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Digital Camera Patent Abstract
A viewfinder system for a digital camera comprises a main optical
path for projecting an outside scene image onto a light sensitive
area facility, which facility determines a user field, and an optical
extraction path for through mirror-operation extracting a fraction
of the outside scene image onto a viewer optical path. The viewer
optical path comprises a first mask for inserting a negative delineating
outline into a viewer field and a second mask for inserting a positive
delineating outline into the viewer field, both said first and second
masks corresponding to the user field. In particular, at least one
of the first and second masks is realized by an electronic device
that has its mask size variably controlled by an electronic facility
on the basis of pixel-wise driving. Advantageously, the electronic
device is controlled by a sensor facility that is adapted for with
respect to the other of the masks that has a fixed size sensing
the latter size.
Digital Camera Patent Claims
1. A viewfinder system for a digital camera that comprises a main
optical path for projecting an outside scene image onto a light
sensitive area facility, which facility determines a user field,
and an optical extraction path for through mirror-operation extracting
a fraction of said outside scene image onto a viewer optical path,
and wherein said viewer optical path comprises a first mask for
inserting a negative delineating outline into a viewer field and
a second mask for inserting a positive delineating outline into
the viewer field, both said first and second masks corresponding
to said user field, wherein at least one of said first and second
masks is realized by an electronic device that has its mask size
variably controlled by an electronic facility on the basis of pixel-wise
driving.
2. A viewfinder system as claimed in claim 1, wherein both said
first and second masks are realized by respective electronic devices
that each have their respective mask size variably controlled by
an electronic facility on the basis of pixel-wise driving.
3. A viewfinder system as claimed in claims 1, wherein both of
said first and second masks allow to view at least a part of said
outside scene that is peripheral with respect to the mask in question,
the mask proper being realized in the form of a thin line or the
like.
4. A viewfinder system as claimed in claim 1, wherein said electronic
device is based on LCD or LED technology.
5. A viewfinder system as claimed in claim 1, wherein said electronic
device is controlled by a sensor facility that is adapted for with
respect to the other of said masks that has a fixed size sensing
the latter size.
6. A viewfinder system as claimed in claim 5, wherein said sensor
facility senses a digital electronic code that is attached on a
substantially flat external surface of said other mask.
7. A viewfinder system as claimed in claim 2, wherein said respective
electronic devices are interconnected by a size signaling facility
with respect to one of said devices.
8. A digital camera being provided with a viewfinder system as
claimed in claim 1.
9. A viewfinder system as claimed in claims 2, wherein both of
said first and second masks allow to view at least a part of said
outside scene that is peripheral with respect to the mask in question,
the mask proper being realized in the form of a thin line or the
like.
Digital Camera Patent Description
BACKGROUND OF THE INVENTION
[0001] The invention relates to a viewfinder system for a digital
camera that comprises a main optical path for projecting an outside
scene image onto a light sensitive area facility, which facility
determines a user field, and an optical extraction path for through
mirror-operation extracting a fraction of said outside scene image
onto a viewer optical path, and wherein said viewer optical path
comprises a first mask for inserting a negative delineating outline
into a viewer field and a second mask for inserting a positive delineating
outline into the viewer field, both said first and second masks
corresponding to said user field, such as being recited in the preamble
of claim 1.
[0002] Digital cameras are abounding for amateur as well as for
professional applications, for still pictures as well as for digital
cinematographic applications. The organization of the light-sensitive
area will determine the size of the image and/or the part of the
outside scene that is available for a user application, such as
in the form of a user field. Pixels outside the size of the user
field will not be taken further into account. The viewer image is
based on a fraction of the intensity of the relevant pixels. Just
as the main optical path, the viewer field can have a particular
size, that however can in principle be different from the size of
the user field.
