JPH0690028B2 - Sun sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a sun sensor used, for example, for detecting an attitude angle of an artificial satellite.

(Prior Art) Generally, as one method of a photoelectric system of a sun sensor such as an artificial satellite, as shown in FIG. 2, a linear slit 1 which transmits one light and a slit 1 which passes behind the slit 1 are provided. There is a technique for detecting the sun direction by a CCD (Charge Coupled Device) linear image sensor 2 arranged in a direction orthogonal to the slit 1 at an appropriate interval for detecting sunlight.

In FIG. 2, X, Y, and Z represent orthogonal coordinate axes, and the sun sensor of this example detects the angle α of the sun direction with respect to the Z axis projected on the YZ plane. First, by processing the signal output of the CCD linear image sensor 2 due to the sunlight passing through the slit 1 with a signal processing system, the distance l from the X axis to the sunlight incident point on the light receiving surface of the CCD linear image sensor 2 is reduced. Desired. The distance h from the slit 1 to the light receiving surface of the CCD linear image sensor 2 is a known value, and if l is known, the angle α of the sun direction in the YZ plane can be calculated by the following equation.

By the way, the structure of the CCD linear image sensor 2 is, as shown in FIGS. 3 (a), (b), and (c), a hermetically sealed front window glass 4 for protecting the CCD linear image sensor semiconductor chip 3 and the like. It has stopped.

Next, the influence of the window glass 4 on the performance of the sun sensor of the above method will be described.

Figure 4 shows the slit image of sunlight through the window glass 4.
FIG. 5 is a diagram for explaining a difference due to a sunlight incident angle when reaching the light receiving surface of the CCD linear image sensor 2.
In Fig. 4, 5 indicates that the sun is α with respect to the Z axis in the YZ plane.
When the angle is, the incident direction of the sun rays passing through the slit 1 is shown, and the slit image in this case is orthogonal to the Y axis at the point A on the light receiving surface of the CCD linear image sensor 2. By processing the signal output of the CCD linear image sensor 2 at this time, the distance l from the X axis of point A can be obtained. Next, when the sun is inclined at an angle α with respect to the Z axis and in a plane perpendicular to the YZ plane, the incident direction of the light passing through the slit 1 is set to 6
And The slit image in this case is orthogonal to the Y-axis at the point B from the X-axis by Δl compared to the case where the sun is in the YZ plane. In each of the above two cases, the angle from the Z axis projected on the YZ plane in the sun direction is the same as α, but the arrival point of the slit image at the light receiving surface of the CCD linear image sensor 2 is different. , Α is directly connected to the detection error of the sun sensor for detecting the angle. This is because the refraction of sunlight by the window glass 4 causes an error in the above two cases (hereinafter, this error is referred to as an axis interference error due to the window glass).

(Problems to be Solved by the Invention) The present invention has been made in view of the situation in which an axial interference error occurs due to the window glass, and a sun sensor capable of removing the axial interference error due to the window glass to achieve high accuracy is provided. The purpose is to provide.

[Structure of Invention]

(Means for Solving the Problem) In order to achieve the above object, an optical system of a sun sensor including a slit and a linear image sensor orthogonal to the slit,
A concave mirror is provided so as not to cause an axial interference error due to the window glass of the linear image sensor.

(Operation) As described above, by providing the concave mirror that cancels the axial interference error due to the window glass of the linear image sensor,
It is possible to detect the direction of the sun without being affected by the refraction of light by the window glass of the linear image sensor.

Embodiments Embodiments of the present invention will be described in detail below with reference to the drawings.

1 (a) and 1 (b) show an embodiment of the present invention, in which one linear slit 1 that transmits sunlight is located at the focal position of a concave mirror, for example, a semi-cylindrical parabolic reflector 7. The parabolic reflector 7 reflects the sunlight, which is arranged and transmitted through the slit 1, substantially in parallel. At a position where the reflected light from the parabolic reflector 7 is received, the linear image sensor 2 is arranged in a direction orthogonal to the substantially parallel reflected light. The linear image sensor 2 is composed of, for example, a CCD linear image sensor semiconductor chip, and the front surface is hermetically sealed with a window glass to protect the chip.

With this configuration, the sun is at an angle α with respect to the Z axis.
Even if tilted in a plane perpendicular to the ZY plane, refraction of incident light by the window glass of the linear image sensor 2 does not act in the column direction of the linear image sensor 2 (direction Y'in FIG. 1). It is possible to eliminate the axis interference error due to the window glass of the linear image sensor 2. Therefore, by providing the semi-cylindrical parabolic reflector 7,
The sun direction can be detected accurately and highly accurately without being affected by the refraction of light by the window glass of the linear image sensor.

In the embodiment shown in FIG. 1, a semi-cylindrical parabolic reflector is described as the concave mirror, but the concave mirror is not limited to this and may be approximately formed by a semi-cylindrical reflector.

〔The invention's effect〕

As described above, according to the present invention, by providing the concave mirror so as not to cause the axial interference error due to the window glass of the linear image sensor, the sun direction is accurately and accurately adjusted without being affected by the refraction of light by the window glass. It is possible to provide a sun sensor that can be accurately detected.

[Brief description of drawings]

1 (a) is a perspective view showing an embodiment of the present invention, FIG. 1 (b) is a view seen from the X-axis direction in FIG. 1 (a), and FIGS. 2 to 4 are conventional suns. It is a block diagram for explaining a sensor. 1 ... Slit, 2 ... Linear image sensor, 3 ...
A semi-cylindrical parabolic reflector.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideo Hamada, No. 1, Komukai Toshiba Town, Komukai-shi, Kawasaki City, Kanagawa Prefecture Komatsu Plant, Toshiba Corporation (56) References JP-A-49-53463 (JP, A)

Claims (1)

[Claims] 1. A linear slit for transmitting sunlight, a concave mirror for arranging the linear slit at a focal position and reflecting incident light transmitted through the linear slit substantially in parallel, and a concave mirror for the concave mirror. A sun sensor, comprising: a linear image sensor disposed at a position where parallel reflected light is received in a direction orthogonal to the substantially parallel reflected light.