Multiple battery camera

A first battery powers the electrical system of an automatic photographic camera throughout each cycle of operation. A second camera battery is normally electrically isolated, and is connected with the first battery selectively during each operating cycle, especially during conditions of relatively high power drain, to ensure reliable battery power.

BACKGROUND 
This invention relates to photographic cameras which incorporate automatic 
electrical systems that operate with periods of relatively high power 
consumption and of low power consumption. The invention provides a 
multiple battery supply for powering such electrical systems with high 
reliability against deficient battery power. 
Modern cameras often include electrical systems which set the exposure 
time, adjust the camera aperture, control the camera shutter, and/or 
advance the film. In self-developing cameras such electrical systems 
transport an exposed film unit through processing-initiating spread rolls, 
and eject it from the camera. The electrical power drain which these 
systems impose on the camera battery can increase significantly during a 
camera operating cycle according to the number and the nature of the 
electrical and electronic functions in the camera. For example, automatic 
exposure timing and even shutter adjustment typically consume relatively 
little battery power, whereas the mechanical drive for film advance 
consumes significantly more power. 
A weak camera battery often can drive the electrical system during low 
power operations, and evidence failure only during a high load or peak 
power portion of the camera cycle. Thus, a camera with a weak battery can 
nevertheless commence an operating cycle which starts with low power 
operations, but will not properly perform the subsequent high power 
operations such as film advance after exposure. The resultant operating 
failure and loss of one or more exposures are at the least annoying, and 
can involve more serious consequences particularly where the user 
collapses a folding camera which has halted operation in mid-cycle. 
Further, replacement of a weakened battery while the camera still contains 
unexposed film can lead to loss of one frame or of all the unexposed film, 
depending on how the battery is packaged within the camera and relative to 
the packaging of the film. 
The occurrence of these and other battery failure problems are difficult to 
rule out, because batteries fail due to many factors, including undue 
dealer storage, improper user care, and exposure to excessive temperature. 
Prior art efforts to diminish the battery problem can include low power 
indicators, and the use of multiple batteries. Thus, two batteries can be 
placed in series to produce a high voltage useful, for example, for film 
advance. More often, the batteries are connected electrically in parallel 
to augment the current supply for high drain operations. The continued 
parallel connection of a fresh battery with a weak one, however, can 
diminish the operating life of the fresh battery far below the expected 
life. U.S. Pat. Nos. 3,853,396 and 3,587,425; and German specification No. 
2,457,002 are among the prior art which disclose these and other battery 
schemes for powering camera operations. 
With the foregoing in mind, it is an object of this invention to provide a 
multiple battery supply for camera electrical systems and which operates 
with relatively high reliance against failure due to a deficient battery. 
Another object of the invention is to provide a novel connection of 
batteries within a camera whereby the premature aging of one battery does 
not degrade the performance of another battery. It is also an object to 
provide a camera system which obtains reliable and long battery operation 
irrespective of premature aging of another battery of the camera system. 
Further objects of the invention are to provide an inexpensive and 
relatively simple system of the above character. 
Yet another object of the invention is to provide a novel connection of 
batteries within a camera wherein a weak battery can drive the camera in a 
low power drain state, and another battery can selectively drive the 
camera in a high power drain state. 
Other objects of the invention will in part be obvious and will in part 
appear hereinafter. 
SUMMARY OF THE INVENTION 
According to the invention, a photographic camera incorporating a 
battery-powered electrical system has a first battery connected to power 
the system throughout the operating cycle, and has a second battery which 
is normally disconnected to be isolated from the electrical system and 
from the first battery. However, a switch element automatically connects 
the second battery electrically in parallel with the first battery during 
intervals of high power consumption in the operating cycle. In one 
preferred embodiment, operation with relatively high power drain continues 
from initiation through to the end of the electrical system operating 
cycle; hence the second battery remains connected to ensure that the 
electrical system completes an operating cycle which the first battery has 
sufficient strength to commence. 
The foregoing selective connection of the second battery with the camera 
electrical system ensures that the system receives enough power to perform 
high drain operations. The isolation of the second battery from the 
electrical system, and from the first battery, enhances the likelihood 
that it will maintain sufficient stored power to operate the camera 
electrical system, and not be drained by a weakened or defective first 
battery or by a short-circuit type malfunction in the electrical system. 
