Electrically operated rotary shutter for television camera aboard spacecraf

Ford, A. G.

English

NASA Technical Reports Server

Nov. 16, 1965 JAMES E. WEBB 3,2 1 7,624 
ASMINISTRATOR O F  THE NAT!ONAL AERONAUTICS 
A N D  SPACE ADMINISTRATION 
ELECTRICALLY-OPERATED ROTARY SHUTTER 
F i l e d  May 14, 1963 2 Shsets-Sheet 1 
https://ntrs.nasa.gov/search.jsp?R=19700030957 2020-03-17T02:08:53+00:00Z
Nov. "n6, 1965 JAMES E. WEBB 3,2 1 "$624 
ADF4IN:STRAYOR OF THE NATiOPdAL AERQi\iAUTICS 
A N D  SPACE ADMINISTRAYIBN 
ELECTRICALLY-OPERATED ROTARY SHUTTER 
F i l e d  May 14, 1963 2 Sheets-Sheet 2 
INVENTOR. 
2 
Thus the uDner limit to the exDosure time o f  the rotarv 
3,217,624 
ELECTRICALLY-OPERATED ROTARY SHUTTER 
James E. Webb. administrator of the National Aeronau- 
tics and §nice Admimistration, with respect to an 
Gent ion  oi? Allen Go Ford 
Filed May 14,1963, Ser. No. 280,776 
3 Claims. (Cl. 95-58] 
blade shutter js the length of  time the solenoid can be 
energized without overheating the windings, which is 
greatly in excess o f  the exposure time requirements, while 
the lower limit is determined by the inertia o f  the shutter 
moving parts. Furthermore, with this rotary blade type 
o f  shutter the ~naximum difference in exposure across 
the field o f  the vidicon tube is eaual to T,-T, rather 
This invention relates to electrically-operated rotary than T O S T ,  as in the case o f  the flag-type scutte;. This 
shutters, and more particularly to a camera shutter for a 10 eases considerably the problem o f  obtaining uniform ex- 
television camera aboard a spacecraft. posures. 
[t has been found in planetary and lunar exploration An  object o f  the invention, therefore, is to  provide an 
that television cameras carried aboard spacecrafts, such electrically-operated rotary shutter which is particularly 
as the Mariner and Ranger, have various exposure times adapted for remote control operation and especialty for 
required of the camera shutter because o f  the variation 15 use on space vehicles, so that the shutter may be automati- 
o f  the planetary brightness or the vidicon sensitivity and cally operated by controls carried by the spacecraft or 
no absolLzte value could be assigned to these factors. In by signals sent from a ground station. 
order to accommodate the uncertainty o f  these factors, the A further object o f  the invention is to provide an elec- 
requirement is placed on the shutter design so that the trically-operated rotary shutter which is in a normally 
exposure time can be varied across the rather broad range 20 closed position, and moved by a solenoid, on command, 
around nominal exposure time o f  100 msec. for a long to an open position and held in this open position for an 
focal length camera and 40 nlsec. for a short focal length accurate predetermined rate, and then closed by spring 
camera. action. 
The two techniques available for controlling the length And, a still further object o f  the invention is to  provide 
of the exposure time are: (1) the adjustment of  a spring 25 a rotary shutter o f  this type wherein the operating time 
tension; and, ( 2 )  electronic pulse con~n~ands to a solenoid of  the solenoid and the spring may be matched so as to 
to control the camera shutter action. It has been found minimize the variation in exposure time across the shutter 
that the latter technique gives a more reliable control of aperture. 
exposure time for space flight conditions. With the above and other objects in view, as may appear 
In order to  simplify the electronic logics and interfaces 30 hereinafter, reference is directed to the accompanying 
o f  the other camera conlponents to the shutter, a further drawings in which: 
reCluirement was placed upon the shutter design that the FIGURE 1 is a fragmentary view o f  a vidicon camera, 
complete exposure cycle require only a single electrical incorporating the electrically-operated rotary shutter; 
pulse, the exposure time being determined by the pulse FIGURE 2 is an enlarged, elevational view o f  the 
width of a telemetered signal or a signal generated on 35 shutter and the plate on which it is mounted, showing 
board the spacecraft. the shutter in its closed position; 
The simplest approach for the purpose o f  achieving an FIGURE 3 is a similar plan view showing the shutter 
electronically-controlled shutter is a flag-type focal plane in its open position; 
shutter in which a solenoid in response to a pulse operates FIGURE 4 is a sectional view taken through 4-4 o f  
a single blade shutter through a very simple linkage to 40 FIGURE 2, that is, through the pivotal axes o f  the shutter 
