Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE IN ENTION
1. Field o~ the Invention
This invention relates to photographic cameras and,
more particularly, to photographic cameras providing electronic
flash illumination.
2. Description of the Prior Art
The use of transient artificial illumination such as
f~om incandescent flash bulbs or electronic strobe units for
providing scene illumination for photographic exposures under
conditions of low ambient scene light intensity, are well known
in the art. Examples of camera systems which utilize strobe
illumination under low ambient conditions are described in U.S.
Patent Nos. 4,007,469 granted on February 8, 1977 to Edwin H.
Land, et al; 4,086,606 granted to Patrick L. Finelli, et al. on
April 25, 1978; 4,085,414 granted on April 18, 1978 to John P.
Burgarella, et al; and 3,438,766 granted on April 15, 1969 to
Conrad H. Biber.
Additionally, the use of transient illumination during
an exposure under higher ambient scene illumination for fill-in
flash are also well-known in the art. In the latter case, the
transient illumination is generally employed, not as the primary
illumination for exposure, but rather as supplementary to the
ambient illumination so as to add foreground illumination of the
subject, soften shadows, or to generally increase the subject
illumination.
In many fill-in arrangements, the camera operator
manually selects the use of fill-in flash and the proper exposure
parameters which determine the relative effectivenes~ of the
transient illumination and the ambient illumination. Examples of
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such fill-in flash systems are described in "Fla8h Fill-in",
page 58, Practical Photography, October, 1978; U.S. Patent No.
4,079,389 issued March 14, 1978 and in U.S. Patent No. 4,023,187
issued May 10, 1977.
The latter patents both describe camera systems which
will operate in a fill-in flash mode when a flash accessory is
mounted on the camera. The camera described in U.S. Patent No.
4,079,389 requires manual selection of the degree of flash
exposure, while U.S. Patent No. 4,023,187 automatically determines
the latter. Consequently, at~least in the latter case, mere
mounting of the flash unit on the camera under normal scene light
conditions provides selection of the fill-in flash mode. However,
the operator must still make a deliberate selection of this mode
and often, either forgets to make use of this fill-in flash
arrangement, or deliberately avoids use of the latter; perhaps
for reasons of economy and a lack of understanding or appreciation
of the value of fill-in flash. Hence, while the prior art suggests
using transient illumination under varying conditions of scene
illumination, the determination of whether to use transient
illumination in addition to the normal scene illumination is
generally left to the decision of the operator. Consequently,
it is an object of this invention to provide a photographic camera
- automatically employing improved exposure control under substan-
tially all conditions of ambient scene illumination.
A further object is to provide a fully automatic strobe
camera which will automatically provide strobe illumination under
all scene lighting conditions at least when the subject is within
range of the strobe illumination. Another object of this inven-
tion is to provide a fully automatic strobe camq~a utilizing a
film cassette and battery combination configured to automatically
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fire a strobe flash during all or substantially all camera exposure oper-
ations.
Briefly, the above and other objects of the invention are obtained
by camera apparatus providing increasing aperture values and witha pulse of
transient illumination produced at an aperture value selected in accordance
with subject distance at all ambient scene light levels, at least for
subjects located within a given maximum subject distance at which the flash
illumination will have effect. The camera is provided with a built-in
electronic flash unit coupled to the camera actuator and energized by the
film pack battery such that the flash device is illuminated for each film
exposure.
In accordance with the invention, the camera includes means for
receiving a film pack containing a battery, a scanning shutter system, and
means for determining subject distance and providing a range signal cor-
responding thereto. Also included is an integral electronic flash
chargeable by the film pack battery for producing a pulse of illumination,
photometric means for evaluating the scene light level, and a control cir-
cuit, responsive to the operation of a manual actuator, for opening the
scanning shutter system to initiate film exposure, for then triggering the
flash unit to produce a pulse of light at an effective aperture value
determined in accordance with the range signal, and in response to the
photometric means for subsequently closing the shutter to terminate the
exposure after an appropriate exposure interval.
