Patent Description:
In one device devised in recent years, light emitted from a light source is reflected forward from the vehicle, and the reflected light is scanned over a region ahead of the vehicle to form a predetermined light-distribution pattern. For example, there has been devised an optical unit that includes a plurality of light sources composed of light-emitting elements and a rotary reflector that rotates unidirectionally about an axis of rotation while reflecting light emitted from the light sources. The rotary reflector includes a reflective surface provided to form a desired light-distribution pattern with the light from the light sources reflected by the rotating rotary reflector (patent document <NUM>).

This optical unit can also form a non-irradiation region in a portion of a light-distribution pattern by turning off a light-emitting element at a predetermined timing.

<CIT> discloses a lighting circuit and vehicular lighting device in which blade receives light emitted from a light source and repeats a predetermined periodic motion to scan the front of a vehicle with reflected light of the emitted light.

<CIT> discloses a vehicular lamp including a movable reflector, a first light-emitting unit, a second light-emitting unit and a light control member that collects and projects reflected light.

<CIT> describes a headlight for motor vehicles incorporating the features of the preamble of claim <NUM>. A further vehicle headlamp is known from <CIT>. patent document <NUM>: <CIT>.

The above-described optical unit, however, has a limitation in terms of the shape of the light-distribution pattern that can be formed, and there remains room for further improvement.

The present invention has been made in view of the above and is directed to providing a novel optical unit that can form a plurality of light-distribution patterns with a simple configuration.

To solve the foregoing issue, an optical unit as set out in the characterizing part of the appended claim <NUM> is provided.

The invention provides a difference between the length of a region formed as the light emitted from the first light-emitting element is scanned as a light source image and the length of a region formed as the light emitted from the second light-emitting element is scanned as a light source image. This configuration makes it possible to form a greater number of light-distribution patterns with different shapes as compared to a case in which the status of each light-emitting element can be selected only from being continuously on and being continuously off.

In the light source, the first light-emitting element and the second light-emitting element are arrayed in a direction intersecting a direction in which the light is scanned as the light source image. This configuration can form a step-like light-distribution pattern with a small number of light-emitting elements.

The plurality of light-emitting elements includes a third light-emitting element. The third light-emitting element is disposed so as to scan a region that overlaps a region that the first light-emitting element scans and a region that the second light-emitting element scans, and the controller controls an output of the third light-emitting element such that a duration T3 for which the third light-emitting element is on satisfies T1 > T3 > T2. This configuration forms a step-like light-distribution pattern with a smaller step.

The controller controls the on state of the plurality of light-emitting elements such that the light-distribution pattern has a cutoff line on a host vehicle's lane side that rises obliquely or stepwise toward an outer side. This configuration forms a light-distribution pattern having an oblique cutoff line suitable for a vehicle headlamp.

In the light source, the plurality of light-emitting elements may be disposed in a matrix of m rows by n columns (m and n may each be an integer no smaller than <NUM>), and the light-emitting elements in a (k-<NUM>)th column may be disposed unlevel with the light-emitting elements in a kth column by approximately one-nth of a pitch (k may be an integer no greater than n). This configuration can form a step-like light-distribution pattern with a smaller step.

Any optional combination of the above constituent elements or an embodiment obtained by converting what is expressed by the present invention among a method, an apparatus, a system, and so on is also effective as an embodiment of the present invention.

With the present invention, a plurality of light-distribution patterns can be formed with a simple configuration.

Hereinafter, the present invention will be described on the basis of embodiments with reference to the drawings. Identical or equivalent constituent elements, members, and processes illustrated in the drawings are given identical reference characters, and duplicate descriptions thereof will be omitted as appropriate. The embodiments are illustrative in nature and are not intended to limit the invention. Not all the features and combinations thereof described in the embodiments are necessarily essential to the invention.

An optical unit according to the embodiments can find its use in a variety of vehicle lamps. In the cases described hereinafter, the optical unit according to the embodiments is applied to, among vehicle lamps, a vehicle headlamp.

<FIG> is a horizontal sectional view of a vehicle headlamp according to the present embodiment. <FIG> is a front view of the vehicle headlamp according to the present embodiment. <FIG> omits some of the components.

A vehicle headlamp <NUM> according to the present embodiment is a right-side headlamp to be mounted in a vehicle's front right portion and has the same structure as a headlamp to be mounted in the left side except that these headlamps are horizontally symmetric. Therefore, the right-side vehicle headlamp <NUM> will be described below in detail, and the description of the left-side vehicle headlamp will be omitted.

