JPS6141929A - Brightness detecting device - Google Patents

Abstract

PURPOSE:To detect the brightness of the visual field in front of an automobile in an excellent state by providing an opening part to a dashboard, fitting a polarizing prism thereto, and arranging the illuminance sensor at its rear side. CONSTITUTION:The opening part 12 is formed in a surface of the dash board 11 which faces the windshield, a step part 12A is formed at the upper end part of the opening part 12 as a prism storage part and the polarizing prism 13 having a plane front surface and a prism cut rear surface is fitted thereto, and the illuminance sensor 14 is arranged at its rear side. Then, the prism 13 is so formed that light from before the automobile when incident on the prism surface 13A at an angle thetax is deflected and strikes the photodetection surface of the sensor 14 at right angles. Then, incident light having an angle thetain to an axial line l1, on the other hand, is refracted by the top surface and refracting prism surface and polarized at right angles to the top surface of the dashboard 11, and incident on the sensor 14 as vertical light. Consequently, the directivity of the sensor 14 is improved and the front visual field of the automobile and the detection direction of the sensor are made coincident with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention is directed to a brightness detection device that detects the brightness of the front field of view of an automobile.

(Prior art) When automatically turning on and off the lights of a car, the brightness of the front field of view is detected by an illumination sensor, and the blinking control is performed according to the brightness (Japanese Patent Application No. 58-249499
(see issue).

In that case, as shown in FIG. 11, a stay 2 is provided near the rearview mirror 1, and the illuminance sensor 3 is attached to this so that its light-receiving surface faces the windshield 4. Alternatively, as shown in FIG. An illuminance sensor 3 is attached to the surface of the dash board 5 facing the windshield 4.

However, in the case of Figure 11, a special stay is required to hold the illuminance sensor 3, which not only takes time and requires parts to install, but also obstructs the front view. .

Further, in the case of FIG. 12, since the dash board of recent automobiles is made flat in order to secure a wide front view, the place where the illuminance sensor 3 can be mounted is restricted.

(Object of the Invention) An object of the present invention is to provide a brightness detection device capable of detecting the brightness of the forward field of view in automatic mode (2) in a good condition.

[Summary of the Invention] The present invention provides a frontage portion on the surface facing the windshield of a dash board of an automobile, attaches a deflecting prism with a flat front surface and a prism-cut back surface to this frontage portion, and arranges an illuminance sensor on the back side of the deflection prism. It is characterized by the fact that

〔Example〕

FIG. 1 shows an embodiment of the present invention, in which an opening 12 is provided on the surface facing the windshield, that is, the upper surface, of a dash board 11 of an automobile, and a stepped portion 12A is formed at the upper end of this opening 12. The deflection prism 13 has a flat front surface and a prism-cut back surface.
is attached, and the illuminance sensor 14 is arranged on the back side.

The deflection prism 13 is formed so that when light enters the prism surface 13Δ at an angle θ' from the front of the automobile, the light enters the light receiving surface of the illuminance sensor 14 at a right angle within G, The details are shown in Figure 2. Angle θ formed by the refraction prism surface 13B with respect to the surface of the deflection prism 13
x is calculated by the following formula.

・・・・・・・・・・・・・・・・・・・・・(A) θ
in=Angle n of the incident light with respect to the axis 11 perpendicular to the surface of the deflection prism: l1il refractive index of the deflection prism Note that 111 in FIG. 2 is the surface 13 of the deflection prism 13.
@ line perpendicular to A, j2 is the axis perpendicular to the refracting prism surface 13BIP of the deflection prism 13, and θout is the axis I! The angle formed by the transmitted light with respect to ρ2, m is the pitch interval of the prism cut, and this pitch I! The distance I is determined by considering the angle θx and the depth dimension of the prism 13.

With this configuration, axis I! The incident light at an angle Oin with respect to the illumination sensor 14 is refracted by the surface and the refraction prism surface and deflected in a direction perpendicular to the top surface (horizontal plane) of the dash board 11, which is an ideal shape for the illuminance sensor 14, that is, vertical light. Enter as) 1.

As a result, the directional characteristics of the illuminance sensor 14 are improved, and it becomes possible to match the front field of view of the vehicle with the detection direction of the sensor.

For example, when there is no deflection prism, the directional characteristics are as shown in FIG. 3(a), whereas with the deflection prism, the directional characteristics are as shown in FIG. 3(b), resulting in a good detection state.

Next, the equation (A) for calculating the angle θ is proven based on FIG. In the figure, θ'in is the refraction angle of the incident light P1, θ'o
ut is the incident angle of the refracted light P2, P3 is the transmitted light, δ is the deflection angle of the light beam, and the other symbols are the same as in FIG.

