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Патент USA US2407800

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Sept. 17, 1946.
R. |_, sM|T|-|
2,407,800
EXPOSURE TIMING MECHANISM
Filed Jan; 26, 1945'
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INVENTOR:
Patented Sept. 17, 1946
2,407,800
UNITED STATES PATENT OFFICE
2,407,800
EXPOSURE TIMING MECHANISM
Roland L. Smith, Belmont, Mass.
Application January 26, 1945, Serial No. 574,662
6 Claims. (Cl. 161-1)
1
2
This invention relates to exposure timing
mechanisms such as are employed in making
mind the length of time, as measured in seconds,
photographic enlargements and prints by electric
light.
A timing mechanism of the class referred to
is employed for controlling and operating an
for each exposure since no indication of this.
factor could be derived from the instrument
itself,
Another objectionable feature of devices of this
class as heretofore provided has been that when
the dial was constructed with a supplemental
electric circuit in which is arranged an electric
series of holes or sockets, more closely spaced
lamp by means of which the enlarging or ‘print
apart than the ?nger holes or sockets, for use in
ing is effected and such a device is, as a practi
cal matter, essential when a number of prints or 10 effecting exposures differing in time from that
possible through use of the ?nger holes, said
enlargements are to be produced from a single
supplemental holes or sockets were necessarily
negative if uniformity in results is to be obtained.
made too small for the reception of the ?nger
A well known type of timing instrument has
so that it was necessary for the operator to equip
heretofore been provided which comprised a
?nger-operated rotatable dial, a spring motor for 15 himself with a pointed skewer-like accessory in
strument such as a pencil, for example, for use
yieldingly urging said dial rotatively in one direc
within the small supplemental holes when op
tion at a predetermined speed, a switch incorpo
erating the dial.
rated in the circuit of the lamp, said switch in
This invention has for its object to provide
cluding a resilient contact serving also as a stop
for limiting the rotary movement of the dial 20 an improved timing instrument of the class de
scribed and in particular to obviate the above
under the in?uence of the spring motor and be
ing normally maintained in open position by the
noted objectionable features characterizing de
dial, and a ?nger-engaging stop on the frame or
vices of this class as heretofore constructed.
To this end I have provided certain improve
base of the instrument for limiting the rotary
movement of the dial in the opposite direction 25 ments in instruments of the class indicated as set
forth in the following description, the several
under the influence of the ?nger oi the operator.
novel features of the invention being separately
The dial was made with a circular series of
sockets or apertures spaced apart equidistantly at
pointed out and de?ned in the claims at the close
of the description, it being understood, however,
intervals of a predetermined number of seconds,
usually ?ve seconds, and in making an exposure, 30 that the illustrated embodiments of the inven
tion are to be taken as preferred examples of the
say for example ?fteen seconds, the operator
latter and that various changes may be resorted
would insert his ?nger in the third aperture or
to without departing from my invention as de
socket in front of the ?nger stop and quickly turn
?ned in the claims.
the dial clockwise away from the switch until
In the accompanying drawing:
movement of his ?nger and the dial in that direc 35
Figure 1 is a top plan view of an exposure tim
tion were arrested by said ?nger stop whereupon
the operator released the dial thereby permitting
ing instrument constructed in accordance with
this invention.
the spring motor to return the same contra
clockwise to its normal position again at said pre
Figure 2 is a side elevation, partly in section, of
determined speed. At the start of the movement 40 the instrument shown in Fig, 1.
Figure 3 is a section on line 3-3 of Figs. 1
of the dial under the in?uence of the operator’s
and 2.
?nger the resilient contact was released thereby
Figure 4 is a sectional detail relating to the dial
closing the circuit through the lamp, and at the
of Figs. 1 and 2.
completion of the return movement of the dial
Figure 5 is a partial top plan view of an ex
under the in?uence of the spring motor the re-, 45
posure timing mechanism embodying an alter
silient contact was restored to its normally open
position by the dial thereby extinguishing the
native form of the invention.
Figure 6 is a side view of the parts shown in
lamp at the expiration of the selected interval of
Fig. 5.
time-?fteen seconds.