As illustrated in <FIG>, the vehicle headlamp <NUM> includes a lamp body <NUM> having a concave portion that opens toward the front. The front opening of the lamp body <NUM> is covered by a transparent front cover <NUM> to form a lamp room <NUM>. The lamp room <NUM> functions as a space that houses one optical unit <NUM>. The optical unit <NUM> is a lamp unit configured to be capable of emitting both a variable high beam and a low beam. A variable high beam refers to a high beam that is being so controlled as to change the shape of a high-beam light-distribution pattern. For example, a non-irradiation region (shaded portion) can be produced in a portion of a light-distribution pattern.

The optical unit <NUM> according to the present embodiment includes a first light source <NUM>, a condenser lens <NUM>, a rotary reflector <NUM>, a projection lens <NUM>, a second light source <NUM>, a diffuser lens <NUM>, and a controller <NUM>. The condenser lens <NUM>, serving as a primary optical system (optical member), redirects an optical path of first light L1 emitted from the first light source <NUM> toward blades 22a of the rotary reflector <NUM>. The rotary reflector <NUM> rotates about an axis of rotation R while reflecting the first light L1. The second light source <NUM> is disposed between the first light source <NUM> and the projection lens <NUM>. The diffuser lens <NUM>, serving as a primary optical system (optical member), redirects second light L2 emitted from the second light source <NUM> toward the blades 22a.

The first light source <NUM> includes <NUM> elements disposed in a matrix. The second light source <NUM> includes four elements arrayed in a line.

The projection lens <NUM> includes a condenser 24a and a diffuser 24b. The condenser 24a condenses the first light L1 reflected by the rotary reflector <NUM> and projects the condensed first light L1 in a light-irradiation direction of the optical unit (the left direction in <FIG>). The diffuser 24b diffuses the second light L2 reflected by the rotary reflector <NUM> and projects the diffused second light L2 in the light-irradiation direction of the optical unit. This configuration makes it possible project a clear light source image toward a space ahead of the optical unit <NUM>.

<FIG> is a side view schematically illustrating a configuration of the rotary reflector according to the present embodiment. <FIG> is a top view schematically illustrating a configuration of the rotary reflector according to the present embodiment.

The rotary reflector <NUM> rotates with a driving source, such as a motor <NUM>, unidirectionally about the axis of rotation R. The rotary reflector <NUM> includes the blades 22a, serving as a reflective surface, provided to form a desired light-distribution pattern by scanning light from each light source reflected by the rotating rotary reflector <NUM>. In other words, the rotating operation of the rotary reflector causes visible light from a light emitter to be emitted as an irradiation beam, and a desired light-distribution pattern is formed as the rotary reflector <NUM> scans the irradiation beam.

The rotary reflector <NUM> includes the two blades 22a, which function as a reflective surface and are identical in shape, and the two blades 22a are provided around a cylindrical rotary portion 22b. The axis of rotation R of the rotary reflector <NUM> is at an angle relative to an optical axis Ax and lies in a plane that includes the optical axis Ax and each light source. To rephrase, the axis of rotation R extends substantially parallel to a scanning plane of light (irradiation beam) from each light source that is scanned in the right-left direction as the rotary reflector <NUM> rotates. This configuration reduces the thickness of the optical unit. Herein, the scanning plane can be regarded as a fan-shaped plane formed by continuously connecting the trajectories of light from each light source, or the scanning light, for example.

Each blade 22a of the rotary reflector <NUM> has a twisted shape in which the angle formed by the optical axis Ax and the reflective surface changes along the circumferential direction about the axis of rotation R. This configuration enables the scan with the light from the first light source <NUM> and the second light source <NUM>, as illustrated in <FIG>.

Each light source is a semiconductor light-emitting element, such as an LED, an EL element, or an LD element. The shape of the convex projection lens <NUM> having the condenser 24a and the diffuser 24b may be selected as appropriate in accordance with the light-distribution characteristics, such as a required light-distribution pattern or an illuminance distribution. An aspherical lens or a free-form surface lens can also be used as the projection lens <NUM>.

The controller <NUM> controls the on/off of the first light source <NUM> and the second light source <NUM> and controls the rotation of the motor <NUM> in accordance with a control signal from the outside. The first light source <NUM> is mounted on a heat sink <NUM>, and the second light source <NUM> is mounted on a heat sink <NUM>.

<FIG> is a schematic diagram in which the first light source according to the present embodiment is viewed from the front. <FIG> omits the condenser lens <NUM>. The light source image illustrated in <FIG> is inverted vertically by the projection lens <NUM>.

As illustrated in <FIG>, the first light source <NUM> includes a first light emitter <NUM>, a second light emitter <NUM>, and a third light emitter <NUM>. The first light emitter <NUM> is turned on to form a first light-distribution pattern that irradiates mainly a range below a horizontal line. The second light emitter <NUM> is turned on to form a second light-distribution pattern that irradiates at least a range above the horizontal line. The third light emitter <NUM> emits light for defining a cutoff line on the host vehicle's lane side near the horizontal line when the first light-distribution pattern is formed. The third light emitter <NUM> is disposed in a region between the first light emitter <NUM> and the second light emitter <NUM>.