First, from the law of 5ne++, sinθin sinθout −−n ・・・・・・・・・・・・(1) sinθ'
in sin θ'out The deflection angle δ of the ray is δ-(Oin-〇'in) + (θout-θ'ou
t)・・・・・・・・・・・・(2) Since <x x x and <X4 =θ'in+θ″o
Since ut, θ −〇゛in 10'out θ'out−θ −〇′in ・・・・・・・・・
・・・・・・・・・(3) From equation (1), θout −5
in ”n5in O'out tet6ru so (3)
Substituting the formula, θout −sin −1n 5in(θX−〇'in
)...-(4)(3), By formula (4), (
2) By replacing θout and θ'out in the equation and under the condition that the transmitted light P3 is perpendicular to the surface of the deflection prism, δ-θ1n...
...(6) By replacing δ in equation (5) and equation (6) (see the margin below), θin= Oin-+-5in -1n5in(θ-θ
'1n)-08θ-5in-1nsin(θ-θ'in
) × × sin θ = n sin (θx - θin) - n (sin θ cos θ'1 n - cos θ
θ'1n) From equation (1), θ'1n-sin-1-!
-! °θi.

By replacing θ゛1n in equation (γ),■ Figure 5 shows that the light receiving surface of the illuminance sensor 14 is changed to the deflection prism 13.
In this case, the angle θx is calculated by the following formula.

1 If α in the above equation (B) is set to zero degrees, the equation (A) will be obtained.

Even if the sensor is tilted in this way, the light is incident perpendicularly to the light receiving surface, so the unidirectional characteristic unique to the illuminance sensor can be utilized. That is, brightness in any direction can be detected while maintaining sharp directivity characteristics and without causing a decrease in relative sensitivity.

Equation (B) will be proven based on FIG.

The deflection angle δ of the light ray is δ-(θin-θ'in) + (θout-θ'ou
t)・・・・・・・・・・・・(8) < f−θ and since f−θ'In 10'out, θ'out−θX−θ゛in ・・・・・・・・
・・・・・・(9) According to 3nell's law, θout −5in−1nsin(θX−〇′in)・
・・・・・・・・・・・・(10) Using equations (9) and (1G), the θOu (and θ'out illuminance sensor 14 of equation (8) is tilted by α degrees with respect to the surface of the deflection prism. As a result, the transmitted light is tilted by α degrees with respect to the surface of the deflection prism, so δ−θin−
α ・・・・・・・・・・・・(12)
By replacing δ in equations (11) and (12),
5in(θx-a>-nsin(Ox-θ'1n)si
naCO3(Z-CO3θsin axx -n (sinθcosθ'1n-cosθX5inθ
'in), so -2n5inθ'1n-cos α+cos 2a+n
2sinθ'In-2n5inθ'1n-sin α+
sin 2(Z)-(n2 sin 2 θ'!n-2
n sin θ'1n-sin a+5in2 (Z)
Sln θ, (n −2n(cos θ′1n−co
s a-sinθ'1n-sina) October-(n5in
θ'1n-sin α) 2Snell's t leaving 1111
1, θ′1n-sin −′ i°θi”, so in FIG. 14 is inclined at an angle α (A),
The angle θX is determined by the following equation.

■ γ: angle of incidence of incident light with respect to the horizontal plane In this case, the upper surface of the dash board is inclined with respect to the horizontal plane, and as in each of the above embodiments, the light enters the sensor directly. , the brightness of the front field of vision can be detected in good conditions.

In the above equation (C), if β is set to zero degrees, then γ-θin is obtained, resulting in equation (B), and if α and β are set to zero degrees, equation <A> is obtained. The proof of equation (C) will be made based on FIG.

The angle θin of the incident light with respect to the 111-line perpendicular to the deflection prism is θin - γ - β as in equation (B), so it can be determined by selecting the material of the deflection prism or by coloring it. , it is possible to add various other viewing functions. For example, as shown in FIG. 9, a plurality of deflecting prisms 13, for example, three deflecting prisms 13 each having a different color filter spacing,
-1.13-2゜13-3 is placed in the opening 12 of the dash board 11, and the illuminance sensor 14 is installed for each deflection prism.
If -1°14-2.14-3 is placed, the following effects can be expected.

That is, if the deflection prisms 13-1 to 13-3 are provided with spectral characteristics that are sensitive to red, green, and blue wavelength regions, color and illuminance judgments can be made based on the outputs of the respective centners 14-1 to 14-3. Therefore, if we take advantage of the fact that the spectral characteristics of sunlight change in red, green, and blue attenuation characteristics, and that the difference in output changes is most significant at dusk and dawn, Taro or It is possible to accurately determine whether the illuminance has decreased at dawn or due to the influence of the main hospital or guards. As a result, changes in brightness can be detected quickly when entering a tunnel, and
If there is a tunnel 20 as shown in the figure, the approach distance is 11
[At D2, the headlamps of l1lI30 come on, and the distance is significantly shortened compared to the distance D1 when there is no deflection prism (see Japanese Patent Application No. 111158-249499)
.

In addition, by providing an infrared cut filter effect to the deflection prism, it is possible to prevent illumination from being affected by sunlight, etc.
! It is possible to prevent a rise in temperature.

Furthermore, when the smoked plate has a tidying effect, a blinding effect is created and the appearance is improved.

Furthermore, the deflection prism can be detected accurately.