~roadly stated, according to a first aspect of the present inven-
tion, there is provided a camera for use under conditions ranging from
insignificant ambient scene light intensity to substantial scene light
intensity, said camera comprising: a housing having means for defining a
focal plane; a lens assembly for directing image forming light rays from
a photographic scene along a given exposure path to said focal plane;
means for positioning a sheet of photographic film at said focal plane;
energizable means for evaluating scene light; an electrically controlled
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shutter arrangement actuatable for unblocking and blocking said exposure
path to define an exposure interval, said shutter arrangement including
means responsive to each actuation of said shutter arrangement for defining
the same pattern of varying aperture values, including progressively
enlarging ayerture values, in operative relation to said exposure path in
the absence of actuation of said shutter to terminate said exposure inter-
val prior to said shutter arrangement defining its maximum achievable
aperture value; an electronic flash unit permanently affixed on said hous-
ing and having a predetermined maximum effective range; means for producing
a range signal corresponding to the distance of a photographic subject from
said camera; a manual actuator; and circuit control means programmed to
be responsive to every operation of said manual actuator, at least when
photographing a subject within the maximum effective range of said flash
unit, for effecting the actuation of said shutter arrangement to initiate
an exposure interval, for automatically firing said electronic flash unit
during each said exposure interval at the instant an aperture value,
correlated to said range signal and selected from said enlarging aperture
values, is presented in operative relation to said exposure path by said
shutter arrangement, and for then actuating said shutter arrangement to
terminate said exposure interval in accordance with a predetermined film
exposure being achieved, whereby, whenever a photographic subject is within
said maximum effective range of said flash unit during different exyosure
operations, said camera is preprogrammed to automatically provide photo- ~.
graphic exposures embodying range dependent, aperture controlled amounts
of flash illumination responsive to all normally intended actuations of
said manual actuator regardless of the levels of ambient scene light
present.
According to a second broad aspect of the present invention,
there is provided a camera for use under conditions ranging from insig-
nificant ambient scene light intensity to substantial scene light intensity,
said camera comprising: a housing having means for defining a focal plane;
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a lens assembly for directing image forming light rays from a photographic
scene along a given exposure path to said focal plane; means for position-
ing a sheet of photographic film at said focal plane; energizable means
for evaluating scene light; an electrically controlled shutter arrangement
actuatable for unblocking and blocking said exposure path to define an
exposure interval, said shutter arrangement including means responsive to
each actuation of said shutter arrangement for defining the same pattern
of varying aperture values, including progressively enlarging aperture
values, in operative relation to said exposure path in the absence of
actuation of said shutter to terminate said exposure interval prior to
said shutter arrangement defining its maximum achievable aperture value;
an electronic flash unit permanently affixed on said housing and having a
predetermined maximum effective range; a manual ac~uator; and circuit
control means programmed to be responsive t.o every operation of said manual
actuator, at least when photographing a subject within the maximum effec-
tive range of said flash unit, for effecting the actuation of said shutter
arrangement to initiate an exposure interval, for automatically firing
said electronic flash unit during each said exposure interval to expose
said sheet of film with a controlled amount of flash illumination reflec-
ted from a photographic subject depending upon the distance of said subject
and the ambient scene light intensity, and for then actuating said shutter
arrangement to terminate said exposure interval in accordance with a pre-
determined film exposure being achieved, whereby, whenever a photographic
subject is within said maximum effective range of said flash unit during
different exposure operations, said camera is preprogrammed to automatically
provide photographic exposures embodying range dependent controlled amounts
of flash exposure responsive to all normally intended actuations of said
manual actuator in accordance with the levels of ambient scene light
present.
The invention will now be described in greater detail with reference
to the accompanying drawings, in which:
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Figure l is a diagrammatic side elevational view of a photographic
camera in accordance with the present invention with portions cut away to
reveal interior elements thereof;
Figure 2 is a front elevational view of the camera shown in Figure
1 with some interior portions shown in dotted outline; and
Figure 3 is a block diagram depicting many of the electrical
functions of the camera shown in Figures 1 and 2.
