WO2008116812A1 - Optical sensor comprising an adaptive color filter - Google Patents

Optical sensor comprising an adaptive color filter Download PDF

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Publication number
WO2008116812A1
WO2008116812A1 PCT/EP2008/053332 EP2008053332W WO2008116812A1 WO 2008116812 A1 WO2008116812 A1 WO 2008116812A1 EP 2008053332 W EP2008053332 W EP 2008053332W WO 2008116812 A1 WO2008116812 A1 WO 2008116812A1
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WO
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Patent type
Prior art keywords
sensor
cell
characterized
cells
sensor according
Prior art date
Application number
PCT/EP2008/053332
Other languages
German (de)
French (fr)
Inventor
Christian Schirp
Andreas Pirchner
Original Assignee
Leopold Kostal Gmbh & Co. Kg
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00Details of television systems
    • H04N5/222Studio circuitry; Studio devices; Studio equipment ; Cameras comprising an electronic image sensor, e.g. digital cameras, video cameras, TV cameras, video cameras, camcorders, webcams, camera modules for embedding in other devices, e.g. mobile phones, computers or vehicles
    • H04N5/225Television cameras ; Cameras comprising an electronic image sensor, e.g. digital cameras, video cameras, camcorders, webcams, camera modules specially adapted for being embedded in other devices, e.g. mobile phones, computers or vehicles
    • H04N5/2251Constructional details
    • H04N5/2254Mounting of optical parts, e.g. lenses, shutters, filters or optical parts peculiar to the presence or use of an electronic image sensor

Abstract

An optical sensor 1 comprises a sensor array 2 made of individual opto-electronic converter elements (pixels) 3. This camera sensor 1 further has a lens for imaging on the photosensitive surface 4 of the pixels 3 of the sensor array 2. In this camera sensor 1, at least one translucent cell that changes the color state thereof as a function of the presence of an electrical field is connected as an electrically switchable optical color filter in the optical path for exposing the photosensitive surface 4 of converter elements 3 of the sensor array 2.

Description

OPTICAL SENSOR WITH ADAPTIVE COLOREDFILTERS

The invention relates to a camera with a sensor of individual optoelectronic transducer elements (pixels) constructed sensor array and an optical system for imaging on the photosensitive surface of the pixel of the sensor array.

To increase the driving safety when driving a motor vehicle increasingly driver assistance systems are used. be used for this purpose, especially for reasons of cost camera sensors that work on black and white base and to which a grayscale image is generated. On such camera sensors that have a two dimensional array of optoelectronic converter elements as a photosensitive sensor array, and an upstream optical system, a detection of the vehicle surroundings, in particular to the front in the direction of travel is carried out looking. On such a driver assistance system, a dimming of the high beam is controlled examples play as when an oncoming vehicle is detected. With a conventional B / W camera sensor, however, is not clearly determined whether detected light points are allocated headlights of an oncoming vehicle or the tail lamps of a preceding vehicle. This is for the process of stopping down of high beam is important because to be dimmed much earlier upon detection of an oncoming vehicle as in the detection of the taillights of a preceding vehicle. A differentiation of white light, which is assigned to an oncoming vehicle, red light, which is assigned to a preceding vehicle in the same direction of the vehicle, would be possible by using a color camera sensor. In such sensors, each pixel is formed by three different color channels and ultimately through three separate sub-pixel. A disadvantage of this solution, however, is that carried out by the necessary training of an image point (pixel) by three sub-pixels and thus the resolution is reduced. Moreover, the use of such sensors is costly.

In EP 1084051 B1 it has been proposed to use two mutually arranged parallel optical systems, each of which receives a different Liehe color information. In order to distinguish the white light of red light one of the two imaging units is adapted to map vornehm- lent red components, while the other imaging unit is for imaging of all colors. Are bright spots detected only with the red-sensitive imaging system, this leads to the conclusion that this light the taillights of a preceding vehicle Fahrzeu- are tot. Blank, mounted onto a same spot or bright spots in the two imaging systems detect this can be concluded that it is in the light received by the light emitted by headlights of an oncoming vehicle light. A disadvantage of this system of double expenditure on equipment and the position comparative evaluation, ultimately the resolution is reduced enforces tolerances to be maintained by the.

Starting from this prior art discussed, the invention is therefore the object of proposing a mentioned camera sensor, in particular for use in a driver assistance system of a motor vehicle, including color information can be obtained with using a B / W camera sensor without disadvantages having to accept terms of resolution capability or two parallel operating systems, such as described in EP ben 1,084,051 B1, having to use.

