DE102011103395A1 - Camera system for recording still or moving pictures in e.g. handy, has magnification changer determining image property of images, and controller changing magnification of changer based on direct user input at system or by external signal - Google Patents

Abstract

The system has a light sensitive transducer for converting location-dependant light signals into electric signals, and a digital zoom. A discrete optical magnification changer e.g. Kepler changer, determines image property e.g. image size or image section, of images recorded by the system. A controller changes magnification of the magnification changer based on direct user input at the system or by an external signal. Discrete actuators control magnification stages of the changer, and a rotatable or switchable mirror is provided for changing direction of light entering the system. An independent claim is also included for a method for using a camera system.

Description

Subject of the invention

The invention relates to a camera system with continuous zoom based on discrete magnification changer.

Motivation:

The demand for cameras with zoom (magnification changer) good quality in mobile devices is growing rapidly. Can it be satisfactorily satisfied with larger devices by the optical zoom, so it is not the case for smart phones, camera phones, tablet computers and laptops because of high cost and large dimensions. The demand for miniaturization and cost reduction in the zoom, which is nowadays only inadequately fulfilled, inspired this invention.

State of the art:

Most optical devices that provide a magnification change will implement an optical zoom if the device has enough space. For example, optical zoom is used in cameras, camcorders, microscopes, and so on. It is a continuous zoom. A focal length change takes place while maintaining the image plane location in an array of at least three lenses, two of which are non-linearly shifted from each other instead. The optical zoom is characterized by a continuous magnification range typically of the order of 3-10 for cameras and 5-20 for camcorders. The different ranges are usually explained by different optical resolution of the device types and thus one is already at one of the serious disadvantages of the optical zoom, the relatively large optical Abberrationen which grow larger with increasing magnification area quickly and allow only small resolutions. Therefore, with the same effort a stronger zoom is allowed with the camcorders, because of the smaller resolution, the optical errors are not so quickly noticed. Other disadvantages of the optical zoom: expensive, heavy, complicated mechanics (forced guidance), large, quality falls quickly with increasing dynamic range in the magnification, high development costs of the optics and mechanics, not foldable. There is still high energy consumption, often no sufficient reproducibility of the magnification, vibration tendency, high operating noise and elaborate production added. A particularly important point is the lack of miniaturization of the optical zoom caused by complicated mechanics. Many zoom variants are treated not only in patents but also in optical books, so it will not be discussed here.

Less known is another magnification changer: the Galileo changer. He will z. T. used in microscopes. It is a discrete magnification changer. Here Galilei telescopes are brought into the afocal beam path, which are used in two positions and thus provide two magnification levels per telescope arrangement. With up to three telescopic arrays with optionally one free passage per beam path, they usually provide between two and six magnification levels, with three and five levels being most common. Discrete magnification changers offer good optical quality and are mechanically and optically relatively easy to develop. But they are due to the size of the optical beam path in a microscope large, heavy, cumbersome and slow and do not offer a continuous magnification change. The magnification change is not intuitive at more than three magnification levels and is classified as non-ergonomic. An example of a Galilei changer is in 1 to see.

A further development of the discrete magnification changer is in DE 10 2007 039 851 A described. The arrangement is faster, smaller, mechanically less expensive, of the same optical quality as the conventional discrete magnification changer, consumes less energy. A combination with zoom of lenses of variable refractive power raises in one variant the important disadvantage that the magnification range can not be addressed in each point. In operation, however, portions of the assembly leave the plane of the optical path, canceling out part of the advantage over conventional discrete magnification changers.

Some advancements of discrete magnification changers are in DE 10 2009 011 681 A1 . DE 10 2010 018 498.5 and DE 10 2010 018 500.0 described.

The few magnification levels of the discrete magnification changers are the knock-out criterion that does not allow use in mobile devices.

