JPH01289001A - Projector type head light - Google Patents

Abstract

PURPOSE:To eliminate an uneven lighting distribution in the hot zone without losing a large freedom of design by making a horizontal belt-form area including the center, the right side, and the left side, in a rotary elliptical surface, and the other parts in a specific reflection surface. CONSTITUTION:A horizontal belt-form reflection surface is made in a rotary elliptical surface in which the first focus is positioned near the light source bulb, while the second focus is near the shade. As a result, the light source image focused by the horizontal belt-form surface is made in an image contracted in the lateral direction. Reflection surfaces at the upper and lower sides are made by estimating numerous surface elements to compose the reflection surfaces, and setting a desired brightness distribution formed by subtracting the reflection light from the rotary elliptical surface, from the light distribution on the shade responding to a desired light distribution pattern, while the numerous surface elements are set so that the directions of the surface elements are set to reflect the respective incident lights and to form a desired brightness distribution. Consequently, a desired composition can be made in respect of the design.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a projector type vehicle headlamp, and particularly to a projector type headlamp with improved light distribution characteristics.

[Conventional technology]

Automobile headlights must have a light distribution pattern that brightly illuminates the area in front of the vehicle's own lane and does not dazzle oncoming vehicles.

A projector-type automobile headlamp has been proposed as a headlamp that has light distribution characteristics that meet the above requirements, has a simple lens configuration, and can be made compact in overall size. The latest technology regarding this projector type headlight is known, for example, in Japanese Patent Application Laid-Open No. 58-209801.

FIG. 3 shows the above-mentioned known projector type headlamp. This known example headlamp is provided with a shell-shaped reflector, and the axial cross section of the inner reflective surface of this reflector is a part of an ellipse. In a vehicle headlamp in which the eccentricity of the ellipse increases from the axial vertical longitudinal section to the axial horizontal longitudinal section, the inner elliptical portion 101° 102 of all axial sections The focal point 105 is also the corresponding vertex 104 of the elliptical portion of all axial sections, 102.
are configured to match.

101 is an outer focus of the ellipse 102, 110 is a light shielding plate-like dimmer, 112 is an outer focus of the ellipse 101, and 113 is a lens.

FIG. 4 is a plan view schematically depicting an example of this type of projector type headlamp, and FIG. 5 is a side view of the same.

FIG. 6 is also a front view.

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 mentioned above.

A convex lens 3 is provided to share the optical axis Z with the concave mirror 1 described above.

4 indicates 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 above incident light is modulated by the convex lens 3 and is directed forward (
4 and 5).

When a screen is provided near the meridional image plane and the light distribution pattern is shown as an isoluminance curve, it becomes as shown in FIG.

H-H is a horizontal line on the screen, and v-■ is also a vertical line.

As shown in FIGS. 4 to 6, a shade 4 having an edge along the meridional image plane is provided. Specifically, a cut line 4a is formed so as to recede from the meridional image plane ij, as shown in 4a shown in FIG. FIG. 8 shows the overlap between the light distribution pattern (FIG. 7) and the shade 4. As shown in FIG. 8, the upper half of the light beam passes through. Although most of the lower half is blocked, light is allowed to pass through the portion corresponding to the cut line 4a.

As the partially covered light beams as described above are focused on the meridional image planes ij and intersect with each other, the light beams projected in front of the headlight have a pattern that is an inversion of the one shown in Fig. 8. form. FIG. 9 is an explanatory diagram showing the general shape of a light projection pattern using isoluminance curves on a screen provided in front of the headlight.

In FIG. 9, shade 4 is missing above the diagonal cut line Ci and above the horizontal cut line ch.
The shadow stands on end.

In addition, in a projector type headlamp in which the shade 4 is omitted, cut lines Ci and C are shown as imaginary lines.
Light is also distributed above h. Such a light distribution pattern is suitable when there are no oncoming vehicles.

FIG. 10 is an explanatory diagram of the light distribution characteristics of a projector type headlamp without the shade 4. In FIG.

FIG. 1O (A) is an isoluminance curve when the screen is illuminated, and the areas shown with spots are hot zones with an illuminance of 100 lux or more.