In Figures 1 and 2, there is shown a camera 10 comprising a housing
12 configured to receive a film pack 14 which includes a plurality of
film units 16 mounted over a flat battery 18 as, for example, is described
in United States Patent Nos. 3,543,662; 3,705,542; 3,748,984 and 3,779,770.
In this regard, the camera 10 is a self-developing camera designed for use
with a film pack of the type manufactured and sold by the Polaroid Corpor-
ation as the Polaroid SX-70 Land film pack.
Within the camera housing 12 is a receiving chamber 20, access to
which is provided by a door member 22. The chamber 20 is designed to
receive the film pack 16 in a fixed l~ocation with a spring member 24, carried
within the film pack 14 as noted in the aforementioned United States Patent
No. 3,543,662, urging the film units 16 forwardly such that the uppermost
unit thereof is positioned at the focal plane of the camera. Included within
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the receiving chamber 23 are a pair of battery contacts 26 which
e~tend within the film pack 14 to provide connection between the
camera 10 and the battery 18.
Mounted on a front wall 30 of the housing 12 is an
adjustable lens assembly 32 which is configured for focusing
image carrying rays from the photographic scene along an exposure
path 34 to a mirror 36 from which they are reflected to the upper-
most film unit 15. Control of the exposure path is provided by a
scanning shutter system 40, under the control of an electrical
solenoid 42 as is explained in detail in U.S. Patent No. 3,942,183.
In this arrangement, the scanning shutter system employs a pair
of blades 44 and 46 which, upon release by the solenoid 42, are
spring biased to bring a pair of primary or taking apertures 45
and 47, respectively, provided within the blades, into increasing
coincidence at the taking path 34 so as to provide increasing
aper~ure values thereat during initiation of the exPosUre interval.
Hence, the scanning shutter system 40 in effect is a diaphragm-
shutter which provides electrically actuatable means for unblocking
and blocking the exposure path to define an exposure interval and
for defining varying aperture values in operative relation to the
exposure path during that interval.
A photoresponsive device or photocell 48 is carried
within the camera 10, behind the shutter 40, and exposed to scene
light through a lens arrangement 50 also mounted on the front
face 30 of the camera. Scene light transmitted to the photocell
is controlled in conjunction with film exposure, as noted in the
aforementioned U.S. Patent No. 3,942,183, by means of a pair of
secondary apertures 49 and 51 also carried by the shutter blades
44 and 46; the secondary apertures operate in ~ tracking relation
to the taking apertures of the blades.
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As previously indicated, the camera lO is of a self-
developing type in which the film is processed to a viewable
condition. Hence, following the exposure of the uppermost film
unit, the latter is transported from the camera by way of a
processing station (not shown) located between the film pack
receiving chamber 20 and the film exit slot 62.
A camera actuator switch or button 64 is also mounted
on~the front face 30 in a convenient location to facilitate camera
actuation by the operator. Additionally, a viewing window 66 is
locàted in the front face 30 and operates in conjunction with a
viewing system 68 to permit viewing and framing of the scene by
the operator.
Permanently affixed to an upper surfaoe 70 of the housing lG
is an electronic strobe unit 72, which includes a flash discharge
tube 74 located in a suitable reflector 76 behind a lens 78; the
latter serving to focus light from the flash tube 74 into the zone
of view of the camera lO. The electronic flash unit 72 is pro-
vided as an integral part of the camera lO in accordance with the
invention and is powered from the battery which is carried in the
film pack. In this regard, the electronic strobe may be of the
type described in U.S. Patent No. 4,074,295 entitled "Compact
Accessory Strobe for Cameras with Battery Enclosed Film Pack"
issued to R. Kee on February 14, 1978. Unlike the aforementioned
electronic flash unit, however, the flash unit of the present
invention is an integral part of the camera and is intended for
use in all exposures or at least where the strobe light is
effective, as will be subsequently e~ lained with regards to
Fig. 3.
