Camera with pointing aid

A camera having a pointing aid emitter that is operable by the user to produce a output beam generally aligned with the optical axis of the camera objective lens such that the output beam illuminates an object in the scene includes a timer for inhibiting repetitious operation of the emitter to reduce the risk of damage to the object that is illuminated by the beam. In a preferred embodiment of a still camera, the operation of the emitter is initiated by partial depression of the camera image capture button so that the beam is emitted and terminated prior to camera shutter opening. The scene captured on full depression of the image capture button is not illuminated by the beam. After light emission and is halted by release of the image capture button or time out of a maximum emission time interval, further attempts to repeat the operation of the emitter are inhibited for a set time period. In a further embodiment, a running time and maximum cumulative emission time interval are employed to allow repetitious emission of the output beam as long as the cumulative repetition time in the running time interval does not exceed the maximum cumulative time interval. The camera preferably includes an ambient light measuring system and a distance measuring system for providing automatic modulation of the power of the light beam emitted during each emission and inhibition of the emission at excessive or insufficient camera-to-object distances. The emitter preferably comprises a laser light source that produces a visible laser output beam.

CROSS-REFERENCE TO RELATED APPLICATION 
Reference is made to my commonly assigned co-pending U.S. patent 
application Ser. No. 08/201,827 filed Feb. 25, 1994, and entitled CAMERA 
WITH POINTING AID, incorporated herein by reference. 
1. Field of the Invention 
This invention relates generally to cameras and, more particularly, to 
cameras employing visible light pointing aids that are controlled to avoid 
prolonged emission of a pointing aid output beam onto an object. 
2. Description of the Related Art 
Cameras serve as image capture devices, taking pictures of an ambient scene 
through an objective lens. For example, a photographic still camera stores 
an image, either photo-electronically into memory or photo-chemically onto 
a filmstrip, when an image capture button, such as a shutter button, is 
fully depressed. In a still camera, pressing the image capture or shutter 
button causes a shutter to be tripped, which permits light from the scene 
to pass through the objective lens and fall onto a photo diode array or 
film strip located at a focal plane of the lens. A video camera or movie 
camera captures a sequence of images that, when played back, presents the 
illusion of motion. 
A camera user typically looks through a camera view finder to aim the 
camera at a particular point or object in the scene that is of interest. 
At times, such as under low light conditions or in a crowded scene, it can 
be difficult to judge the point in the scene on which the camera is 
directed. At other times, such as when tracking fast moving objects in the 
scene or when picture taking discretion is desired, it might be desirable 
to aim the camera without looking through the view finder at all. 
For these and other reasons, a variety of pointing aids that help a camera 
user determine where in the scene the camera is directed have been 
proposed. Generally, the pointing aid comprises a source of radiant 
energy, e.g. visible light, directed in an output beam that is 
substantially aligned with the optical axis of the camera taking or 
objective lens. If an object in a scene is illuminated with the output 
beam, the camera user is assured that light from the object will be 
directed through the objective lens and onto the focal plane for image 
capture. Aiming the pointing aid output beam onto an object of interest 
can be done with or without looking through the view finder, making it 
easier to aim the camera accurately at moving objects. 
For example, U.S. Pat. No. 5,189,463 to Capper et al. describes a video 
camera with a laser pointing system that is said to obviate the need for 
looking through a view finder to aim the camera. British Patent No. 2 252 
836 describes a security camera that includes a laser which is said to 
emit a beam that is aligned with the camera lens so that the camera can be 
aimed at a suspicious person to be photographed. 
Emitted radiant energy, e.g visible light from a laser, LED or flashlight, 
is also commonly employed in automatic range finding systems for detecting 
the reflected light beam and automatically setting the focus of the camera 
taking lens, as disclosed in these patents and in commonly assigned U.S. 
Pat. No. 3,442,193 to Pagel. Such active auto focus systems set the camera 
focus and then allow the shutter to be opened to make the photographic 
exposure. An auto focus system is included with a laser pointing system of 
the type disclosed in the Capper '463 patent in PCT application 
publication No. WO 93/13452 to Capper. 
For ease of aiming the camera in a rapid "point and shoot" motion, visible 
radiant energy emitted in an intense and tightly focussed output light 
beam is preferred. The output beam of a laser diode provides sufficient 
range and can be controlled in intensity, at a certain cost in battery 
energy consumed, to provide a visible spot on the object to be 
photographed even under bright ambient scene illumination. 
While it is important that the emitted beam should be sufficiently bright 
to be readily seen by the camera user, it also is important that the beam 
not be so extraordinarily bright and applied for such a time period that 
it distracts persons or animals in the scene. In addition, it is important 
that the output power of the beam not be so great that objects, persons, 
or animals in the scene might be damaged by the beam. For example, if the 
pointing aid output beam produced by a laser were to enter through the 
pupil of a person or animal in the scene, and if the laser output power 
was sufficiently great, then the laser beam could possibly cause damage to 
the retina. 
In each of the above referenced patents, the laser beam is emitted and 
aimed onto the object to be photographed or video taped each time or as 
long as the image capture button is depressed. As disclosed in the PCT 
'452 publication, steps are taken to ensure that the output beam is 
extinguished when the camera shutter is open, but the output beam is 
emitted again as soon as the shutter is closed. In the '463 patent, the 
laser output beam is delivered during each video frame blanking interval 
as long as the video camera is recording, so that the user can see the 
illuminated spot on the object continuously, due to the 60 Hz. repetition 
rate. 