[0003] Now, the actual scene can count both elements that must
appear in the user field, and also other elements that may not appear
in the user field. Nevertheless, such other elements are often provided
intentionally near the scene for realizing certain effects that
may relate to the image itself (such as lighting apparatus or an
air-fan to mimick winds and the like) or to other aspects of the
scene such as audio (microphone dollies and the like). The camera
user will want to see such elements in the viewer field without
letting them intrude into the scene image proper as determined by
the user field. Thus, for optimum discrimination, the representation
of the user field is delimited by a mask that will often be just
a framing line or even part of such framing line, such as by indicating
only the comers of the frame.
[0004] Now, for optimum visibility, in lighter scenes the frame
should be relatively darker, or negatively delineated, whereas in
darker scenes the frame should preferably be relatively lighter,
or positively delineated. The activation of the two frame versions
could be simultaneously or alternately, such as by time division.
Generally, the two masks are produced in or by respective separate
facilities.
[0005] Now, in various situations, the frame size should allow
adapting, such as being governed by a standard organization for
transmission or storage, by a more or less arbitrary user choice,
by a size and format (A, B, etcetera) of the paper on which the
image would ultimately be printed or otherwise hard-copied, or by
other considerations.
[0006] Prior art, in U.S. Pat. No. 6,088,545 to Abe et al., has
proposed the use of hardware diaphragms for both positive and negative
delimiting of the scene field. The present invention has recognized
the great usefulness that is brought about by driving the size of
at least one of the masks by an electronic facility on the basis
of pixel-wise driving.
SUMMARY TO THE INVENTION
[0007] In consequence, amongst other things, it is an object of
the present invention to introduce flexibility in the control of
the mask size. Now therefore, according to one of its aspects, the
invention is characterized in that at least one of said first and
second masks is realized by an electronic device that has its mask
size variably controlled by an electronic facility on the basis
of pixel-wise driving, as recited in the second paragraph of claim
1. Both for fixed and also for variable mask size this offers an
elementary realization. In case only one such mask is variably controlled,
the other mask could have a fixed size, but could then be physically
removable.
[0008] Advantageously, the electronic device is based on LCD technology.
Low power consumption, a low price through LCD mass-production levels,
and easy installing are some of the prominent advantages of LCD.
[0009] Advantageously, both of said first and second masks allow
to view at least a part of said outside scene that is peripheral
with respect to the mask in question, the mask proper being realized
in the form of a thin line or the like. This will allow an operator
to let necessary but unwanted objects approach as closely as possible
the scene image fraction that is actually used. In contradistinction,
the above reference U.S. Pat. No. 6,088,545, in its diaphragm elements
20A and 18 (FIG. 1) has only an outside restriction by a mechanical
diaphragm, so that objects outside the mask will be readily obscured.
Moreover, the prior art has only little flexibility. By itself,
the present invention could have such diaphragms realized by pixel-wise
driving.
[0010] Advantageously, the electronic device that has its mask
size variably controlled is controlled by a sensor facility that
is adapted for with respect to the other of said masks that has
a fixed size sensing the latter size. Even in the case where one
of the masks is based on a physically fixed size, the other's size
will then be automatically adjusted. By way of example, the fixed-size
mask could be exchangeable.
[0011] The invention also relates to a digital camera being provided
with a viewfinder system as recited supra. Further advantageous
aspects of the invention are recited in dependent Claims.
BRIEF DESCRIPTION OF THE DRAWING
[0012] These and further features, aspects and advantages of the
invention will be discussed more in detail hereinafter with reference
to the disclosure of preferred embodiments of the invention, and
in particular with reference to the appended Figures that illustrate:
[0013] FIG. 1, an exemplary mask geometry and associated exemplary
control facilities;
[0014] FIG. 2, an optical path geometry;
[0015] FIG. 3, an elementary camera geometry;
[0016] FIG. 4, a facility for producing an electronic code.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0017] FIG. 1 illustrates an exemplary mask geometry, such but
without limitation as may be used for generating a negative delineating
outline. The outer dimensions of the image are shown by line 20.