FIG. 10(B) is an illuminance distribution curve on the line HH in FIG. 10(A). Although this illuminance distribution curve changes depending on the length of the ellipse and how to take the short axis ratio, etc., it has a certain tendency and is determined by itself, and there is no degree of freedom in design.

As a technology for solving the above problems (inconveniences in design) and freely setting the illuminance distribution, JP-A-62-18
No. 6402 [Projector type headlamp] is known.

In the above-mentioned known technology, the reflecting surface of the reflecting mirror is divided into a central portion and left and right peripheral portions.

(i) The reflective surface at the center is an ellipsoid of revolution with the first focal point near the light source bulb and the second focal point near the shade, so that the reflected light is concentrated near the intersection of the shade and the optical axis. Configure.

(ii) The reflective surface at the left and right peripheral portions assumes a large number of surface elements constituting the reflective surface, and the reflected light from the spheroidal reflective surface is calculated from the luminous intensity distribution on the shade corresponding to the desired light distribution pattern. Set the desired luminous intensity distribution by subtracting
The direction of each surface element is set so as to reflect each incident light to form the desired luminous intensity distribution, and these many surface elements are assembled and arranged smoothly.

In the headlamp reflector configured as described above, the light reflected by the spheroidal reflecting surface in the center is concentrated near the intersection of the shade and the optical axis, resulting in a central luminous intensity distribution (in the left-right direction). This makes it easier to design the left and right peripheral areas of the reflector (based on the luminous intensity distribution on the shade that corresponds to the desired light distribution pattern).

It is sufficient to satisfy the remaining luminous intensity distribution after subtracting the light reflected by the spheroidal reflecting surface), and the shape of the reflecting surface at the left and right periphery is similar to that of a concave mirror in the prior art (
For example, a paraboloid of revolution, an ellipsoid of revolution, etc.)
All you have to do is find the desired light distribution characteristic on the shade and assemble the surface elements of the concave mirror to form this characteristic.
It can be configured to have arbitrary light distribution characteristics.

However, the above-mentioned "dividing the reflective surface and assuming surface elements" and "assembling the surface elements of a concave mirror" are division 1 assembly during design thinking, and dividing the actual tangible members. It's not something you have to do or assemble.

It is possible to divide the reflective surface to be constructed into hundreds of thousands of surface elements of 1, for example, 0.21 square, and calculate the direction (represented by the normal direction) for each surface element. It is almost impossible to do it manually, but it is not difficult if you use an electronic computer.

Next, an embodiment of the projector type vehicle headlamp according to the above-mentioned known example will be described with reference to FIGS. 11 to 21.

FIG. 12 is a cross-sectional view showing the design configuration of the reflector 6 in the above-mentioned known example, and its I-1 cross section is shown in FIG. 11.
This is a horizontal sectional view corresponding to FIG. 3 in No. 01), but the optical path in the right half is omitted because it is bilaterally symmetrical. Further, FIG. 13 shows a cross section taken along line 1--2 in FIG. 12.

The central part of the reflecting surface shown as area C' in FIG.
It is constructed as an ellipsoid of revolution with S as the first focal point and point S as the second focal point. In FIG. 12, the spheroidal surface portion is shown with spots.

Since the central portion C' shown in FIG. 11 is configured as a spheroidal surface, the light that enters the spheroidal surface 07 from the light source provided at one point F as shown by arrow 49 is as shown by arrows C and 2. Point Sr
(the second focal point placed on the intersection of the shade 4 and the optical axis)-).

In this way, the light intensity distribution near the center of the shade 4 is increased by the reflected light from the spheroidal surface C', so that the design of the portion other than the spheroidal surface C' becomes easier. in particular,
One spheroid C from the desired luminous intensity distribution on the shade
The remaining luminous intensity distribution after subtracting the luminous intensity distribution formed by the reflected light of C' (concentrated in the center) may be formed by the portion other than the spheroidal surface C' (the central portion of the reflecting mirror).

As a design method, consider dividing the area other than the above-mentioned spheroidal surface C', that is, the peripheral part D shown in FIG. 11 (the part not marked in FIG. 12) into a large number of surface elements.

