Optical film encoder for camera

An optical film encoder for recording discrete data bits on a length of film, includes a single light source capable of receiving electrical current to produce artificial light; at least two light emission openings positioned to individually emit artificial light produced by the light source, to record respective data bits on the length of film; a light intensity-reducing filter positioned to reduce the intensity of artificial light that can be emitted from one of the openings, but not from the other opening; and a current limiting device capable of reducing the intensity of artificial light produced by the light source to allow the filter to reduce the intensity of artificial light that can be emitted from the one opening at least sufficiently to prevent the light from recording a data bit on the length of film, whereby only the light to be emitted from the other opening will record a data bit on the length of film.

INCORPORATION BY REFERENCE 
Reference is made to commonly assigned U.S. Pat. No. 5,870,639, entitled 
OPTICAL DATA RECORDING CIRCUIT FOR A PHOTOGRAPHIC CAMERA and issued Feb. 
9, 1999 in the name of Douglas W. Constable. 
The patent is incorporated into this application. 
FIELD OF THE INVENTION 
The invention relates generally to the field of photography, and in 
particular to cameras. More specifically, the invention relates to an 
optical film encoder for recording discrete data bits on a length of film 
in a photographic camera such as a one-time-use camera. 
BACKGROUND OF THE INVENTION 
Film and cameras that are all in one, commonly referred to as single-use or 
one-time-use cameras, have become well known. The one-time-use camera is a 
simple point-and-shoot type comprising an opaque plastic main body part 
which supports a conventional film cartridge in a cartridge receiving 
chamber, an unexposed film roll prewound from the film cartridge onto a 
film take-up spool in a film supply chamber, a backframe opening between 
the cartridge receiving and film supply chambers for exposing successive 
frames of the filmstrip, a fixed-focus taking lens, a film metering 
mechanism with a rotatably supported metering sprocket that engages the 
filmstrip, a manually rotatable film winding thumbwheel rotatably engaged 
with a film spool inside the film cartridge, a single-blade shutter, a 
manually depressible shutter release button, a rotatable frame counter for 
indicating the number of exposures remaining to be made on the filmstrip, 
a direct see-through viewfinder having front and rear viewfinder lenses, 
and in some models an electronic flash. A pair of opaque plastic front and 
rear cover parts house the main body part between them to complete the 
camera unit. The rear cover part connects to the main body part and/or to 
the front cover part to make the main body part light-tight. A decorative 
cardboard outer box or label at least partially covers the camera unit and 
has respective openings for the taking lens, etc. 
After each picture is taken with the one-time-use camera, the photographer 
manually rotates the thumbwheel in a film winding direction to similarly 
rotate the film spool inside the film cartridge. This winds an exposed 
frame of the filmstrip into the film cartridge and moves a fresh frame of 
the filmstrip from the unexposed film roll to the backframe opening. The 
rewinding movement of the filmstrip the equivalent of slightly more than 
one frame width rotates the metering sprocket in engagement with the 
filmstrip to decrement the frame counter to its next lower-numbered 
setting and to pivot a metering lever into engagement with the thumbwheel 
in order to prevent further manual rotation of the thumbwheel. Manually 
depressing the shutter release button to take another picture pivots the 
metering lever out of engagement with the thumbwheel to permit renewed 
rotation of the thumbwheel. When the maximum number of exposures available 
on the filmstrip have been made, and the filmstrip is completely wound 
into the film cartridge, the one-time-use camera is given to a 
photofinisher who tears the outer box off the camera unit, separates the 
rear cover part from the main body part, and removes the film cartridge 
with the exposed filmstrip from the cartridge receiving chamber. Then, he 
removes the exposed filmstrip from the film cartridge to develop the 
negatives and make prints for the customer. At least some of the used 
camera parts may be recycled, i.e. reused, to remanufacture the camera. 
One-time-use cameras, as well as reloadable cameras, for the new "Advanced 
Photo System" can give you not just one print format, but a choice of 
three print formats. For the classic proportions of a 35 mm print, the 
photographer chooses the "C" format. For a wider view, the full-frame "H" 
format is chosen. And for an even wider look, the "P" format is chosen to 
provide a sweeping panoramic print. The camera records the choice of print 
format magnetically and/or optically on one longitudinal edge of the 
filmstrip for each exposed frame on the filmstrip. The standard encodement 
on film for the "H" format is the binary 0, 0, i.e. no recorded data bits. 
The standard encodement on film for the "P" format is either the binary 0, 
1 or the binary 1, 0, i.e. one recorded data bit. The standard encodement 
on film for the "C" format is the binary 1, 1, i.e. two recorded data 
bits. 