The invention thus significantly diminishes the likelihood that the user 
will encounter a loss of battery power, particularly during an operating 
sequence. The user is thus spared of lost exposures, wasted film and the 
potential of more serious consequences involving the camera itself. 
The invention accordingly comprises the features of construction, 
combinations of elements, and arrangement of parts exemplified in the 
constructions hereinafter set forth, and the several steps and the 
relation of one or more of such steps with respect to each of the others 
which the apparatus can perform, and the scope of the invention is 
indicated in the claims.

DESCRIPTION OF ILLUSTRATED EMBODIMENTS 
FIG. 1 shows a camera 10 typical of those having an automatic electrical 
system 12 with different power requirements at different times in an 
operating cycle. The camera is illustrated as of the self-developing type, 
but the invention can be used with other types of cameras. As 
conventional, for example, with the self-developing cameras which the 
Polaroid Corporation markets under the registered designations SX-70 and 
PRONTO!, when the user depresses a shutter release button 14, the camera 
10 automatically exposes through a shutter 16 a film unit packaged in a 
film cassette 18. The shutter is behind a lens 20 which may be fitted with 
an adjustable aperture 22. After exposure, a film advance mechanism 24 
powered by a motor 24a advances the exposed film unit out of the cassette 
with a pick mechanism 24b, and transports it to the bite between a pair of 
press rolls 24c which initiate photoprocessing and then eject the film 
unit from the camera. A housing 28 forms the camera body which mounts the 
foregoing elements and includes a compartment 30 which replaceably and 
removably seats the film cassette 18. 
The camera electrical system 12 is diagrammatically illustrated as having 
low power circuits 12a and high power circuits 12b. The former includes, 
for example, circuits which operate with the shutter release button 14 and 
elements of the shutter 16 mechanism; and the latter includes elements of 
the film advance mechanism 24, all of which are shown electrically 
connected in the system 12. A photocell 32, which receives light from the 
camera field of view, is connected with the illustrated system 12, and a 
flash unit 35 is shown and connected with dashed lines. As also shown, the 
camera has a first battery 34 and a second battery 36, each arranged for 
selective connection with the electrical system 12. Although the batteries 
are shown separate from the film cassette 18, either one can be packaged 
in the cassette and typically the battery 34 is provided in this manner. 
(The electrical connections in FIG. 1 are diagrammatic only, and reference 
should be made to other Figures and this description for operative 
interconnections.) 
The designation of the system 12 as having low power circuits and high 
power circuits corresponds with the battery power which the electrical 
elements of the camera system 12 draw during operation. That is, the 
system, which operates with a multiple-step cycle for each exposure, 
consumes relatively low battery power during some operations in each 
cycle, and draws significantly more battery power during other operations. 
By way of specific example, when the electrical system is quiescent, the 
power drain is essentially zero. During typical initial exposure control 
operations, initiated when the shutter release is depressed, the power 
consumption is relatively low. On the other hand, during film transport 
and processing operations, when the film advance mechanism 24 is 
operating, the power consumption is significantly higher. 
In accordance with the invention, the camera draws power from the first 
battery 34 continuously during each operating cycle and normally maintains 
the second battery 36 disconnected from both the electrical system and 
from the first battery 34. However, during one or more selected times in 
the operating cycle, including times of high power consumption, the second 
battery 36 is applied electrically in parallel with the first battery to 
provide power for the electrical system. 
FIG. 2 illustrates such a camera operating sequence with the two batteries 
34 and 36. As diagrammed, the camera is initially inactive, and draws no 
electrical power. The user activates the camera cycle by pressing the 
shutter release button 14, and a first step is to switch the primary 
battery 34 in circuit to power the electrical system 12. The electrical 
system operates the low load circuits 12a, which in the illustrated 
embodiment include the exposure control elements of the camera. Prior to 
operating the high power or heavy load circuits 12b, the electrical system 
switches the second battery 36, which up to now has remained electrically 
isolated from the electrical system and the first battery, in parallel 
with the first battery 34. In the illustrated embodiment, the high power 
operations include advancing the exposed film unit out of the film 
cassette with the pick mechanism 24b and driving it through the rolls 24c, 
all by operation of the motor 24a. Upon completion of these operations, 
the exposed film unit has been discharged from the camera and a fresh film 
unit is ready for exposure in the cassette 18. Accordingly, the film 
advance mechanism is turned off, and assuming there is no other high drain 
electrical requirement, the second battery 36 is switched out of the 
circuit. At the end of the camera cycle, the first battery 34 is 
disconnected from the electrical system 12, and the camera reverts to the 
inactive condition. 