(2) An opening is provided in the dash board, a deflection prism is attached to this opening, and an illuminance sensor is placed on the back side of the opening, which eliminates the need for a dedicated stay and is effective in securing visibility.

(3) Since the installation angle of the illuminance sensor can be freely selected, the degree of freedom in designing the dash board increases, and it becomes possible to integrate the b-intensor and the circuit section.

(4) By changing the vJ quality and tooth angle of the deflection prism, the deflection angle and direction can be freely changed.

(5) By making the pitch m of prism cuts finer, it is possible to form a deflecting prism with a wall thickness of 89 mm, and the thinner wall thickness provides high transmittance.

(6) Any resolution can be obtained by changing the pitch m.

(7) Since the surface of the deflection prism is flat, it is maintenance-free and easy to coat.

(8) Various spectral sensitivities and filter characteristics can be obtained by selecting or coloring the material of the deflection prism, and the internal sensor can also be made invisible from the outside.

(9) When entering a tunnel during the day, the light inside the tunnel can be quickly detected, and the headlamp lighting can be controlled appropriately. It is particularly effective for detecting lighting of sodium lamps installed in tunnels that are powered by an AC power source.

(10) Since the deflection prism can be molded from synthetic resin, it can be integrally molded with the sensor case and can be manufactured easily at low cost.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of a brightness detection device according to the present invention, FIG. 2 is a detailed view of a deflection prism in the same embodiment, and FIGS. 3(a) and 3(b) are directional characteristic diagrams. Figure 4,
Figures 6 and 8 are explanatory diagrams for proving the formula for calculating the angle formed by the refracting prism surface with respect to the surface of the deflection prism, and Figures 5, 7, and 9 show other examples. 10 (a), (b) and (C) are explanatory diagrams of headlamp flashing control operation when entering a tunnel,
FIG. 11 and FIG. 12 are schematic diagrams showing the conventional illuminance senryi ζJ state. 11... Datsushi board 12... Listen] Part 13.
... Deflection prism 13A... Prism surface 13
B... Refraction prism surface 14... Teru Uren - Fig. 1 Fig. 2 (b) Fig. 1 14 Fig. 1 O) - Fig. 11 Fig. 12 , 1m ;! '? +111 (March 1160) 71-11, Incident Display 1981 Special n'1rA No. 1rA 3734 JT
J2, Invention name used detection IIA 3,? Relationship with the IIi Correct Person Case Applicant Name: Honda Gi (D Kogyo Co., Ltd. 3-kun (1 idiot)) 4, Agent Address: Tokyo RAS Minamimonde-1-1-5, Minato-ku, ?
Il] The kiss of a positive command (Jiko) 7. Contents of the drawing (1) Details tj+, 3rd shell, line 6, 1 is taken as j1, but 1゛ is taken as 11th trial. 1. ; and amend it. 2nd) Ii+I+'i, 5th line 10 to 5th line is determined by considering ``, J5 is corrected as below. The prism cut is used when detecting light from the front with directionality in the left and right directions (i.e. when detecting only light from a certain direction in the left and right direction, or when detecting light from a narrow range of directions). ), when the prism cut is formed into a kamabo shape and does not have directivity (i.e., when detecting light from a direction with a certain angle range in the left and right direction), the prism cut A hat whose cut is formed into a ring shape is determined as necessary.'' (3) Same 2;
Correct X X J as "/X5X1x6 and /X4X3X6.1".
I am corrected. (5) Same town, 1Fil, negative 2nd line [<Correct CI as 1ZfJ. On the 7th line of the page, "<"-0xguari,
and <I' = J (if-θ guari, and /f
I am corrected. (8) l1jl Fl, 12th line 4th line to 5th line is corrected. (9) Same as 1!1, page 15, line 14 [Also, the deflection prism is detected at the target l1m. ] has been revised as follows (
Mizuru. ``[Efficacy!,)!1 (1) (σ of light received through a 1m prism) - (゛, ~l-'t) ', r light receiving angle and /, [Brightness of the front view of the car can be detected at 1+') +lV., j or more

Claims (4)

[Claims] (1) An opening is provided on the surface of the automobile dashboard facing the windshield, a deflection prism with a flat front surface and a prism-cut back surface is attached to this opening, and an illuminance sensor is placed on the back side of the deflection prism. brightness detection device. (2) In the deflection prism, the angle θ_x formed by the refraction prism surface on the back side with respect to the front surface is expressed by the following formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ α: Inclination angle of the illumination sensor with respect to the surface of the deflection prism β: Horizontal plane The angle that the surface of the deflection prism makes with respect to γ: The angle that the incident light makes with respect to the horizontal plane (=β+θin) n: The refractive index of the deflection prism θin: The angle that the incident light makes with the axis perpendicular to the surface of the deflection prism The brightness detection device according to claim 1, which is formed to have a value calculated by. (3) The brightness detection device according to claim 1 or 2, which uses a deflection prism having a filter effect for detecting an arbitrary wavelength range. (4) The brightness detection device according to claim 1 or 2, wherein the deflection prism has the effect of an infrared cut filter.