Flash firing is controlled by a transducer 56, mounted
on the front face 30 of the camera lO, which operates as later
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explained in conjunction with a sonar range network 58. The range network
58 includes appropriate circuitry (not shown) which, by means of the trans-
ducer 56 emits an ultrasonic burst directed towards a central portion of
the photographic scene so as to be reflected from subjects positioned
therein and which, upon receipt of an echo from such subjects, by virtue
of the elapsed time from emission to echo, provides an appropriate signal
corresponding to this time interval and, hence, to the distance of the sub-
ject from the camera 10. This subject distance signal is utilized in the
illustrated embodiment primarily for controlling the firing time of the
electronic flash unit 72 to ensure the selection of a proper aperture
value as will be more fully explained below. Additionally, although not
necessary to the present invention, the sonic signal is also preferably
utilized for focusing of the lens assembly 32, and in the latter case, an
electrically energizable lens driving arrangement (not shown) would be
provided for lens focusing.
Turning now to Figure 3, wherein the operational arrangement of
the camera 10 is shown in block diagram form, it should be first noted
that the film pack 14 or, more particularly, the battery 18 thereof, is
employed as the sole source of energy for the complete camera which includes
the strobe unit 72. In this arrangement, operation of the actuator button
64by the camera operator powers up the camera and through a logic sequence
as later explained, triggers each of the operation units into operation at
an appropriate point in the camera cycle. A conventional latching arrange-
ment tnot shown) is employed in conjunction with
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the camera button 64 to maintain camera operation throughout the
complete cycle; the latch being activated with initial button
operation and released upon the operation of the final event in
the cycle.
In the illustrated circuit, actuation of the button 6a
initiates energization of a strobe charging network 82 which,
when fully charged, enables the strobe unit 72 for subsequent
~: firing. During charging of the charging network 82, operation
.
o~ other components is inhibited by appropriate logic circuitry,
deslgnated by a range inhibit circuit 84 ana an exposure.inhibit
: ; network 86. The latter networks may be provided by any suitable
~ means, such as a flip flop circuitry or conventional logic
: a~rangements wherein network 84 clamps or holds the sonic range
network 58 inoperative until strobe charging is complete and
network 86 holds the shutter system inoperative until both strobe
~ . charging and subject ranging is complete.
: ~ Consequently, in this arrangement during strobe
charging the inhibit networks 84 and 86 are active due to a
"charging" signal on lines 88 and 90. When charging ceases, the
range inhibit network 84 is released, which in turn triggers the
:,
~i sonic range network 58 into operation. Activation of the exposure
,
inhibit network continues, however, due to a "ranging" signal.
presented on line 92.
Upon activation, the sonic range network 58 initially
operates in a transmit mode to pulse the transducer 56 which
transmits a sonic burst toward the subject to be photographed and
then in a receive mode listens for the sonic echo therefrom. The
elapsed time,being proportional to subject distance, is stored as
a timed range singal in a storage network 96, fo~ example, a
digital clock and counter system which is activated in synchronism
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with the sonic transmission and stopped upon the echo return, such that
the stored count provides an appropriate range signal.
Prior to completing the operational description of the camera, the
utilization of the range information will be described. As indicated, the
range signal is principally employed herein for dynamic selection of a
flash aperture. Hence, the aperture scanning shutter system produces
changing aperture values during the exposure and the strobe is fired at a
time value coordinated with subject range and the scanning rate of the
shutter so that the pulse of strobe light is synchronized in time with an
aperture or, more precisely, a very narrow range of aperture values selec-
ted in dependence upon subject distance.
That is, as the shutter opens, increasingly enlarging aperture
values are provided until adequate scene light has been received by the
photocell 48 to charge a summing capacitor included within the light
integrating network 52 to an appropriate level determined in accordance
with the exposure parameters of the film unit 16. During this scanning
operation of the shutter, various aperture values are defined, each in
accordance with an elapsed time interval as measured from either first
light or the opening actuation of the shutter. Consequently, the strobe
unit is timed to be fired when an appropriate aperture selected in accor-
dance with the subject distance is provided by the shutter system 40.
This may be accomplished by design of the shutter system to provide aperture
values varying at a rate comparable to the distance time relationship of the
sonic range network,
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or by converting the sonically derived ranging time in proportion
to the desi~n curve of the opening rate of the shutter. In either
case, the shutter system 40 and the storage network 96 are
coordinated so that the strobe unit 72 will be fired at a time
at which an appropriate aperture selected in accordance with
subject distance is in operative relation over the exposure
path 34 in the camera 10.