FIG. 14 shows 1/4 of the reflective surface of the reflector 6.
FIG. 15 is an explanatory diagram schematically depicting a state where this is divided into a large number of surface elements, and FIG. 15 is an explanatory diagram of the optical path of the incident light and reflected light of the surface element Q5.

Find the relationship between a point Q on the reflector 6 corresponding to a point S at an arbitrary distance x5 from the center S1 of the shade 4 (see FIG. 11), that is, a microsurface element located at a distance xl from the center T of the reflector 6. The relationship between the set QI Q-Q2 (Fig. 12) is determined as follows.

First, when xl=o as the initial value, the set Q of microsurface elements
3-QaQ4 determines the direction of the surface element (represented by the normal direction) so that the reflected light reaches the point S1.

Set of surface elements Qs-Q6 with initial values set as above
Regarding the adjacent portion of Q4, the direction is determined so that the reflected light reaches the portion adjacent to the point S1, and the calculation is repeated in the same manner.

The above-mentioned Xs and Xl have a functional relationship, which is X5 f (x spirit).This function is determined based on the desired light distribution on the shade, but specifically, f (x+) =axl+b f (xl) =ax1”+bx1+cf (XI
)=axl”+bx1”+cxl+df (XI
) =alxln+a2xl ”'anXl+an+
Various methods such as 1f (XI) = aebX' can be considered, and 5alb, c, and d are constants that can be arbitrarily selected or used in combination.

A few examples will be described below.

In the case f (xl) = axl + b, a = 0
．． 5. Assuming b = O, f (xl) =
0.5 xl and xI=2. x5=1 is one of the solutions. If this is expressed on the coordinate plane, it will now look like Figure 16.

If the above state is replaced with the relationship between the horizontal cross-sectional shape of the reflector 6 and the meridional image plane (upper edge of the shade), the result will be as shown in FIG. 17. That is, light in two ranges on the reflector 6 side is collected in one range on the meridional image plane, and the light distribution pattern in this case is as shown by the solid line in FIG. 18.

The light reflected by the spheroidal surface C' is concentrated near the center, forming the pattern shown by the chain line, and what actually works effectively is the sum of both patterns (the solid line and the chain line).

Under normal usage conditions of an automobile headlamp, it is desirable that the luminous intensity in the central portion be concentrated and higher than in the above-mentioned light distribution pattern (FIG. 18).

So first order.

f (xl) = a xl”+b a in x1+c
=0.125. Assuming b=o, c=0, f (x
l) =0.125xl'', and one solution is, for example, xI = 4 and xs = 2.

When this is expressed on the coordinates, it is as shown in FIG. 19, and the relationship between the reflector and the shade is as shown in FIG. 20. The light distribution characteristics in this case are as shown by the solid line in FIG. 21, and the center luminous intensity is higher than that in FIG. 3 described above.

Although not shown, the above-mentioned high-level function equation, f (X
I) =axl"+bxl"+cxl+d, and further, f (XI) =alx+"+a2x4
・=anxl+a As the value of n in n44 increases to 4 or 5, the central luminous intensity increases, and is a logarithmic formula.

f (x+) = a ebX' If you use , the center luminosity will be even higher.

What is necessary is to select these formulas appropriately and arbitrarily select the constants a, b to d to obtain the desired light distribution characteristics.
Since the luminous intensity distribution characteristics vary widely depending on which order of I is used and the selection of constants, any luminous intensity distribution characteristics can be obtained within a practical accuracy range.

[Problem to be solved by the invention]

In the above-mentioned projector type headlamp, when the filament of the light source bulb 2 is installed horizontally (see Fig. 4), the light beam emitted from the filament is reflected by the concave mirror 1 and forms a real image at the second focal point F. This image is projected forward by the convex lens 3.

As a result, as shown in FIG. 10(B), unevenness occurs at the peak portion (corresponding to the hot zone) of the illuminance distribution curve. In other words, uneven light distribution occurs.

Such unevenness makes it difficult to drive at night, and also makes it difficult to measure the maximum illuminance during maintenance work.

The purpose of the present invention is to solve the above-mentioned known technology (Japanese Patent Application Laid-open No. 62-1864).
The unevenness of light distribution in the hot zone has been eliminated without compromising the ``great degree of freedom in design,'' which is the advantage of ``No. 02''.
The purpose of the present invention is to provide a projector type headlight (with a monotonous illuminance distribution).

