Vehicle headlamp

• US 4,985,816 A
• Filed: 03/27/1989
• Issued: 01/15/1991
• Est. Priority Date: 03/28/1988
• Status: Expired due to Fees

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Saito, Tomoko, Seko, Yasutoshi
• Primary Examiner(s): Husar, Stephen F.
• Application Number:
  US07/329,226
• Time in Patent Office: 659 Days
• Field of Search: 362/61, 362/80, 362/268, 362/277, 362/293, 362/300, 362/303, 362/319, 362/351, 362/280
• US Class Current: 362/303
• CPC Class Codes: B60Q 1/0023 the element being a sensor, e.g. distance sensor, camera
• 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 1/1438 Actuating means for dimming masks or screens
• CPC Class Codes: B60Q 2300/054 Variable non-standard intensity, i.e. emission of various beam intensities different from standard intensities, e.g. continuous or stepped transitions of intensity
• 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 2300/112 Vehicle speed
• CPC Class Codes: B60Q 2300/122 Steering angle
• CPC Class Codes: B60Q 2300/134 Yaw
• CPC Class Codes: B60Q 2300/21 Manual control
• CPC Class Codes: B60Q 2300/42 oncoming vehicle
• CPC Class Codes: F21S 41/43 characterised by the shape thereof
• CPC Class Codes: F21S 41/645 by electro-optic means, e.g. liquid crystal or electrochromic devices
• CPC Class Codes: F21S 41/689 Flaps, i.e. screens pivoting around one of their edges
• CPC Class Codes: F21W 2102/15 wherein the light is emitted under L-shaped cut-off lines, i.e. vertical and horizontal cutoff lines
• CPC Class Codes: F21W 2102/16 having blurred cut-off lines

Abstract

Disclosed herein is a vehicle headlamp which comprises an ellipsoidal light reflector having first and second focuses; a light source positioned at the first focus, so that light rays produced by the light source are reflected forward by the light reflector and converged at the second focus; a converging lens positioned in front of the second focus; a shading device positioned near the second focus for partially shading the light rays which have been reflected by the light reflector; and control means for controlling the shading characteristic of the shading device in accordance with an operation mode of the vehicle, wherein said shading device comprises a liquid crystal matrix which has a plurality of small light transmitting elements independently and electrically controlled by said control means.

Claims

1. A vehicle headlamp, comprising:

an ellipsoidal light reflector having first and second focuses;

a light source positioned at said first focus, so that light rays produced by said light source are reflected forward by said light reflector and converged at said second focus;

a converging lens positioned in front of said second focus;

a shading device positioned near said second focus for partially shading the light rays which have been reflected by said light reflector; and

control means for controlling the shading characteristic of said shading device,

wherein said shading device comprises a liquid crystal matrix which has a plurality of small light transmitting elements independently and electrically controlled by said control means.

2. A vehicle headlamp as claimed in claim 1, wherein said liquid crystal matrix comprises:

outer and inner polarizing plates which face each other in such a manner that their polarizing directions are perpendicular to each other; and

a liquid crystal plate sandwiched between said outer and inner polarizing plates, said liquid crystal plate including the plurality of small light transmitting elements.

3. A vehicle headlamp as claimed in claim 2, wherein said plurality of light transmitting elements produce a given image on said liquid crystal plate when some of the elements are electrically energized.

4. A vehicle headlamp as claimed in claim 3, wherein said image comprises an opaque part, a semitransparent part and a transparent part.

5. A vehicle headlamp as claimed in claim 4, wherein said control means for controlling the characteristic of the liquid crystal matrix is a switch which is manually operated.

6. A vehicle headlamp as claimed in claim 4, further comprising:

a heat reflecting filter which is located behind said liquid crystal matrix for preventing heat transfer from said light source to said liquid crystal matrix.

7. A vehicle headlamp as claimed in claim 4, in which said control means for controlling the characteristic of the liquid crystal matrix is an automatic conrol means which controls said characteristic in accordance with an operation mode of the vehicle.

8. A vehicle headlamp as claimed in claim 7, in which said control means comprises a CCD (charge coupled device) camera having an image memory installed therein, said image memory issuing iamge signals by which the light transmittance of each light transmitting element of said liquid crystal matrix is controlled.

9. A vehicle headlamp as claimed in claim 8, in which said image memory includes a plurality of picture elements whose number is the same as that of said liquid crystal matrix.

10. A vehicle headlamp as claimed in claim 9, in which said control means further comprises an image reversing circuit by which the image signals from said image memory of the CCD camera are reversed in signal intensity.

11. A vehicle headlamp as claimed in claim 10, further comprising a ND filter which is arranged in front of said CCD camera.

12. A vehicle headlamp as claimed in claim 10, in which one side of the image memory of said CCD camera is covered with a cover member for preventing the picture elements concealed by the cover member from operation.

13. A vehicle headlamp as claimed in claim 12, further comprising a liquid crystal filter which is arranged in front of said CCD camera.