In the just mentioned zoom with lenses of variable refractive power (s. US 4,678,899 . US 7,411,739 B2 and US 2009/0021843 A1 ) are normally controlled in detuning two lenses of variable refractive power in opposite directions. In this variant, no optical elements are moved. In another, an optical element is linearly moved while a variable power lens is driven. This zoom is light, fast, small, needs little energy, but has a rather small dynamic range with reasonable optical quality.

The digital zoom is known from the consumer products (digital cameras, digital camcorders, cell phone cameras, etc.) as another magnification changer. It is essentially realized by "enlarging" the pixel size of the camera chip, d. H. the image section corresponding to one pixel is displayed larger. The process is sometimes refined by interpolating between the pixels by software and pasting these interpolated pixels into the image, then re-adjusting the image size. However, this "refinement" does not mean that the resolution is improved, but the presentation appears only "softer" and less grainy. The picture remains poor in detail and out of focus. The resolution based on object size remains, based on image size, it deteriorates. The drop in quality increases very rapidly with the magnification. The use of a digital zoom up to factor 1.3-1.5 seems justifiable. Nevertheless, the digital zoom in photography is used at most in the amateur field. Isolated applications are also found in the technical field, when the resolution requirements are low. Recently, fun camcorders with digital zoom are offered. The implementation is still relatively poor, the zoom is hakelig and far from liquid, although this should be possible with some effort. This fails but probably still in the offered price segment. The digital zoom is a newer date than the optical zoom, but unfortunately not better.

Another new variant of the digital zoom is Tesseras OptiML Zoom. The image is captured by a lens with induced optical distortion, which produces a better resolution in the center of the image than at the edge of the image. Digital zooming of the center area with the simultaneous use of a correction algorithm for optical distortion produces an image with slightly better resolution than if you had omitted this optical distortion during recording. However, this is paid with a lower resolution at the edge of the non-zoomed image. The advantage of this zoom is therefore extremely questionable.

All digital zooms are bound to an electronic image capture and thus only found in devices with a camera, so the devices with purely optical observation not accessible.

task

It is therefore an object of the present invention to provide a camera with a zoom (magnification changer), the o. G. Disadvantages not that any existing benefits each retains and provides new, in particular miniaturizable, fast, easy, easy to manufacture, easy to develop, which manages with as few and simple optical elements as possible, by simple mechanics a high degree of reliability and Longevity, while a maximum magnification dynamics and continuous detuning offers.

This object is achieved by the camera according to the invention according to independent claim 1. Advantageous developments can be found in the subclaims.

description

There is proposed a camera system with a zoom, which consists of a combination of a discrete magnification changer and a digital zoom, especially for small and very small applications such as cell phone cameras, endoscopes, surveillance cameras, but also compact cameras with large zoom factor or in digital microscopes and other optical or medical devices. The camera system is intended to record or observe still or moving images, with simplicity being often referred to as recording in the following. The camera system is a light-sensitive transducer, which can convert locally dependent light signals into electrical signals containing these electrical signals can be stored, sent, forwarded or otherwise processed. Furthermore, the camera system should include a controller that can change the magnification of the discrete magnification changer in response to a direct user input to the camera system or by an external signal. Optionally, the camera system may include a device that can read the magnification and / or the type of discrete magnification changer depending on the setting and / or the type of magnification changer connected. At least one image characteristic of the images supplied by the camera system should be roughly determined by the discrete magnification changer and fine by digital zoom according to the user's specifications. This one image property can be z. As the magnification, the image size or image detail. Fine means here: smaller to significantly smaller (one to several orders of magnitude) distances than the largest distance of the magnification levels of the discrete magnification changer (larger resolution). In the limiting case, the digital zoom can provide all magnification levels appropriate to the application to the magnification levels of the discrete magnification changer and also magnifications above the largest discrete magnification level.

The discrete magnification changer may be a Galileo or a Kepler changer or more of these changers in series. This statement expressly refers to the changer designs in the patents cited here. Thus, it may be that the telescope arrangement of the changer the camera system is not movable (see, for. DE 10 2010 018 498.5 ).