The first light emitter <NUM> includes five first light-emitting elements S11 to S15 disposed in a zigzag manner along the horizontal direction (H-H line) (to rephrase, the position of one element in the vertical direction is offset upward or downward relative to the position of its adjacent element). The first light-emitting elements S11 to S15 each have a rectangular light-emitting surface and are each disposed with one side of the rectangle extending in the horizontal direction.

The second light emitter <NUM> includes nine second light-emitting elements S21 to S29 disposed in a zigzag manner along the horizontal direction. The second light-emitting elements S21 to S29 each have a rectangular light-emitting surface and are each disposed with one side of the rectangle extending in the horizontal direction.

The third light emitter <NUM> includes two third light-emitting elements S31 and S32 disposed between the first light-emitting elements S11 to S15 and the second light-emitting elements S21 to S29. The third light-emitting elements S31 and S32 are each disposed with one side of its rectangular light-emitting surface extending in the horizontal direction. This configuration makes a dark portion resulting from a gap between the elements less likely to occur in a light-distribution pattern.

Each light-emitting element is preferably a semiconductor light-emitting element that can be easily controlled on/off in a short period of time, and examples include an LED (Light Emitting Device), an LD (Laser Diode), and an EL (Electroluminescent) element.

<FIG> is a schematic diagram illustrating a state in which light source images of the first light emitter and the third light emitter that are on are reflected and projected forward by the stationary rotary reflector. <FIG> illustrates a first light-distribution pattern formed as the light source images illustrated in <FIG> are scanned by the rotating rotary reflector.

Light source images L11 to L15 illustrated in <FIG> correspond to the light-emitting surfaces of the respective first light-emitting elements S11 to S15. Light source images L31 and L32 correspond to the light-emitting surfaces of the respective third light-emitting elements S31 and S32. As the light source images L11 to L15, L31, and L32 are scanned, scan patterns P11 to P15, P31, and P32 illustrated in <FIG> are formed, and as the scan patterns are superposed on each other, a low-beam light-distribution pattern PL serving as the first light-distribution pattern that irradiates mainly a range below the horizontal line is formed.

If the third light-emitting elements S31 and S32 are kept on, like the first light-emitting elements S11 to S15, not only a cutoff line CL1 on the host vehicle's lane side but also a cutoff line CL2 on the oncoming vehicle's lane side is formed above the horizontal line in the low-beam light-distribution pattern PL, as illustrated in <FIG>. This may cause glare on an occupant in an oncoming vehicle.

Therefore, the controller <NUM> controls the on state of the first light source <NUM> such that the on duration of the third light-emitting elements S31 and S32 is shorter than the on duration of the first light-emitting elements S11 to S15 when the low-beam light-distribution pattern PL is formed. To be more specific, the controller <NUM> turns on the corresponding element at a timing at which the light source image L31 or L32 of the third light-emitting element S31 or S32 passes through a region on the left side of the V-V line indicated in <FIG> and turns off the corresponding element at a timing at which the light source image L31 or L32 passes through a region on the right side of the V-V line. This control makes it possible to raise only an upper end of the cutoff line CL1 on the host vehicle's lane side, for example. In addition, the position (length) of the cutoff line CL1 on the host vehicle's lane side can be changed by controlling the on/off of the third light-emitting elements S31 and S32 while scanning the light emitted from the third light-emitting elements S31 and S32.

<FIG> is a schematic diagram illustrating a state in which a light source image of the second light emitter that is on is reflected and projected forward by the stationary rotary reflector. <FIG> illustrates a second light-distribution pattern formed as the light source image illustrated in <FIG> is scanned by the rotating rotary reflector.

Light source images L21 to L29 illustrated in <FIG> correspond to the light-emitting surfaces of the respective second light-emitting elements S21 to S29. As the light source images L21 to L29 are scanned, scan patterns P21 to P29 illustrated in <FIG> are formed, and as the scan patterns are superposed on each other, a high-beam light-distribution pattern PH serving as the second light-distribution pattern that irradiates at least a range above the horizontal line is formed. The first light emitter <NUM> may be turned on when the high-beam light-distribution pattern PH is formed. This can achieve a new light-distribution pattern in which the low-beam light-distribution pattern PL and the high-beam light-distribution pattern PH are superposed on each other.