Problems to be Solved by the Invention 
In my above-referenced, co-pending '827 application, the intensity of the 
laser beam is controlled in order to avoid excessive power drain and to 
reduce risk of damage or injury to objects, persons and animals in the 
scene. However, there is still a need for a camera with a pointing aid 
output beam that is visible under a variety of ambient conditions and does 
not use excessive power, and for a control system that reduces the risk of 
damage or injury to objects, persons, and animals in the ambient scene 
that could occur through ignorance of the danger or intentional mis-use of 
the aiming system. The present invention fulfills this need through a 
further inventive solution that may be practiced alone or in conjunction 
with laser beam intensity control of my above-referenced '827 application. 
SUMMARY OF THE INVENTION 
The present invention provides a camera with a pointing aid beam to assist 
a user in capturing images of a scene, the camera including a pointing aid 
emitter that produces a visible beam generally aligned with the optical 
axis of the camera objective lens such that the visible beam illuminates 
an object in the scene, a scene measurement system that measures an aspect 
of the scene, and an emitter controller that controls the rate or 
frequency of repetition of the emission of the output beam so as to limit 
the average output power delivered by the pointing aid emitter over time 
to a safe level. 
The present invention is practiced in methods of operating a camera 
pointing aid for assisting a camera user in pointing the camera so as to 
capture an image of an object in a scene through a camera objective lens 
upon pressing an image capture button and apparatus for practicing the 
methods, the methods and apparatus comprising in one embodiment the steps 
of and means for: detecting the pressing of the image capture button of 
the camera; responding to the pressing of the button by emitting a 
visible-light output beam from an emitter such that the output beam is 
generally aligned with the optical axis of the objective lens and 
illuminates the object; and following emission of the light beam over a 
first predetermined emission time interval, inhibiting the further 
emission of the output beam in response to the repeated pressing of the 
button for a second predetermined, inhibit time interval so as to reduce 
the risk of damage to the object in the scene that is illuminated by the 
output beam through repetitious illumination of the object. 
The methods and apparatus for practicing the methods preferably are 
realized by the steps of and means for: on detecting the pressing the 
image capture button, determining if emission is inhibited, and if not 
inhibited, starting the timing of the first, emission time interval and 
emitting the visible-light output beam from the emitter such that the 
output beam is generally aligned with the optical axis of the objective 
lens and illuminates the object; and following emission of the light beam 
for said emission time interval, terminating the emission of the light 
beam and starting the inhibit time interval. 
The methods and apparatus are carried out in one embodiment preferably by 
timing the emissions of the light beam in response to repetitive 
depression of the button over a running time window to provide an 
accumulated emission time within the running time window; comparing the 
accumulated emission time to a reference cumulative emission time to 
provide an inhibit trigger signal when the accumulated emission time 
exceeds the reference cumulative emission time; and starting an inhibit 
timer in response to the inhibit trigger signal. 
In one preferred embodiment the output power level of the pointing aid 
output beam is further controlled so that the camera user perceives the 
beam to be of equal brightness over a range of scene aspects, such as 
ambient light level and camera-to-object distance, so that power 
consumption by the emitter is reduced, and so that the risk of injury or 
damage is reduced. In this way, the pointing aid beam is visible under a 
variety of conditions using minimal power and with reduced risk of damage 
or injury to objects, persons, and animals in the ambient scene. 
In another aspect of the invention, the pointing aid emitter comprises a 
laser light source that produces a visible laser beam generally aligned 
with the optical axis of the camera objective lens such that the laser 
beam illuminates an object in the scene whose image will be captured 
through the objective lens. The emitter controller preferably controls the 
output power of the laser in accordance with both the detected distance to 
a nearest object and the detected ambient light level. 
Advantageous Effects of the Invention 
In controlling the frequency of operation of the emitter output beam the 
emitter controller maintains the average power delivered over time to a 
safe limit. The user may not intentionally or inadvertently cause harmful 
emission levels by holding the capture release button depressed or 
repeatedly depressing the button.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The camera in which the pointing aid and control system of the present 
invention is provided can be any one of a variety of image capture 
devices, such as a still camera that records images into an electronic 
memory for storage or onto a silver-halide filmstrip for exposure, or a 
video camera, or a movie film camera. The preferred embodiments will be 
described in particular with respect to a photographic still camera of the 
general type depicted in FIG. 1. 
FIG. 1 therefore illustrates a still camera 10 having a camera body 12 in 
which an objective lens 14 directs light from an ambient scene onto a 
focal plane for image capture. A camera user can view the scene through a 
view finder 16. The camera 10 includes a pointing aid emitter 18 that 
produces a visible light output beam generally aligned with the optical 
axis 19 of the objective lens such that the visible output beam 
illuminates an object in the ambient scene and appears, for example, as a 
readily visible small dot on the object. A scene measuring system 20 
measures a characteristic or aspect of the scene, e.g. the level of 
ambient scene illumination for setting exposure parameters and controlling 
synchronous operation of the electronic flash unit 24 that provides 
supplemental illumination of the scene, if necessary. 
In the above referenced, co-pending '827 application, the output power of 
the beam emitted from the pointing aid emitter 18 is adjusted in 
accordance with the measured scene aspect so as to increase beam 
visibility, minimize power consumption, and reduce the risk of damage to 
an object or person in the scene that is illuminated by the beam. The 
scene aspect that is used to control the pointing aid emitter 18 can 
assume a variety of measured characteristics. For example, the output 
power of the pointing aid beam can be controlled according to the detected 
amount of ambient light in the scene. Alternatively, the output power of 
the beam can be controlled in accordance with the distance from the camera 
10 to an object of interest aligned with the optical axis 19 or to the 
object nearest the camera. The output power of the beam also can be 
controlled in accordance with both aspects, that is, the ambient light 
level and also the distance to the object. 
The output power of the emitter beam can also be controlled manually by an 
optional adjustment switch 26. These beam intensity control features of 
the '827 application may be incorporated in a camera 10 in combination 
with the present invention. 
