JPH0711449B2 - Solar sensor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a solar radiation sensor that detects the irradiation amount of light such as sunlight.

[Conventional technology]

As such a solar radiation sensor, conventionally, a light receiving element that outputs an electric signal according to the amount of light received on a light receiving surface is covered with a cover glass made of parallel flat plate glass, or
As shown in the figure, it is known that the light receiving element 1 is covered with a concave lens 2.

When the light receiving element 1 is covered with the concave lens 2, its directivity is relaxed as compared with the case where it is covered with the parallel plate glass, but when light is incident from the direction perpendicular to the light receiving surface of the light receiving element 1, The output of the light receiving element 1 is maximized, and the output decreases as the incident direction of light is inclined.

[Problems to be Solved by the Invention]

When such a solar radiation sensor is used together with a temperature sensor as a sensor for an auto air conditioner installed in an automobile, the solar radiation sensor is arranged at a horizontal position such as a hood or a roof so that the light receiving surface of the light receiving element 1 is horizontal. Therefore, in the summer when the frequency of use of the automatic air conditioner is high, the solar radiation sensor outputs the strongest signal when the sun is at a high position in the vicinity of the south central part.

However, passengers in the car are not exposed to direct sunlight while the sun is in the high position near the south central part. Therefore, although passengers feel the heat due to the rise in temperature inside the vehicle,
I hardly feel the heat of direct sunlight. On the contrary, when the sun leaves the central part of the country and direct sunlight enters the car from an oblique direction, the passengers are exposed to the direct sunlight, and the passengers strongly feel the heat caused by the direct sunlight itself.

As can be understood from the above, in the conventional solar radiation sensor, the relationship between the directivity of the solar radiation sensor and the heat felt by the passengers of the vehicle depending on the direction of direct sunlight is not compatible, and the vehicle auto It was hard to say that it was suitable for a solar radiation sensor for an air conditioner.

Therefore, an object of the present invention is to provide a solar radiation sensor suitable for being used for an automobile air conditioner.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, in the solar radiation sensor according to the present invention, the lens member covering the light-receiving surface of the light-receiving element determines the amount of incident light reaching the light-receiving surface through the light-receiving surface in the incident direction. It is formed so that it increases as it inclines from the direction perpendicular to the plane, and becomes maximum when it inclines by a predetermined angle.

Here, the light-receiving surface is formed in a point-symmetrical shape, and the surface of the lens member has a circular plane whose outer side far from the light-receiving element passes through the center of the light-receiving surface and is substantially coincident with the center on a central axis perpendicular to the light-receiving surface.
It is formed of an envelope convex curved surface formed by a spherical body that moves in contact with the outer peripheral edge of this circular plane, and the inner side close to the light receiving element has a projection area substantially the same as the inscribed circle enclosed by the light receiving surface. And a conical inner surface in contact with the outer peripheral edge of a spherical concave surface whose center is substantially coincident with the center axis with a radius larger than the radius of the inscribed circle and smaller than the diameter of the inscribed circle. I am trying.

[Action]

With the configuration described above, the light receiving element outputs the maximum electric signal when the direction of the incident light is tilted by a predetermined angle from the direction perpendicular to the light receiving surface.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 1 is a sectional view showing an embodiment of the solar radiation sensor according to the present invention.

As shown, in the solar radiation sensor according to the present invention,
A light receiving element 1 such as a photodiode is mounted in the form of an Au-Si eutectic on the bottom of a bowl-shaped eyelet 3 made of Kovar material. Are welded. The light receiving element 1 has a light receiving surface 1a on its upper surface, and the light receiving surface 1a has a point-symmetrical shape, and preferably has a circular shape. The upper surface of the light receiving element 1 is connected to a lead wire 7 on the anode side via a bonding wire 6. The lead wire 7 is provided so as to penetrate from the lower side through a small hole 3a formed in the bowl-shaped eyelet 3, and the borosilicate glass 8 filled in the lower side of the bowl-shaped eyelet 3 allows the lead-shaped eyelet 3 to be formed. It is also insulated from the lead wire 5 and held by the prone bowl-shaped eyelet 3. A cylindrical eyelet 10 is externally fitted and welded to the outer peripheral portion of the prone bowl-shaped eyelet 3. The cylindrical eyelet 10 is fitted onto the lens member 11 that covers the light receiving surface 1a of the light receiving element 1 at the upper open end, and carries this.