Now, the second light source <NUM> will be described. The second light L2 emitted from the second light source <NUM> is reflected off a blade of the rotary reflector <NUM> at a position that is closer to the projection lens <NUM> than the position where the first light L1 emitted from the first light source <NUM> is reflected off a blade of the rotary reflector <NUM>. Thus, it is better if the light emitted from the second light source <NUM> spreads in order to irradiate a broader range. Therefore, the diffuser lens <NUM> is disposed near the light-emitting surface of the second light source <NUM>. This configuration can enlarge a light source image formed by the second light L2 that has been reflected by the rotary reflector <NUM> and passed through the diffuser 24b of the projection lens <NUM>. The second light source <NUM> includes a fourth light emitter <NUM> having four fourth light-emitting elements S41 to S44 arrayed in a line (see <FIG>).

<FIG> is a schematic diagram illustrating a state in which a light source image of the fourth light emitter that is on is reflected and projected forward by the stationary rotary reflector. <FIG> illustrates a third light-distribution pattern formed as the light source image illustrated in <FIG> is scanned by the rotating rotary reflector.

Light source images L41 to L44 illustrated in <FIG> correspond to the light-emitting surfaces of the respective fourth light-emitting elements S41 to S44. As the light source images L41 to L44 are scanned, scan patterns P41 to P44 illustrated in <FIG> are formed, and as the scan patterns are superposed on each other, a diffused low-beam light-distribution pattern PL' serving as the third light-distribution pattern that irradiates mainly a broad range below the horizontal line is formed.

<FIG> illustrates a high-beam light-distribution pattern PH' formed when all the light-emitting elements in the first light source and the second light source are turned on to scan the light. As illustrated in <FIG>, a new light-distribution pattern different from the first light-distribution pattern and the second light-distribution pattern can be achieved.

As described above, the optical unit <NUM> according to the present embodiment can form a plurality of light-distribution patterns (PL, PL', PH, PH') with different irradiation ranges with the use of the rotary reflector <NUM> that rotates unidirectionally about the axis of rotation while reflecting the light emitted from the first light source <NUM> and the second light source <NUM>.

The first light emitter <NUM> and the second light emitter <NUM> may be provided as completely different regions, as in the first light source <NUM> according to the present embodiment. Alternatively, some of the light-emitting elements and/or light-emitting regions may overlap each other. In other words, there may be a light-emitting element or a light-emitting region that is used for both the first light-distribution pattern and the second light-distribution pattern.

<FIG> illustrates a control device of the vehicle headlamp according to the present embodiment. As illustrated in <FIG>, a control device <NUM> of the vehicle headlamp <NUM> according to the present embodiment includes a camera <NUM>, a radar <NUM>, a switch <NUM>, a detector <NUM>, a sensor <NUM>, the controller <NUM>, the motor <NUM>, the first light source <NUM>, and the second light source <NUM>. The camera <NUM> captures an image of a space ahead of the vehicle and an image of the surroundings of the vehicle. The radar <NUM> detects the presence of and the distance to another vehicle or a pedestrian in front of the vehicle. The switch <NUM> allows the driver to control the on state of the vehicle headlamp and its irradiation mode (selection between a high-beam light-distribution pattern and a low-beam light-distribution pattern, automatic control mode, etc.). The detector <NUM> detects the steering status. The sensor <NUM> includes, for example, a vehicle-speed sensor and an acceleration sensor.

The controller <NUM> controls the rotation of the motor <NUM> and the on/off of each light-emitting element in the first light emitter <NUM> to the fourth light emitter <NUM> included in the first light source <NUM> and the second light source <NUM> on the basis of information acquired from the camera <NUM>, the radar <NUM>, the switch <NUM>, the detector <NUM>, and the sensor <NUM>. This can achieve the novel optical unit <NUM> that can form a plurality of light-distribution patterns with a simple configuration.

In the low-beam light-distribution pattern PL obtained by superposing the scan patterns P11 to P15, P31, and P32 on each other as illustrated in <FIG> and the high-beam light-distribution pattern PH obtained by superposing the scan patterns P21 to P29 on each other as illustrated in <FIG>, each scan pattern has a substantially equal length. In other words, the on durations of the light-emitting elements corresponding to the respective scan patterns are substantially equal. Thus, there is a limitation in the shape of the light-distribution pattern that can be formed by controlling the on/off of the light-emitting elements.

Accordingly, the controller <NUM> is configured to be capable of controlling the on durations of the plurality of light-emitting elements included in each light source individually or per group. This configuration makes it possible to form a desired light-distribution pattern by combining scan patterns of different lengths, and thus an optical unit that can form light-distribution patterns of a large number of shapes can be achieved.

<FIG> is a schematic diagram illustrating a state in which the light sources images of the first light emitter to the third light emitter that are on are reflected and projected forward by the stationary rotary reflector. <FIG> illustrates a fourth light-distribution pattern formed as the light source images illustrated in <FIG> are scanned by the rotating rotary reflector.

