JPH0789445B2 - Projector headlight - Google Patents

Description

The present invention relates to a projector-type vehicle headlight.

[Conventional technology]

The vehicle headlamp must have a light distribution pattern that brightly illuminates the front of the own lane and does not dazzle an oncoming vehicle.

A projector-type automotive headlamp has been proposed as a headlamp that has a light distribution characteristic that meets the above requirements, has a simple lens configuration, and can be downsized in its overall shape. As the latest technology relating to this projector type headlight, for example, JP-A-58-209801 is known.

FIG. 12 shows the above-mentioned known projector-type headlight. The headlight of this known example is provided with a shell-shaped reflector, and the axial cross section of the inner reflecting surface of this reflector forms a part of an ellipse, and the eccentricity of the ellipse is perpendicular to the axial direction. In a vehicle headlamp increasing from a longitudinal section to a horizontal axial longitudinal section, the elliptical portion of all axial sections
The focal points 105 of 101, 102 are also arranged such that the corresponding vertices 104 of the elliptical portions 101, 102 of all axial cross sections coincide.

110 is the outer focus of the ellipse 102, 111 is a dimmer (light shield), 112
Is the outer focus of the ellipse 101, 113 is the lens, and 110 is its focus.

[Problems to be solved by the invention]

When the reflector is constructed by the above-mentioned known technique, (a) the effective utilization rate of the luminous flux emitted from the light source bulb is low. And (b) It is difficult to arbitrarily set the luminous intensity distribution characteristics.

There is such a problem. This will be explained below.

FIG. 13 is a diagram showing an isolux curve near the above-mentioned dimmer (which is a shading plate or shade if it is called by focusing on its function), and FIG. 14 is a headlight projecting the light onto the screen. It is a chart which shows an isoilluminance curve in a case. H in both figures
-H is a horizontal line, V-V is a vertical line, and the intersection is the optical axis (perpendicular to the paper surface).

As shown in FIG. 13, the shade 111 intercepts most of the luminous flux below the H-H line by the cut line 111a on the top surface thereof. The unobstructed part is projected forward,
Since the light flux converges and intersects at the focus 110 shown in FIG. 13, the isolux curve on the screen (FIG. 15) has an inverted shape.

As can be easily understood from the above-mentioned action, in FIG. 13, nearly half of the maximum illuminance portion (small ellipse in the center of the concentric ellipse) of the isoilluminance curve is covered with the shade 111. As a result, the 100 lux line in Fig. 14 does not have an elliptical shape, but nearly half of it has a notched shape.

Thus, the known headlight (FIG. 12) has a low effective utilization rate of the luminous flux.

Further, the luminous intensity distribution on the surface on which the shade 111 is installed becomes like the curve k shown by the solid line in FIG. This luminous intensity distribution curve changes depending on the length and minor axis ratios of the ellipse described above, but it has a certain tendency and is determined by itself, and there is no design freedom.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a projector-type headlight having a large effective utilization rate of light emitted from a light source and capable of arbitrarily setting a luminous intensity distribution.

[Means for solving problems]

In order to achieve the above-mentioned object, a projector type headlight of the present invention is provided with a light source bulb near the focal point of a reflecting mirror, and the light emitted from the light source is reflected by the reflecting mirror and has a cut line. In a projector-type vehicle headlight that focuses in the vicinity and projects the reflected light forward by a convex lens, the reflecting mirror reflects the light incident from the light source bulb, and near the meridional image plane of the convex lens. It is characterized in that it is configured to be adjacent to above the cut line of the positioned shade and above the optical axis so as to form a maximum luminous intensity area.

[Action]

In the headlight configured as described above, the area of maximum illuminance in the vicinity of the shade is formed above the cut line of the shade, and the maximum illuminance portion is not blocked by the shade, so that the effective utilization rate of the light flux is high.

In addition, the incident light from the reflecting mirror and the light source bulb may be configured to be condensed above the cut line of the shade, and is regulated in terms of analytical geometry such as a paraboloid of revolution or a spheroid of revolution. Since the shape is not the desired shape, the degree of freedom in design is large, and it is easy to obtain a desired luminous intensity distribution.

〔Example〕

Next, an embodiment of a projector type vehicle headlamp according to the present invention will be described in detail with reference to FIGS. 9 to 11 before describing in detail with reference to FIGS. 1 to 11. Of 1
An outline of the arrangement of the constituent members of the embodiment will be described.

FIG. 9 is an explanatory diagram in which a cross section including the optical axis Z is drawn in a schematic view and an optical path is added. Similarly, FIG. 10 is an explanatory view in which a light path is added to a vertical section including the optical axis Z, and FIG. 11 is an explanatory view schematically illustrating the front viewed from the lens side.

The basic structure of the projector type automotive headlamp according to the present invention is arranged such that the optical axis of the concave mirror and the optical axis of the convex lens are aligned with each other, and a light source bulb is installed in the vicinity of the focal point of the concave mirror. The light emitted from the light source is reflected by the concave mirror and is incident on the meridional image plane of the convex lens, and a shade having a cut line is provided near the meridional image plane.