[Means to solve the problem] FIG. 22 is a detailed explanatory diagram of the present invention.

When a filament is placed horizontally at the focal point of a spheroidal concave mirror and perpendicular to the optical axis, the filament image formed by each part of the concave mirror is different for each part (reflected location). FIG. 22(C) shows filament images drawn at each reflection location. However, the imaging range of the filament is shown as a rectangle.

As can be seen from the diagram in book (C), the following rules are observed.

(b) The image reflected at the center is large and in the correct posture.

(b) The image becomes slightly smaller as it moves upward or downward.

(c) The image becomes smaller as it moves to the right or left, especially to the left or right.

(d) If you go diagonally upward or downward, the statue will be in a tilted position.

The present invention utilizes this principle.

FIG. 22(A) is a schematic and simplified drawing of FIG. 12 in the prior art, in which the center portion C' (area shown with spots) divided in the left and right direction is a spheroidal ellipsoid. The area without a single spot is the special reflective surface.

FIG. 22(B) is a schematic diagram of the reflector in the present invention (
(front view), the area marked with one spot is the spheroidal surface.

The horizontal band-shaped area (spotted area) including the central part, the right side of the central part, and the left side thereof is an ellipsoid of revolution, and the other parts (the upper and lower non-spotted areas) are similar to those in the above-mentioned known technology. It is a special reflective surface.

However, regarding the names of left and right, (because it is a front view)
The left and right sides of the page are opposite.

[Effect]

The condensing pattern near the second focal point of a projector-type headlamp is configured to have a flat shape that is long on the left and right and short on the top and bottom, as shown in Figure 7 (forming an illumination area that is diffused in the left and right). For).

As a result, the light source image formed by the spotted portion C' (mainly the spheroidal surface forming the hot zone) in FIG. 22(A) (conventional example), The image of the filament) is relatively elongated laterally.

In comparison, the light source image formed by the horizontal band-like portions shown with spots in FIG. 22(B) (present invention) has a shape that is shrunk in the left-right direction.

In the conventional example (A), since the hot zone was formed by a reflective surface in a vertical area forming a horizontally wide image, the coil shape of the filament was projected, causing uneven light distribution within the hot zone.

In the present invention (B), a hot zone is formed in a horizontal band-shaped area (center, right, and left spots) connecting left and right shrunk images, so the coil shape of the filament in a horizontal position shrinks left and right. Eliminate uneven light distribution.

〔Example〕

FIG. 1 is an explanatory diagram of the structure and operation of an embodiment of a projector type headlamp according to the present invention.

FIG. 1(A) schematically depicts a front view of the concave mirror 7 in this embodiment, and the configuration is essentially the same as that of FIG. 22(B) described above.

That is, the central, right, and left parts shown with spots are one spheroidal part, and the spots are not shown.
The lower part is from the above-mentioned known document (Japanese Unexamined Patent Publication No. 186402/1986)
It is a special aspect similar to .

Let us now temporarily place a point a in the area above the central part formed by one spheroidal surface as in the above-mentioned known technique.

Considering b and c, the outline of the range where the light emitted from the filament is reflected at these points a, b, and c and connected is a' and b' shown in Figure 1 (B).

As shown in C', the area is relatively spread from side to side.

Although not shown, the central lower part of the concave mirror 7 is symmetrical to the upper part thereof, and therefore the image of the filament is also similar.

A point jek is placed in the area to the right of the center shown in Figure 1 (A).
Taking mQ and considering it, jZ shown in Figure 1 (C) of this book
A filament image is formed in the range of k' and Q', and the above (
The area is shrunk in the left and right direction compared to B).

The left area shown in FIG. 1(A) is also similar (opposed) compared to FIG. 1(C).

Point d is located in the upper left area of the four corners of the concave mirror 7.

Considering s and f, the imaging range of the filament image is d' and e', respectively, as shown in FIG. 1(D).

It is like f'.

The lower right portion is the same as in FIG. 1(D) described above.

The range of the filament image reflected at the lower left point g+)lel of the concave mirror 7 is g' and h' in FIG. 1(E).

It becomes like i'. The same applies to the upper right corner.

