JPH07280585A - Solar sensor - Google Patents

Abstract

PURPOSE:To detect direction of the sun with high precision and reliability. CONSTITUTION:Relating to the sun light incident surfaces of optical detectors 10 and 11, rectangular parts 10b and 11b are provided in succession on one side of the first right-angled triangle parts 10a and 11a. In addition, on one side orthogonal to a slit 13a of a mask plate 13 of the rectangular parts 10b and 11b, the second right-angled triangle parts 10c and 11c which, with one side of rectangular parts 10b and 11b as one side, have an oblique line inclining from one side of the other optical detector side toward the other side with large width are provided in succession, so that desired objective is attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sun sensor used for determining, for example, an attitude angle of an artificial satellite.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 2, in a sun sensor, a pair of photodetectors 1 and 2 having a sunlight incident surface are linearly opposed to each other. The photodetectors 1 and 2 are formed such that the sunlight incident surface thereof is formed by connecting the rectangular portions 1b and 2b to one side of the right triangle portions 1a and 2a, respectively, and the hypotenuses of the right triangle portions 1a and 2a. Are arranged facing each other. Then, on these photodetectors 1, the slits 3a of the slit plate 3 are arranged facing each other at a predetermined interval so as to be substantially orthogonal to the arrangement direction. Further, the output ends of the photodetectors 1 and 2 are respectively connected to the signal processing unit 4 including, for example, an adder, a subtractor and a divider.

In the above structure, when the sunlight is irradiated at a constant angle with respect to the reference axis, the sun image 5 passing through the slit 3a is formed on the photodetectors 1 and 2, and the photodetector 1 is formed. ，
2 generates the A and B output voltages. These A and B outputs are
For example, the sun angle signal C is generated by being guided to the signal processing unit 4 including an adder, a subtractor, a divider, etc. and performing the calculation of C = (A−B) / (A + B). This sun angle signal C does not depend on the value of the non-sensitivity axis (off-axis) angle β (incident angle in the slit direction), but the sensitivity axis (on-axis) angle α (incident angle in the direction substantially orthogonal to the slit). Determined by The portion (linear range) capable of detecting the sun angle signal C determines whether the angle is positive or negative, as shown in FIG.

On the other hand, the sun angle signal C corresponds to a value represented by the formula C = D · tanα (where D is a constant determined by the shape and efficiency of the photodetectors 1 and 2 and the characteristics of the divider). As a result, α is provided as sun angle information in an angular range approximated by tan α. The on-axis (sensitivity axis) region in which sunlight is applied to only one of the pair of photodetectors 1 and 2 is the saturation region of the sun angle signal C.

By the way, in such a sun sensor, a sun presence signal indicating that the sun is in the field of view and the sun angle signal C has no error is generated by the absolute value of the (A + B) output. That is, the (A + B) output has a predetermined characteristic when the sensitivity axis (on-axis) angle is α and the non-sensitivity axis (off-axis) angle is β, and the (A + B) output is higher than the threshold value E. When is large, the sun direction signal is detected by turning on the sun presence signal. This detection signal is guided to, for example, the attitude control system of the artificial satellite and used for detecting the attitude angle of the artificial satellite.

As the photodetectors 1 and 2, photoelectric conversion elements such as solar cells and photodiodes are generally used. However, in the above-mentioned sun sensor, if the sunlight passing through the slit 3a of the mask plate 3 is incident on the rectangular portions 1b and 2b of the photodetectors 1 and 2 and if it is separated from the right triangular portions 1a and 2a, There is a problem in that the acquisition of the solar presence signal becomes unstable because the (A + B) output decreases as the distance increases. According to this, it becomes difficult to acquire a desired sun presence signal depending on the incident position of sunlight in the saturation region, which may lead to erroneous detection.

[0007]

As described above, in the conventional sun sensor, there is a possibility that a desired sun presence signal may not be acquired depending on the incident position of sunlight, which causes a problem of erroneous detection. .

The present invention has been made in view of the above circumstances, and an object thereof is to provide a sun sensor having a simple structure and capable of realizing highly reliable and highly accurate detection.

[0009]

According to the present invention, a sunlight incident surface having a shape in which a rectangular portion is connected to one side of a right triangular portion is formed, and a hypotenuse of the right triangular portion of the sunlight incident surface is formed. It has a pair of photodetectors arranged to face each other, and a slit for transmitting sunlight, which is arranged to face the sunlight incident surface of the pair of photodetectors so as to be substantially orthogonal to the arrangement direction of the photodetectors. In a sun sensor comprising a mask plate and detecting the sun direction by receiving the sunlight incident on the photodetector through the slit, the rectangular portion of the sunlight incident surface of the photodetector A structure in which a second right-angled triangular portion having a slanted side inclined in a wide direction from one side of the other photodetector to the other side is provided on one side orthogonal to the slit, with one side of the rectangular section being one side. Is.

[0010]

According to the above construction, when the rectangular portion of the photodetector is irradiated with sunlight, the action of the second right triangular portion of the photodetector does not affect the position in the arrangement direction. , Each output is constantly output. Therefore, it is possible to obtain a stable solar presence signal in the saturation region,
It enables highly reliable and highly accurate detection.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a sun sensor according to an embodiment of the present invention. In the figure, 10 and 11 are a pair of photodetectors 10 and 11, which are features of the present invention, and a signal processing unit is provided at each output end thereof. 12 are connected.

