US 3503146 A
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March 31, 1970 P. J. WOPLIN 3,503,146
HEAD-UP DISPLAY SYSTEMS Filed Sept. 1. 1967 INVENTOR PETE F \Z WOPZ/A BY M M ATTORNEY United States Patent 3,503,146 HEAD-UP DISPLAY SYSTEMS Peter J. Woplin, London, England, assignor to Elliott Brothers (London) Limited, London, England, a British company Filed Sept. 1, 1967, Ser. No. 665,007 Claims priority, application Great Britain, Sept. 3, 1966, 39,495/ 66 Int. Cl. G09f 11/00 US. Cl. 4051 7 Claims ABSTRACT OF THE DISCLOSURE A mechanism for removing from the line of sight of an observer the reflector of head-up display apparatus of an aircraft in the event of sudden deceleration. The mechanism includes a spring acting as an energy store, the energy of which is released by a latch either on impact with the observers head or on receiving a movement of deceleration sensitive device.
This invention relates to automatic retraction mechanisms for display members in head-up display systems.
According to the present invention there is provided in head-up display apparatus, a display member arranged in the line-of-sight of an observer, and means for retracting said display member fromsaid line-of-sight on occurrence of a predetermined condition.
Further according to the present invention there is provided in head-up display apparatus, a partial reflector displaceably mounted in the line-of-sight of an observer, and a retraction mechanism for displacing the reflector from the line-of-sight position to a retracted position whenever a predetermined force acts on the reflector.
Still further according to the present invention there is provided an automatic retraction mechanism for retracting a display member of a head-up display system, said mechanism comprising energy store means, and release means arranged to hold said display member in an operational position and to act on said energy store means to release the energy thereof to retract the display member from said operation position to a retracted position.
It will be appreciated that the store of energy may be mechanical, pneumatic, hydraulic, electrical or magnetic in form.
An embodiment of an automatic reflector retraction mechanism in accordance with the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawing, the sole figure of which is a side elevation of the mechanism.
In the drawing a partial reflector 1 is connected by coaxial pivots 2 to the ends 3 of a pair of leading arms 4 and by coaxial pivots 5 to the ends 6 of a pair of following arms 7 (one only of each of these components being shown in the drawing). The leading arms 4 are connected at their other ends 8 by coaxial pivots 9 to a bracket 10. The following arms 7 are connected by coaxial pivots 11 to the bracket 10. Energy storage means in the form of a spring 12 is located adjacent the coaxial pivots 9 and acts between a pin 13 and the leading arms 4 to move the leading arms 4 and consequently the reflector 1 from an operating position (as shown in full lines) to a retracted position (as shown in chain lines at 1a).
A latch assembly 14 of the mechanism includes a single latch arm 15 connected at one end 16, by a pivot 17, to the bracket and having a slot 18, adjacent the other end 19, arranged (in the full lin position shown) to cooperate with a pin 20 which is rigidly attached to one of the following arms 7. The latch assembly 14 also includes a torsion spring 21 and a latch release mechanism in the form of a bell-crank lever 22. The torsion spring 21 urges the slot 18 of the latch arm 15 into engagement with the pin 20 and with the release mechanism 22, which release mechanism is connected by a pivot, coaxial with the pivots 11, to the bracket 10, and is connected by a tension spring 23 to the one said following arm 7. The release mechanism has a pin 24 which cooperates with a ramp 25 on the latch arm 15. The tension spring 23 acts to bias the release mechanism 22 about the pivot coaxial with the pivots 11 and thus tends to move the pin 24 away from the ramp 25 and to urge the release mechanism 22 against a stop 26 on the one said following arm 7.
A padded bar or other member 28 is connected to one end of one of the arms of the lever 22. Movement of the release mechanism 22 against the tension spring 23 away from the stop 26 causes the pin 24 to engage the ramp 25 to move the latch arm -15 against the bias of the torsion spring 21 thereby to disengage the slot 18 from the pin 20 which in turn allows the torsion spring 12 to move the reflector 1 from its operating .(full lines) to its retracted position (chain lines).
An air-filled dashpot 29, rigidly mounted on the bracket 10 is arranged to be operated by movement of the one said following arm 7 and is connected thereto by a pivot 30, a longitudinally slotted link 31 and a pivot pin 32. The pivot pin 32 is connected to the one said following arm- 7 and slidably cooperates with the slot 33 in the link 31. Initial movement of the one said following arm 7 slides the pivot pin 32 along the slot 33 until the pivot pin 32 abuts against the end of the slot 33 nearest to the dashpot 29. Continued movement of the one said following arm 7 operates the piston of the dashpot to reduce the velocity of the said movement.
The reflector retraction mechanism is particularly, though not exclusively, suitable for use in head-up display systems in aircraft in which the display is projected on to the reflector 1, which is located in an operating position in the normal line-of-sight 35 of a member 34 of the aircrew and in close proximity to the face of the said member 34. The bracket 10 could in this case be rigidly attached to the structure of the aircraft above the level and forwards of the head of the said member 34. In the event of retraction of the reflector becoming desirable, a blow to the padded bar 28, for example by the head of the member 34, directed towards the left of the drawing, will operate the release mechanism 22 and the latch arm 15 to unlatch the following arms 7 and allow the torsion spring 12 to move the leading and following arms 4 and 7, and consequently the reflector 1 from the operating position to the retracted position 1a, the latter part of this movement being damped by the dashpot 29.
In an alternative construction the padded bar 28 is replaced by means for actuating the release mechanism on occurrence of a predetermined deceleration in the form of a weight which acts to produce an inertia force on occurrence of the said deceleration.
1. In head-up display apparatus,
bracket means arranged to be secured to a vehicle carrying the apparatus,
a linkage pivoted to the bracket means and generally depending therefrom,
a partial reflector forming an optical component of the head-up display apparatus pivotally mounted on the linkage, and movable together with the linkage between an operative position in which the reflector is in the optical vision of an observer and a displaced position in which the reflector is spaced from said optical path,
latch means operative to maintain the reflector in the operative position,
energy-store means biasing the reflector towards the displaced position, and
latch-release means operative on the receipt of a predetermined force to release the latch means whereby the energy-store means move the linkage and the reflector to the displaced position.
2. Apparatus according to claim 1, wherein said latch release means includes a padded bar arranged to engage an observers head on sudden deceleration of the apparatus and to yield under the loading imposed thereon whereby injury to the observers head is at least reduced.
3. Apparatus according to claim 1, wherein the linkage comprises,
a pair of leading arms each pivoted at respective ends thereof to the bracket means and to the partial refiector, and
a pair of following arms each pivoted at respective ends thereof to the bracket means and to the partial re- Hector.
4. Apparatus according to claim 3, wherein said latchrelease means includes a bell-crank lever pivoted to the bracket means, and
a. tension spring connecting one end of the bell-crank lever to one of the said following arms,
said tension spring acting to bias the latch-release means as a whole about the pivot axis of the bellcrank lever to rest against said following arm.
References Cited UNITED STATES PATENTS 1,263,902 4/1918 Kieper. 3,133,746 5/1964 'Zazzara. 3,188,112 6/1965 Oelkrug.
FOREIGN PATENTS 957,548 2/1957 Germany. 964,471 5/1957 Germany.
EUGENE R. CAPOZIO, Primary Examiner RICHARD CARTER, Assistant Examiner