The light source images L11 to L15 illustrated in <FIG> correspond to the light-emitting surfaces of the respective first light-emitting elements S11 to S15. The light source images L21 to L23, L26, and L27 correspond to the light-emitting surfaces of the respective second light-emitting elements S21 to S23, S26, and S27. The light source images L31 and L32 correspond to the light-emitting surfaces of the respective third light-emitting elements S31 and S32. When a fourth light-distribution pattern PH" is formed, the second light-emitting elements S24, S25, S28, and S29 remain off for the entire duration. In other words, it can be said that the second light-emitting elements S24, S25, S28, and S29 have the shortest on duration.

Meanwhile, the first light-emitting elements S11 to S15 have the longest on duration T1 per cycle, and as the scan patterns P11 to P15 illustrated in <FIG> are formed and these scan patterns are superposed on each other, the first light-emitting elements S11 to S15 irradiate mainly a range R1 below the horizontal line.

The light-emitting element S31 has an on duration of T31 (T31 < T1) per cycle, and the light-emitting element S32 has an on duration of T32 (T32 < T31 < T1) per cycle. As illustrated in <FIG>, the light-emitting elements S31 and S32 irradiate mainly a range R2 including the H-H line on the host vehicle's lane side. The range R2 partially overlaps the range R1.

The light-emitting element S21 has an on duration of T21 (T21 < T1) per cycle, and the light-emitting element S23 has an on duration of T23 (T23 < T21 < T1) per cycle. As illustrated in <FIG>, the light-emitting elements S21 and S23 irradiate mainly a range R3 immediately above the H-H line on the host vehicle's lane side. The range R3 partially overlaps the range R2.

The light-emitting element S22 has an on duration of T22 (T22 < T1) per cycle. As illustrated in <FIG>, the light-emitting element S22 irradiates a range R4 that overlaps an upper portion of the range R3.

The light-emitting element S27 has an on duration of T27 (T27 < T1) per cycle. As illustrated in <FIG>, the light-emitting element S27 irradiates a range R5 that overlaps an upper portion of the range R4.

The light-emitting element S26 has an on duration of T26 (T26 < T1) per cycle. As illustrated in <FIG>, the light-emitting element S26 irradiates a range R6 that overlaps an upper portion of the range R5.

The relationship among the on durations of the respective light-emitting elements is T27 ≤ T32 < T26 < T23 < T22 < T31 < T21 < T1.

The controller <NUM> can form the fourth light-distribution pattern in which the cutoff line on the host vehicle's lane side rises obliquely or stepwise toward the outer side, as illustrated in <FIG>, by not only selecting the light-emitting elements to be turned on but also controlling the on durations of the respective light-emitting elements to be turned on. In this manner, the optical unit according to the present embodiment can form a light-distribution pattern having an oblique cutoff line suitable a vehicle headlamp.

As described above, the optical unit <NUM> according to the present embodiment includes the first light source <NUM> having a plurality of light-emitting elements (S11 to S15, S21 to S29, S31, and S32) disposed in arrays, the rotary reflector <NUM> that rotates while reflecting light emitted from the first light source <NUM>, and the controller <NUM> that controls the on state of the plurality of light-emitting elements. The rotary reflector <NUM> includes a reflective surface provided to form a light-distribution pattern by scanning the light reflected by the rotating rotary reflector <NUM> as light source images (L11 to L15, L22 to L29, L31 and L32), and the plurality of light-emitting elements include the first light-emitting elements (S11 to S15) and the second light-emitting elements (S21 to S29, S31, and S32). The controller <NUM> controls the on state of the first light-emitting elements and the second light-emitting elements (or third light-emitting elements) such that the on duration T1 of the first light-emitting elements (S11 to S15) becomes longer than an on duration T2 (T2 > <NUM>) of the second light-emitting elements (S21 to S29). The plurality of light-emitting elements that are to have different on durations can be combined in any manner.

The optical unit <NUM> according to the present embodiment can provide a difference between the length of a region formed as the light emitted from the first light-emitting elements (S11 to S15) is scanned as light source images and the length of a region formed as the light emitted from the second light-emitting elements (S21 to S29) is scanned as light source images. This configuration makes it possible to form a greater number of light-distribution patterns with different shapes as compared to a case in which the status of each light-emitting element can be selected only from being continuously on and being continuously off.

In the first light source <NUM>, the first light-emitting element (S12), the second light-emitting elements (S22, S26), and the third light-emitting element (S31) are arrayed in a direction intersecting a direction D1 in which the light is scanned as light source images. This configuration can form a step-like light-distribution pattern with a small number of light-emitting elements.

The third light-emitting element S32 according to the present embodiment is so disposed as to scan the region (R2) that overlaps a region (range R1) that the first light-emitting elements S11 to S15 scan and a region (R3 to R6) that the second light-emitting elements S21 to S29 scan. The controller <NUM> controls an output of the third light-emitting element S32 such that a duration T3 (T32) for which the third light-emitting element is on satisfies T1 > T3 > T2. This configuration can form a step-like light-distribution pattern with a smaller step.