Reference numeral 1 is a concave mirror, and F is its focal point. The light source bulb 2 is provided so that the filament is located near the focal point F.

A convex lens is provided so as to share the optical axis Z with the concave mirror 1.

Reference numeral i-j shown in FIG. 12 denotes the meridional image plane of the convex lens 3, and the light emitted from the light source and reflected by the concave mirror 1 is incident on this meridional image plane.

The incident light is dimmed by the convex lens 3 and projected forward (rightward in FIGS. 9 and 10).

A screen is provided in the vicinity of the meridional image plane and the light distribution pattern is shown by isolux curves as shown in FIG.
H-H is a horizontal line on the screen, and V-V is a vertical line.

The light distribution pattern of FIG. 2 (this example) is the maximum illuminance part M.
Is located above the intersection of both H and V axes (a method of constructing such a light distribution pattern will be described later with reference to FIGS. 7 and 8).

As described above, since the maximum illuminance part M is biased upward, as shown in FIG. 1 in relation to the cut line 4a of the shade 4, the center point of the maximum illuminance part is a dimension h larger than the cut line 4a of the shade 4. It will be in a high position. Therefore, the maximum illuminance portion M is hardly blocked by the shade 4.

Therefore, the illuminance pattern on the screen is as shown in FIG. 3, and the 100lux curve has an almost elliptical shape with almost no cutout. In this way, the effective utilization rate of the luminous flux is improved.

The setting of the dimension h will be described below.

Reference numeral 1'shown in FIG. 4 shows a spheroidal surface that is close to the reflector 1 in this example (an assumed spheroidal surface for explaining the approximate calculation for calculating the dimension h).
ZZ is an optical axis, and 4 is a shade.

Light source bulb filament 2a slightly behind the focal point F of the ellipse
When is positioned, the optical arrow (a) emitted from the filament 2a is reflected as shown in (b) and forms an image near the cut line of the shade 4.

FIG. 5 is an explanatory view showing the relationship between the shade 4 and the filament image 2a '. The filament image 2a' is covered with the shade 4 by the height dimension h '.

Assuming that the focal length of the ellipse (Fig. 4) is 15 mm, the major radius is 50 mm, the filament length is 5.5 mm, and the filament diameter is 0.8 mm, the dimension h'shown in Fig. 5 is 5 mm.
Becomes Therefore, as in the filament image 2a "shown in FIG. 6, if the image is biased upward by h'dimension (5 mm) from that in FIG. 5, it will not be blocked by the shade 4.

As can be understood from the above approximate calculation, when the present invention is carried out, it is desirable to set the maximum illuminance portion near the shade above the shade by about 5 mm. Increasing this size above 5 mm does not increase the effect of the present invention. Further, the effect of the present invention is exhibited even when the thickness is 5 mm or less, but the effect decreases as the size becomes smaller, and the practical effect becomes difficult to recognize when the thickness is 0.5 mm or less.

As shown in FIGS. 1 and 2, FIG. 7 shows a method for making the light distribution pattern near the shade 4 (that is, near the meridional image plane of the convex lens 3) a desired characteristic.
Next, referring to FIG.

FIG. 7 is an explanatory view schematically showing a state in which 1/4 of the reflecting surface of the reflector 1 is divided into a large number of surface elements, and FIG. 8 shows incident light and reflected light of the surface element Q ₅ . FIG.

The reflective surface of the concave mirror 1 described above is considered by dividing it into a large number of surface elements as shown in FIG. 7, and the position and direction (represented by the direction of the normal line) of each of these large number of surface elements are determined.
Connect to each other to make one concave curved surface.

Of the many surface elements shown in FIG. 7, the surface element at the lower right corner of the figure is located at the center of the concave mirror 1. Therefore, the position of this central plane element is located at the origin of the X, Y, Z coordinates and is orthogonal to the Z axis (XY plane as shown in FIGS. 9 and 10). Parallel to).

When the position of the central surface element is determined in FIG. 7, the adjacent surface element to be connected to it is specified if its direction is determined.

Further, the reflective surface is calculated and enlarged toward the adjacent surface element.

Next, how to determine the direction of each surface element will be described.

The relationship of points on the reflector 6 corresponding to an arbitrary distance x _s point S from the center S _{1 of the} shade is obtained.

First, when x ₁ = 0 as an initial value, a set of small surface elements (Y
The arrangement in the axial direction) defines the direction of the surface element (represented by the normal direction) so that the reflected light reaches the point S ₁ .

As for the adjacent portion of the set of surface elements for which the initial value is set as described above, the direction is determined so that the reflected light reaches the adjacent portion of the point S ₁ , and the calculation is repeated in the same manner.