During photofinishing to make prints for the customer, the photofinisher's 
equipment reads the optical or magnetic encodements on film, and 
automatically prints each print in the encoded "C", "H" or "P" format. A 
"C" format print is typically 4.times.6 inches. An "H" format print is 
typically 4.times.7 inches. And a "P" format print is typically 4.times.10 
inches or 4.times.11.5 inches. No matter which format "C", "H" or "P" is 
selected in the camera, the exposed frames on the filmstrip are always in 
the "H" format. This allows re-prints to be made in any of the three 
formats rather than just in the selected format. 
The photographer will know how much of the subject being photographed will 
be included in the "C", "H" or "P" format print because the viewfinder in 
the camera typically includes a variable state masking device, such as a 
mechanical masking blade or an electronic masking liquid crystal display, 
for framing the subject according to the particular format that is 
selected. A manually operated format selector is provided to change the 
state of the masking device to the view the desired format in the 
viewfinder and to record the choice of format magnetically and/or 
optically on one longitudinal edge of the filmstrip for each exposed frame 
on the filmstrip. 
Prior Art Problem 
Typically, to record the choice of print format optically on the filmstrip, 
the camera includes two light-emitting diodes such as shown in 
incorporated U.S. Pat. No. 5,870,639, in U.S. Pat. No. 5,619,737 and in 
U.S. Pat. No. 5,574,521. A flash charge storage capacitor in an electronic 
flash is used to apply stored charge energy to one, both, or none of the 
light-emitting diodes in order to optically record the standard encodement 
for the "P" format or for the "C" format, i.e. one or two recorded data 
bits, on the filmstrip, or alternatively to leave the standard encodement 
for the "H" format, i.e. no recorded data bits, on the filmstrip. 
Respective switches selectively shunt the light-emitting diodes to 
establish the choice of "P", "C" or "H" format. 
Another way to record the choice of print format optically on the filmstrip 
is for the camera to include only one light-emitting diode, two light 
emission openings positioned to individually emit the light produced by 
the light emitting diode, and a mask moveable to block one, none, or both 
of the openings to optically record the standard encodement for the "P" 
format or for the "C" format on the filmstrip, or alternatively to leave 
the standard encodement for the "H" format on the filmstrip. See U.S. Pat. 
No. 5,740,479 and incorporated U.S. Pat. No. 5,870,639. 
It is a continuing goal in the manufacture of one-time-use cameras to make 
them as low cost as is reasonably possible. Thus, the elimination of one 
of the light-emitting diodes in the first example, and the elimination of 
the movable mask in the second example, is a worthy pursuit. 
SUMMARY OF THE INVENTION 
An optical film encoder for recording discrete data bits on a length of 
film, comprising 
a single light source capable of receiving electrical current to produce 
artificial light; 
at least two light emission openings positioned to individually emit 
artificial light produced by the light source, to record respective data 
bits on the length of film; 
a light intensity-reducing filter positioned to reduce the intensity of 
artificial light that can be emitted from one of the openings, but not 
from the other opening; and 
a current limiting device capable of reducing the intensity of artificial 
light produced by the light source to allow the filter to reduce the 
intensity of artificial light that can be emitted from the one opening at 
least sufficiently to prevent the light from recording a data bit on the 
length of film, whereby only the light to be emitted from the other 
opening will record a data bit on the length of film.

DETAILED DESCRIPTION OF THE INVENTION 
The invention is disclosed as being embodied preferably in a one-time-use 
camera with an electronic flash. Because the features of a one-time-use 
camera with an electronic flash are generally known, the description which 
follows is directed in particular only to those elements forming part of 
or cooperating directly with the disclosed embodiment. It is to be 
understood, however, that other elements may take various forms known to a 
person of ordinary skill in the art. 
Referring now to the drawings, FIGS. 1 and 2 partially show a one-time-use 
camera 10 which includes a plastic opaque main body part 12, a plastic 
opaque front cover part 14, and a plastic opaque rear cover part (not 
shown). The front cover part 14 and the rear cover part house the main 
body part between them and are connected to one another and to the main 
body part 12 via known hook-in-hole connections (not shown) such as 
disclosed in prior art U.S. Pat. No. 5,815,740 issued Sep. 29, 1998, and 
prior art U.S. Pat. No. 5,349,510 issued Sep. 20, 1994. 
