Combiner alignment detector for head up display system

• US 4,775,218 A
• Filed: 04/17/1987
• Issued: 10/04/1988
• Est. Priority Date: 04/17/1987
• Status: Expired due to Fees

• Current Assignee: Flight Dynamics (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Flight Dynamics (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Hodel, Thomas E., Stockwell, Robert E., Thomas, Mark A., Wood, Robert B.
• Primary Examiner(s): Corbin, John K.
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US07/039,513
• Time in Patent Office: 536 Days
• Field of Search: 350/174, 350/169, 350/632, 340/705, 340/718, 340/716, 358/93, 358/103, 358/250, 356/400
• US Class Current: 359/14
• CPC Class Codes: G02B 2027/0138 comprising image capture systems, e.g. camera
• CPC Class Codes: G02B 2027/014 comprising information/image processing systems
• CPC Class Codes: G02B 2027/0154 with movable elements
• CPC Class Codes: G02B 27/01 Head-up displays
• CPC Class Codes: G02B 27/0149 characterised by mechanical features G02B27/0176 takes precedence

Abstract

A head up display system includes a combiner alignment detector (24) that determines whether the combiner (22) and a cathode-ray tube (CRT) (18) are aligned within a preassigned operational tolerance. The CRT emits display symbology that reflects off the combiner toward an observer. The combiner is secured to a combiner bracket (38) which is pivotally mounted to a mounting structure (70) having a stationary relationship with the CRT. A light emitting diode (LED) (86) and a light-sensitive linear position detector (88) are secured to the mounting structure. Light rays emanating from the LED are reflected by a mirror (34), which is secured to the combiner bracket, and strike the position detector. Pivotal motion of the combiner bracket relative to the mounting structure results in movement of the mirror relative to the LED and the position detector. The pivotal motion of the mirror causes light reflected by the mirror to strike varying locations on the position detector, which provides corresponding output signals. A processing circuit (110) receives the signals provided by the detector and provides to a control circuit (129) a signal corresponding to the alignment of the combiner and the CRT and to the position of the display symbology reflected by the combiner. The control circuit provides a warning signal whenever the information provided by the processing circuit indicates that the display symbology is not located at a preselected position.

Claims

1. In a head up display system having a movable combiner positioned in an observer'"'"'s forward line-of-sight, the combiner being configured to superimpose on a scene display symbology emanating from a stationary image source, the symbology being projected from the image source toward a preselected position on the combiner and reflected from the surface of the combiner, the improvement comprising:

detecting means for detecting the orientation of the combiner relative to the image source and including;

(a) a light source;

(b) a light reflector mounted near the surface of the combiner to be movable therewith;

(c) a light detector, the light source, light reflector and light detector configured and arranged so that the light emanating from the light source is reflected by the light reflector to a position on the light detector that corresponds to the orientation of the combiner relative to the image source;

processing means responsive to the detecting means to provide information corresponding to the position of the display symbology on the combiner, the position of the display symbology on the combiner being related to the orientation of the combiner relative to the image source; and

control means in communication with the processing means and operable to provide a signal whenever the processing means indicates that the display symbology is not located at the preselected position.

2. The system of claim 1 in which the control means is in communication with the image source and includes means to deliver a signal to the image source to reposition the display symbology to the preselected position whenever the information indicates that the display symbology is not located in the preselected position.

3. The system of claim 1 in which the light source comprises a light emitting diode.

4. The system of claim 1 in which the light detector comprises a light-sensitive position detector.

5. The system of claim 1 wherein the combiner includes a hologram constructed to reflect light emanating from the image source and to transmit light emanating from the light source.

6. In a head up display system for aircraft having a holographic combiner positioned in an observer'"'"'s line-of-sight, the combiner configured to superimpose display symbology on a real world scene, the display symbology emanating from a stationary image source and being projected toward a preselected position on the combiner, and the combiner being secured to a bracket that is pivotally mounted to a mounting structure, the improvement comprising:

a light reflector secured to the bracket adjacent to the combiner and in optical communication with a light source secured to the mounting structure;

a light-sensitive detector secured to the mounting structure and in optical communication with the light reflector;

processing means responsive to the light-sensitive detector to provide information corresponding to the position of the display symbology on the combiner, the position of the display symbology on the combiner being related to the orientation of the combiner which is related to the pivotal position of the bracket; and

control means in communication with the processing means to provide a signal whenever the information indicates that the display symbology is not located at the preselected position.

7. The system of claim 6 in which the image source is secured in a position above the observer.

8. The system of claim 6 in which the control means is in communication with the image source and includes means to interrupt the projection of the display symbology whenever the information indicates that the display symbology is not located at the preselected position.

9. The system of claim 6 in which the control means is in communication with the image source and includes means to deliver a signal to the image source to reposition the display symbology to the preselected position whenever the information indicates that the display symbology is not located in the preselected position.

10. The system of claim 6 in which the processing means further comprises first means for sensing the intensity of light received by the light-sensitive detector and second means responsive to the first means for adjusting the intensity of the light emanating from the light source, thereby to maintain the accuracy of the information corresponding to the position of the display symbology on the combiner.

11. A detector system for a head up display system, comprising:

a stationary image source configured for projecting display symbology therefrom;

a combiner mounted in the line of sight of an observer that utilizes the display system, the combiner reflecting the display symbology and being mounted for movement into and out of a predetermined deployed position;

detection means for detecting and signaling when the combiner is not in the deployed position; and

warning means interconnected between the detection means and the image source for directing the image source to project a warning symbol when the detection means signals that the combiner is not in the deployed position.

12. The system of claim 11 in which the detection means further comprises means to detect whether the combiner is mispositioned in a first direction by a first amount and means to detect whether the combiner is mispositioned in a second direction by a second amount.

13. The system of claim 12 in which the first and second amounts are different.