This object is achieved by an above-mentioned, the generic camera sensor, wherein the at least one light transmissive, their color state in response to the application of an electric field changing cell is turned on as an electrically switchable optical color filter in the beam path for exposing the photosensitive surface of transducer elements of the sensor array.

In this camera sensor in the beam path for the exposure of the transducer elements, an electrically switchable optical color filter is switched. This is a state of their color in response to the concerns of a changing light transmissive cell electric field. Such a cell can be switched into the beam path for the exposure of each transducer element of the sensor array. Depending on the application, such a cell may also extend over a plurality of pixels of the sensor array or, in particular when switched directly in the optical path of the optical system, can be arranged, acting on a larger area or the entire sensor array. Is one such as an optically switchable color filter serving cell to each pixel of the sensor array associated with, it is sufficient if the cell has translucent properties. If the cell is, however, switched in the optical system of the optical path of the camera sensor and thus acting on a portion or the whole sensor array, the cell is designed transparent.

For use, for example, those cells which are designed working by utilizing the capillary are electrical. In such cells is known as electrowetting cells. Such a cell is constructed in the manner of a capacitor, wherein the space between the electrodes with a hydrophobic liquid, in particular oil and filled with water. One of the two electrodes is coated hydrophobic. Is at no electric field, the oil sets as a film on the hydrophobic coated electrode. If, however, an electric field, the surface tension is changed, so that the water displaces the oil film. It is essential that two immiscible liquids are contained in such a cell. The oil film is colored and constitutes the desired color filter. In the context of a recognition of light sources, whether these as a headlight of an oncoming vehicle or as rear light are associated with a preceding vehicle, one will use red colored oil, to provide a red filter in this manner. Such cells have a very quick response time, so that in a short time consecutively two shots, for example of the forward vehicle environment can be made. A first receiving such a receptacle pair is made with switched-on electric field to the cells and thus without the filter, while the other recording made without applied electric field in the cells and then with the process provided by the oil film color filters. By subtracting the pixel information can be so-then readily determine whether the detected light from a light source in the case of a driver-assistance system is red or white. In contrast to a color camera sensor as part of a driver assistance system is not necessarily video quality in terms of the sequence of images, the color information in a short time after the other and not simultaneously obtained in this camera sensor must have. Electrowetting cells are fast switching and even meet standards of the video quality, so that ultimately in this camera sensor itself that the prospects of losses have to be accepted. It is essential that is not affected by the desired and obtained color information, the resolving power of such a sensor.

In the event that additional color information to be obtained with such a B / W camera sensor is readily possible to install two or more cells connected in series in the beam path of the camera sensor. These cells can form a structural unit. Every single cell of such a multi-color filter cell is addressed in the context of the above, as a sub-cell. The subcells can be recovered are preferably independently controllable so that not only based color information on the respective color of the oil of an subcell, but also color information corresponding to the mixed color of two or more one behind dergeschalteten subcells.

Electrowetting cells can also be prepared in such a size that they are to be incorporated into the beam path of the optical system itself. Similarly, such an electrically switchable color filter cell may also be of the optics immediately upstream or downstream. At this point, it is possible to increase the winning with a B / W camera sensor color information in that composite multi-color filter cells are used and have the individual subcells color filters of different colors.

The invention is described by way of examples with reference to the accompanying figures. Show it:

Fig. 1 shows a schematic sectional representation of a detail of a camera sensor having a color filter array formed from single NEN electrically switchable optical color filters and

FIG. 2 shows another camera sensor to a switched-in optics in the beam path electrically switchable optical color filter.

A B / W camera sensor 1 has a single of a plurality, in a two dimensional array arranged mutually optoelectronic conversion elements (pixels) 3 constructed sensor array 2. Figure 1 shows only a section of the camera sensor 1, in particular without the sensor array 2 upstream optics. Due to the necessary releases for the electrical connections of the pixels 3, the light-sensitive surface of such a pixel 3 is the same to a range loading limits. The photosensitive area of ​​the pixels 3 is indicated in Figure 1 by the reference numeral. 4