An objectionable feature characterizing the 50
Figure '7 is a detail hereinafter referred to re
lating to the embodiment illustrated in Figs. 5
above described and other constructions hereto
fore proposed has been that in making many en
and 6.
largements or prints from one and the same
The embodiment of my invention illustrated
in Figs. 1, 2, 3, and 4 of the drawing comprises
negative it was necessary, throughout this pro
cedure, for the operator to remember or bear in 55 a molded base 10 of any suitable non-conducting
2,407,800
3
moldable material, said base being in the form of
an inverted cup which provides a housing for a
spring motor I I and an electric switch comprising
a ?xed contact I2 and a resilient contact l3.
Contacts I2 and [3 are arranged in an electric
circuit I4 in series with the usual electric lamp
4
it is possible to provide for an exposure that
prevails for a de?nite measured length of time
appropriate to the characteristics of the particu
lar negative or the like that is being employed,
provided said appropriate time is ?ve seconds or
a multiple of ?ve seconds.
(not shown) by means of which the photographic
The above described construction is as here
tofore and serves its purpose very well when
making a small number of enlargements or prints
Spring motor II is fastened by screws Ila (Fig. 10 from a single negative or the like requiring com
1) to the under side of the top wall of base I0
paratively long exposures, but when making a
and includes a vertical shaft 15 which extends
considerable number of enlargements from one
upwardly therefrom loosely through an aperture
and the same negative or the like, the operator
provided in the top wall of base It! to the ex
would often inadvertently use the wrong ?nger
terior thereof where it has ?xedly mounted on 1.5 hole during his repeated operations of the dial
it a circular molded dial I6 that is formed near
because of the absence of any means for visually
its periphery with a circular row of ?nger holes
indicating the proper hole to use. Moreover,
or sockets I1 disposed concentrically with respect
when operating with a thin negative requiring
to the axis of motor shaft I5.
short accurately timed exposures other than of
Upon its under side the dial I6 is made with 20 five seconds or a multiple thereof, it was not
a depending boss IB which is normally pressed
possible to operate the instrument accurately as
laterally against one side of the upper end of
required except through the use of the accessory
the resilient contact I3 by motor l I so as to hold
skewer-like implement and the relatively small
said contact out of engagement with the ?xed
supplemental holes or sockets, hereinbefore re
contact I2. The ?xed contact I2 is disposed en~
ferred to. My improvements, now to be de
tirely within base I0 where it is fastened by
scribed, obviate these objectionable features char
screws to a pad I9 (Figs. 2 and 3) forming part
acterizing instruments of this kind as heretofore
of the top wall of the base. The resilient con
constructed and with which I am familiar.
tact I3 is fastened by screws to another pad Ell
In accordance with this invention I provide
forming part of the top wall of the base and
the timer mechanism with a ?nger-operated arm
includes a free end portion extending upwardly
24 (Fig. 1) of resilient sheet metal disposed
through an aperture ZI formed in the top wall
radially above, and in close proximity to, the dial
of the base to the exterior of the latter where
I6, said arm being pivotally secured at its inner
its upper extremity occupies a position in the
end to the upper end of the motor shaft I5 by
path of the boss I8. One side of this aperture - a screw 25 so that it is normally free to be swung
2! serves as a stop to positively limit the move
laterally relatively to said shaft and the dial in
ment of contact I3 occasioned by the pressure
either direction. The outer end of this arm is
of the boss against the same.
provided with a depending ratchet tang 26 (Figs.