The camera 10 includes an image capture button 22 that is used to activate 
a mechanism of the camera 10 to capture an image of the ambient scene. In 
a still camera, the image capture button 22 may be referred to as a 
shutter release button and is typically a two-position switch. Touching 
the button or pressing the button to a first, "pointing" position 
activates the pointing aid emitter 18 (as well as other camera functions), 
and pressing the button to a second position deactivates the pointing aid 
emitter and activates the image capture mechanism of the camera 10. In a 
still camera, for example, the image capture mechanism or system comprises 
an aperture setting mechanism for selecting an aperture size and a shutter 
mechanism for opening the aperture during a shutter opening interval or 
shutter speed (neither illustrated). The aperture setting and shutter 
speed are derived by an automatic exposure control, or auto exposure, 
system that is part of the scene measuring system 20 that measures ambient 
scene illumination at a time after the image capture button 22 is touched 
or depressed to the first position when the output beam of the emitter 18 
is off and before the shutter release mechanism operates. If the user 
touches and depresses the button 22 to the second, image capture position 
in a single motion, the camera's image capture system operation may be 
delayed to allow the completion of the operations of the emitter 18 and 
the auto focus system and the auto exposure control system. In any case, 
the emitter 18 is already turned off during image capture to ensure that 
the pointing aid output beam illuminating an object in the scene will not 
be visible in the captured image. FIG. 2 schematically illustrates the 
camera elements and electronic control system components involved in the 
control of the emission of the laser light output beam. FIG. 2 shows that 
the camera has a field of view such that light from an object 29 in the 
ambient scene 30 enters the camera 10 through the objective lens 14 and is 
directed onto a focal plane 32 at which an image capture medium 33 is 
located. The image capture medium can comprise, for example, electronic 
photoreceptors such as a CCD array for making a digital representation of 
the captured image or can comprise a silver-halide filmstrip or plate that 
is exposed and then developed in conventional photography. 
The camera operating system of FIG. 2 preferably comprises a 
micro-controller or micro-computer 70 which typically includes a 
microprocessor, with on-chip RAM, ROM and associated circuits of a type, 
e.g the micro-processor based electronic control system for diverse camera 
functions disclosed in commonly assigned U.S. Pat. No. 5,130,739, 
incorporated herein by reference in its entirety. The micro-controller 70 
is interconnected with the scene measuring system 20 and other components 
described hereafter and operates in one or more modes through operating 
software instruction sets for carrying out the inventive methods 
illustrated in the remaining figures. As illustrated in FIG. 2, the 
micro-controller 70 includes a first, emission Timer 1 block 72 and a 
second, inhibit Timer 2 block 74 which may be implemented as discrete, on 
board, counter IC chips that are loaded and down counted by the 
micro-processor or may constitute timer functions of the micro-processor 
memory registers to, in either case, time out the emission and inhibit 
times in a manner well known in the art. As described hereafter a single 
timer may be employed which is either loaded with the emission or inhibit 
time counts. In either case, the timers or timer form an integral part of 
the micro-controller 70 and are depicted within its architecture as 
indicated by the broken lines. 
It will be understood that only the components of the camera operating 
system deemed necessary to explain the present invention are depicted in 
FIG. 2, and that the camera electronic control system illustrated may be 
combined with other components, e.g. artificial illumination, motorized 
filmstrip advance and rewind, etc. for controlling other camera functions. 
Before explaining the present invention, attention is first directed to 
the associated components of the camera system that are depicted in FIG. 
2. 
In a preferred embodiment, the scene measuring system 20 measures both 
ambient light level and camera-to-object distance or range. Thus, the 
scene measuring system 20 of the camera 10 includes an ambient light 
sensor 34 that receives and measures ambient light 23 from the scene 30 
and includes a distance beam sensor 36 that receives light reflected off 
the object 29. The reflected light preferably may comprise the light that 
is emitted in the pointing aid output beam 21 from the pointing aid 
emitter 18, reflected off the object 29, and then received back at the 
camera by the distance beam sensor 36. The reflected light beam 25 is used 
to determine the distance from the camera to the object in a range finding 
operation known in the art. 
In the preferred embodiment illustrated in FIG. 2, the ambient light sensor 
34 and distance sensor 36 provide input signals to an auto exposure system 
35 and an auto focus system 38 of the camera, respectively, when the image 
capture button 22 is depressed to make contact with a first set of 
terminals 15. The ambient light sensor 34 may be an image area photo diode 
or array of photosensitive elements that provide an ambient light signal 
or signals to the auto exposure system 35 that sets the exposure 
parameters, including the lens aperture diaphragm diameter and the shutter 
open time as described above in a manner well known in the art. The 
distance sensor 36 may be spaced linear arrays of photo diodes that 
provide signals to the auto focus system 38 that determines the 
camera-to-object distance in a range finding manner well known in the art. 
The auto focus system 38 processes the signals and controls focus setting 
of lens 14 through lens position adjustment in the direction of arrow 46 
during the operation of the lens focus motor 44. 
The pointing aid emitter 18 thus preferably comprises the emitter of the 
light beam 23 that is reflected from the object 29 in the reflected light 
beam 25 and sensed by the distance beam sensor 36. Alternately, two 
separate emitters of the same or different types may provide the output 
beam 21 for the pointing aid emitter 18 and a separate output beam for 
reflecting light off the object 29 in the reflected light beam 25. 