The sensor array 2 of the camera sensor 1 is covered in the region of 3 with a pixel electrode. 5 The electrode 5 is transparent. The elec- trode 5 is already part of a color filter array indicated generally by the reference numeral 6 in FIG. 1 The color filter array 6 further comprising a coating applied to the electrode 5 layer 7 having hydrophobic properties. The layer 7 has not only hydrophobic properties, but also serves as an electrical insulator. Therefore, the layer 7 may be continuously applied to the spaced apart electrodes 5 of the individual pixels. 3 At a distance from the hydrophobic layer 7, another electrode 8 is arranged complementary to the electrodes 5 of each pixel. 3 These, too, like the electrode 5 and the hydrophobic insulation layer 7 translucent. The electrodes 8 have a range that can be addressed as a discharged electrode surface. 9 End side of the intermediate space between the electrodes 8 and the insulation layer 7 is closed. Filling the space between the electrodes 8 and the hydrophobic layer 7 is provided with oil 10 and water 11. The oil 10 is colored, namely red in the illustrated embodiment.

In the example shown in Figure 1 left pixel 3 is located between the two electrodes 5 and 8, no voltage. Due to the hydrophobic properties of the insulating layer 7, the oil has superimposed on the layer 7. 10 and not the water is 11. Based on the red color of the oil 10 formed in this manner, an optical red filter for the system shown in Figure 1 left pixel 3, which thus in is on the optical path of the camera sensor. 1 The beam path ends at the top of the light-sensitive surface. 4

Is via the two electrodes 5, 8 is applied an electric field to one or more pixels 3, as this is relative to the right pixel 3 shown in Figure 1, the water 11 displaces the voltage applied to the hydrophobic layer 7 of oil film, since the electric field applied the polarization of the dipoles in the water surface cancels. The oil 10 is then pushed away laterally, namely into the discharged electrode region. 9 The discharged electrode portion 9 is located in the direction of the beam path above the areas that are not associated with the light-sensitive surface 4 of a pixel. 3 Thus, loading the displaced in this way, the oil 10 does not influence the light-sensitive surface 4 of the pixel. 3 The pixel 3 on the right shown in Figure 1 is thus exposed in the switching position shown of the color filter without switched Farbfil- ter. During the left shown in Figure 1 pixels 3 showing the color filter in its ON position, this is shown in the right pixel 3 in its initial position.

In the individual cells of the color filter array 6 is, like the description makes clear, in order, consequently to such cells, the change electrowetting cells with respect to an exposure of the sensor array 2 of the camera sensor 1 in response to the application of an electric field, its color condition.

The control of the individual cells of the color filter array 6 is made individually and pixel dependent, in the illustrated embodiment. Therefore, individual cells or groups of cells can be connected in one way or another filtering position the color filter array 6 independently of other areas of the sensor array. 2 Depending on the desired infor- mation to be obtained by the camera sensor 1, it may be sufficient if all the cells of the color filter matrix are thus connected 6 simultaneously and in parallel.

The individual addressable cells (color filter) in the color filter array 6 does not offer the possibility of evaluation such that the color information only of particular interest appearing captured regions or even individual pixels is read by others against it. This allows, in conjunction with a driver assistance system a better distinction between, for example, conditional tail light reflections on wet roads and road markings. Likewise, this makes it possible to run the manner of a "rolling shutter" a filter bar over the image. Figure 2 shows in a schematic representation of another camera sensor 13. In contrast to the camera sensor 1 of Figure 1 is in this camera sensor 13 in the beam path an electrically switchable color filter formed as electrowetting cell 12 turned on. the electrowetting cell 12, the optics 14 of the camera sensor 13 assigned net. the sensor array of the camera sensor 13 is identified in Figure 2 by the reference numeral 15. the sensor array 15 is also a two-dimensionally structured black and white sensor array, as this is already described in the embodiment of FIG. 1, the electrowetting cell 12 is constructed as the cells of the color filter array 6. the electrowetting cell 12 described in connection with the embodiment of Figure 1 is in the embodiment of Figure 2 both transparent, and in se iner color filter position and in its other position. Through the color filter 12 of Figure 2 is influenced the entire sensor array 15 in the illustrated embodiment, so that from the sensor array 15, either an image with switched color filters or without switched color filters can be made. The electrowetting cell 12 needs to be formed of the same same not excessively large within the optics 14 of the camera sensor 13, or by pre- or resetting at a skillful arrangement.

The description of the invention reveals that it suffered with simple means without sacrificing the resolution of a black and white sensor array is possible to win color information, such as those that are required in connection with a driver-assistance system of a motor vehicle , Therefore, in a particularly preferred embodiment, the camera sensor part of such a driver assistance system.