As shown in FIG. 2, the lens member 11 is a circular lens whose cross section has a unique shape. The shape of the lens member 11 will be described in detail. When the center axis C passing through the center of the light receiving surface 1a of the light receiving element 1 and perpendicular to the light receiving surface 1a is considered, The distant outer upper surface has a circular flat surface with a diameter d ₁ whose center substantially coincides with the central axis C at its central portion. From the outer periphery of this circular plane to the outside, a sphere having a radius r ₂ that moves along the outer peripheral edge of the circular plane while contacting the outer peripheral edge (at this time, the center of the spherical body is a diameter d whose center is substantially coincident with the central axis C). ₁ will be moved on the circumference of the circle) to form a convex convex curved surface.

On the other hand, the inner lower surface of the lens member 11 near the light receiving element 11 has a spherical concave surface with a radius of curvature r ₁ whose center substantially coincides with the central axis C at the center thereof. The projected area of the spherical concave surface with respect to the light receiving surface 1a is the same as the area of the inscribed circle included in the light receiving surface 1a, and its radius of curvature r ₁ is larger than the radius of the inscribed circle and larger than the diameter of the inscribed circle. Is also getting smaller. A conical inner surface is formed on the outer peripheral edge of the spherical concave surface and contacts the outer peripheral edge of the spherical concave surface.

A more preferable shape of the above-mentioned lens member 11 is a lens member.
When a material having a refractive index of about 1.51 is used for 11, as shown in FIG. 2, the diameter of the inscribed circle included in the light receiving surface 1a is D, the diameter of the circular plane on the upper surface of the lens member 11 is d ₁ , and The radius of a sphere that forms an envelope convex curved surface in contact with this circular flat surface is r ₂ , the radius of curvature of the spherical concave surface of the lower surface of the lens member 11 is r ₁ , the outer diameter of the cone inner surface in contact with this spherical concave surface is d ₂ , and the lens member 11 outer diameter
d ₃ , the shortest distance between the circular flat surface and the spherical concave surface, that is, the thickness of the central part of the lens member 11 is e ₁ , the center of the spherical concave surface and the light receiving surface 1a
When the distance between the lens member 11 and the lens member 11 is e ₂ and the dimension of the lens member 11 in the central axis C direction (optical axis direction) is E, the dimensions of each part of the lens member 11 are relatively specified as follows. .

D / 2 <d ₁ <2D <3 (1) 5D / 3 <d ₂ (2) 5D / 2 <d ₃ (3) D / 2 <r ₁ <D (4) D <r ₂ <2D (5) D / 8 <e ₁ <D / 4 (6) D / 2 <e ₂ <D (7) In order to satisfy the equations (1) to (7), For example, D = 1, d ₁ = 0.6, d ₂ = 1.8, d ₃ = 2.6, r ₁ = 0.8, r ₂
= 1.6, e ₁ = 0.2, and e ₂ = 0.8, the optical path diagram when the lens member 11 is formed is shown in FIG.