In any case, the emitter light output beam 21 is preferably a small 
diameter laser light beam of a particular visible frequency. The auto 
exposure function should not be affected by the spot of light reflected 
from the object in bright ambient light conditions, as its energy in 
reflected beam 25 would be minor under such conditions. In low light 
conditions, it may augment the energy of the reflected light beam 25 and 
aid in setting proper focus. With respect to the auto exposure function, 
the energy of the reflected laser light in the measured ambient light 23 
is so tightly focused that it should have negligible effect on the spot or 
area averaging auto exposure operation. Or the particular laser frequency 
may be filtered out at the ambient light sensor 34. 
In accordance with one embodiment of the invention, the emission of the 
output beam 21 is controlled by an emitter controller operation comprising 
emitter output controller 40, image capture button 22, and 
micro-controller 70, including timers 72 and 74 or a single timer, 
operating under the software program illustrated in FIGS. 3-10. The 
emitter controller operation controls the output power during delivery of 
each output beam and establishes the rate or frequency of repetition of 
the beam by the states of the timers 72 and 74 to control the average beam 
power delivered over time upon the object 29. 
In a further embodiment, the emitter output controller 40 also controls the 
emitter 18 to adjust the output beam 21 power during each emission cycle 
in accordance with the ambient light signal provided by the ambient light 
sensor 34 (or a signal processed by the auto exposure system 35) and, 
optionally, the distance to the object 29 information determined by the 
auto focus system 38. As described more fully in the above-referenced, 
co-pending '827 application, in this preferred embodiment, the emitter 18 
is pulsed on and off to modulate beam power or energy delivered in each 
pulse but at a frequency sufficiently high that the output beam 21 is 
perceived to the eye to be steadily illuminated. The beam output power is 
thus modulated by controlling the duty cycle of the emitter 18. 
Alternatively, the beam output power may be a constant, fixed value 
established in the emitter output controller without regard to ambient 
light level or the camera-to-object distance. 
The image capture button 22 illustrated schematically in FIG. 2 is a spring 
loaded three position switch and can be depressed from a rest position to 
the pointing position closing the first set of terminals 15 and to the 
image capture position to close the first and second set of terminals 15 
and 17. The button 22 is coupled to the parallel switch segments 76 and 78 
through a load spring and shaft 80. The first set of terminals 15 are 
closed by the switch segment 76 when the button 22 is depressed to the 
pointing position depicted in FIG. 2. Further depression of the button 22 
compresses the load spring and pushes the switch segment 78 across the 
second set of terminals 17 to develop the timing trigger signal S2. Any 
switch construction, including separate switches or commands, that 
provides the timing trigger signals S1 and S2 in sequence may be 
substituted for the depicted construction of image capture button 22. 
When the first set of terminals is closed, the signal S1 is applied to the 
micro-controller 70. When the second set of terminals 17 is closed, the 
signals S1 and S2 are applied to the micro-controller 70. As depicted, 
signals S1 and S2 are at battery or a regulated voltage B+, although the 
signal level may typically be at ground level, since the leading edge of 
the signal is processed to activate the timing functions as described 
below. Thus, the signal leading edges at the closure of the first and 
second sets of terminals provide the timing trigger signals S1 and S2 
although the state of the trigger signals S1 and S2 may be queried and 
employed in certain operations. For example, a timing trigger signal S1 
may start on the leading edge closure of terminals 17 and end on leading 
edge closure of terminals 15. Timing trigger signal S2 may commence on 
leading edge closure of terminals 15 and end a fixed time later, 
independent of when the user releases the image capture button 22. The 
following discussion assumes such a generation of the trigger signals S1 
and S2. 
Before proceeding further with the description of the preferred 
embodiments, it should also be noted that micro-controller based camera 
operating systems also include power down circuitry that responds to a 
prolonged period of inactivity or the closure of a lens cover or an on-off 
switch to power down the operating system and power up circuitry that 
responds to these events to restore power and initialize the operating 
system as explicitly shown in FIGS. 8-10. 
Typically, the user depresses the image capture button 22 fully and then 
releases it in a single motion so that the first and second trigger 
signals are simultaneously provided only momentarily. In a further 
variation, the construction of image capture button 22 may be changed so 
that the first trigger signal S1 at the first set of terminals 15 is 
extinguished when the user further depresses the image capture button 22 
to close the second set of terminals 17 and generate the second trigger 
signal S2. The timing operations may be responsive to the leading edges of 
the trigger signals S1, S2, and the last trigger signal state may be 
memorized for use in the program and interrupt service routines described 
below where it is necessary to query the state of the image capture button 
22. 
It is anticipated, that the user will intentionally press the image capture 
button to the pointing position and point the camera around the scene 
until the spot of light is visible on the desired object effecting a power 
up/reset function, if the camera was previously powered down. During that 
selection process, the auto focus and auto exposure operations commence 
and continue, as in the typical automatic camera system. The 
micro-controller 70 enables the pointing aid emitter 18 to be operated to 
emit the light beam 21 to enable camera aiming if the inhibit time 
interval T2 has elapsed since the last emission of the output beam 21. At 
the same time and even if output beam emission is inhibited, the auto 
exposure system 35 sets the exposure parameters and the auto focus system 
38 sets the taking lens 14 focus, as the scene shifts during camera 
aiming. The auto exposure and auto focus functions are completed in a 
relatively short measure and set time intervals which is governed by the 
micro-controller 70. Once aiming is completed, the user may fully depress 
the image capture button 22 to provide the trigger signal S2. 
The trigger signal S2 is employed by the micro-controller 70 to first 
extinguish the emitter output beam (if it has not already been 
extinguished by time out of the emission time interval) and to then enable 
image capture by the image capture system 50. In the photographic still 
camera embodiment, this operation involves opening and closing the shutter 
for the exposure interval, operating the artificial flash illumination 
synchronously with the shutter opening and operating a filmstrip advance 
motor, if provided. Other information recording operations may also be 
accomplished. Then, the camera is ready to again make an exposure. 