LIST OF REFERENCE NUMBERS

Camera sensor array pixels photosensitive surface electrode layer color filter array electrode exuberant electrode region Oil Water electrowetting cell camera sensor optical sensor array

Claims

claims
1. Optical sensor with one of individual optoelectronic transducer elements (pixels) (3) constructed sensor array (2, 15) and an optical system (14) for imaging on the photosensitive surface (4) of the pixel (3) of the sensor array (2, 15) characterized in that at least one light transmissive, AEN its colored state in response to the application of an electric field-promoting cell (12) in the beam path for exposing said photosensitive surface (4) of transducer elements (3) of the sensor array (2, 15) electrically switchable optical color filter is switched.
2. Sensor according to claim 1, characterized in that the at least one cell (12) is designed taking advantage of the electric working capillary (electrowetting cell).
3. Sensor according to claim 1 or 2, characterized in that in the beam path in front of each pixel (3) of the sensor array (2, 15) or before one or more by combining individual pixels (3) formed pixel groups in each case such a cell as a color filter in is switched on the beam path.
4. Sensor according to any one of claims 1 to 3, characterized in that all cells in the switched-on state to show the same color.
5. Sensor according to claim 1 or 2, characterized in that the at least one such cell (12) is transparent.
switched 6. Sensor according to claim 5, characterized in that such a cell in the beam path of the optical system (14) of the sensor (13) or the upstream and / or downstream.
7. Sensor according to one of claims 1 to 6, characterized in that a cell is constructed from a plurality respect to the beam path series-connected sub-cells, wherein the sub-cells with activated filter function having a different filter color, and the sub-cells are controlled independently of each other.
8. Sensor according to one of claims 1 to 7, characterized in that the sensor (1, 13) is part of a driver assistance system of a motor vehicle.
is 9. A sensor according to any one of claims 1 to 8, characterized gekennzeich- net that the sensor is a camera sensor (1, 13).
PCT/EP2008/053332 2007-03-23 2008-03-19 Optical sensor comprising an adaptive color filter WO2008116812A1 (en)

Priority Applications (2)

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DE102007014126.4 2007-03-23
DE200710014126 DE102007014126A1 (en) 2007-03-23 2007-03-23 optical sensor

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Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102009021638A1 (en) 2009-05-16 2010-11-18 Leopold Kostal Gmbh & Co. Kg Optical sensor has opto-electronic transducer elements, where one of its transmission characteristics is brought in beam path depending on contact of electric field changing cell for exposing photosensitive surface
EP2560364A1 (en) * 2011-08-17 2013-02-20 Autoliv Development AB Driver assisting system and method for a motor vehicle
DE102011081358A1 (en) * 2011-08-23 2013-02-28 Robert Bosch Gmbh Method and apparatus for adjusting a filter characteristic of an adaptive color filter and for operating an imager

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WO1997008897A1 (en) * 1995-08-23 1997-03-06 Smith & Nephew, Inc. Remote video display system with liquid crystal colour filter
WO1999064267A1 (en) * 1998-06-09 1999-12-16 Gentex Corporation Imaging system for vehicle headlamp control
WO2004027489A1 (en) * 2002-09-19 2004-04-01 Koninklijke Philips Electronics N.V. Switchable optical element
US20060177098A1 (en) * 1997-04-02 2006-08-10 Stam Joseph S System for controlling exterior vehicle lights
US20070019006A1 (en) * 2005-07-12 2007-01-25 Marcu Gabriel G Subtractive display

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US4967264A (en) * 1989-05-30 1990-10-30 Eastman Kodak Company Color sequential optical offset image sampling system
JP4402358B2 (en) * 2003-03-05 2010-01-20 キヤノン株式会社 Color image display panel and a driving method
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Publication number Priority date Publication date Assignee Title
WO1997008897A1 (en) * 1995-08-23 1997-03-06 Smith & Nephew, Inc. Remote video display system with liquid crystal colour filter
US20060177098A1 (en) * 1997-04-02 2006-08-10 Stam Joseph S System for controlling exterior vehicle lights
WO1999064267A1 (en) * 1998-06-09 1999-12-16 Gentex Corporation Imaging system for vehicle headlamp control
WO2004027489A1 (en) * 2002-09-19 2004-04-01 Koninklijke Philips Electronics N.V. Switchable optical element
US20070019006A1 (en) * 2005-07-12 2007-01-25 Marcu Gabriel G Subtractive display

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