Preferably, the size of the at least one of the enlargement steps is less than 1.7, more preferably less than 1.5. A magnification step is the quotient of the associated magnifications of the magnification levels.

Most interesting in terms of miniaturization are single changers with 2, 3 or 4 discrete magnification levels.

Most interesting in terms of mechanical simplicity are the discrete changers whose magnification levels are controlled by rotational motions.

The camera system may advantageously comprise at least one lens of variable refractive power, e.g. B. for focusing purposes or for the correction of optical aberrations.

From the point of view of economy, the changers are interesting, which provide at least 1.25 magnification levels per functional lens group of the discrete changer, ie 3-way or 5-way changer or their series connection. The small footprint speaks for 3-way or 4-way changer or their series connection.

The control of the discrete magnification changer is preferably carried out electromagnetically. Since the discrete magnification changers are only operated in a few positions, and it does not matter as much as they get there, they also come with discrete actuators, which are particularly compact, even if they can be operated with motors. Considering that the camera system modules for mobile phones are always delivered in cuboid form, it makes sense, at least large parts, eg. B. half if not the entire mechanics in the space between the body of revolution, which is caused by the optical movement, and the circumscribed cuboid accommodate. This takes advantage of the already available space and gives you a particularly compact design. If the largest lens of the changer has the diameter a, then the directly circumscribed cuboid has the volume 2a ³ and the housing volume of a single discrete changer, preferably 2a ³ within the limits -10% and + 50%, preferably within the limits -5% and +25 % and more preferably in the limits 0% and + 10%.

Many cell phones today contain two cameras, one for video telephony and one for other recordings. A camera system in which the direction from which light enters the camera system can be changed, e.g. B. via a rotatable or switchable mirror, offers the ability to operate both applications with only one system. The mirror would have z. B. rotated 90 ° to a "viewing direction" of the camera to accomplish by 180 °.

If the optics are mass-produced from plastic, so it is sometimes useful when using z. As the injection molding technique, at least equal parts of the mechanics in a joint operation to produce. This at least partially eliminates the problem of assembly.

If devices are equipped with the camera system according to the invention, it sometimes makes sense to offer a cheaper entry-level variant which contains the same optics except for the discrete changer. Such a device family is cheaper to develop than if both variants had been developed independently. Of course, a camera system can also include a magnification changer without the digital zoom.

The camera system according to the invention must also be operated meaningfully. The method for using the camera system must therefore comprise at least the following steps: (i) presetting the magnification factor within the possible range by a corresponding input directly by users on the camera system or by an external control signal, (ii) selecting a discrete magnification from the list of possible magnifications of the discrete magnification changer, this one discrete magnification being the next smaller magnification to the desired, under (i) predetermined magnification, (iii) driving the discrete magnification changer at the magnification selected under (ii), and (iv) selecting the magnitude of the digital zoom factor such that the product of the digital zoom factor selected here, with the magnification value of the one discrete magnification selected at (ii), is just the desired, under (i) predetermined, magnification. Here, the next smaller magnification to the desired magnification is: (a) less than the desired magnification and (aa) simultaneously the largest of the magnifications satisfying (a) in this set; also reduction and enlargement equal to 1 are called enlargement.

For some applications, including cell phones, you could also use 2, 3 or more cameras or a camera with several internally interchangeable lenses or lens parts combined with digital zoom and synchronized accordingly. Depending on the specification of the user, a corresponding camera or camera lens would be selected and provided with a suitable digital zoom. This with respect to the required space not necessarily cheap solution had the advantage that no or only a few parts are moved.

In the camera system according to the invention, finished zoomed images with the desired magnification or whole, non-zoomed images at a discrete magnification and optionally selected digital zoom parameters can be stored or forwarded. This can be achieved, especially in the second solution, subsequently image stabilization.