In accordance with one method of operation of the preferred embodiment of 
the present invention, each time the camera button 22 is depressed 
partially to the pointing position and released or depressed fully to the 
image capture position commences an inhibit interval T2 to prevent the 
user from using the pointing aid output beam until the inhibit interval 
times out. The inhibit time interval in this simple mode would ordinarily 
be fixed to about 3 seconds and include the time that the camera 
components take to complete the image capture and motorized film advance 
operations. The inhibit time interval T2 in the two timer embodiment of 
FIG. 2 is provided by loading the counter of Timer 2 block 74 to a timeout 
count value T2 at generation of the trigger signal S2 and down counting to 
a certain count. The user may operate the camera to take photographs at a 
faster rate than the inhibit time interval T2 times out, but would only be 
able to enable the emission of the output beam after timeout of the most 
recent inhibit time interval T2. During the inhibit time interval T2, the 
active auto focus system 38 would not be enabled to reset focus through 
operation of the auto focus system 38. 
In a second method, which may be combined with the first method, the 
emission time of the output beam 21 is limited to the emission time 
interval T1 if the user depresses the button 22 to the pointing position 
continuously for a prolonged time interval and does not depress the button 
22 to the image capture position. Thus, the emission is extinguished if 
the user depresses the button 22 to the pointing position for a time 
exceeding the timeout of the emission time interval T1 and may not be 
re-initiated until the lapse of the inhibit time interval T2. In this 
method, the continuous emission time interval T1 may be on the order of 
3-5 seconds and the inhibit time interval T2 may again be on the order of 
3 seconds. Again, the camera may be used to take photographs without use 
of the pointing aid and the auto focus system 38. 
In these methods, Timer 2 block 74 provides the 3 second inhibit interval 
T2 between each successive emission of the output beam 21 regardless of 
how long the user has depressed the button 22 to the pointing position. In 
a further method, which may be combined with the above methods, successive 
emissions of the light output beam 21 (caused by depressions of the button 
22 to the pointing position) each shorter than the maximum emission time 
interval T1 are allowed to take place and continue so long as the 
accumulated emission time in a running time window does not exceed a 
pre-set percentage of the running time window or a fixed cumulative time 
interval threshold. The emission of the output beam is extinguished and 
the inhibit time interval T2 commenced upon exceeding the cumulative time 
interval threshold which may or may not be the same as the emission time 
interval T1. 
Through each of these methods, the power delivered over time by the laser 
light output beam is maintained at an average that falls below an exposure 
standard to protect the retina from damage. The prolonged or repeated 
exposure of the retina to the energy in the emitted beam could cause 
injury since the accumulated power delivered could exceed a dangerous 
level. 
FIGS. 3-5 viewed together with the timing diagram of FIG. 6 illustrate 
these methods in a flow chart for setting the emission and inhibit time 
intervals by the timers 72 and 74 (referred to as Timer 1 and Timer 2 in 
FIGS. 3-5). FIGS. 4 and 5 are timer interrupt service routines for the 
time out of the emission and inhibit time intervals, T1 and T2, 
respectively. The timeout of Timer 1 block 72 (in FIG. 2) in program block 
100 sets a laser emission disable flag to "True" in block 102. Similarly, 
the timeout of Timer 2 block 74 (in FIG. 2) in block 104 sets a laser 
emission or emitter disable flag to "False" in block 106. The laser 
disable flag setting is queried in the main operating program of FIG. 3 at 
two points in the operation. 
In FIGS. 3 and 6, when the image capture button 22 is partially depressed 
to the pointing position of FIG. 2, the trigger signal S1 is generated and 
detected at block 110 as "I.C. Button Activated". The state of the emitter 
disable flag set in either block 102 or 106 is queried at decision block 
112. If the flag is "True", then the inhibit Timer 2 (i.e., Timer 2) is 
still timing out, and the micro-controller 70 inhibits emitter output 
controller 40 to prevent the emission of the laser light output beam 21. 
If the laser disable flag is "False", then the inhibit Timer 2 has timed 
out per the interrupt service routine of FIG. 4, and the emission Timer 1 
is loaded with the down count timeout value T1 in block 114. Timer I is 
started in program block 116, and the emitter output controller 40 is 
enabled in block 118 to energize the emitter 18, while the auto exposure 
system 35 and auto focus system 38 continue their functions as the user 
aims the camera. 
In FIG. 6, these events are depicted starting in the first instance at time 
1.0. The auto exposure and auto focus functions continue as long as 
trigger signal S1 is present and are disregarded, if they continue when 
the trigger signal S2 is generated. The user continues to depress the 
button 22 presumably to point the camera at the object until the button 22 
is fully depressed at t=8.0, when the second trigger signal S2 is 
generated. The duration of trigger signal S2 is set by the camera image 
capture operations, whereupon both trigger signals S1 and S2 terminate. 
The shutter release functions in this simple example are completed at time 
t=9.0, although motorized film advance, if present, may continue for 
another second or so. 
In the first example of FIG. 6, the user has depressed the button 22 and 
generated trigger signal S1 for 7.0 seconds, which exceeds the maximum 
emission time interval T1, which is set at 5.0 seconds in this 
illustration. Thus, at t=6.0 the Timer 1 times out, and the emitter 
disable flag is set to true in block 102 of FIG. 4. At the same time 
t=6.0, the inhibit Timer 2 commences timing out. The auto exposure and 
auto focus functions continue until time t=8.0 seconds. 
Returning to FIG. 3, these operations are carried out in blocks 120-130, 
but it should be noted that when the button 22 is either released or fully 
depressed to the image capture position (resulting in its automatic 
release as described above), the response to decision block 120 changes. 