In Figure 1 CB) and (C) above, 1 point at b.

In cyJ*, only the range of the filament image at +2 (imaging range near the second focal point) is roughly expressed as a', b',
Fig. 2 shows the shape of each filament image.

In order to explain the operation, FIG. 2 depicts a case where the entire surface of the concave mirror is constituted by an ellipsoid of revolution.

a' shown in Figure 2 is the luminous flux reflected at five points a,
This is the image formation shape near the second focal point.

Similarly, b' is the shape of the reflected image at point C, and c' is the shape of the reflected image at point C.
The shape of the reflected image.

j', kI, Ql are the shapes of the reflected images at Q at point j.

Reflection image a1. When bl and cI are superimposed, (a
'+b'+c'), which relatively represents the outline of a coiled filament, so the area where such an image is formed (the upper and lower areas including points a, b, and c) is a spheroid. Instead of a surface, use the above-mentioned special surface.

On the other hand, when the reflected images j', k', and a' are superimposed, it becomes as shown in Figure 1 ('+g' on j'+), and the shape of the coiled filament is almost indistinguishable. Does not occur.

The superimposed image of the filament shown in Figure 2 (j′+ is ′+Ω
') forms a hot zone (10 on j+) on the screen as shown in the first @ (F).

Since this hot zone j+2 is a projection of '+a' onto the filament image j'+ shown in FIG. 2, there is no uneven light distribution.

Above the areas other than those marked with spots in Figure 1 (A).

The reflected light beam at the bottom forms the diffuser shown in FIG. 1(F). The light distribution characteristics of this diffusion section can be determined by the known technology (
Applying JP-A-62-186402), a large number of surface elements constituting the reflective surface are assumed, and the reflected light from the spheroidal reflective surface is subtracted from the luminous intensity distribution on the shade corresponding to the desired light distribution pattern. The desired luminous intensity distribution is set, and the direction of each surface element is set so that each of the plurality of surface elements reflects the incident light to form the desired luminous intensity distribution. I can do it.

〔Effect of the invention〕

As explained above, the projector-type headlamp to which the present invention is applied has the advantage that it has a large degree of freedom in designing its light distribution characteristics as desired, and can prevent uneven light distribution inside the hot zone. It has practical effects.

Figure 1 (A) is an explanatory diagram that schematically divides the front view of the concave mirror, Figures 1 (B) to (E) are explanatory diagrams of the imaging range of the filament, and Figure 1 (F) is an explanatory diagram of the image forming area on the screen. FIG. 3 is an explanatory diagram of light distribution characteristics.

FIG. 2 is an explanatory diagram showing images of the filament reflected at various points on the concave mirror.

FIGS. 3 to 10 are explanatory diagrams of commonly used projector type headlamps.

11 to 21 show the latest known technology (Japanese Unexamined Patent Publication No. 62
-186402) is an explanatory diagram of a projector type headlamp according to the invention.

FIG. 22 is an explanatory diagram of the basic configuration of the present invention.

DESCRIPTION OF SYMBOLS 1... Concave reflecting mirror, 2... Light source bulb, 3... Convex lens, 4, 4'... Shade, 4a... Cut line provided at the upper end of the shade, 5, 6... Reflector,
7... Concave mirror in one embodiment of the present invention.

Claims (1)

[Claims] 1. A projector in which a light source bulb is installed near the focal point of a reflecting mirror, the light emitted from the light source bulb is reflected by the reflecting mirror and focused, and the reflected light is projected forward by a convex lens. In the type headlight, (a) a horizontal band-shaped area including the central part of the reflector and the left and right parts of the central part is assumed; (b) above the horizontal band-shaped area, (c) the reflective surface of the horizontal strip is a spheroidal surface with a first focal point near the light source bulb and a second focal point near the shade; (d) the upper and lower reflective surfaces assumes a large number of surface elements constituting the reflective surface, and sets a desired luminous intensity distribution by subtracting the reflected light from the spheroidal reflective surface from the luminous intensity distribution on the shade corresponding to the desired light distribution pattern, The direction of each of the plurality of surface elements is set so as to reflect each incident light to form the desired luminous intensity distribution, and the large number of surface elements are assembled and arranged smoothly. A projector-type headlight.