|
Digital Camera Patent Abstract
The invention relates to a camera for generating digital images
with an image sensor that is configured to convert an image formed
by a lens into electronic signals. The digital camera is characterized
by that the image sensor is attached to a movement element with
a controllable drive, the movement element rendering the image sensor
tiltable so that an angle between the axis of the lens and a plane
of the image sensor is modifiable.
Digital Camera Patent Claims
1. Camera for generating digital images with an image sensor that
is configured to convert an image formed by a lens into electronic
signals, characterized by that the image sensor is attached to a
movement element with a controllable drive, the movement element
rendering the image sensor tiltable so that an angle between the
axis of the lens and a plane of the image sensor is modifiable.
2. Camera according to claim 1, having a further autofocus element
that is configured to determine from a distance measurement of an
area a focus value of the lens and a tilt of the image sensor so
that the area is sharply focusable onto the image sensor.
3. Camera according to claim 2, wherein the focusable area is visually
marked in a display of the image for a user of the camera.
4. Camera according to claim 2, having a further provision for
inputting a target area, wherein the autofocus element from a distance
measurement of the target area aims for a tilt of the image sensor
that renders the target area sharply focusable on the image sensor.
5. Camera according to claim 1 with a further control element with
which a tilt of the image sensor is controllable by a user.
6. Camera according to claim 1, further with at least one control
area that permits a visual control of the focus by the user.
Digital Camera Patent Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application claims priority to German Patent Application
No. 10 2005 041 431.1-51, filed on Aug. 31, 2005, and entitled "Digitale
Kamera mit verschwenkbaren Bildsensor," which is incorporated
herein by reference for all purposes.
FIELD OF THE INVENTION
[0002] The invention relates to a camera for generating digital
images.
BACKGROUND
[0003] In recent years the spreading of digital cameras has increased.
A digital camera has an image sensor that has the ability to record
light beams and convert them into electrical signals. Examples for
an image sensor are charge coupled devices (CCD) semiconductor detectors
or complementary metal oxide semiconductors (CMOS) elements. A processing
of the electrical signals allows for a representation of the recorded
light beams in a format of electronic data. In case that an image
is formed on a light sensitive layer the image may for example be
stored in an electronic file. The electronic file may have a standard
format so that the electronic file is transferable to a computer
and displayable on a monitor using a suitable program.
[0004] The digital camera includes a lens that forms an image.
An image area is sharply focused on the image sensor in case that
the image area can be perceived as sharp in a representation following
a processing. A sharp perception depends on the requirements for
the representation and is influenced by further properties of the
total optical system as for example by the resolution of the image
sensor. According to the requirements there is a volume of sharp
focus that includes a plane of sharp focus. Objects that are within
the volume of sharp focus may be formed in a sharp way on the image
sensor by the lens, that is, that the image of the objects is focused
sharply on the image sensor. In case that the longitudinal axis
of the lens is perpendicular, that is orthogonal, to the image sensor
the plane of sharp focus is also perpendicular to the longitudinal
axis and therefore parallel to the image sensor. This is the case
in most digital cameras. In certain situations a plane of sharp
focus that is not perpendicular to the longitudinal axis of the
lens may be desirable. Cameras with a tilt lens have a lens that
is tiltable and a plane of sharp focus may be obtained that is tilted
with regards to the longitudinal axis of the lens. Such tilt lenses
are mechanically complex and expensive to manufacture. They are
specialty lenses that are offered only in few focal distances. Furthermore,
a sharp focusing of a large image area may be difficult due to missing
options to control the sharpness and automated adjustments. There
are further large format cameras with a movable center piece. The
movable center piece allows for a tilting of standard lenses. Such
large format cameras are also mechanically very complex, expensive
to manufacture, and involved when used. A sharp focusing is possible
but complex.
SUMMARY
[0005] An object of the invention is a flexible digital camera
with a plane of sharp focus that is tiltable with regards to the
longitudinal axis of the lens.