First considering the time prior to time t=8.0, the status of the first 
trigger signal S1 is monitored in decision block 120, and the status of 
the emitter disable flag is monitored in decision block 125. The emitter 
disable flag remains "False" until the Timer 1 times out (FIG. 4) or the 
image capture button is released or fully depressed, whichever occurs 
first. 
In the first example of FIG. 6, the emission Timer 1 times out before the 
button 22 is either released or fully depressed to generate the second 
trigger signal S2. At time t=6.0, the laser disable flag is set to "True" 
by the timer interrupt service routine of FIG. 4, satisfying decision 
block 125, and the laser emitter 18 is turned off by a command of the 
micro-controller 70 to the emitter output controller 40 per block 126. At 
the same time, the Timer 2 block 74 is loaded with the count value to time 
out the inhibit time interval T2 in block 128 and started in block 130. 
The program then waits for a trigger signal S1 to be generated in block 
132. 
If the button 22 is again depressed to the pointing position and the signal 
S1 is generated while the inhibit Timer 2 block 74 is still timing out, 
the signal S2 is detected at block 110. The laser disable flag is still 
set to "True", according to FIG. 4, since the inhibit Timer 2 is still 
timing out. Thus, the trigger signal S1 causes the decision block 112 to 
query the state of the laser emitter disable flag in block 112. Since the 
flag is "True", the response is "YES", and the state of the shutter button 
continues to be monitored while the Timer 1 block 72 is not loaded and 
started in blocks 114 and 116, and the laser light emitter is not turned 
on in block 118. 
Whether or not the user continues to depress the button 22 to the image 
capture position and generates the second trigger signal S2 is not 
material to this operating program as long as the inhibit Timer 2 is still 
timing out and the emitter disable flag is still set at "True". The steps 
of blocks 114-118 cannot be followed under that condition. Therefore, the 
emission of the pointing aid light output 21 beam cannot be restarted in 
block 118, and the inhibit Timer 2 cannot be re-loaded and started in 
blocks 128 and 130. In this fashion, the duration of emission is 
controlled to no more than the emission time interval T1 for each partial 
or full depression of the button 22 to the pointing position. Only a 
single inhibit time interval T2 is triggered in response, and interval T2 
cannot be indefinitely prolonged by continued intermittent depression of 
the image capture button 22. 
The user can, however, take photographs without the benefit of the laser 
light output beam 21 while the inhibit time interval T2 times out, and the 
emitter output controller 40 is again enabled after the inhibit time 
interval T2 times out. This operation allows the camera to be used to take 
a picture on the assumption that the user is still aiming the camera at 
the same object. When the user depresses the image capture button 22 in 
this instance, it will be apparent to the user that the laser light output 
beam was not emitted, and the user can decide to fully depress the image 
capture button and make the exposure. The user may alternatively be 
alerted by audio or visual indications that the aiming and auto focus 
functions are disabled on initial depression of the image capture button. 
The user may partially depress the image capture button 22 several more 
times in rapid succession, closing the first set of terminals 15, trying 
to trigger generation of the laser output beam 21. The effort will be 
fruitless until the inhibit time interval T2 times out. Thus, the user 
will learn to wait until time out occurs if it is desired to shift to a 
new scene 30 or object 29 in the scene. 
In the second instance depicted in FIG. 6, the user depresses the button 22 
at time t=9.5 and completes full depression of button 22 at t=13.0. In 
this instance, the preceding inhibit time interval T2 has timed out, but 
this is not necessary. In either case, once the emitter disable flag is 
False, the emission interval Timer 1 is loaded and started in blocks 114 
and 116 and the laser light emitter is restarted in block 118. 
In the depicted second instance, the shutter button 22 is fully depressed 
to provide trigger signal S2 before emission time interval T1 Timer 1 
times out, and the image capture button is released satisfying decision 
block 120. When this occurs, Timer 1 is halted in block 122, and the 
emitter disable flag is set to "True" in block 124 to turn off the laser 
light emitter in block 126 and again start and time out the inhibit time 
interval T2 in blocks 128 and 130. 
In the methods depicted and described above, two timers 72 and 74 are 
employed sequentially as Timer 1 and Timer 2. Alternatively, it is 
possible to use a single timer or register and to load the same timer with 
the time out values for timing the emission and inhibit time intervals T1 
and T2 sequentially. In this variation of the general operating program of 
FIG. 3, the Timer 1 of blocks 114 and 116 would be the same as Timer 2 of 
blocks 128 and 130. In this variation, the timer interrupt service 
routines of FIGS. 4 and 5 would be changed to the single timer interrupt 
routine depicted in FIG. 7. 
The timer interrupt service routine of FIG. 7 starts at the timeout of the 
single timer at start block 134. At that time, the state of the image 
capture button 22 is queried to determine if it is depressed to generate 
the trigger signal S1 in decision block 136. If signal S1 is present, then 
the inference is that the timer was previously loaded to time out the 
emission time interval T1. The emitter disable flag is set to "True" in 
block 138, ending the interrupt service routine. If the timer has been 
timing out interval T1, the "True" flag satisfies decision block 125 of 
FIG. 3. The timer is loaded with the inhibit time interval T2 timeout 
value in block 128 and started in block 130 as the emitter output 
controller 40 is instructed to cease emission of the output beam in block 
126. 
Then, at the subsequent timeout of the single timer at start block 134, the 
position of the button 22 is again queried at decision block 136. If the 
first trigger signal S1 is not present, the inference is that the timer 
was timing out the inhibit time interval T2. The emitter disable flag is 
then set to "False" in block 140, enabling the emission program of FIG. 3 
to be repeated in response to a subsequent depression of the button 22 at 
block 110. 