In the first light source <NUM> according to the present embodiment, a plurality of light-emitting elements are disposed in a matrix of m rows by n columns (m and n are each an integer no smaller than <NUM>; in the first light source <NUM>, m is <NUM>, and n is <NUM>), and the light-emitting elements in a (k-<NUM>)th column are disposed unlevel with the light-emitting elements in a kth column by approximately one half of a pitch (k is an integer no greater than n). In this case, a step-like light-distribution pattern with a smaller step can be formed as compared to a case in which the light-emitting elements in adjacent columns are not unlevel with each other by one half of a pitch.

A primary feature of an optical unit according to a second embodiment lies in that the first light source has a different configuration, and there is no substantial difference from the first embodiment in other respect. Therefore, the first light source will be described below in detail.

<FIG> is a schematic diagram in which a light source according to the second embodiment is viewed from the front, <FIG> illustrates a high-beam light-distribution pattern formed by the optical unit according to the second embodiment, and <FIG> illustrates another high-beam light-distribution pattern formed by the optical unit according to the second embodiment.

In a first light source <NUM> illustrated in <FIG>, nine light-emitting elements S11' to S31' are disposed in a matrix of m rows by n columns (m and n are each an integer no smaller than <NUM>; in the first light source <NUM>, m is <NUM>, and n is <NUM>), and the light-emitting elements S11' to S13' in a (k-<NUM>)th column are disposed unlevel with the light-emitting elements S21' to S23' in a kth column by one third of a pitch (one pitch = p') (k is an integer no greater than n).

The optical unit <NUM> including the first light source <NUM> configured in this manner can form not only a high-beam light-distribution pattern PH illustrated in <FIG> but also a partial high-beam light-distribution pattern PH" having an oblique cutoff line illustrated in <FIG>.

In the high-beam light-distribution pattern PH illustrated in <FIG>, scan patterns P11' to P33' formed as the light source images of the light-emitting elements S11' to S33' are scanned are superposed on each other.

In the partial high-beam light-distribution pattern PH" illustrated in <FIG> as well, the scan patterns P11' to P33' formed as the light source images of the light-emitting elements S11' to S33' are scanned are superposed on each other, but the partial high-beam light-distribution pattern PH" differs in terms of the on durations of the respective light-emitting elements.

The light-emitting elements S11', S21', and S31' have the longest on duration T1' per cycle, and as the scan patterns P11', P21', and P31' illustrated in <FIG> are formed and these scan patterns are superposed on each other, the light-emitting elements S11', S21', and S31' irradiate mainly a range R1' below the horizontal line.

The light-emitting element S12' has an on duration of T12' (T12' < T1') per cycle, the light-emitting element S22' has an on duration of T22' (T22' < T1') per cycle, and the light-emitting element S32' has an on duration of T32' (T32' < T1') per cycle. As illustrated in <FIG>, the light-emitting elements S12', S22', and S32' irradiate mainly a range R2' including the H-H line on the host vehicle's lane side and a space immediately above the H-H line. The range R2' partially overlaps the range R1'.

The light-emitting element S13' has an on duration of T13' (T13' < T1') per cycle, the light-emitting element S23' has an on duration of T23' (T23' < T1') per cycle, and the light-emitting element S33' has an on duration of T33' (T33' < T1') per cycle. As illustrated in <FIG>, the light-emitting elements S13', S23', and S33' irradiate mainly a range R3' above the H-H line on the host vehicle's lane side. The range R3' partially overlaps the range R2'.

The relationship among the on durations of the respective light-emitting elements is T13', T23', T33' < T12', T22', T32' < T1.

The controller <NUM> can form a light-distribution pattern in which the cutoff line on the host vehicle's lane side rises obliquely or stepwise toward the outer side, as illustrated in <FIG>, by not only selecting the light-emitting elements to be turned on but also controlling the on durations of the respective light-emitting elements to be turned on. In this manner, the optical unit according to the present embodiment can form a light-distribution pattern having an oblique cutoff line suitable for a vehicle headlamp.

In addition, in the first light source <NUM> according to the second embodiment, the light-emitting elements in adjacent columns are disposed unlevel with each other by one third of a pitch. Therefore, the step between the scan patterns contributing to forming an oblique cutoff line is smaller as compared to a case in which the light-emitting elements are disposed unlevel with each other by approximately one half of a pitch as in the first light source <NUM> according to the first embodiment. As a result, a light-distribution pattern having a smoother oblique cutoff line can be obtained.