The field of view or area of interest AOI that will correspond to
the user field is delineated by line 22. This line may be realized
as a rectangular scratch applied to a glass plate. The extended
field of view between lines 20, 22 is not used for the ultimate
imaging, but can be viewed by the camera operator who may let unwanted
objects such as microphones come as close as possible to the scene,
but not closer. In the terminology of the art, this device in question
is the "ground glass". In a particular embodiment, the
ultimate CCD light sensitive area (maximum user field) is 34 mm
wide and 17.2 mm high (4096.times.2048 pixels at a pixel size of
8.4 microns). Common reducing formats include 1.85:1, and 2.35:1.
The unwanted image data will usually be deleted during post-processing.
The frame format can then be stored in the image output file header,
but the camera will still capture the full data content, without
removal of information inside the camera. In many instances, the
camera is manually set up to match the image requirements for the
envisaged application. Calibration ensures that the area of interest
depicted on the viewing monitor and the area of interest on the
viewfinder are identical. If the identity of the ground glass is
known beforehand, it can be used to change the frame format automatically,
and if desired, even reduce the amount of data captured during recording.
[0018] The mask proper can be realized by a single file or by a
multiple file of pixels, and if necessary, in an appropriate color.
In LCD technology, it is straightforward to drive pixels in question
for either transmitting or non-transmitting operation.
[0019] FIG. 2 illustrates an optical path geometry. At left, the
arrow 30 symbolizes the light rays emanating from the object or
outside scene. Block 32 symbolizes an optical lens system that may
comprise all such optical elements deemed necessary for getting
an image of appropriate quality on the CCD light sensitive area
36 that is located within subsystem 38 that accommodates all appropriate
electrical and other elements. Just for discrimination, dotted lines
34 indicate the outer edge of the useful image cone or other geometry.
The outputting of useful optical information from items 36, 38 to
a user or user facility (storage, transmission, or other) has been
omitted for brevity. This user field should effectively correspond
to the mask effected by the ground glass; the degree of equality
being governed by the quality level envisioned. For example, the
mask effected by the ground glass could be just a little bit larger.
[0020] Now, shutter 40 with shutter drive mechanism 42 will allow
to produce successive pictures or screens from the outer scene,
which by itself is irrelevant to the invention. However, incidentally,
the shutter allows a time wise split of the ray pattern 30 into
rays 44 and 46, cf. the realization shown in FIG. 3. Rays 44 contribute
to the scene image on element 36. On the other hand, rays 46 are
reflected on shutter mirror plane 40 and constitute a secondary
optical path. The so-called ground glass 48 will block rays organized
in a delineating pattern such as item 22 in FIG. 1. The viewer path
will thus allow easy discrimination between the inner part that
is encompassed in the user image with respect to item 36, and an
outer part that can be seen by the operator, but is otherwise blocked
with respect to user output facility 36, 38. The ground glass can
be realized in the form of a rectangular scratched line on a removable
glass plate, so that different configurations of the useful image
can be attained. Otherwise, the plate can be executed as an LCD
that can be rendered un-transmitting on a pixel-by-pixel basis,
so that in either case item 22 will appear as a dark line when effecting
a relatively lighter image. The geometry of the non-transmitting
pixels can be a single row or column. If necessary, other configurations,
such as two or three rows and/or columns may be used.
[0021] Ground glass 48 will thus transmit rays 50 that are substantially
parallel, onto prism 52 that consists of two parts interconnected
at a semi-reflecting mirror plane at a slope that is within a range
near 45.degree.. In a particular embodiment, the actual slope was
42.5.degree.. In consequence, rays 50 will in part be reflected
to the left, where a further prism 54 is used for reflecting the
rays 50 to a viewfinder arm that will place the viewer image in
an appropriate angle and position with respect to a user, cf. FIG.
3.
[0022] On the other hand, the so-called glow mask 56 will present
a pattern that corresponds to the pattern from ground glass 48,
but which in contradistinction to item 48, appears lighted, so that
a lighted perimeter figure to the useful scene image can be inserted.
Prism 58 will result in a reflection over 90.degree. or other appropriate
angle, and semi-reflecting prism 52 will transmit the light from
glow mask 56 straight on. The images from items 48 and 56 will therefore
be substantially identical, while only the lighting intensities
thereof are relatively inverse. In a darker scene will therefore
the image from glow mask 56 appear relatively lighter. Is appropriate,
the user person will select one of the two as active. Preferably,
glow mask 56 is realized in the form of a rectangular configuration
of LEDs. Also for glow mask 56, the lighted figure could be one
or more than one pixel thick, if necessary with a thickness that
can be controlled for realizing certain effects.