move the blade in a clockwise direction to expose the drive mechanism; 
vidicon tube to the lunar or planetary image and then FIGURE 5 is a diagrammatical view illustrating the 
upon command from the Earth or within the spacecraft action of the spring which controls rotation o f  the shutter. 
the pulse is turned o f f  and a biasing spring returns the T'he electrically-operated rotary shutter is particularly 
flag-type shutter blade in a counter-clockwise position 45 adapted for use with a vidicon camera 1 installed on a 
to the closed position. It has been found that such a flag- Space vehicle. The vidicon camera illustrated fragmen- 
type shutter has an inherent uneven exposure across the tarily in FIGURE 1 includes a lens system 2 which 
field o f  view o f  the vidicon tube due to the fact that duling focuses an image On a sensitive element, not shown, of 
the opening cycle the blade is traveling in a direction a camera structure 3. 
opposite to that which it travels during the closing cycle. 50 Interposed between the lens system and the camera 
This results in one side o f  the field being exposed to structure 3 is a base plate 4 having a square aperture 5 
TO+T, seconds longer than the other side where T O  is therein. A Post 6 is disposed at one side o f  the aperture 
the transit time o f  the shutter blade edge across the field 5 and is provided with bearings 7 which support a shutter 
o f  view during the opening cycle and T ,  is the transit disk by means o f  a central hub 9. The shutter disk 8 
cycle o f  the shutter blade edge during the closing cycle. 55 is circular except for a notched segment forming a shutter 
Also, high speed photography requires shutter operation gate 10. 
of  such sho~t  duration that the shutter would bounce At one side o f  the hub 9 is an eccentric boss 11 which 
and therefore this is another inherent defect in the flag- carries a crank pin 12. The crank pin is joined to a 
type shutter. connecting rod 13 through a bearing 14. The extended 
The rotary blade shutter o f  the present invention sub- end of the connecting rod 13 is joined by a pivot 15 to 
stantially reduces the effect o f  the shutter bounce during the major arm 16 o f  a crank lever 17. The crank lever 
the high speed photography requirements and at the same 119 is jou~naled on a fixed shaft 170 projecting outwardly 
time provides an even exposure across the field of  view. fro111 the base plate 4. The crank lever 17 includes a 
This is accomplished by using a solenoid revponsive to minor arm 18 joined by a journal pin 19 to a link 20, 
an electrical pulsed signal, to move the shutter blade 13' which in turn is connected by a pin 21 to one end o f  a 
through a suitable linkage to an open position and main- solenoid armature 22. 
tain it in the open position for the prescribed length o f  The solenoid arrnat~tre 22 is adapted to reciprocate 
exposure time. Upon termination o f  the puked signs1 a within a soIenoid casing 23 having therein a solenoid coil, U-shaped spring acts on the shutter blade through the 70 not shown. The solenoid casing is secured to the base 
same linkage to rotate the shutter in the same clockwise plate 4 by a bracket 230. Connected to the journal pin 
movement to its closed position. 19 is a U-shaped spring 24 having pairs o f  out-turned lugs 
3,217, 
3 
25 at its extremity, one of which is con~~ected with the 
journal pin 19, and the other of which is connected to 
an adjustable anchor bracket 26 secured to the base plate 
4 in such a manner as to be rotated in order to adjust 
the force of the U-shaped spring 24. 5 
Forrned integrally with the shutter disk 8 is a ratchet 
27 having two stop shoulders 28 and 29. These shoulders 
are engaged in succession by a catch lever 30 supported 
by a pivot 31 and urged toward the ratchet 29 by a 
spring-32. 10 
Operation of the electrically-operated rotary shutter is 
as follows: 
When the solenoid is de-energized, the U-shaped spring 
24 pulls outwardly on the arnlature 22 and exerts a force 
through the crank lever 17 and connecting rod 13, tend- 15 
ing to cause a counterclockwise rotation of the shutter 
disk 8. This movement is prevented by the catch lever 
30 engaging the stop shoulder 28. 
When the solenoid is activated, the armature 22 is 
drawn into the solenoid and exerts a force tending to 20 
rotate the shutter disk 8 in a clockwise direction until the 
stop shoulder 29 passes the catch lever 30. That is, 
movement of the armature 22 shifts the shutter disk 8 
in a clockwise direction from the closed position shown 
in FIGURE 2 to the open position shown in FIGURE 3. 25 
The shutter disk 8 remains in its open position for the 