In the vehicle headlamp <NUM> according to the first embodiment, each blade 22a of the rotary reflector <NUM> has a twisted shape in which the angle formed by the optical axis Ax and the reflective surface changes along the circumferential direction about the axis of rotation R. In contrast, in the vehicle headlamp <NUM> according to a third embodiment, which does not form part of the invention, a polygon mirror is used as a rotary reflector, and there is no substantial difference from the first embodiment in other respect. Therefore, the rotary reflector will be described below in detail. Components identical to those in the first embodiment are given identical reference characters, and descriptions thereof will be omitted as appropriate.

<FIG> is a horizontal sectional view of a vehicle headlamp according to the third embodiment. A vehicle headlamp <NUM> according to the third embodiment includes the lamp body <NUM> having a concave portion that opens toward the front. The front opening of the lamp body <NUM> is covered by the transparent front cover <NUM> to form the lamp room <NUM>. The lamp room <NUM> functions as a space that houses one optical unit <NUM>. The optical unit <NUM> is a lamp unit configured to be capable of emitting both a variable high beam and a low beam.

The optical unit <NUM> according to the present embodiment includes a light source <NUM>, the condenser lens <NUM>, a polygon mirror <NUM>, a projection lens <NUM>, and the controller <NUM>. The condenser lens <NUM>, serving as a primary optical system (optical member), redirects the optical path of the first light L1 emitted from the light source <NUM> toward a reflective surface 122a of the polygon mirror <NUM>. The polygon mirror <NUM> rotates about an axis of rotation R while reflecting the first light L1.

The light source <NUM> includes a plurality of elements disposed in a matrix. The projection lens <NUM> condenses the first light L1 reflected by the polygon mirror <NUM> and projects the condensed first light L1 in the light-irradiation direction (the left direction in <FIG>) of the optical unit. This configuration can project a clear light source image toward a space ahead of the optical unit <NUM>.

The polygon mirror <NUM> rotates with a driving source, such as a motor, unidirectionally about the axis of rotation R. The polygon mirror <NUM> includes the reflective surface 122a provided to form a desired light-distribution pattern by scanning light from each light source reflected by the rotating polygon mirror <NUM>. In other words, the rotating operation of the polygon mirror <NUM> causes visible light from a light emitter to be emitted as an irradiation beam, and a desired light-distribution pattern is formed as the polygon mirror <NUM> scans the irradiation beam.

The axis of rotation R of the polygon mirror <NUM> is substantially perpendicular to the optical axis Ax and intersects a plane that includes the optical axis Ax and the light source <NUM>. To rephrase, the axis of rotation R is substantially orthogonal to a scanning plane of light (irradiation beam) from the light source that scans in the right-left direction as the polygon mirror <NUM> rotates. The vehicle headlamp <NUM> that includes such a polygon mirror <NUM> can also form a variety of light-distribution patterns described above.

In each of the embodiments described above, the light source images reflected by a stationary rotary reflector and projected forward all have the same-sized rectangular shape. However, as the magnitude of an input current (power) is controlled (changed), each light-emitting element having a rectangular light-emitting surface can vary the size of a light source image in a stationary state.

<FIG> is a schematic diagram for comparing the size of the light source images obtained when the output of a light-emitting element having a rectangular light-emitting surface is varied. The light source image L21 illustrated in <FIG> is obtained, for example, when a light-emitting element is caused to emit light at its working upper limit output (the quantity of light of <NUM>%), and a range R21 enclosed by the solid line indicates a region having a luminous intensity higher than a predetermined luminous intensity. In the case of a typical light-emitting element, such as an LED, the center of the light-emitting surface is brightest, and the light-emitting surface tends to become less bright toward its outer periphery. The predetermined luminous intensity corresponds to such brightness that allows the user of the optical unit to recognize the region's edge as the outline of a light-distribution pattern when the light-distribution pattern is formed by scanning a light source image, for example.

A light source image L21' illustrated in <FIG> is obtained, for example, when a light-emitting element is caused to emit light at one half of its working upper limit output (the quantity of light of <NUM>%), and a range R21' enclosed by the solid line indicates a region having a luminous intensity higher than the predetermined luminous intensity. The range R21' of the light source image L21' is smaller than the range R21 of the light source image L21.

A light source image L21" illustrated in <FIG> is obtained, for example, when a light-emitting element is caused to emit light at <NUM>% of its working upper limit output (the quantity of light of <NUM>%), and a range R21" enclosed by the solid line indicates a region having a luminous intensity higher than the predetermined luminous intensity. The range R21" of the light source image L21" is smaller than the range R21' of the light source image L21'.

In this manner, varying the output of the light-emitting element changes the range irradiated at the predetermined luminous intensity (the size of the light source image). Thus, the controller <NUM> can form a light-distribution pattern having a new shape by varying the output of the light-emitting elements when the light reflected by the rotating rotary reflector <NUM> is scanned as a light source image.