As is known, the main body part 12 has a rearwardly open cartridge 
receiving chamber 16 for a conventional "Advanced Photo System" film 
cartridge 18 and a rearwardly open film supply chamber 20 for a rotatably 
supported film supply spool (not shown). See FIGS. 1 and 2. During 
manufacture, a filmstrip 22 is prewound from the film cartridge 18 into an 
unexposed film roll 24 in the film supply spool. A rearwardly open 
backframe opening (not shown) is located between the cartridge receiving 
chamber 16 and the film supply chamber 20 for exposing successive frames 
of the filmstrip 22 when ambient light is received through a front 
aperture 26 in the main body part 12. 
A film winding thumbwheel (not shown), rotatably supported on the main body 
part 12, protrudes outwardly from a slot (not shown) in the rear cover 
part and has a depending coaxial stem in coaxial engagement with an 
exposed top end (not shown) of a film spool inside the film cartridge 20. 
Manual winding rotation of the film winding thumbwheel, clockwise in FIGS. 
1 and 2, similarly rotates the film spool inside the film cartridge 20 to 
wind each exposed frame of the filmstrip 22 into the film cartridge and to 
move a fresh frame of the filmstrip from the unexposed film roll 24 to the 
backframe opening. 
A built-in electronic flash 28 comprises a generally flat flash circuit 
board 30 supported on the main body part 12, a concave-shaped flash 
reflector 32 located (partly) in a rectangular hole 34 in the flash 
circuit board, a flash illumination-producing flash tube 36 positioned 
rearmost within the flash reflector against an inner side of the flash 
reflector, and a light-transmitting transparent (or alternately 
translucent) plastic flash cover-lens 38 positioned over a front open end 
of the flash reflector. See FIGS. 1-3. The flash cover-lens 38 is located 
within a flash opening 40 in the front cover part 14. 
A viewfinder masking device 42 has a "C" format opening 44, an "H" format 
opening 46 and a "P" format opening 48, and is supported for translation 
on the inside of the front cover part 14 to manually move any one of the 
openings between a front viewfinder opening 50 in the front cover part and 
a front viewfinder lens 52 on the main body part 12. When any one of the 
"C", "H" or "P" format openings 44, 46 and 48 is located between the front 
viewfinder opening 50 and the front viewfinder lens 52, the 
through-the-viewfinder view of the subject to be photographed is framed in 
accordance with the selected format. 
A single light-emitting diode 54 is supported on the flash circuit board 30 
facing a rearward pair of light emission openings 56 and 58 in the main 
body part 12. See FIGS. 1, 2 and 4. The two light emission openings 56 and 
58 are positioned adjacent the backframe opening in the main body part 12 
to individually emit artificial light produced by the light-emitting diode 
54, to record respective data bits on one longitudinal edge 59 of the 
filmstrip 24 for any exposed frame on the filmstrip. A flash charge 
storage capacitor 60 is supported on the flash circuit board 30 to apply 
stored charge energy to the light-emitting diode 54, for the 
light-emitting diode to produce a maximum intensity (brightness) of 
artificial light. 
The standard encodement on film for the "H" format is the binary 0, 0, i.e. 
no recorded data bits. The standard encodement on film for the "P" format 
is either the binary 0, 1 or the binary 1, 0, i.e. one recorded data bit. 
The standard encodement on film for the "C" format is the binary 1, 1, 
i.e. two recorded data bits. 
A neutral density filter 62 is positioned over the light emission opening 
58 to reduce the intensity of the artificial light that can be emitted 
from that opening, by means of the light-emitting diode 54. The filter 62 
has a value of "1.0", which means that the filter allows only 50% of the 
incident light to pass through the filter. 
A known flash circuit 64 on the flash circuit board 30, identical to the 
one disclosed in incorporated U.S. Pat. No, 5,870,639, includes a flash 
energy supply circuit 66, the flash charge storage capacitor 60, a flash 
trigger circuit 68, and the flash tube 32. See FIG. 5. 
The flash energy supply circuit 66 comprises a battery 70, a 
self-oscillating flash charger sub-circuit 72, and an oscillation 
arresting sub-circuit 74. A neon ready-light 76 provides a visual 
indication of when charge to the flash charge storage capacitor 60 has 
reached a sufficiently high charge to fire the flash tube 32. 