[0006] Accordingly a digital camera is disclosed in claim 1. The
disclosed digital camera has an image sensor that is tiltable with
regards to the longitudinal axis of the lens. A tilting of the image
sensor leads to a desired tilt of the plane of sharp focus with
regards to the longitudinal axis of the lens. The disclosed camera
is flexible because it can be used with a standard lens and its
operation is easy. Furthermore, the disclosed camera is robust because
internal components are tiltable. The disclosed camera can be manufactured
without a large increase in proportions or weight compared to a
conventional digital camera without the inventive characteristics.
Furthermore, the disclosed camera can be manufactured cost-efficiently.
[0007] Further embodiments of the digital camera are disclosed
in following claims that depend on claim 1.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 shows an example digital camera with a tilted image
sensor and an accordingly tilted plane of sharp focus.
[0009] FIG. 2A is a front view of an embodiment of a movement element.
[0010] FIG. 2B is a side view of the embodiment of a movement element.
[0011] FIG. 3A is a front view of a further embodiment of a movement
element.
[0012] FIG. 3B is a side view of the further embodiment of a movement
element.
[0013] FIG. 4 is an example digital camera with a display of an
image with marked autofocus areas.
[0014] FIG. 5 is an example digital camera with a display of a
control area.
DETAILED DESCRIPTION OF THE FIGURES
[0015] FIG. 1 shows an example digital camera 100 with a tilted
image sensor 120 and an accordingly tilted plane 206 of sharp focus.
The figure is not drawn to scale. The digital camera 100 is configured
to generate digital images using the image sensor 120 that is configured
to convert an image from a lens 110 into electrical signals. The
image sensor is attached to a movement element having a controllable
drive, wherein the movement element renders the image sensor tiltable
so that an angle between an axis 112 of the lens and a plane 122
of the image sensor is modifiable. The movement element includes
the controllable drive and is controllable by the drive. A controlling
of the movement element by the drive may be obtained for example
using electrical signals to the drive or the movement element. The
movement element may for example convert the electrical signals
so that they may be used to control the drive. The electrical signals
may control the drive to mechanically move the movement element
leading to an according tilting of the image sensor. The axis 112
of the lens is the longitudinal axis of the lens. The tilted plane
of sharp focus 206 and the plane 122 of the image sensor meet in
a line that is represented in FIG. 1 as a point. According to the
Scheimpflug principle, in this line also meets a lens plane that
is perpendicular to the axis 112 of the lens. The line is also called
Scheimpflug line. In case of a non-tilted image sensor, meaning
an image sensor perpendicular to the axis 112 of the lens the plane
of sharp focus 206 is parallel to the plane 122 of the image sensor
and the Scheimpflug line may be described as being located infinitely
far away.
[0016] An opening angle of the lens is represented by a top opening
line 114 and a bottom opening line 116. The lens produces an image
of objects within the opening angle. Accordingly, the lens produces
an image of a near object 202 and a far object 204. The near object
202 is for example a ball in a distance of 2 meters and the far
object 204 is for example a mountain range in a distance of 5000
meters. The plane of sharp focus cuts the near object 202 and the
far object 204. With an appropriate opening of the aperture follows
a volume of sharp focus that includes the near object and the far
object. Therefore, with an appropriate opening of the aperture the
near object and the far object may be in sharp focus. With an untilted
image sensor such focusing is not obtainable and the near object
and the far object may be formed with reduced image quality by using
a small aperture. For the mentioned example of the 5000 meters far
away mountain range and of the 2 meters far away ball an approximate
tilt of the image sensor may be calculated using the lens equation,
also called thin lens formula. The lens equation is: the sum of
reciprocal value of object distance to lens and reciprocal value
of image distance to lens is equal to the reciprocal value of the
focal length of the lens. In case of for example a focal length
of the lens of 20 millimeters and a distance between the images
of the near object and the far object of 10 millimeter on the image
sensor follows a tilt of approximately 1.1 degrees compared to a
perpendicular image sensor.