A bracket 22 is fastened by screws to the ex
2 and 4) to cooperate with a composite circular
terior of base It and the upper end portion
row or series of relatively small closely spaced
of said bracket is made with a lateral ?nger?stop
sockets or recesses 21 and 28 formed in the mar-.
extension 23 which overhangs the marginal por
ginal portion of dial I 6 and disposed concen
tion of dial I6 just above the path traversed by
trically with respect to the axis of shaft I5. Each
the ?nger-holes or sockets l1 when the dial is
of these sockets or recesses is adapted to re—
rotated on the axis of shaft I5.
ceive the tang 26 as shown in Fig. 4 and pro
The ?nger-holes or sockets I1 are angularly
vides at one side thereof an abrupt abutment
spaced apart relatively to each other alike
shoulder facing away from stop 23 and adapted
throughout the row a distance equaling the an~
to be engaged by one side of tang 25 which
gular movement of shaft I5 during a predeter
is parallel with said shoulder. The opposite side
mined. length of time as measured by a number
of tang 25 may be beveled as shown so that the
of seconds and the angular distance between
tang may slide freely over the sockets when arm
hole or socket #1 and ?nger stop 23 is the same.
24 is rotatively adjusted in that direction. The
Assuming this distance between the holes and
resiliency of arm 24, however, permits the free
between hole #1 and stop 23 to be equal to the
end thereof to be manually lifted away from
angular displacement of shaft I5 and dial I6 55 the dial when the arm is to be adjusted in either
during an interval of time of ?ve seconds, as
direction.
in the drawing, it will be clear that by inserting
Each socket 27 of the composite series is co
a ?nger in either one of the holes I] and turn
operatively associated with one of the ?nger-holes
ing dial I6 and shaft l5 clockwise until movement
of the dial in that when occupied by the tang
of the ?nger and dial in that direction is ar 60 of arm 24 the latter then serves to indicate that
rested by stop 23 and immediately releasing the
the ?nger-hole associated with that socket is
dial, then the spring motor will rotate dial I6
being used. This is an important function when
and shaft I5 contra-clockwise back to their nor
a number of enlargements or prints are being
mal positions again and this return movement
made from one and the same negative since
will be effected by motor ll during a period of 65 it guides the photographer in his operation of
time corresponding with the angular distance
the dial and relieves him of the necessity of re
between the hole that is used and the stop 23,
membering the particular timing being employed.
said period of time being either ?ve seconds or
Arm 24 likewise serves as an indicator when en
a multiple of ?ve seconds according to the posi
gaged ‘with either of the sockets 28.
tion of said hole.
70 When the dial occupies its normal position
It will also be clear that during the time that
the composite portion of the supplemental row‘ of
enlargements or prints are made from a negative
or the like.
the dial is away from its normal position switch
I2—~I3 is closed and the lamp (not shown) of
sockets 2‘I—28 starts at the ?nger-stop 23 and
extends therefrom contra-clockwise around the
the apparatus is lighted. Thus, by using the
marginal portion. of dia1 It as far as ?nger-hole
proper hole or socket I’! in operating the dial 75 #6, an angular distance corresponding with the
2,407,800
5
distance traveled by the dial during thirty sec
onds while being actuated by spring motor H
and throughout this composite portion all of the
sockets are spaced apart relatively equidistantly
6
teeth 29, said tang being yieldingly held against
the dial by the resiliency of the arm of which it
forms part.
What I claim is:
1. In a timing instrument, the combination of
a distance corresponding with the extent of an
gular displacement of dial it e?ected by motor
a
rotatably supported switch-operating dial
whose outer marginal portion is made with a con
l l during a one second. period of time.
centric row of ?nger-sockets angularly spaced
In making enlargements from a thin negative
apart equidistantly at relatively large intervals
or the like not only is much less time required
than with a dense or strong one, but much ?ner 10 and also with a concentric row of supplemental
sockets spaced apart equidistantly at smaller
regulation or control of the exposure period is
necessary with the thinner negative or the like,
angular intervals that subdivide the intervals
which is, as Will be clear, obtainable through use
between said ?nger-sockets; a radial arm pivot
of arm 24 and the sockets of the composite por
ally supported for independent rotative adjust
tion of the supplemental row, the latter being 15 ment at times on the axis of said dial to set said
spaced apart relatively one second.
arm in a de?nite time-indicating position rela-
When using a ?nger-hole or socket beyond the
composite portion of the supplemental row,
tively to said dial; a ?xed ?nger stop, and means
on said arm for engaging one of said supple
which will be the case in producing enlargements
mental sockets to positively adjust said dial ro
from a strong or dense negative or the like, the 20 tatively when said arm is swung by ?nger pres—
arm as is set in engagement with the socket 21
sure toward said ?nger-stop.