The photodetectors 10 and 11 are formed of, for example, well-known solar cells, and their sunlight incident surfaces are rectangular portions 10b and 11 on one side of the first right triangle portions 10a and 11a.
b are arranged in series. Then, each of these rectangular portions 10b, 1
The first right-angled triangular portion 10a, 11a of 1b has a second right-angled triangular portion 10c, 11 on one side continuous with the hypotenuse.
c are integrally formed in a continuous shape. Then, the second right-angled triangular portions 10c and 11c are obtained such that the sunlight incident area thereof is constant in the output in the saturation region, and the other photodetector 11 (10) is obtained.
It is integrally connected to one side of the rectangular portions 10b and 11b so as to widen from one side to the other direction.

A mask plate 13 is arranged on the sunlight incident surface of each of the photodetectors 10 and 11 so as to face it with a predetermined space. A substantially rectangular slit 13a is formed on the mask plate 13 so as to be substantially orthogonal to the arrangement direction of the photodetectors 10 and 11.

In the above structure, when the sunlight passing through the slit 13a of the mask plate 13 is applied to the first right-angled triangular portions 10a and 11a of the photodetectors 10 and 11, the photodetectors 10 and 11 are exposed. The A and B outputs are input to the signal processing unit 12. Here, the signal processing unit 12 uses C =
The calculation of (A−B) / (A + B) is performed to obtain the sun angle signal C.
To determine the sun direction.

When sunlight is applied to the rectangular portions 10b and 11b of the photodetectors 10 and 11, the photodetector 10 and 11b are exposed.
Although the output of 11 reaches the saturation region (see FIG. 3), it is affected by the position of the rectangular portions 10b, 11b in the arrangement direction by the action of the second right triangular portions 10c, 11c. Instead, it outputs constant A and B outputs to the signal processing unit 12. Here, the signal processing unit 12 obtains the sun angle signal C based on the input A and B outputs and generates a sun presense signal.

As described above, in the above-mentioned sun sensor, the sunlight incident surfaces of the photodetectors 10 and 11 are arranged so that the first right-angled triangular portion 10 is formed.
The rectangular portions 10b and 11b are continuously provided on one side of a and 11a, and the rectangular portion 1b is provided on one side of the rectangular portions 10b and 11b orthogonal to the slit 13a of the mask plate 13.
The second right-angled triangular portions 10c and 11c each having one side of 0b and 11b and having a hypotenuse inclined in a wide direction from one side of the other photodetector to the other side are continuously provided.

According to this, in the photodetectors 10 and 11, the slits 1 of the mask plate 13 are formed in the rectangular portions 10b and 11b.
When the sunlight passing through 3a is irradiated, the second right-angled triangular portions 10c and 11c act so that the irradiation position is not affected by the position in the arrangement direction and the A and B outputs are kept constant. Be drunk Therefore, it is possible to stably acquire the sun presence signal in the saturated region, and to realize highly reliable and highly accurate detection.

In the above embodiment, the second right-angled triangular portions 10c and 11c are provided with one side that is continuous with the hypotenuses of the first right-angled triangular portions 10a and 11a of the rectangular portions 10b and 11b. However, the present invention is not limited to this, and the second right triangular portion 10 is not limited to this.
Alternatively, the c and 11c may be arranged so that the other sides of the rectangular portions 10b and 11b are connected as one side. Therefore, it goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

[0019]

As described above in detail, according to the present invention, it is possible to provide a sun sensor having a simple structure and capable of realizing highly reliable and highly accurate detection.

[Brief description of drawings]

FIG. 1 is a diagram showing a sun sensor according to an embodiment of the present invention.

FIG. 2 is a diagram shown for explaining a conventional sun sensor.

FIG. 3 is a diagram shown for explaining the operation of the sun sensor.

[Explanation of symbols]

 10, 11 ... Photodetector. 10a, 11a ... A first right triangular portion. 10b, 11b ... Rectangular portion. 10c, 11c ... A second right triangular portion. 12 ... Signal processing unit. 13 ... Mask plate. 13a ... slit.

Claims (2)

[Claims] 1. A pair of a pair of right-angled triangular portions, each of which has a sunlight-incident surface formed by connecting a rectangular portion to one side of the right-angled triangular portion, and the oblique sides of the right-angled triangular portions of the sunlight-incident surface are opposed to each other. A pair of photodetectors, and a mask plate having a slit for transmitting sunlight, which is arranged on the sunlight incident surface of the pair of photodetectors so as to face each other substantially orthogonal to the arrangement direction of the photodetectors, In the sun sensor that receives the sunlight incident on the photodetector through the slit to detect the sun direction, on one side orthogonal to the slit of the rectangular portion of the sunlight incident surface of the photodetector, A sun sensor comprising: a second right triangular portion having one side of the rectangular portion and one side of the other photodetector that is wide and inclined in the other direction. 2. The sun sensor according to claim 1, wherein the second upper portion of the right triangle is provided on one side of the rectangular portion which is continuous with the hypotenuse of the right triangle.