[0017] The digital camera 100 may for example be a digital single
lens reflex camera, a digital view finder camera, a digital camera
without a view finder, or a camera with a digital back. The lens
may for example be a lens with a fixed focal length or a zoom lens.
The lens may be also a macro lens and for a macro photo the difference
between the distances of a near and a far object may be a few centimeters.
[0018] FIG. 2A is a front view of an embodiment of a movement element.
The drive of the movement element consists of units 132, 134, 136.
The image sensor 120 is attached to a platform and the units connect
the platform with a rear panel of the 102 of a digital camera. The
platform is a part of the movement element. The units 132, 134,
136 may be attached in a flexible way to the platform so that the
angles between the units and the platform is modifiable. The units
may be also attached to the rear panel in a flexible way. In a further
embodiment the number of units may be larger of smaller. Furthermore,
an embodiment may enable a tilt of the image sensor only in one
direction. Such an embodiment may be obtained with one unit and
for example a hinge.
[0019] FIG. 2B is a side view of the embodiment of a movement element.
The side view is such that the units 132, 134, 136 are visible.
The units may change their length in the indicated direction. Therefore
a tilt of the image sensor 120 may be obtained in any direction.
There are many possibilities to embody a unit with a modifiable
length. As an example, a piezo-electric element may change its length
when a voltage is impressed on it. In a further example, the unit
may include a small electric motor that turns a threaded spindle
so that the distance between an end of the threaded spindle and
a mount of the threaded spindle changes leading to a change of the
length of the unit. Electric wires for controlling the units are
not shown in the figures (FIG. 2A and FIG. 2B).
[0020] FIG. 3A is a front view of a further embodiment of a movement
element. In the further embodiment an attachment element 142 is
attached to the image sensor 120. Behind the image sensor is in
front of the rear panel 102 of the digital camera.
[0021] FIG. 3B is a side view of the further embodiment of a movement
element. The attachment element 142 is held movable in an attachment
housing 146 by a mounting 148 so that the longitudinal axis of the
attachment element 142 is tiltable. A tilt in the vertical direction
is controlled through a unit 144 that is part of the controllable
drive and that has a modifiable length in the indicated vertical
direction. A tilt in the horizontal direction may be controlled
by a further, not displayed unit with modifiable length. The further
unit may be for example turned by 90 degrees around the longitudinal
axis of the attachment element 142 compared to the unit 144. The
unit 144 with a modifiable length may have embodiments that have
been represented and described in a previous figure (FIG. 2B). The
movement element includes the attachment element 142, the attachment
housing 146, the mounting 148 and the unit 144. A further embodiment
of a controllable drive for controlling a mechanical movement of
the movement element is an ultra sonic motor. Ultra sonic motors
are known to a person skilled in the art from lens focusing. Furthermore,
a movement element may be moved by a purely mechanical drive. The
purely mechanical drive may for example convert a turning of a steering
wheel by a user into a mechanical movement of the movement element.
The drive should allow for a very precise adjustment by the mechanical
components because a precise adjustability of the movement element
is desirable.
[0022] FIG. 4 is an example digital camera 100 with a display 160
of an image with marked autofocus areas 162 and 164. The example
camera 100 is a digital single lens reflex camera with an additional
autofocus element that is configured to determine from a distance
measurement of an area a focus value of the lens and a tilt of the
image sensor so that the area is sharply focused on the image sensor.
The area may consist of one or more partial areas that may be separate
or connected. The area may consist for example of 45 autofocus points
that determine the distance in 45 different partial areas. The autofocus
points may be evenly distributed like a lattice over the whole area
that is imaged by the lens on the image sensor. In a further example
the distribution may deviate from the lattice structure. A person
skilled in the art knows different embodiments of autofocus elements.