[0023] FIG. 3 illustrates an elementary camera geometry of a viewfinder
system, wherein reference is had to the geometry discussed with
regard to FIG. 2. Shutter 40 has been realized in the form of a
rotating mirror. In non-reflecting orientations of the rotating
mirror, the user image will be provided. In reflecting orientations,
the viewer image will be provided. The viewfinder system encompasses
an optical path that has various (more or less) right angles. The
ground glass is not visible in this exploded view. Various numerals
indicate parts discussed earlier with reference to FIG. 2, such
as the housings of prisms or mirrors 54, 58 (that effectively has
two reflecting planes, plus a further invisible one) and glow mask
56. Further elements are the optical path 60 of the viewfinder and
the eyepiece 61.
[0024] FIG. 4 illustrates a facility for producing an electronic
code, in particular for use with the ground glass, and will be discussed
with further reference to earlier FIG. 1. The code in this embodiment
is digitally produced in hardware as based on pads 70 that have
been selectively positioned on the ground glass plate 48: if a pad
is present, such will signal a logical "1". If absent,
such will signal a logical "0". Interconnect 72 allows
to feed a first voltage level, in this case ground level as shown.
Sensor pins 74 will connect to pads 70 if the ground glass is in
position with respect to the viewfinder's housing. Resistors 76
will connect pins 74 to a second voltage level such as VCC at 77.
Feelers will feed the voltage on the pads to a sensing arrangement
not shown for brevity. In the arrangement shown, a four-bit cade
can be effected. Although not explicitly shown, in certain situations,
an analog or mixed code would be feasible. Generally, but not restrictively,
the glow mask would not have a passive code applied thereon, inasmuch
as a flexible control thereof is preferred.
[0025] With regard to FIG. 1, here both the first (22) and second
(23) masks are shown, that have corresponding sizes with regard
to the ultimate display. As being preferably based on parallel light
rays, generally also their physical sizes will correspond. Only
with respect to the second mask, various possibilities for sizing
the mask have been shown (23, 80, 82). Similar sizes would apply
to the first mask, to keep it corresponding to the actual version
of the second mask. Various control arrangements will now be discussed
hereinafter. [0026] a. First, with respect to the code generating
in FIG. 4, the code on the ground glass 20 will be outputted on
lines 83 as represented by the arrows to the right and detected
by sensor arrangement 84. Next, in the form of a bit series through
interconnect 86 they will feed glow mask controller 88. The latter
will then through interconnect 90 drive the correct pattern in glow
mask 92, so that patterns 22 and 23 will have corresponding sizes.
A non-steady alternation in time between ground glass activation
and glow mask activation is possible, but has not been shown for
brevity. [0027] b. In a second arrangement, a user person can activate
interface facility 94. The latter can be as complicated as necessary,
and can serve for inputting and signaling a variety of user data.
A keyboard, local display, audio warning and various other items
can be present according to needs. The control signalizations for
the ground glass and the glow mask can run along lines 98 and 96,
respectively, so that in this case both ground glass and glow mask
will operate as slaves with respect to the user interface device
94. Interconnects 83 and 90 will then operate for driving, such
as through the arrows pointing to the left. In that case, interconnect
86 need not be present. On the other hand, also in this case, ground
glass and glow mask could operate with one being slave to the other.
Then, interconnect 96 could be absent, with interconnect 86 controlling
the slave. Alternatively, the ground glass can operate as slave.
[0028] Now, the present invention has here above been disclosed
with reference to preferred embodiments thereof. Persons skilled
in the art will recognize that numerous modifications and changes
may be made thereto without exceeding the scope of the appended
Claims. In consequence, the embodiments should be considered as
being illustrative, and no restriction should be construed from
those embodiments, other than as have been recited in the Claims.
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