<FIG> is a schematic diagram illustrating an example of a light-distribution pattern. As illustrated in <FIG>, the controller <NUM> drives a light-emitting element at its working upper limit output, and the light source image L21 is scanned from the left to the right in the drawing. Thereafter, the controller <NUM> starts reducing the output of the light-emitting element at a predetermined timing to gradually reduce the size of the light source image from the light source image L21, to the light source image L21', and to the light source image L21". Thus, a light-distribution pattern P21" is formed. The light-distribution pattern P21" is rectangular from its left end region to the center region, and an upper side E1 and a lower side E2 of the right end region are oblique. Therefore, the oblique upper side E1 of the light-distribution pattern P21" can be used as an oblique cutoff line.

<FIG> is a schematic diagram illustrating a state in which a light source image of a light emitter that is on according to a fourth embodiment is reflected and projected forward by a stationary rotary reflector. <FIG> illustrates a fifth light-distribution pattern formed as the light source image illustrated in <FIG> is scanned by the rotating rotary reflector.

The light source images L11, L21, L22, and L31 illustrated in <FIG> correspond to the light-emitting surfaces of the respective light-emitting elements S11, S21, S22, and S31. When a fifth light-distribution pattern PH‴ is formed, the light-emitting element S11 has the longest on duration T1 per cycle, and a scan pattern P11" illustrated in <FIG> is formed. The light-emitting elements S21, S22, and S31 are controlled such that the output gradually decreases toward the end of the on duration per cycle, and a light-distribution pattern P21" and similar light-distribution patterns P22" and P31" illustrated in <FIG> are formed. Each scan pattern is so formed as to partially overlap its adjacent scan pattern.

The controller <NUM> can form the fifth light-distribution pattern PH‴ in which the cutoff line on the host vehicle's lane side rises obliquely or stepwise toward the outer side, as illustrated in <FIG>, by not only selecting the light-emitting elements to be turned on but also controlling the on durations and the outputs of the respective light-emitting elements to be turned on. It is also possible to form a light-distribution pattern PH‴ in which the cutoff line on the oncoming vehicle's lane side rises obliquely or stepwise toward the outer side by control the output to gradually increase from the beginning of the on duration per cycle. In this manner, the optical unit according to the present embodiment can form a light-distribution pattern having an oblique cutoff line suitable for a vehicle headlamp.

Thus far, the present invention has been described with reference to the foregoing embodiments. The present invention, however, is not limited to the foregoing embodiments but rather by the appended claims.

<NUM> vehicle headlamp, <NUM> optical unit, <NUM> first light source, <NUM> rotary reflector, <NUM> projection lens, <NUM> second light source, <NUM> controller, <NUM> motor, <NUM> first light emitter, <NUM> second light emitter, <NUM> third light emitter, <NUM> fourth light emitter, <NUM> control device, <NUM> vehicle headlamp, <NUM> optical unit, <NUM> first light source, <NUM> polygon mirror, <NUM> projection lens, <NUM> light source.

Claim 1:
An optical unit (<NUM>) for a vehicle headlamp, comprising:
a light source (<NUM>) having a plurality of light-emitting elements disposed in an array;
a rotary reflector (<NUM>) structured to rotate while reflecting light emitted from the light source (<NUM>); and
a controller (<NUM>) for controlling an on state of the plurality of light-emitting elements, wherein
the rotary reflector (<NUM>) includes a reflective surface provided to form a light-distribution pattern by scanning light reflected by the rotating rotary reflector as a light source image, wherein
the plurality of light-emitting elements include a first light-emitting element (S11-S15), a second light-emitting element (S21-S29), and a third light-emitting element (S31-S32), the first light-emitting element arranged for forming a low beam light-distribution pattern that irradiates a range below a horizontal line, the second light-emitting element arranged for forming a high beam light-distribution pattern that irradiates at least a range above the horizontal line, and
the third light-emitting element being so disposed as to scan a region that overlaps a region that the first light-emitting element scans and a region that the second light-emitting element scans,
in the light source, the first light-emitting element (S11-S15) and the second light-emitting element (S21-S29) are arrayed in a direction intersecting a direction in which the light is scanned as the light source image, and
characterized in that the controller (<NUM>) is structured to control the on state of the first light-emitting element, the second light-emitting element and the third light-emitting element such that an on duration T1 of the first light-emitting element arranged for forming the low beam light-distribution pattern, an on duration T2 (T2 > <NUM>) of the second light-emitting element arranged for forming the high beam light-distribution pattern and on duration T3 of the third light-emitting element satisfy T1 > T3 > T2 and T2 > <NUM>, so that the light-distribution pattern has a cutoff line across the horizontal line on a host vehicle's lane side that rises obliquely or stepwise toward an outer side.