There are active autofocus elements that measure for example the
reflection of infra red light and there are passive autofocus elements.
The autofocus elements may for example determine the distance by
contrast comparison. The contrast comparison may be used for example
with digital view finder cameras. The passive autofocus elements
may determine the distance also for example by phase comparison.
The phase comparison may be used for example with digital single
lens reflex cameras.
[0023] The camera 100 has a finder 155 in which the focusable area
is visually marked in a display 160 of an image for a user. In the
example are two visually marked focusable areas 162 and 164. The
area 162 includes a part of the near object 202 and the area 164
includes a part of the far object 204. Both areas 162 and 164 may
be focused in a sharp way on the image sensor in accordance with
the focus or distance value of the lens, the tilt of the camera,
and the distances measured by the autofocus elements. Therefore,
both areas 162 and 164 will be formed as sharp images on the light
sensitive layer of the image sensor when the shutter is opened or
an exposure of the camera is triggered. In a further camera with
multiple autofocus points a larger number of sharply focusable areas
may be marked according to the circumstances.
[0024] Furthermore, the camera 100 has a further provision for
inputting a target area, wherein the autofocus element aims for
sharply focusing the target area on the image sensor by a distance
measurement of the target area, an according adjustment of the focus
of the lens, and an according tilt of the image sensor. In a further
embodiment, the autofocus element may also determine the aperture
value so that the target area is sharply focused on the image sensor.
By adjusting the aperture value the thickness of the volume of sharp
focus is determined, that is, the objects that are focused in a
sharp way and that are outside of the plane of sharp focus.
[0025] Furthermore, the camera 100 has a further control element
150 with which the tilt of the image sensor is controllable by a
user. With the control element a user may adjust the tilt manually.
The user may move a button or a stick to the top, bottom, left,
or right and such an adjustment is mapped to a corresponding tilt
of the image sensor. In an example, a movement of the button may
lead to a tilt wherein the top edge of the image sensor is tilted
to the front. A movement of the button to the left may for example
lead to a tilt wherein the left edge of the image sensor is tilted
to the front. The user may see the effects of the tilt on the areas
that are sharply focused on the display 160 for example by using
the marked areas that may be sharply focusable. The control element
150 may also be used for example to determine one or more target
areas by separately moving each target area with the button in the
display.
[0026] The camera 100 is a digital single lens reflex camera that
allows for a representation of the display 160 through the view
finder. With a digital camera of a different type, for example a
digital view finder camera or a digital compact camera the display
160 may be represented for example by a liquid crystal display (LCD)
monitor. The LCD monitor may receive a part of the information of
the display 160 from the image sensor.
[0027] FIG. 5 is an example digital camera 100 with a display of
a control area 172. The control area 172 of the camera 100 permits
a visual control of the focus by the user. The control area is represented
in the figure by a LCD monitor 170. In a further embodiment of the
digital camera the control area may be also represented in the view
finder for example as a split circle or split screen. For a digital
single lens reflex camera the LCD monitor 170 may represent the
representation 172 following an exposure of the image sensor. The
user may take for example a test photo, let one or more control
areas be displayed to check the sharpness of the control areas,
and take a further photo following a change of the tilt. The representation
172 shows the near object 202 (see FIG. 1) that is a ball in an
enlargement so that a sharp focusing may be verified. The user may
for example use the control element 150 to move the control area
or jump to a further, predefined control area to check the focusing
for the further control area.
[0028] The digital camera 100 permits with regards to the tilt
of the image sensor a manual manipulation through which the tilt
is controllable by the control element. Furthermore, the digital
camera permits an automated tilt that is determined by aiming for
a sharp focusing of as many areas as possible or of large areas.
The automated tilt may be controlled by the camera without the user
for example influencing the adjustments or perceiving the tilt.
However, the user may be able to see the enhanced area of sharpness
in a representation of the image when the image composition permits
it.
|