Thus, during a complete cycle of the illustrated camera, the first battery 
34, which is selected to provide sufficient power for operating the entire 
camera electrical system throughout a number of film exposing cycles, is 
connected to drive all elements of the electrical system 12. The second 
battery 36, which also is selected to have sufficient power for driving 
all elements of the camera electrical system, is electrically isolated so 
that normally no current is drawn from it. The selective connection of 
this second battery to power the electrical system 12 together with the 
first battery 34, during conditions of relatively high electrical power 
consumption, ensures adequate battery power for the electrical system 
while protecting the second battery 36 from being discharged at other 
times, particularly if the first battery is weak. Conversely, if the 
second battery is weak, such selective connection also protects the first 
battery from being discharged by the second battery. 
Alternative to connecting the second battery 36 with the first battery 34 
automatically to power the electrical system during all operations of high 
battery power consumption, other switching logic can be employed. For 
example, a switching circuit can connect the second battery in parallel 
with the first battery only when the voltage from the first battery drops 
below a selected level, or when the current from the first battery exceeds 
a selected level, or in response to a combination of first battery current 
and voltage. In addition, the switching circuit can connect the second 
battery in parallel with the first battery solely in response to the user 
depressing the button 14 to actuate the automatic exposure cycle. Those 
skilled in the art can implement these battery switching operations with 
available circuits according to known procedures. 
FIG. 3 shows an embodiment of the camera 10 electrical system 12 in which a 
normally-open switch 40 is coupled to be closed upon actuation of the 
shutter release button, and remains latched, as by conventional electronic 
or mechanical elements, until the operating cycle ends. The switch 40, 
when closed, applies the battery 34 in parallel to a low light level 
circuit 42, an exposure control circuit 44, and the electrical elements of 
the film advance mechanism 24. A battery switch control element 46 
selectively closes and alternatively releases a normally-open switch 48; 
when closed the switch connects the second battery 36 electrically in 
parallel with the first battery 34. Otherwise the battery 36 is 
disconnected from any load or other drain and hence is electrically 
isolated. 
When the user depresses the shutter release button 14, which latches switch 
40 closed and thereby initiates a camera operating cycle, the first 
battery 34 applies operating power through the closed switch 40 to the 
circuits 42 and 44 and to the mechanism 24. The energized low light level 
circuit 42 measures with photocell 32 whether sufficient light exists to 
expose the film properly. When there is sufficient light, the circuit 42 
signals the exposure control circuit 44 to perform the exposure with the 
shutter 16. On the other hand, when the circuit 42 determines that there 
is insufficient light, it can initiate one of numerous operating sequences 
or simply halt operation, in a manner and with mechanisms well known in 
the art. By way of illustrative example, the low level circuit 42 can 
delay exposure and other further operation, whereupon the camera cycle 
ends if the user during the delay time releases the shutter button 14. 
However, if the button 14 remains depressed at the end of the delay 
period, the low level circuit signals the exposure control circuit 44 to 
operate the shutter 16. 
Upon being signalled by the low level circuit 42, the exposure control 
circuit 44 opens the shutter 16 for an exposure time dependent on the 
level of light which the exposure circuit measures through the camera 
lens. The closure of the shutter 16 mechanism actuates the film advance 
mechanism 24 and actuates the battery switch control unit 46 to close the 
normally-open switch 48. This connects the normally-isolated second 
battery 36 electrically in parallel with the first battery 34. The control 
unit 46 continues to maintain the switch 48 closed while the film advance 
mechanism 24 operates the pick mechanism 24b (FIG. 1) to index the exposed 
film unit out of the cassette 18 and during the succeeding operation where 
the press rolls engage the exposed film unit to initiate photographic 
processing and to transport it from the camera 10. Upon completion of 
these film transporting and processing operations, the mechanism 24 
signals the control unit 46 to release or otherwise open both switches 40 
and 48. These switch openings disconnect the second battery 36 from the 
electrical system 12 as well as from the first battery 34, and disconnect 
the latter battery from the electrical system. 
