Vehicular headlamp

• US 8,523,417 B2
• Filed: 07/09/2010
• Issued: 09/03/2013
• Est. Priority Date: 07/14/2009
• Status: Expired due to Fees

• Current Assignee: Koito Manufacturing Company Limited
• Original Assignee: Koito Manufacturing Company Limited
• Inventors: Kobayashi, Shoji
• Primary Examiner(s): Mai, Anh
• Assistant Examiner(s): SANTONOCITO, MICHAEL P
• Application Number:
  US12/833,450
• Publication Number:
  US 20110013412A1
• Time in Patent Office: 1,152 Days
• Field of Search: 362/512, 362/539
• US Class Current: 362/539
• CPC Class Codes: B60Q 1/085 due to special conditions, e.g. adverse weather, type of road, badly illuminated road signs or potential dangers B60Q1/10, B60Q1/12, B60Q1/1423 take precedence
• CPC Class Codes: B60Q 2300/056 Special anti-blinding beams, e.g. a standard beam is chopped or moved in order not to blind
• CPC Class Codes: B60Q 2300/312 Adverse weather
• CPC Class Codes: B60Q 2300/32 Road surface or travel path
• CPC Class Codes: F21S 41/135 Polarised
• CPC Class Codes: F21S 41/645 by electro-optic means, e.g. liquid crystal or electrochromic devices

Abstract

A vehicular headlamp includes a projection lens, a light source, a reflector, and a liquid crystal shutter. The liquid crystal shutter includes a pair of transparent plates, a liquid crystal member, and a pair of polarization plates. The liquid crystal member is disposed only in a part of an area between the pair of transparent plates. The pair of polarization plates are disposed only in an area of the outer surface of the pair of transparent plates corresponding to an area in which the liquid crystal member is disposed. The area in which the liquid crystal member is disposed includes a first area for blocking a part of reflected light from the reflector such that light emitted from the projection lens forms a low-beam distribution pattern having a cut-off line at an upper end edge, and a second area for blocking light emitted from the projection lens and then reflected by a road surface ahead of a vehicle toward a space above the cut-off line.

Claims

1. A vehicular headlamp comprising:

a projection lens disposed on an optical axis extending in a vehicular longitudinal, direction,

a light source disposed rearwardly of a rear-side focal point of the projection lens,

a reflector disposed rearwardly of the rear-side focal point of the projection lens to reflect light from the light source toward the projection lens, and

a liquid crystal shutter disposed in the proximity of the rear-side focal point of the projection lens,

wherein the liquid crystal shutter comprises;

a pair of transparent plates disposed at a predetermined interval in a direction of the optical axis,

a liquid crystal member disposed between the pair of transparent plates, and

a pair of polarization plates disposed on an outer surface of the pair of transparent plates,

wherein the liquid crystal member is disposed only in a part of an area between the pair of transparent plates,

wherein the pair of polarization plates are disposed only in an area of the outer surface of the pair of transparent plates corresponding to an area in which the liquid crystal member is disposed, and

wherein the area in which the liquid crystal member is disposed comprises;

a first area for blocking a part of reflected light from the reflector such that light emitted from the projection lens forms a low-beam distribution pattern having a cut-off line at an upper end edge, and

a second area for blocking light emitted from the projection lens and then reflected by a road surface ahead of a vehicle toward a space above the cut-off line.

2. The vehicular headlamp according to claim 1, wherein the liquid crystal member disposed in the second area has an outer shape that is slightly larger than an outer shape of the pair of polarization plates disposed in correspondence with the second area.

3. The vehicular headlamp according to claim 1, wherein the pair of polarization plates disposed in correspondence with the second area are configured to have an outer shape of a generally inverted trapezoid.

4. The vehicular headlamp according to claim 1,

wherein the light source is disposed on an axis line intersecting the optical axis, and

wherein the reflector comprises:

a first reflector that reflects light from the light source toward the optical axis, and

a second reflector that reflects reflected light from the first reflector forward.

5. The vehicular headlamp according to claim 4,

wherein the light source is disposed below the optical axis, and

wherein the second reflector is formed by a heat-ray transparent mirror.

6. The vehicular headlamp according to claim 5, wherein the first reflector has a generally semi-dome shape, and second reflector is inclined obliquely forward and upward in the proximity of the intersection of the optical axis and the axis line intersecting the optical axis.

7. A method of manufacturing a vehicular headlamp comprising:

disposing a projection lens on an optical axis extending in a vehicular longitudinal direction,

disposing a light source rearwardly of a rear-side focal point of the projection lens,

disposing a reflector rearwardly of the rear-side focal point of the projection lens to reflect light from the light source toward the projection lens,

disposing a liquid crystal shutter in the proximity of the rear-side focal point of the projection lens, wherein the liquid crystal shutter comprises;

a pair of transparent plates disposed at a predetermined interval in a direction of the optical axis,

a liquid crystal member disposed between the pair of transparent plates, and

a pair of polarization plates disposed on an outer surface of the pair of transparent plates,

disposing the liquid crystal member only in a part of an area between the pair of transparent plates, and

disposing the pair of polarization plates only in an area of the outer surface of the pair of transparent plates corresponding to an area in which the liquid crystal member is disposed, wherein the area in which the liquid crystal member is disposed comprises;

a first area for blocking a part of reflected light from the reflector such that light emitted from the projection lens forms a low-beam distribution pattern having a cut-off line at an upper end edge, and

a second area for blocking light emitted from the projection lens and then reflected by a road surface ahead of a vehicle toward a space above the cut-off line.

8. The method according to claim 7, wherein the liquid crystal member disposed in the second area has an outer shape that is slightly larger than an outer shape of the pair of polarization plates disposed in correspondence with the second area.

9. The method according to claim 8, wherein the pair of polarization plates disposed in correspondence with the second area are configured to have an outer shape of a generally inverted trapezoid.

10. The method according to claim 9, wherein the light source is disposed on an axis line intersecting the optical axis, and wherein the reflector comprises:

a first reflector that reflects light from the light source toward the optical axis, and a second reflector that reflects reflected light from the first reflector forward.

11. The method according to claim 10, wherein the light source is disposed below the optical axis, and wherein the second reflector is formed by a heat-ray transparent mirror.

12. The method according to claim 11, wherein the first reflector has a generally semi-dome shape, and second reflector is inclined obliquely forward and upward in the proximity of the intersection of the optical axis and the axis line intersecting the optical axis.