The camera system according to the invention preferably contains a motion or acceleration sensor. Its data for the period of image acquisition could be used and / or stored to achieve even better image stabilization. In the areas where the image has been digitally zoomed, there is a lot of room for image stabilization because the camera chip is only partially used for the actual image. If the image is processed directly in the camera with image stabilization, it can be immediately saved in the final format. If the data of the sensor are stored for later image stabilization, a larger image area or the entire image content of the chip should be stored.

• – sehr gute optische Qualität
• – einfache Optik
• – schnelle, große Vergrößerungswechsel
• – leichte Korrektur der optischen Aberrationen, weil die Rechnung nur bei einer Vergrößerung erfolgt (und nicht in einem ganzen Bereich, wie beim klassischem Zoom)
• – sehr einfache Mechanik: nur Rotaionsbewegungen (keine Zwangsführugen, diskrete Aktuatoren ausreichend)
• – einfach miniaturisierbar
• – große Vergrößerungsschritte möglich
• – Energie-sparend
• – geringes Gewicht
• – faltbar
• – sehr gute Reproduzierbarkeit der Vergrößerung
• – niedriger Preis
• – geringe Vibrationsneigung
• – geringer Störgeräuschpegel
• – einfach herzustellen

For a better understanding of the cumbersome combination according to the invention, the advantages of the individual zoom components are listed here, wherein it should be emphasized that some of the advantages of the discrete magnification changer apply especially or even only to small beam paths and thus differ in part from the properties in microscopes. These advantages can be seen especially in comparison with the optical zoom. Advantages of discrete magnification changers:

• - very good optical quality
• - simple look
• - fast, big magnification changes
• - slight correction of the optical aberrations, because the calculation is done only at a magnification (and not in a whole range, as in the classical zoom)
• - very simple mechanics: only rotatory movements (no forced guides, discrete actuators sufficient)
• - easily miniaturized
• - large magnification steps possible
• - Energy-saving
• - low weight
• - foldable
• - very good reproducibility of the magnification
• - low price
• - low tendency to vibrate
• - low noise level
• - easy to make

• – extrem gute Qualität bei sehr kleinen Zoomfaktoren
• – schnell
• – Volumen und Gewicht tendieren gegen Null

Advantages Digital Zoom:

• - extremely good quality with very small zoom factors
• - fast
• - Volume and weight tend to zero

The digital zoom is actually known for its poor quality, so first surprise the statement made above. It should be noted, however, that the general assessment of the digital zoom is made at larger zoom factors. Here, the digital zoom actually performs extremely poorly compared to the optical zoom. However, if you look at very small zoom factors, you notice that the digital zoom is magnified absolutely true to nature and the deterioration in resolution is not noticeable at first. It even beats the optical zoom in this area, because it neither reflects the light nor absorbs, breaks, bends or scatters and shows absolutely no aberrations, which would have to be elaborately corrected. The reason is that the digital zoom physically does not intervene in the optical beam path.

The efindungsgemäße camera system thus uses the very good optical quality of the discrete magnification changer to achieve large magnification factors, the disadvantage of the discrete magnification changer with respect to the lack of continuity of the magnification change it compensates by the digital zoom, which is practically weightless and volumeless, while surprisingly very maintains good quality of the discrete magnification changer in the small area of the magnification step. Of course, this statement is valid only as long as the size of the enlargement step is actually not too large. Depending on the application, this may require a larger number of enlargement steps.

So we see that the combination of the camera system according to the invention, the initially inferior components so compiled that they can indeed play their strengths, but their weaknesses fall under the table. Exactly these weaknesses have hitherto prevented a reasonable use of the individual components.

1 shows a triple Galileo changer 1 as an example of a discrete magnification changer of the prior art. The triple Galileo changer consists of a Galilei-type telescope assembly and contains a positive lens 2 and a negative lens 3 , These lenses, too Lens groups are rotatable about the axis 4 arranged. The beam path 5 is usually afocal, but may differ if necessary. In 1a ) the magnification factor is M, in 1b ), where where the telescope arrangement is located outside the beam path, is the magnification 1 and in 1c ), where the telescope arrangement is reversed, the magnification factor is 1 / M.