FIG. 3 shows each optical path when the incident direction of the incident light is inclined at 15 ° intervals from the direction perpendicular to the light receiving surface 1a until it is inclined by 60 °. As shown, the effective width of the incident light to effectively reach the light-receiving surface 1a, the incident direction of the b ₁ ~b ₅ in order from the perpendicular incident light on the light receiving surface 1a, the ratio of the effective width of the incident light adjacent b _{Let n} / b _{n + 1} be m _n (m _n = b _n / b _{n + 1} , where n
Is an integer from 1 to 4), and the ratios m _{1 to} m ₄ obtained by measuring the effective width of the actual incident light are m ₁ = 1.09, m ₂ = 1.10, m ₃ =
1.09, m ₄ = 0.81. As can be seen from this, the incident direction of the incident light is 45 ° from the direction perpendicular to the light receiving surface 1a.
Until it is tilted, the effective width of the incident light is almost constant (about 1.1
Doubled) and decreases with further inclination. Therefore, the light receiving surface 1a
The amount of light received by is increased at a constant rate as the incident direction of the incident light is tilted from the direction perpendicular to the light receiving surface 1a, becomes maximum around a 45 ° tilt, and decreases when tilted further. Therefore, the directional characteristics of the solar radiation sensor formed as described above are as shown in FIG.

By the way, the directional characteristic of the solar radiation sensor used for an automobile air conditioner has an incident direction of 45 ° to 50 ° from a direction perpendicular to the light receiving surface 1a of the light receiving element 1.
The output of the light receiving element 1 becomes maximum when it is tilted to some extent, and when the output at this time is 100%, the output of the light receiving element 1 when the incident light enters from the direction perpendicular to the light receiving surface 1a
It is preferably 70 to 80%, and further, the increase rate of the output of the light receiving element 1 which increases as the incident direction of the incident light inclines from the direction perpendicular to the light receiving surface 1a is almost constant. preferable. That is, when considering the increase rate every time the incident direction of the incident light is inclined by 15 °, if the increase rate is M, the increase rate M is within the range of the numerical value obtained from the following equation.

70 × M × M × M = 100 ... 80 × M × M × M = 100 ... That is, the rate of increase M is within the range of 1.077 <M <1.126.

The directional characteristics of the solar radiation sensor described here are in good agreement with the directional characteristics shown in FIG. From this, it can be seen that the solar radiation sensor according to the present invention formed as described above is suitable for use as a solar radiation sensor for an automobile automatic air conditioner.

Next, the dimensions of each part of the lens member 11 are from the above (1) to
The case where the expression (7) is not satisfied is explained. For example, when d ₁ <D / 2, the above-mentioned effective width ratios m _n of adjacent incident lights are m ₁ <1.077, m ₂ ＞ 1.126,
m _3> 1.126, and conversely, d1> when was 2D / 3 is, m
_{1> 1.126, m 2> 1.126} , the m ₃ <1.077. Thus, d ₁
If the value of is not within the range of D / 2 <d ₁ <2D / 3 shown in the equation (1), the amount of light received by the light receiving surface 1a is the direction in which the incident direction of the incident light is perpendicular to the light receiving surface 1a. It will not increase at a constant rate as it leans from.

Further, d ₁ is within the range of D / 2 <d ₁ <2D / 3 shown by the equation (1), but the values of d ₂ and d ₃ are 5D / 3 <d of the equations (2) and (3). _{If 2} and 5D / 2 <d ₃ are not satisfied, the vignetting phenomenon is likely to occur as the incident light is tilted. Therefore, m ₁ > 1.126, m
₂ <1.077, m ₃ <1.077, and in this case as well, the amount of light received by the light receiving surface 1a does not increase at a constant rate as the incident direction of the incident light inclines from the direction perpendicular to the light receiving surface 1a.

Also, when the expression (4) is not satisfied, that is, r ₁ is D /
If it is less than 2, m _{1 to} m ₃ are all 1.14 or more,
On the contrary, when r ₁ is larger than D, m _{1 to} m ₃ are all 1.06 or less.

Also, when the expression (5) is not satisfied, that is, r ₂ <D
In the case of, m ₁ <1.077, m ₂ > 1.126, m ₃ > 1.126, and conversely, in the case of r ₂ > 2D, m ₁ > 1.126, m ₂ <1.077,
Since m ₃ <1.077, the amount of light received by the light receiving surface 1a does not increase at a constant rate as the incident direction of the incident light inclines from the direction perpendicular to the light receiving surface 1a.