length of time that current is applied to the solenoid. 
By accurate control of the duration of the electrical pulse 
applied to the solenoid, the exposure time may be accu- 
rately controlled. 30 
When the solenoid is de-energized, after movement of 
the shutter disk 8 to the position shown in FIGURE 3, 
the U-shaped spring 21 exerts a clockwise rotation to the 
shutter disk 8. Sufficient energy is stored in the shutter 
disk 8 that the shutter disk not only moves to its closed 35 
position covering the aperture 5, but also continues to 
travel until the catch lever 30 again engages the stop 28. 
That is, the energy supplied by the U-shaped spring 24 
is utilized to return the shutter disk 8 from the position 
shown in FIGURE 3 to the position shown in FIG- 40 
URE 2. 
Reference is directed to FIGURE 5. The spring 24 
is so adjusted that it passes through a relaxed or neutral 
position when the pin 12 passes through the black dot 
positions thereof, and a dead-center condition occurs at 45 
the circle dot position of the pin 12. Thus, in the posi- 
tion shown in FIGURE 2, the force of the spring is 
counterclockwise on the pin 12. The solenoid forces the 
spring past the dead-center position to that shown in 
FIGURE 3 so that the force of the spring is now clock- 50 
wise on the pin 12. The instant the solenoid is de-ener- 
gized the spring 24 turns the shutter disk 8 clockwise, 
and stores sufficient energy to carry the pin past the black 
dot portions shown in FIGURE 5 and to the latched 
position shown in FIGURE 2. 55 
While a particular embodiment of this invention has 
been shown and described, it is not intended to limit the 
same to the exact details of the construction set forth, 
and it embraces such changes, modifications, and equiva- 
lents of the parts and their fornlation and arrangement 
as come within the purvieiv of the appended claims. 
What is claimed is: 
1. (a)  An electrically-operated rotary shutter, com- 
prising: 
(b) a means having a shutter aperture thelein; 65 
524 
4 
(c) a rotatable shutter disk having a shutter gate posi- 
tioned to pass said aperlure; 
(d) a reciprocable armature; 
(e) a solenoid for urging said armature in one direc- 
tion; 
( f )  a spring for urging said armature in the opposite 
direction; 
(g)  a link and lever means connecting said armature 
to said shutter disk to effect partial rotation upon op- 
eration of said solenoid to bring said gate in registry 
with said aperture, and to effect continuing rotation 
upon operation of said spring to move said gate out 
of registry with said aperture. 
2. (a)  An electrically-operated rotary shutter, com- 
prising: 
(b)  a means having a shutter aperture therein; 
(s) a rotatable shutter disk having a shutter gate posi- 
tioned to pass said aperture; 
(d) remotely controlled means for partially rotating 
said shutter disk from an initial position closing said 
aperture to a second position wherein said gate is 
in registry with said aperture; 
(e) yieldable means operable on release of said re- 
motely col~trolled means for continuing rotation of 
said shutter disk from said second position to  said 
initial position; 
( f)  a ratchet carried by said shutter disk having shoul- 
ders corresponding to the initial and second positions 
of said shutter disk; 
(g) and catch means engageable with said shoulders to 
secure said shutter disk against counter-rotation from 
said positions. 
3. (a) An electrically-operated rotary shutter, com- 
prising: 
(b)  a means having a shutter aperture therein; 
(c) a rotatable shutter disk having a shutter gate posi- 
tioned to pass said aperture; 
(d) a crank pin on said shutter disk for effecting rota- 
tion thereof; 
(e) link and lever means for driving said crank pin; 
(f) remotely controlled means for moving said link 
and lever means to effect partial rotation of said 
shutter disk from an initial position, closing said 
aperture, to a second position, exposing said aper- 
ture; 
(g) yieldable means operable on release of said re- 
motely controlled means for moving said link and 
lever means to eiFect continued rotation of said shut- 
ter disk from said second position to said initial 
position; 
(h) a ratchet carried by said shutter disk having shoul- 
ders corresponding to the initial and second positions 
of said shutter disk; 
(i) and catch means engageable with said shoulders 
to secure said shutter disk against counter-rotation 
from said positions. 
References Cited b y  the Examiner 
UNITED STATES PATENTS 
JOHN M. HORAN, Prirncriy Esnnlirzer. 


Electrically-operated rotary shutter Patent

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