The flow chart of FIG. 4 summarizes the foregoing operation of the FIG. 1 
camera 10 with the electrical system of FIG. 3. The camera cycle is 
actuated by depressing the shutter control 14 which causes the first 
battery to be connected to the electrical elements. After the low light 
level determination with circuit 42, the sequence either jumps to the last 
step and no exposure is made, or the shutter is opened to initiate an 
exposure. The exposure control circuit 44 closes the shutter after the 
proper exposure. Closure of the shutter causes the second battery to be 
connected in parallel with the first battery and actuates the film advance 
mechanism 24; in particular it turns on the film transport motor. The 
electrical system is now changed from the initial operating state, which 
is a state of relatively low power consumption, to a state of high power 
consumption, and accordingly the second battery 36 together with the 
primary battery are connected for powering it. At the end of the film 
advance and processing steps, the second battery is disconnected and 
returned to its normally electrically-isolated condition, and the primary 
battery is disconnected from the electrical system. The camera reverts to 
the inactive, shut-down condition. 
With this operating sequence, the second battery 36 remains isolated and 
only the first battery 34 is connected with the electrical system during 
low power operations such as light measurement and exposure control. The 
second battery 36 is connected in circuit with the first battery 34 for 
powering the electrical system only during high power operations. The 
isolation of the second battery 36 at all other times, whether during a 
camera exposure cycle or when the camera electrical system is inactive, 
protects it from discharge due to a weakened condition of the first 
battery. Similarly, power dissipating faults in the electrical system do 
not degrade the isolated second battery. Further, the illustrated 
operating cycle ends with operations of heavy power consumption. 
Accordingly, the second battery 36 powers the electrical system, together 
with the first battery 34, from the initiation of the high power 
operations through to the end of the operating cycle. This has the 
advantage of ensuring not only that the operations of high electrical 
drain are adequately powered, but further that the electrical system has 
adequate power for completion of the operating cycle. 
FIGS. 5 and 6 illustrate an embodiment of the invention in which a camera 
has an electrical system which can operate with two time independent and 
generally nonoverlapping intervals of relatively high electrical power 
consumption in a single operating cycle. The camera 10 of FIG. 1, which 
operates in a high-power state during automatic film advance, can operate 
in this manner when the strobe lamp 35 is in use. For this operation, the 
camera electrical system is similar to that of FIG. 3 with the addition of 
strobe controlling circuits 50 and 52, and a modified battery control unit 
54. The two strobe circuits are connected to receive battery power in 
parallel with the elements 42', 44' and 24'. (Elements of prior figures 
which appear in FIG. 5 are designated with the same reference numeral plus 
a superscript prime.) 
Prior to the initiation of a camera cycle with the system of FIG. 5, the 
electrical system is at rest and the primary battery 34' and the secondary 
battery 36' are electrically isolated from each other and from the camera 
electrical system 12'. Upon initiation of the camera cycle by means of the 
shutter release button 14', the now-closed switch 40' connects the primary 
battery 34' to power the electrical system. As FIG. 6 shows, with these 
steps the camera cycle is activated and the first operation is the low 
light evaluation, which the low light level circuit 42 performs in 
response to the light-responsive signal from the photocell 32'. Where 
sufficient light is available for a proper exposure, as designated in FIG. 
6 with a "Normal Light" legend, the circuit 42' signals the exposure 
control circuit 44' to initiate an automatically-timed exposure. The 
circuit 44' accordingly opens the shutter 16' and integrates the light 
detected from the field of view to determine the time for automatically 
closing the shutter. 
As with the system of FIG. 3, upon closure of the shutter, the shutter 16' 
mechanism signals the battery control unit 54 to close the normally-open 
switch 48' and apply the secondary battery 36' in parallel with the 
primary battery 34'. The shutter closure also actuates the film advance 
mechanism 24' to transport and initiate processing of the exposed film 
unit, which also readies the next film unit for exposure. At the end of 
these operations, the film advance mechanism 24' provides a signal to the 
control unit 54 to open the switch 48' and thereby return the secondary 
battery 36' to its normally disconnected isolated condition and, further, 
to disconnect the primary battery 34' from the system by way of the switch 
40'. 