However, if the image capture button 22 is depressed by the user and 
provides the first trigger signal S1 at that timeout, the emitter disable 
flag will remain set to "True" in block 138. The "True" flag state would 
satisfy the decision block 112 of FIG. 3, preventing the loading of the 
emission time interval T1 and the emission of the light output beam. The 
user would see that the output beam 21 is not emitted and release or fully 
depress the button 22 satisfying block 136 and setting the emitter disable 
flag to "False". Then, at the next activation of the image capture button, 
block 112 would be satisfied allowing the repeat of the steps of blocks 
114-132. After the next timeout, the timer interrupt service routine of 
FIG. 7 would be repeated with the presumption that the timer has been 
timing out the emission interval T1. 
In these methods of operation, once the user depresses the button 22 to the 
pointing position, and the laser light output beam 21 is generated, it 
cannot be restarted until time out of the inhibit time interval T2, no 
matter how short the actual emission time. In the further embodiment of 
the invention depicted in the flow charts of FIGS. 8-10, the emission of 
the light output beam 21 is allowed each time the button 22 is depressed 
to the pointing position until the cumulative emission time in a running 
time window expressed in seconds extending back in time from the point of 
measurement does not exceed an accumulated emission time threshold stated 
as a percentage of the running time window. The accumulated emission time 
threshold may be either a fixed time value or a percentage of the running 
time window. For example, the running time window may be on the order of 8 
seconds, and the cumulative emission time threshold may be either 6 
seconds or 75% of the running time interval. Again, the inhibit time 
interval T2 may be on the order of 3 seconds and timing functions may be 
accomplished by discrete IC timers or be functionally carried out by the 
timing functions programmed into the micro-controller 70. Since 
continuously running timing functions is current intensive, it is 
desirable to only commence the operations depicted by FIGS. 8-10 when 
camera usage is about to commence. 
Turning first to FIG. 8, it depicts a power up/reset operating routine 
commenced when the camera user takes some action, e.g. depressing the 
image capture button 22 after a long time delay, to cause the operating 
system to power up after power down as described above. In FIG. 8, the 
power up and reset function may be employed to initialize an array of 
memory registers in block 150 into which emitter on state data will be 
written on a FIFO basis as the state is sampled at a rate governed by a 
fixed sampling interval timer. At the same time, the emitter disable flag 
is set "False" in block 152 and a the fixed interval timer, e.g. Timer 1, 
block 72, may be commenced in block 154. In this case, the fixed interval 
timer times out shorter sampling times, e.g. a 0.5 or 1.0 second fixed 
intervals. The array may be incremented and store 16 state values sampled 
every 0.5 second or 8 state values sampled every 1.0 seconds, so that the 
array represents 8 seconds of emitter state when filled. Thus, the array 
operates as an 8 second running time window and may store the cumulative 
emission time to be compared to an accumulated emission time threshold to 
trigger the 3 second inhibit time interval. A number of other camera 
functions may be initiated on power up that are unrelated to the present 
invention. 
The sampling of the emitter state and loading of the array occurs each time 
the fixed sampling interval timer times out at 164 in FIG. 10. The image 
capture button may be actuated in block 156 of the routine of FIG. 9 at 
any time to initiate the emission of the light output beam, unless 
emission is inhibited. At block 158, the status of the emitter disable 
flag is queried, and emission is triggered in block 160 if the flag is 
"True". The routine of FIG. 10 determines whether emission is permitted or 
inhibited by setting the emitter disable flag accordingly. 
The FIG. 10 interrupt routine is entered to shift the array on a FIFO basis 
at block 166 and write in the state of the emitter every time Timer I 
times out at 164. If the emitter is on, as determined in block 168, the 
"True" state is written into a register of the array at block 170. If the 
emitter is not on the state is unchanged at the initialized "not True" 
state. After the array is written into in block 170, the states are 
averaged (i.e. the True states are summed and compared to the total number 
of states in the array) in block 172 to provide a representation of the 
cumulative emission time over the immediately preceding 8 second interval. 
That cumulative emission time interval is compared to an accumulated 
emission time threshold in block 174. 
For example, the accumulated emission time threshold may be 5 out of 8 
seconds for an average of 62.5% of the running time window. The threshold 
may not be exceeded, if the user were to depress and release the image 
capture button repetitively every 4 seconds, since the 50% average would 
not exceed the threshold in that case. Then, since the interrupt routine 
of FIG. 10 is entered every time the sampling interval timer times out, 
the routine reloads the fixed interval Timer 1 to time out the sampling 
time in block 176. 
If the accumulated emission time threshold T.sub.acc is exceeded in block 
174, then the emitter controller is commanded to turn off the emitter in 
blocks 180-188 until the inhibit time interval T2 times out. The emitter 
disable flag is set to "True" in block 182 to prevent the image capture 
button from having any effect in the routine of FIG. 9. The Timer 2, block 
74, is loaded and down counted in block 184 to timeout the inhibit time of 
3 seconds, for example. After timeout of the inhibit time interval T2, the 
registers of the array are cleared to the "not-True" state as initialized 
in block 186, and the emitter disable flag is set "False" in block 188 to 
clear the way for re-starting emission on depression of the image capture 
button 22 in block 156. 
All of the above described modes of emitter control are effected through 
the operation of the micro-controller 70 providing commands to the emitter 
output controller 40. In addition, all of the above methods and 
embodiments of the invention contemplate the operation of the emitter 
output controller 40 to provide either the fixed intensity light output 
beam or the variable intensity/duty cycle light output beam of the 
above-incorporated '827 application. Preferably, if the latter operation 
is provided, an override switch is also provided to allow the user to 
switch to the fixed intensity operation. It may be desirable to vary the 
emission time interval T1 or the cumulative emission time interval 
threshold and the inhibit time interval T2 to the intensity of the emitted 
light output beam depending on the light intensity applied in either 
operating mode. 