Operation of the self-oscillating flash charger sub-circuit 72 begins when 
a flash charging button 78 on the front cover part 14 is manually 
depressed. This effects closing of a normally open momentary switch 80, 
which establishes current flow from the battery 70 through a resistor 82 
to the respective bases of a pair of high gain transistors 84 and 86, and 
in turn initiates current flow through the primary winding of a charging 
transformer 88. The induced stepped up voltage in the secondary winding of 
the transformer 88 is fed back to the base of the transistor 84 to 
continue the current flow in the primary winding of the transformer. When 
the transformer 88 saturates, the current flow in its secondary winding 
reverses, turning off current flow to the base of the transistor 84. This 
completes a cycle of oscillation. Noise in the base of the transistor 84 
caused by the changing field in the secondary winding of the transformer 
88 is sufficient to initiate conduction in the transistor 84, thereby 
starting the cycle of oscillation over again. The transistors 84 and 86 
provide enough loop gain to sustain the oscillations whether the momentary 
switch 80 is open or closed. 
The oscillatory current flow in the secondary winding of the transformer 88 
is rectified by a rectifier diode 90 and charges the flash charge storage 
capacitor 60 to a negative voltage at the terminal 92. Charging of the 
flash charge storage capacitor 60 continues until the self oscillation of 
the self-oscillating flash charger sub-circuit 72 is terminated by the 
operation of the oscillation arresting sub-circuit 74, which includes a 
110 v zener diode 94 and a PNP transistor switch 96. When the voltage 
across the flash charge storage capacitor 60 reaches -270 v at the 
terminal 92, the neon ready-light 76 begins to conduct, illuminating the 
ready-light and providing a visible indication there is sufficient charge 
on the storage capacitor to initiate a flash exposure. When the 
ready-light 76 conducts, the voltage drop across the ready light falls to 
220 v, leaving a voltage of -70 v at the terminal 92. Charging of the 
flash charge storage capacitor 60 continues until the voltage at the 
terminal 92 reaches -330 v. When the flash charge storage capacitor 60 is 
thus fully charged, the zener diode 94 begins to conduct, applying current 
to the base of the PNP transistor switch 96, thereby switching the 
transistor switch "on". This grounds the base of the transistor 84, in 
turn arresting the self-oscillations in the self-oscillating flash charger 
sub-circuit 72 and terminating further charging of the flash charge 
storage capacitor 60. 
The flash trigger circuit 68 is conventional and its operation is well 
known. Briefly, the flash trigger circuit 68 includes a trigger capacitor 
98, a transformer 100, a flash tube trigger electrode 102 and a 
shutter-flash synchronization switch 104. In operation, the 
synchronization switch 104 is momentarily closed by a shutter mechanism 
(not shown) at the proper time in the flash exposure sequence. The trigger 
capacitor 98 discharges through the primary winding of the transformer 98, 
inducing a high voltage on the trigger electrode 102 which ionizes the gas 
in the flash tube 32. The flash charge storage capacitor 60 then 
discharges through the flash tube 32, exciting the gas and producing the 
desired flash illumination. A high-value isolation resistor 106 is 
provided to maintain the dc charge voltage across the trigger capacitor 98 
at the same level as the flash charge storage capacitor 60, while 
minimizing current drain on the latter capacitor during the flash trigger 
operation. 
An optical data recording circuit 106 comprises the single light-emitting 
diode 54, a multi-mode switch 108, a high-value (4800 ohms) current 
limiting resistor 110, a comparatively low-value (300 ohms) resistor 112, 
and a 12 v zener diode 114 coupled across a resistor 116 and the 
base-emitter junction of a transistor 118 to form a constant current 
source for the light-emitting diode. The high value of the current 
limiting resistor 110 is specifically chosen to reduce the intensity of 
artificial light produced by the light-emitting diode 54 in order to allow 
the neutral density filter 62 to reduce the intensity of artificial light 
that can be emitted from the one opening 58 at least sufficiently to 
prevent the light from recording a data bit on the longitudinal edge 59 of 
the filmstrip 22. The light-emitting diode 54 is connected at one end 
indirectly to a normally open contact 104a of the shutter-flash 
synchronization switch 104 and at another end indirectly to the terminal 
92, The multi-mode switch 108 has a conductive pad 120 connected to the 
high-value resistor 110, a conductive pad 122 connected to the low-value 
resistor 112, and a pair of flexible switch-fingers 124 and 126. The two 
switch fingers 124 and 126 are constructed to be individually bent against 
the respective pads 120 and 122 to make selective contact with the two 
pads in order to separately shunt the light emitting-diode 54. See FIGS. 
1-3 and 5. 
The viewfinder masking device 42 has one cam 128 for bending the switch 
finger 126 against the pad 122 and another separate cam 130 for bending 
the switch finger 124 against the pad 120. See FIGS. 1-3. 