Also, when the expression (7) is not satisfied, that is, e ₂ <D /
In the case of 2, m _{1 to} m ₃ are all smaller than 1.077, and conversely, when e ₂ > D, m ₁ and m ₂ are larger than 1.126 and m ₃ is smaller than 1.077.

Note that in the equation (6) where D / 8 <e ₁ <D / 4, the value of e ₂ is the equation (7).
In the case of being within the range of D / 2 <e ₂ <D, it is a conditional expression necessary for all the ratios m _{1 to} m _{3 to} be about 1.1.

In the above-described embodiment, the lens member 11 is formed so that the dimensions of each part of the lens member 11 satisfy the conditional expressions described above, but the lens member 11 is similar to the lens member 11 thus formed. The lens member may be formed by doping a parallel plate glass with a doping material to generate a refractive index distribution so as to obtain a refractive property.

〔The invention's effect〕

As described above, in the solar radiation sensor according to the present invention, the lens member covering the light receiving surface 1a of the light receiving element has the light amount of the incident light reaching the light receiving surface 1a therethrough in the incident direction of the incident light. Since the light-receiving element is formed so that it increases as it inclines from the direction perpendicular to 1a and becomes maximum when it inclines by a predetermined angle, the direction of the incident light is a direction perpendicular to the light-receiving surface 1a. When the vehicle is tilted at a predetermined angle from, the maximum electric signal is output, and the directional characteristic is suitable for use as an automobile air conditioner.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a solar radiation sensor according to the present invention, FIG. 2 is a sectional view showing a lens member and a light receiving element according to the present invention, and FIG. 3 is a light receiving surface 1a of the light receiving element. 5 is an optical path diagram showing an optical path of incident light incident on the light source, FIG. 4 is a directional characteristic diagram showing directional characteristics of a solar radiation sensor according to the present invention, FIG.
The figure is a sectional view showing a conventional solar radiation sensor. 1 ... Light receiving element, 11 ... Lens member.

Claims (2)

[Claims] 1. A solar radiation sensor comprising: a light receiving element that outputs an electric signal according to the amount of light received by a light receiving surface; and a lens member that covers the light receiving surface, wherein the light receiving surface is formed in a point-symmetrical shape. In the surface of the lens member, the outer side far from the light receiving element is a circular plane whose center substantially coincides with a center axis passing through the center of the light receiving surface and perpendicular to the light receiving surface, and an outer peripheral edge of the circular plane. It is formed from an envelope convex curved surface formed by a sphere that moves in contact with this, and the inside close to the light receiving element has a projection area that is substantially the same as the inscribed circle enclosed by the light receiving surface, and the inscribed circle Is larger than the radius of the inscribed circle and is smaller than the diameter of the inscribed circle, and is formed from an inner peripheral surface of a conical surface that is in contact with the outer peripheral edge of a spherical concave surface whose center is substantially aligned with the central axis. Sensor. 2. A diameter of an inscribed circle included in the light receiving surface is D,
The diameter of the circular plane is d ₁ , the outer diameter of the inner surface of the cone is d ₂ , the outer diameter of the lens member is d ₃ , the radius of curvature of the spherical concave surface is r _1, and the convex convex curved surface is formed. When the radius of the sphere to be r ₂ , the shortest distance between the circular plane and the spherical concave surface is e _1, and the distance between the center of the spherical concave surface and the light receiving surface is e ₂ , each of these values , D / 2 <d ₁ <2D / 3 5D / 3 <d ₂ 5D / 2 <d ₃ D / 2 <r ₁ <DD <r ₂ <2D D / 8 <e ₁ <D / 4 D / The solar radiation sensor according to claim 1, wherein each conditional expression of 2 <e ₂ <D is satisfied.