When, on the other hand, the circuit 42' determines that the light level is 
insufficient to expose a film unit properly at the time the shutter button 
is depressed, as indicated in FIG. 6 with a "Low Light" determination, the 
FIG. 5 system 12' employs the strobe charging circuit 50 to charge the 
strobe lamp 35 and subsequently flashes the lamp by way of the strobe 
firing circuit 52. More particularly, the signal indicating insufficient 
light, which the low level light circuit 42' produces on line 42'a, 
actuates the strobe charging circuit 50 to ready the lamp 35 for flash 
illumination. This operation draws significant battery current and 
accordingly is another example of an operation involving high power 
consumption. Accordingly, actuating the charging circuit 50 also causes it 
to signal the battery control unit 54, by way of conductor 50a, to switch 
the secondary battery 36' by way of switch 48' to power the electrical 
system 12' together with the primary battery 34'. Both batteries thus 
power the strobe charging circuit to prepare the flash lamp for a flash 
exposure. 
When the flash lamp 35 is charged, the charging circuit 50 removes the 
signal on line 50a and signals the exposure control circuit 44' via line 
50b to commence the exposure operation. In response to removal of the 
signal on line 50a, the battery control unit 54 allows switch 48' to open, 
thereby returning the secondary battery 36' to its normally-isolated 
condition. The exposure control circuit 44' responds to the strobe ready 
signal from the circuit 50 and signals the shutter 16 mechanism to open 
the shutter. It also signals the strobe firing circuit 52 to actuate the 
flash lamp. The duration of the open shutter and correspondingly of the 
exposure can be fixed, as the sequence of FIG. 6 shows, or can be 
controlled by again employing the exposure control circuit 42' to monitor 
the light reflected from the subject and close the shutter accordingly. 
In either event, upon closure of the shutter, the electrical system 12' 
resumes the operation previously discussed as illustrated in FIG. 6 to 
transport and process the exposed film unit and ready a fresh film unit 
for exposure. 
The camera electrical systems embodying the invention as described above 
with reference to the functional block diagrams and flow charts can be 
constructed in conventional form as found for example in 
presently-available cameras. Such cameras employ automatic film advance, 
automatic exposure timing, automatic aperture adjustment, and automatic 
flash timing. In addition, self-developing cameras are available with both 
automatic exposure control, and automatic film transport and processing. 
Those skilled in this art can apply these known constructions to the 
practice of this invention with only conventional skills. The electronic 
portions of the electrical systems, including the switches as well as the 
FIG. 3 circuits 42, 44 and 46 and the FIG. 5 circuits 50, 52 and 54, 
typically employ solid state devices. These can be combined with 
electro-mechanical latches and linkages commonly found in the photographic 
camera art. 
The invention can be employed in camera systems having operating 
characteristics different from those illustrated above. For example, the 
invention can be used with a camera electrical system in which there is a 
continuous trickle current or low power drain at times other than during 
an exposure cycle. This can occur where the light measuring elements are 
operative outside the exposure cycle. With reference for example to FIG. 
3, in these circumstances, the primary battery 34 can be connected across 
some or all elements of the electrical system without the switch 40 to 
produce the necessary stand-by current. The secondary battery 36, however, 
is electrically isolated from the electrical system during these times of 
stand-by operation, as during other times of low power operation. It 
should also be understood that each battery 34 and 36 can be provided as a 
single battery or as an interconnected set of several batteries. 
Illustrative of a further variation is to connect the battery switch 
control unit 46 of FIG. 3 to receive a signal responsive to the voltage of 
the first battery 34, or to the current drawn from that battery (or even 
to receive signals responsive to both the battery current and voltage). In 
response to this signal or signals, the control unit can switch the second 
battery 36 selectively to power the electrical system when these monitored 
parameters of the first battery indicate that the electrical system is 
unduly loading the first battery. 
It will thus be seen that the objects set forth above, among those made 
apparent from the preceding description, are efficiently attained by 
providing two sets of batteries in a camera, one of which powers the 
camera electrical system continuously during the operating cycle, and the 
other of which is normally isolated from any load and powers the 
electrical system together with the first set of batteries only at 
selected operating times, which normally includes times of high current 
drain or high power consumption. In one specific embodiment, the first and 
second battery sets are stored within the camera body. In another specific 
embodiment, the first battery set may be packaged with self-developing 
film units and hence stored in the film compartment of the camera, with 
the camera housing the second battery set elsewhere in the camera body 
outside the film compartment. Since certain changes can be made in the 
above constructions without departing from the scope of the invention, it 
is intended that all matter contained in the above description or shown in 
the accompanying drawings be interpreted as illustrative and not in a 
limiting sense. 
It is also to be understood that the following claims are intended to cover 
all of the generic and specific features of the invention herein 
described, and all statements of the scope of the invention which as a 
matter of language might be said to fall therebetween.