A further user operated switch may be provided to allow the user to disable 
the emitter output controller 40 and the above described timing operations 
at low battery voltage to allow the camera to be continued to be operated 
until replacement batteries can be loaded or for other reasons where use 
of the pointing aid is either unnecessary or inappropriate. 
The FIG. 2 embodiment of the camera system includes a pointing aid emitter 
18 that is integrated with the automatic exposure system 35 and automatic 
focus system 38 of the camera operating system. As noted, it is not 
necessary to include all of these systems in the camera, and it is not 
necessary to control the pointing aid beam 21 in accordance with both 
systems. It should be noted that the camera may include a passive 
automatic focus or automatic distance measuring system that does not 
depend on or is not influenced by the emitted light output beam 21. In 
such a case, the auto focus operation may be conducted each time the image 
capture button is depressed to the pointing position whether or not the 
light output beam is emitted. 
Those skilled in the art will appreciate that other implementations of 
emitter control are possible for other types of cameras to avoid the 
presence of the pointing aid output beam on objects in the captured 
images. For example, the image capture button of a video camera is 
depressed continuously during video image recording, and emission of the 
output beam would be electronically synchronized to the vertical blanking 
interval. In accordance with the present invention the frequency at which 
the output beam may be emitted would be controlled by timing and counting 
the number of image frames recorded and periodically allowing the output 
beam to be emitted during a vertical blanking period. In a video camera, 
the image capture button is typically held closed continuously while 
recording takes place. Thus emission may be selectively user actuated and 
take place continuously while actuated but periodically inhibited to 
provide an average emission rate below a threshold. For example, emission 
may be inhibited despite continuous actuation as a function of image frame 
timing to effect an average emission rate and on time that is less than 
that possible if emission were allowed during every vertical blanking 
interval. 
Although the system of FIG. 2 is primarily implemented in a 
micro-controller based camera operating system, it will be understood that 
the various methods of operating and means for performing the operations 
described above may also be implemented in digital logic blocks and 
components arranged in the equivalent camera electronic control and 
operating system. In such an implementation, the timer 38 of the 
embodiment of FIGS. 2 and 3 may constitute a discrete timer or timers or 
the time periods may be calculated by operation of the micro-processor, 
both methods being well known in the art. Moreover, both the calculation 
of the variable output beam power and/or the inhibit time interval T2 
could be accomplished by the digital camera operating system each time an 
output beam 21 is delivered. Similarly, in the video camera 
implementation, the rate or frequency of delivery of the output beam could 
be calculated by the digital logic operating system as a function of the 
calculated variable or the fixed output pulse power as the camera is 
directed by the user from scene to scene. 
Thus, when employing a fixed power output beam set at a certain average 
brightness and object distance, the rate of emission may increase (or the 
inhibit time interval signal T2 may be decreased) within a safe range as 
it is necessary to compensate for increased object distance or ambient 
brightness. 
Conversely, the rate of emission may decrease (or the inhibit time interval 
T2 may be increased) within the safe range as it is necessary to 
compensate for increased object distance or ambient brightness. In such an 
implementation, the ambient light signal from the ambient light sensor 34 
and the object distance calculated by the auto focus system 38 of FIG. 2 
may be employed by the micro-processor to calculate the count to be loaded 
into a counter to set the rate of emission in the video camera embodiment 
or the inhibit time interval T2 in the still camera embodiment. When 
employing a variable power output beam 21, the same calculations may be 
made, but the range of the emission rate and inhibit time interval T2 
would be narrowed as the output beam power is varied. 
Thus, a camera constructed in accordance with the present invention emits a 
pointing aid beam that can assist a camera user in pointing the camera to 
capture the image of an object of interest with or without using a view 
finder. The average output power of the beam is controlled by frequency of 
emission so that the user cannot intentionally or inadvertently 
repetitively operate the pointing aid output beam. In accordance with the 
invention, the emitter output controller is operable following emission of 
the visible laser output beam for inhibiting the further response of the 
pointing aid emitter output controller to the pressing of the image 
capture button for a pre-determined time interval so as to reduce the risk 
of damage to the object in the scene, particularly the retina of a person 
or animal, that is illuminated by the output beam. 
The present invention has been described above in terms of presently 
preferred embodiments so that an understanding of the present invention 
can be conveyed. There are, however, many configurations for camera 
pointing aids not specifically described herein, but with which the 
present invention is applicable. The present invention should therefore 
not be seen as limited to the particular embodiments described herein, but 
rather, it should be understood that the present invention has wide 
applicability with respect to camera pointing aids generally. All 
modification, variations, or equivalent arrangements that are within the 
scope of the attached claims therefore should be considered within the 
scope of the invention. 
The following elements and their corresponding reference numerals are used 
in the drawings: 
camera 10 
camera body 12 
objective lens 14 
first set of terminals 15 
view finder 16 
second set of terminals 17 
pointing aid emitter 18 
objective lens optical axis 19 
scene measuring system 20 
output beam 21 
image capture button 22 
ambient light 23 
flash unit 24 
reflected light beam 25 
emitter adjustment switch 26 
adjustment switch signal line 27 
object 29 
ambient scene 30 
focal plane 32 
image capture medium 33 
ambient light sensor 34 
automatic exposure system 35 
distance beam sensor 36 
automatic focus system 38 
emitter output controller 40 
lens focus motor 44 
arrows 46 
time delay one shot 48 
image capture system 50 
system clock 68 
micro-controller 70 
Timer 1 block 72 
Timer 2 block 74 
switch segments 76 and 78 
load spring and shaft 80 
program blocks 100-188