The above-mentioned x _s and x ₁ have a functional relationship and are x _s f (x ₁ ). Thus, the method of defining this function is determined based on the desired light distribution on the shade. Specifically, f (x ₁ ) = ax ₁ + b f (x ₁ ) = ax ₁ ² + bx _{1 + c f (x 1) =} ax 1 3 + bx 1 2 + cx 1 + d f (x 1) = a 1 x 1 n + a 2 x 1 n-1 ... a n x 1 + a n + 1 f (x 1) = ae Various techniques such as ^bx1 are conceivable and can be arbitrarily selected or used in combination. a, b, c, d are constants.

Hereinafter, a few examples will be described.

In the case of f (x ₁ ) = ax ₁ + b, assuming that a = 0.5 and b = 0, f (x ₁ ) = 0.5x _{1 and} x ₁ = 2, x _s = 1 is one of the solutions. .

The light distribution pattern in this case is as shown by a curve 1 shown by a chain line in FIG.

Under normal conditions of use of a vehicle headlight, it is desired that the luminous intensity of the central portion is intensively higher than that of the above light distribution pattern (curve 1).

Therefore, next, assuming that a = 0.125, b = 0, and c = 0 at f (x ₁ ) = ax ₁ ² + bx ₁ + c, then f (x ₁ ) = 0.125x ₁ ² , for example x ₁ = 4 , X _s = 2 is one of the solutions.

The light distribution pattern in this case is as shown by the broken line curve m in FIG. 15, and the central luminous intensity is higher than that of the curve l.

Although not shown, the higher-order functional expression f (x ₁ ) = ax ₁ ³ ＋ bx ₁ ² ＋ cx ₁ ＋ d, and f (x ₁ ) ＝ a ₁ x ₁ ⁿ ＋ a ₂ x ₁ ^{n As the value of} _{n in} ^-1 ... a _n x ₁ + a _{n + 1} is increased to 4,5, the central luminous intensity becomes higher, and the central luminous intensity becomes higher by using the logarithmic expression f (x ₁ ) = ae ^bx1 .

A desired light distribution characteristic may be obtained by appropriately selecting these equations and arbitrarily selecting constants a, b to d. Since the luminous intensity distribution characteristic remarkably changes widely depending on the order of the expression of x ₁ and the selection of the constant, any luminous intensity distribution characteristic can be obtained in a practical accuracy range.

However, the above-mentioned "practically any characteristic" means any luminous intensity distribution characteristic within the range of "a mode in which the luminous intensity is maximum in the central part and symmetrically in the left and right directions, and the luminous intensity decreases as the distance from the center increases". It is said that it can correspond to.

FIGS. 16 and 17 show an embodiment different from the embodiment shown in FIGS. 9 and 10, and the difference from the previous example is as follows. Compared to the shade 4 of the previous example (FIGS. 9 and 10) which is cylindrically shaped along the meridional image plane i-j,
The shade 4'in this example (Figs. 16 and 17) is formed in a flat plate shape in contact with the meridional image plane i-j and orthogonal to the optical axis Z.

Even with the configuration as in this example, the same effect as that of the previous example (FIGS. 9 and 10) can be obtained within the accuracy range practically required.

〔The invention's effect〕

As described above, the projector-type headlight of the present invention has a high effective utilization rate of the luminous flux emitted from the light source bulb, and can further arbitrarily set the luminous intensity distribution on the meridional image plane, resulting in easy It has an excellent practical effect that it can be configured to have a desired light distribution pattern.

[Brief description of drawings]

FIGS. 1 to 3 are tables showing optical characteristics in one embodiment of the present invention, FIGS. 4 to 6 are explanatory views relating to setting of the maximum illuminance area in the above embodiments, FIGS. 7 and 8 Is an explanatory view of the designing method in the above embodiment, FIG. 9 is a schematic plan layout view of the above embodiment, FIG. 10 is a side view layout thereof, and FIG. 11 is a front view thereof. FIG. 12 is a plan view of a known projector-type headlight.
13 and 14 are tables showing the optical characteristics of the above-mentioned known example. FIG. 15 is a chart showing luminous intensity distribution characteristics drawn by comparing the above-mentioned known example with the above-mentioned example. FIG. 16 is a plan view of an embodiment different from the above, and FIG. 17 is a side view of the same. 1 ... Concave reflecting mirror, 2 ... Light source bulb, 3 ... Convex lens, 4 ... Shade, 4a ... Cut line provided at the top of the shade.

Claims (1)

[Claims] 1. A light source bulb is installed near a focal point of a reflecting mirror,
In a projector-type headlight in which light emitted from the light source bulb is reflected by a reflecting mirror and focused near a shade having a cut line, and the reflected light is projected forward by a convex lens, the reflecting mirror is The light incident from the light source bulb is reflected so that it is adjacent to above the cut line of the shade positioned near the meridional image plane of the convex lens and above the optical axis to form the maximum luminous intensity area. A projector-type headlight, which is characterized by being