of the appropriate ?nger-hole and utilized in
2. The combination of claim 1 wherein said
operating the dial. With this type of negative
arm is a resilient member and wherein said last
or the like regulation of the time of exposure
mentioned means consists of a depending tang
to the extent of ?ve seconds or multiple thereof 25 provided adjacent to the outer end of said arm
is ordinarily suf?cient and this is provided for by
and yieldingly held in socket-engaging position
the ?ve seconds spacing of the ?nger-holes that
by the resiliency of said arm.
are beyond the composite portion of the supple
3. The combination of claim 1 wherein said
mental row.
?nger-stop overhangs said dial and wherein the
As shown in Fig. 2 of the drawing the stop 30 outer end portion of said arm is movable with said
extension 23 is disposed above the path of the
dial on a path between the latter and said ?nger
dial operating arm 24 so that the latter can, at
stop.
times, pass beneath the same.
4. The combination of claim 1 wherein said
In starting enlarging operations with a given
supplemental sockets are provided by a circular
thin negative the operator usually makes some 35 row of teeth formed upon the outer marginal por
preliminary trial exposures by means of the ?nger
tion of the dial.
holes I‘! and after thus ascertaining the approx
5. The combination of claim 1 wherein said
imate time he can then obtain the exact timing
supplemental sockets are provided by a circular
through use of the pawl-like arm 24 and the
row of ratchet teeth formed upon the outer mar
composite row of supplemental sockets 2'l—28. 40 ginal portion of the dial, and wherein said arm
In many instances this will avoid the necessity
is a resilient pawl-like member that is main~
of regulating the intensity of the light.
tained in socket-engaging position by its resil
In the embodiment of the invention illustrated
iency.
in Figs. 5. 6 and 7 the periphery of the dial [6a
6. In a timing instrument, in combination, a
is made throughout its circuit with a circular row 45 rotatably supported switch-operating dial whose
of ratch~like teeth 29 which provide abutment
outer marginal portion is made with a row of
shoulders 39 facing away from the ?xed ?nger
relatively large ?nger-sockets that are angularly
stop 23a, said shoulders co-operating with. a ver
spaced apart at relatively large intervals con
tically resilient pawl-like arm 24a. This arm is
centrically with respect to the axis of said dial,
pivoted loosely upon the upper end of the shaft 50 and made also with a concentric row of relatively
15 of the spring motor (not shown) and held in
small supplemental sockets spaced apart at
position thereon by a nut 25a having threaded
smaller angular intervals that subdivide the in.
engagement with said shaft.
tervals between said ?nger-sockets; a spring mo
The teeth 29 are spaced apart relatively an
tor having a vertically disposed shaft on which
angular distance corresponding with the extent 55 said dial is ?xed,_ said motor yieldingly main
of rotary motion imparted to the dial by the
taining said dial normally at the limit of its r0
spring motor during one second and within this
tary movement in one direction; a radial ?nger
circular row of teeth 29 the dial is formed with a
operated arm pivotally mounted loosely upon said
circular row of ?nger holes or socket-s I'ia which
shaft for independent rotative adjustment
are spaced apart relatively an angular distance
thereon at times to set said arm in a de?nite
corresponding with the extent of rotary motion
time-indicating
position relatively to said dial;
imparted to the dial by the spring motor during
means carried by said arm for engaging one of
?ve seconds, each of said holes or sockets Ila
said ‘supplemental sockets to positively adjust
being disposed radially opposite one of the abut
said dial rotatively when said arm is swung by
ment shoulders 30a of teeth 29 so that the holes
?nger pressure in the opposite direction, and a
of the group or row Ila serve as indicators to
?xed ?nger-stop in the path of the ?nger for
guide the operator in accurately placing the arm
24a in any desired position.
limiting the movement of the dial in said oppo
The free end of arm 24a is made with a de
site direction.
pending tang 26a (Fig. 7) to co-operate with the 70
ROLAND L. SMITH.
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