JPH02238676A - Color sensor - Google Patents

Abstract

PURPOSE:To detect color of light with one element using no color filter by constructing a color sensor from a laminated member, consisting of a P-type layer of an amorphous semiconductor, an I-type layer of nearly I-type to which trace quantity of impurity is added, and an N-type layer, and a voltage source for applying various voltages to this laminated member. CONSTITUTION:A laminated member, in which a light transmitting electrode 2, consisting of a light transmitting conductive oxide such as ITO, SnO2 or a metal film such as a platinum film, a P-type a-SiC:H layer 3, a nearly I-type a-SiC:H layer 4 to which B is added, an N-type a-SiC:H layer 5, and a rear surface electrode 6 are laminated in this order, is formed on a light transmitting substrate 1 consisting of glass or light transmitting plastic, etc., and a voltage source 7, for applying various voltages between the light transmitting electrode 2 and the rear surface electrode 6, is provided. Then, various voltages are applied to the sensor to utilize the fact that photosensitivity is different according to the applied voltage, and the color of light is detected based on the output signal. Thus, precise color can be detected by a simple structure.

Description

Detailed Description of the Invention (a) Industrial Application Field The present invention relates to a color sensor for detecting the color of light, such as a white balance sensor. As a sensor, JP-A-58-12
As shown in Japanese Patent No. 5867, there is a device in which color filters of different colors are arranged on the surfaces of a plurality of elements made of a stack of amorphous semiconductors.

(c) Problem to be solved by the invention-1 In the color sensor described above, f of each element that detects each color is:
Since each position is different, if the incident light has uneven intensity or color, accurate color detection will not be possible. Also,
Because of the structure in which a plurality of elements are arranged, the size of the apparatus becomes large, and the manufacturing process becomes more complicated due to alignment of each element and color filter, etc.

The present invention provides a color sensor that has a simple structure and can accurately detect colors.

<2) Means for Solving the Problems The color sensor of the present invention comprises a laminate consisting of a P-type layer of an amorphous semiconductor, an approximately I-type layer to which a trace amount of impurity is added, and an N-type layer, and this laminate. and a power source that applies various voltages to the device.

(Honkomeki's color sensor utilizes the fact that the light sensitivity varies depending on the magnitude of the voltage applied to it. Various voltages are applied to the sensor, and the output signal is used to determine the light intensity. Detect colors.

f) Embodiment FIG. 1 is a diagram showing one embodiment of the present invention,
On a transparent substrate 1 such as glass or transparent plastic,
To. Transparent electrode 2, such as a transparent conductive oxide such as SnO2, or a metal thin film such as a platinum thin film with a thickness of 50 or less, thickness 1
50 P-type a-SiC:H layer: 3. 0. 3p
Thickness with addition of pm of B・1υ00 people approximately type I a
-S i: H layer 4, thickness 40 (') N-type a
-S i: A laminate in which the H layer 5 and the back electrode 6 are laminated in this order, and a voltage source 7 that can apply various voltages is provided between the transparent electrode 2 and the back electrode 6. It is.

In this configuration, -5V is applied between the transparent electrode 2 and the back electrode 6 from the voltage source, respectively. When voltages of O and 0.5 were applied, the photosensitivity of the laminate varied with the applied voltage, as shown in FIG. That is, the change in short wavelength photosensitivity such as 400 to 50 (l nm) due to applied voltage is large, and on the contrary, the change in long wavelength photosensitivity such as 600 to 70 f) nm due to applied voltage is small.

Therefore, when a pulsed voltage varying between 0.5V and -5V is applied from the voltage source 7 between the transparent electrode 2 and the back electrode ( ) as shown in FIG. 3(a), blue light is emitted. If so, the current changes greatly as shown by the broken line in Figure (b), and if the light is red, the current does not change much as shown by the dashed line in Figure (}+). It is obtained from between the translucent electrode 2 and the back electrode 6. Therefore, the color of the light can be detected by detecting the state of change in the current obtained from between the translucent electrode 2 and the back electrode 6. becomes.

In this way, the wavelength sensitivity of light that differs depending on the applied voltage is obtained by adding a small amount of impurity (in this case, B) to the a-Si:H layer 1, which creates a '& field in the layer 4. This is due to having an intensity distribution. That is, as shown in Figure 1,
The electric field distribution in the a-Si゜I-1 layer 4 is P-type a-S
iC: weakest on the H layer 3 side, \-type a-S'+
: Since the slope gradually becomes stronger toward the H layer 5 side, when the voltage applied between the transparent electrode 2 and the back electrode 6 is a reverse bias (-5 to '), the electric field distribution is a - S i:
Since it is deep in the entire H layer 1, a −S iIH
A current that exposes all the light absorbed in the layer 4 is taken out, but the voltage applied between the transparent electrode 2 and the hidden electrode 6 is f)
V or forward bias (05X'), the light incident side,
That is, since the electric field strength on the transparent electrode 2 side becomes weaker, the current exposed to the short wavelength light absorbed in this part is not extracted,
Only the current based on the long wavelength light absorbed in the portion close to the back electrode 6 side is extracted.

As a result of the above results, a current having characteristics as shown in FIG. 3(b) is extracted.

By the way, the impurity added to the approximately I-type a-Si:H layer 4 is not limited to the above-mentioned B, but may also be a group III element.
Of course, it may be a V group element such as P. When a group V element is added, the photosensitivity of the laminate is 4 (JO ~ 5 (lon m
The change in short-wavelength photosensitivity due to applied voltage is small;
On the other hand, the change in photosensitivity for long wavelengths such as 600 to 700 nm due to applied voltage becomes large, which is the opposite of the embodiment described above.

Note that the characteristics shown in the figure are specifically obtained when 1 ppm of P is added to the a-SiIH layer 4.

Incidentally, the electric field strength distribution as described in L is approximately type I aS i:H
O in layer 4. It is obtained by adding impurities at a concentration of 1 ppm to 10 ppm.

In addition, -1 P-type a-Si:H layer 3 in the first embodiment
and the X-type a-Si:H layer 5, the N-type a-Si:
It may be an H layer 3 and a P-type a-S i:H layer 5.

In this case, the photosensitivity characteristics similar to those shown in FIG. 2 and FIG. can get.

Furthermore, the light may be incident from the side opposite to the substrate 1, and in that case, the order of lamination of the laminate may be reversed to the above-mentioned case.

g) Effects of the Invention According to the color sensor of the present invention, a laminate consisting of a P plastic layer made of a non-quality semiconductor, a 1-type layer of approximately I type to which a trace amount of impurity has been added, and an N-type layer; Since it consists of a voltage source that applies various voltages, it is possible to detect the color of light with a single element and without using a color filter, so there is no error due to light intensity or color unevenness. In addition to being able to detect colors without color, the element structure is simple and can be easily manufactured.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a characteristic diagram showing the photosensitivity characteristics of this embodiment, and FIG. 3(a). FIG. 4 is a characteristic diagram showing the electric field intensity distribution of approximately the I layer, and FIG. 5 is a characteristic diagram showing the photosensitivity characteristics of another example.

Claims (3)

[Claims] (1) It consists of a laminate consisting of a P-type layer of an amorphous semiconductor, an approximately I-type layer doped with a small amount of impurity, and an N-type layer, and a voltage source that applies various voltages to this laminate. Characteristic color sensor. (2) The color sensor according to item 1, wherein the impurity is a group III element or a group V element. (3) The concentration of the above impurity added is 0.1 ppm to 10 p
2. The color sensor according to claim 1 or 2, wherein the color sensor is pm.