The disclosure of the cited patents and patent applications is fully incorporated by reference.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007039851 A [0005]
• DE 102009011681 A1 [0006]
• DE 102010018498 [0006, 0015]
• DE 102010018500 [0006]
• US 4678899 [0008]
• US 7411739 B2 [0008]
• US 2009/0021843 A1 [0008]

Claims (20)

A camera system for capturing still or moving images, the camera system comprising at least (i) a photosensitive transducer capable of spatially converting light signals to electrical signals, which electrical signals can be stored, transmitted, relayed or otherwise processed, (ii) a discrete optical Magnification changer and (iii) a controller, characterized in that the controller can change the magnification of the discrete magnification changer in response to a direct user input to the camera system or by an external signal. Camera system according to claim 1, characterized in that it additionally comprises a digital zoom. Camera system according to claim 2, characterized in that at least one image characteristic of the images supplied by the camera system are roughly determined by the discrete magnification changer and finely by digital zoom according to the user's specifications. A camera system according to claim 3, characterized in that said one image characteristic is the magnification, image size or image detail. Camera system according to one of the preceding claims, characterized in that the digital zoom can deliver all magnification intermediate levels to the magnification levels of the discrete magnification changer and also magnifications above the largest discrete magnification level. Camera system according to one of the preceding claims, characterized in that the discrete magnification changer is a Galilei or a Keplerwechsler or more of these changer in series. Camera system according to claim 6, characterized in that the telescope arrangement of the changer is not movable relative to the camera system. Camera system according to one of the preceding claims, characterized in that the number of discrete magnification levels per individual changer is 2, 3 or 4. Camera system according to one of the preceding claims, characterized in that the magnification levels of the discrete changer are controlled by rotational movements. Camera system according to one of the preceding claims, characterized in that it contains at least one lens of variable refractive power. Camera system according to one of the preceding claims, characterized in that it supplies at least 1.25 magnification levels per functional lens group of the discrete changer. Camera system according to one of the preceding claims, characterized in that at least half of the mechanism of the discrete changer is housed without the optical parts in the space between the body of revolution circumscribed by the movement of the changer optics and the circumscribed circumscribe this cuboid. A camera system according to claim 12, characterized in that the housing volume of a single discrete changer 2a ³ in the limits of -10% and + 50%, preferably in the limits of -5% and + 25%, and more preferably in the limits 0% and +10 %, in case the largest lens of the changer has the diameter a. Camera system according to one of the preceding claims, characterized in that at least parts of the optics and the mechanics of the discrete changer in a single operation, for. B. were produced in injection molding technique. Camera system according to one of the preceding claims, characterized in that the control of the magnification stages of the discrete magnification changer is effected electromagnetically. Camera system according to one of the preceding claims, characterized in that the control of the magnification stages of the discrete magnification changer is effected by discrete actuators. Camera system according to one of the preceding claims, characterized in that the direction from which light enters the camera system, can be changed, for. B. via a rotatable or switchable mirror. Camera system according to one of the preceding claims for use in a mobile phone, endoscope, surveillance camera, microscope or other optical or medical devices. Method for using the camera system according to one of the preceding claims comprising at least the following steps: (i) specification the magnification factor within the possible range by a corresponding input directly by users on the camera system or by an external control signal, (ii) selection of a discrete magnification from the list of possible magnifications of the discrete magnification changer, this one discrete magnification the next smaller magnification to the desired (iii) driving the discrete magnification changer at the magnification selected under (ii), and (iv) selecting the size of the digital zoom factor such that the product of the digital zoom factor selected here matches the magnification value of the one under (ii) selected discrete magnification is just the desired, under (i) predetermined magnification. A device family that includes both devices with the camera system of any one of the preceding claims and devices with a camera system that has the same optics except for the discrete changer.

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