When the viewfinder masking device 42 is translated to manually move the 
"C" format opening 44 between the front viewfinder opening 50 and the 
front viewfinder lens 52, the cam 128 bends the switch finger 126 against 
the pad 122. The cam 130 does not bend the switch finger 124 against the 
pad 120. As a result, the low-value resistor 112, but not the high-value 
current limiting resistor 110, is used in the optical data recording 
circuit 106. When the shutter-flash synchronization switch 104 is 
momentarily closed, the stored charge voltage from the flash charge 
storage capacitor 60 is briefly applied to the optical data recording 
circuit 106. Current flows through the zener diode 114, establishing a 
fixed 12 v bias potential at the base of the transistor 118 which causes a 
constant collector-emitter current flow through the transistor and the 
resistor 116 to the light-emitting diode 54. The light-emitting diode 54 
then produces artificial light. The high-value current limiting resistor 
110 cannot act to reduce the intensity of the light produced by the 
light-emitting diode 54. Thus, the light is emitted from the opening 58 as 
well as from the opening 56 to record respective data bits on the 
longitudinal edge 59 of the filmstrip 22. The two recorded data bits 
constitute the "C" format encodement the binary 1, 1. 
When the viewfinder masking device 42 is translated to manually move the 
"P" format opening 44 between the front viewfinder opening 50 and the 
front viewfinder lens 52, the cam 130 bends the switch finger 124 against 
the pad 120. The cam 128 does not bend the switch finger 126 against the 
pad 122. As a result, the high-value current limiting resistor 110, but 
not the low-value resistor 112, is used in the optical data recording 
circuit 106. When the shutter-flash synchronization switch 104 is 
momentarily closed, the stored charge voltage from the flash charge 
storage capacitor 60 is briefly applied to the optical data recording 
circuit 106. Current flows through the zener diode 114, establishing a 
fixed 12 v bias potential at the base of the transistor 118 which causes a 
constant collector-emitter current flow through the transistor and the 
resistor 116 to the light-emitting diode 54. The light-emitting diode 54 
then produces artificial light. The high-value current limiting resistor 
110 acts to reduce the intensity of the light produced by the 
light-emitting diode 54. Thus, the light is emitted from the opening 56, 
but not from the opening 58, and only one data bit is recorded on the 
longitudinal edge 59 of the filmstrip 22. The recorded data bit in one 
instance and the absence of a recorded data bit in the other instance 
constitutes the "P" format encodement the binary 1, 0. 
When the viewfinder masking device 42 is translated to manually move the 
"H" format opening 46 between the front viewfinder opening 50 and the 
front viewfinder lens 52, the respective cams 128 and 130 are spaced from 
the switch fingers 126 and 124. See FIGS. 1-3. Thus, neither one of the 
switch fingers is bent against the respective pads 122 and 120 and the 
light-emitting diode 54 is not shunted. In this instance, no data bits are 
recorded on the longitudinal edge 59 of the filmstrip 22. The absence of 
any recorded data bits constitutes the "H" format encodement the binary 0, 
0. 
The invention has been described with reference to a preferred embodiment. 
However, it will be appreciated that variations and modifications can be 
effected by a person of ordinary skill in the art without departing from 
the scope of the invention. 
TS LIST 
10. one-time-use camera 
12. main body part 
14. front cover part 
16. cartridge receiving chamber 
18. film cartridge 
20. film supply chamber 
22. filmstrip 
24. unexposed film roll 
26. front aperture 
28. electronic flash 
30. flash circuit board 
32. flash reflector 
34. hole 
36. flash tube 
38. flash cover-lens 
40. flash opening 
42. viewfinder masking device 
44. "C" format opening 
46. "H" format opening 
48. "P" format opening 
50. front viewfinder opening 
52. front viewfinder lens 
54. light-emitting diode 
56. light emission opening 
58. light emission opening 
59. longitudinal film edge 
60. flash charge storage capacitor 
62. neutral density filter 
64. flash circuit 
66. flash energy supply circuit 
68. flash trigger circuit 
70. battery 
72. self-oscillating flash charger sub-circuit 
74. oscillation arresting sub-circuit 
76. neon ready-light 
78. flash charging button 
80. momentary switch 
82. resistor 
84. transistor 
86. transistor 
88. charging transformer 
90. rectifier diode 
92. terminal 
94. zener diode 
96. PNP transistor switch 
98. trigger capacitor 
100. transformer 
102. flash tube trigger electrode 
104. shutter-flash synchronization switch 
104a. open contact 
106. optical data recording circuit 
108. multi-mode switch 
110. high-value current limiting resistor 
112. low-value resistor 
114. zener diode 
116. resistor 
118. transistor 
120. conductive pad 
122. conductive pad 
124. switch-finger 
126. switch finger 
128. cam 
130. cam