Since the ratio of sonic range time versus subject
distance is known as well as the aperture scanning rate, the
clock or count rate of the storage network can be provided such
that the timed output thereof for any given subject distance will
be equal to the time it takes for the shutter, as measured from
first light, to reach an aperture value selected in accordance
with subject distance. For low ambient scene light, the selected
aperture value is directly related to subject distance in a
conventional manner such that with a constant flash output,
proper exposure of the film is assured independently of subject
range up to a maximum subject range which is determined by the
maximum aperture of the camera and the strobe output.
For fill-in flash, where the ambient scene light is
no longer negligible, the strobe contribution to the exposure
is reduced by selecting a smalier flash aperture than that
previously described. This is accomplished in the illustrated
circuit by a mode selector 98 which alters or switches the storage
network 96 to provide a flash time sianal appropriate to a fill-in
flash mode. For example, when the ambient scene light is above a
selected threshold value,the mode selector 98 maybe appropriately
triggered to shift the counting of the storage network to a slower
rate, thereby providing a shorter time value for a given subject
distance. This, in turn, provides an earlier flash fire, and
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hence, a smaller aperture value which, in turn, results in less
strobe contribution for a given subject distance.
As descrihed, the mode selection requires pre-exposure
evaluation of scene light, for example, by an additional photocell
or provision for presentation of the photocell 48 to scene light
prior to shutter opening,in which case a flash mode signal may
be made available from the photocell 48 by way of line 100 prior
to exposure actuation. Alternately, the mode selection may be
provided simultaneously with initiation of exposure by altering
the readout rather than the read in of the range storage network
as previously described. That is, the range signal ~ay always
be stored as a timed count suitable for fill-in flash fire time
and then, upon readout, appropriately altered by a given ratio
or fixed delay to provide flash fire for the flash mode.
Returning once again to the overall operation, when the
sonic range network receives the subject echo, indicating co~ple-
tion of ranging, the ranging signal presented to the exposure
inhibit network 86 over line 92 is terminated, such that this
inhibit network is released and the shutter 40 is, in turn,
triggered via line 102 to open. ~his, in turn, emits scene light
to the uppermost film unit of the film pack 16 and to the photo-
cell 48; with current from the latter being summed in the light
integrating network 52 in a conventional manner.
Simultaneous with opening of the shutter system 40, the
storage network 96 is triggered to initiate its readout or, that
i5, start the count down for flash fire. For example, the storage
network 96 may include an up and down counter which reads up
on range storage and is then read down, with the strobe fire
signal being provided via line 104 to the strobe unit 72, when
the count readout i5 complete. As indicated, the burst of light
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from the strobe unit 72 by virtue of the tailored flash time
will occur when an aperture value selected in accordance with
subject range is provided by the shutter.
Subsequently, when the integrating network reaches a
predetermined summing value, a close command signal is delivered
to the shutter system 40 which closes the shutter to thereby
terminate the exposure. While not depicted in Fig. 3, following
the closing of the shutter, the exposed film unit is advanced
from lts exposure position through a processing station (not
shown) and from the camera.
While not necessary to the operation of the illustrated
embodiment, since the strobe will be ineffective at large subject
distances, a switching arrangement (not shown) can be provided to
eliminate strobe flash for such exposures. Hence, it should be
understood that the circuit of Fig. 3 provides control means
programmed to be responsive to every operation of the actuator 64,
at least when photographing a subject within the maximum effective
range, for actuating the shutter, or unblocking and blocking means,
for determining the ambient light level, for firing the strobe 72
at an appropriate aperture as selected by the range system, and
for then terminating the exposure in accordance with the ambient
scene light level.
Since certain changes may be made in the above-described
system and apparatus without departing from the scope of the
25 invention herein involved, it is intended that all matter contained
in the description thereof or shown in the accompanying drawings
shall be interpreted as illustrative and not in a limiting sense.
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