100χ, and 35z, respectively.

If this is applied to the above-mentioned optical sensor having the same light receiving area, only the bright current output from the green (G) photoconductive region G will protrude. If the bright current output from the green (G) photoconductive region G is 100, then the blue (B) photoconductive region B is about 40, and the red (R) photoconductive region R is about 20.

Therefore, the relative intensity of the bright currents in the photoconductive regions R, G, and B (
It is extremely important to set the area of the stacked body Ras Ga, Ba (actually, the area of the conductive films 4Ra, 4Ga, 4Ba) to a predetermined size so that the sensitivity (sensitivity to light amount) is the same. Become.

Here, as shown in FIG. 1(a), the light guiding glans Jl, G
, B, and the areas of the stacked bodies Ra, Ga, and Ba, which serve as reverse biases, and the areas of the conductive films 4Ra, 4Ga, and 4Ba are different from each other.

As a method of setting the areas of the conductive films 4Ra, 4Ga, and 4Ba, the amount of incident light reaching the amorphous semiconductor layer 3 in each photoconductive region R, G, and B must be made the same. That is, in each photoconductive region, the product of the spectral sensitivity intensity of the amorphous semiconductor layer 3, the light transmittance of the color filter, and the area of the conductive film is made to be the same. For example, in the photoconductive region G, if the conductive film 4Ga is 1, the spectral sensitivity intensity of green (G) 550 nm is 1, and the light transmittance of the color filter 5G is 1, the product is 1.

Regarding the photoconductive region R, the spectral sensitivity intensity of red (R) 650 nm is 0.35 compared to the spectral sensitivity intensity of green (G) 550 nm, and the light transmittance of color filter 5R also depends on the difference in manufacturing method. is 16 for the light transmittance of the color filter 5G. Therefore, the product of the intensity of the spectral sensitivity, the light transmittance of the color filter, and the area of the conductive film is the same as that of the photoconductive region G. In order to do so, conductive film 4R
The area of a should be approximately 4.7.

Similarly, for photoconductive region B, blue (B) 450 nm
The spectral sensitivity intensity of green (G) is 0.5 with respect to the spectral sensitivity intensity of 550 nm, and the light transmittance of color filter 5B is 0.8 with respect to the light transmittance of color filter 5G.
It is. Therefore, in order to make the product of the intensity of spectral sensitivity, the light transmittance of the color filter, and the area of the conductive film the same as the photoconductive region G, the area of the conductive film 4Ba is set to about 2.5
And it is sufficient.

Figure 3 shows the conductive film 4R of the optical sensor shown in Figure 1(a).
a, 4Rb, 4Ga, 4Gb, 4Ba.

4Bb and the amorphous semiconductor layer 3 with only the output terminals exposed and an insulating protective film 6 made of epoxy resin, acrylic resin, etc. formed thereon. FIG.

The optical sensor has a total of six output terminals, two terminals in each photoconductive region.

FIG. 4 is a plan view of an optical sensor according to another embodiment of the present invention.

In this embodiment, the conductive film of the laminated body Rb, Gb, and Bb, which serves as the forward bias for each photoconductive region R, G, and B, is a common film 4b.

As a result, as shown in FIG. 3, it is possible to cover with the insulating protective film 6 and use only four terminals in total, and the configuration of an external circuit (not shown) for controlling the output signal can be extremely simplified.

In the above embodiment, the three RGB photoconductive regions on the transparent substrate were explained as one optical sensor, but it is also possible to form a large number of the three RGB photoconductive regions in an array on the transparent substrate. do not have.

Further, the area of the conductive film is appropriately set depending on the light transmittance of the color filter used in the optical sensor and the spectral sensitivity of the amorphous semiconductor layer.

〔Effect of the invention〕

As described above, the present invention provides a transparent conductive film, a P
-In an optical sensor in which a plurality of photoconductive regions each consisting of an amorphous semiconductor layer with an I-N junction and two conductive films for applying a bias voltage are formed, and different color filters are formed in the photoconductive regions. , one conductive film in which the P-1-N junction amorphous semiconductor layer is in the opposite direction with respect to the bias voltage of the photoconductive region, and the amount of light incident through the color filter between each photoconductive region is controlled. The structural operation of setting a predetermined area in a corrective manner makes it possible to derive a constant sensitivity (relative intensity) of the output signal output from the photoconductive region corresponding to the color filter.

Furthermore, since one photoconductive region has a structure in which a photodiode in the opposite direction and a photodiode in the forward direction are hugged together, even when a high voltage is applied, the amorphous semiconductor layer with the P-I-N junction remains intact. It is not destroyed, and a linear response with good resistance change over a wide range of illuminance changes is obtained, with a T value of about 1.

[Brief explanation of the drawing]

FIG. 1(a) is a plan view showing the structure of the optical sensor of the present invention, and FIG. 1(b) is a sectional view taken along line X--X in FIG. 1(a). FIG. 2 is a characteristic diagram showing the intensity of the spectral sensitivity of the amorphous semiconductor layer. FIG. 3 is a plan view of the non-light receiving surface side showing an advanced structure of the optical sensor of the present invention. FIG. 4 is a plan view showing another embodiment of the present invention. FIGS. 5(a) and 5(b) are a sectional view and a plan view showing the structure of a conventional photodiode combined type optical sensor. FIG. 6 is a sectional view of a conventional color sensor. ■...Transparent substrate 2...Transparent conductive film 3...Amorphous semiconductor layer 4Ra, 4Rb, 4Ga, 4Gb, 4Ba, 4Bb・
-Conductive films 5R, 5G, 5B...color filters R, G
, B...Photoconductive areas a, b...Laminated body

Claims (1)

[Scope of Claims] A plurality of photoconductive regions each consisting of a transparent conductive film, an amorphous semiconductor layer with a P-I-N junction, and two conductive films for applying a bias voltage are formed on a transparent substrate, Furthermore, in a photosensor in which different color filters are formed in the photoconductive region, one of the conductive films in which the amorphous semiconductor layer connected by P-I-N is in the opposite direction with respect to the bias voltage of the photoconductive region, A light sensor characterized in that a predetermined area is set between each photoconductive region so as to correct the amount of light incident through a color filter.