DE102010011025B3 - sensor arrangement - Google Patents

Abstract

The invention relates to a sensor arrangement with a transmitter for emitting a light beam and a receiver, for example for realizing a light barrier or a proximity sensor. The receiver has at least two sensitive areas that are designed as organic photodiodes and with which the light beam can be detected. Viewed in the x direction, the areas are arranged at a certain distance dx from one another. The sensitive areas also each have a certain extent in the x direction. The beam spot which the light beam forms at the location of the surface of the receiver has a diameter d. This diameter d, the distance dx and the dimensions of the sensitive areas are matched to one another in such a way that, on the one hand, the diameter d is smaller than the dimensions and, on the other hand, the diameter d is greater than the first distance dx. With this sensor arrangement, it is possible with simple means to detect a movement in the x direction. Due to the use of organic photodiodes, the receiver has a very small component depth.

Description

The invention relates to a sensor arrangement with a transmitter and a receiver, for example, for the realization of a light beam or a proximity sensor.

Photocells and proximity sensors (hereinafter referred to as "light barriers") are used, for example, in safety and / or automation technology. A light barrier is an electro-optical system with a transmitter and a receiver, the transmitter emitting a signal registered by the receiver.

The general term "light barrier" can be understood to mean through-beam sensors, retro-reflective sensors and reflection light sensors: The one-way photocell enters into an alarm condition or the like if the light signal is interrupted and the receiver no longer receives a signal. The same applies to the retro-reflective sensor, in which the signal emitted by the transmitter is deflected via a reflector to the receiver. Again, the alarm state occurs when the light signal is interrupted. Reflection light scanners operate on the principle that the signal emitted by the transmitter is reflected by a reflection object to be detected and thus finally registered by the receiver. Here, the alarm condition is triggered when the receiver receives a signal and not when the signal is interrupted.

In order to increase the working distance between the transmitter and receiver and at the same time to ensure that the emitted light beam strikes the receiver, commercially available photocells have integrated optics which, for example, focus the emitted and / or received light beams with the aid of optical lenses. The disadvantage here is that such sensors due to the optics achieve an undesirably high component depth in the order of several centimeters. The installation of such photocells in tight spaces such as. In machinery or equipment is made difficult or even impossible. The required optics also increase the complexity of the light barrier as well as the manufacturing costs and the production time. Also, the applicability of the light barrier equipped with a certain optics is limited insofar as the optics prescribes a certain distance between transmitter and receiver.

In addition, in commercial light barriers, a comparatively high effort in the alignment of transmitter and receiver is required because these light barriers are operated in the infrared or near-infrared range.

Typically, the receivers of commercially available photoelectric sensors are based essentially on silicon photodiodes. In order to keep costs down, Si photodiodes are used which have a sensitive surface of the order of a few mm 2. As transmitters usually light-emitting diodes or laser diodes are used. Both require relatively complex lens optics for limiting the divergence to the desired transmission distance or on the surface of the receiver to be illuminated. Again, this results in a relatively high component depth. In addition, the installation costs are relatively high due to the necessary precise adjustment.

Optic-free photoelectric sensors based on large-area receivers are not economical due to the high cost of large-area Si photodiodes. Instead of the Si photodiodes, organic photodiodes based on solution-processed semiconductors have been proposed as a cost-effective alternative. Such photodiodes can be produced in a comparatively large-area construction of several cm 2. The use of organic photodiodes is, for example, in DE 10 2006 025 469 A1 . EP 1 752 795 A2 and in US 2001/0028026 A1 described.

It is an object of the present invention to provide a light barrier with a sensor arrangement that does not have the mentioned disadvantages of conventional light barriers.

This object is achieved by the inventions specified in the independent claims. Advantageous embodiments emerge from the dependent claims.

The light barrier according to the invention has a sensor arrangement, which is equipped with a transmitter for emitting a light beam and a receiver with an electronic assembly, transmitter and receiver are arranged to each other such that the light beam impinges on a surface of the receiver and generates a beam spot S. , In this case, the receiver has at least two first organic photodetectors for detecting the light beam, which emit an output signal when illuminated and which are arranged on or on the surface of the receiver in a first direction (x) at a first mutual distance dx next to one another that the beam spot S, at least when no object interrupts the light beam, at least partially covers each of the organic photodetectors. The organic photodetectors are connected to the electronic assembly and the outputs of the organic photodetectors are monitored by the electronics assembly. The first organic photodetectors point in the first Direction (x) each have certain first expansions. The diameter d of the beam spot S at the location of the surface of the receiver, the first distance dx and the first expansions are selected such that on the one hand the diameter d is smaller than the first expansions and on the other hand the diameter d is greater than the first mutual distance dx.

In an advantageous development, the receiver has at least one further organic photodetector for detecting the light beam, which emits an output signal when illuminated. The further organic photodetector is arranged at a second distance dy from one of the first organic photodetectors in a second distance dy from the first direction (x), so that the beam spot S is also at least when no object interrupts the light beam at least partially covers the further organic photodetector. The other organic photodetector is connected to the electronic assembly and the output of the further organic photodetector is monitored by the electronics assembly.

In this case, the first organic photodetectors and the further organic photodetector are arranged on or on the surface of the receiver in such a way that they lie at the vertices of an imaginary triangle. This ensures that, for example, a detection of a movement in the second direction is possible with little additional effort.

Alternatively, the receiver comprises at least two further organic photodetectors for detecting the light beam which emit an output signal when illuminated, the first and the further organic photodetectors of the receiver being arranged in a two-dimensional array on or on the surface of the receiver, so that the Beam spot S at least when no object interrupts the light beam, the first and the other organic photodetectors at least partially covers. The two other organic photodetectors are connected to the electronics assembly and the outputs of the two other organic photodetectors are monitored by the electronics assembly. Again, this allows additional motion detection in the second direction.

• – weisen die weiteren organischen Photodetektoren in der ersten Richtung (x) gesehen jeweils bestimmte weitere Ausdehnungen auf,
• – weisen die ersten und die weiteren organischen Photodetektoren in einer zweiten Richtung (y) gesehen jeweils bestimmte zweite Ausdehnungen auf,
• – sind die ersten organischen Photodetektoren in der zweiten Richtung (y) gesehen in einem zweiten gegenseitigen Abstand dy von den ersten organischen Photodetektoren angeordnet, wobei
• – der Duchmesser d des Lichtstrahls am Ort der Oberfläche des Empfängers,
• – der erste dx und der zweite gegenseitige Abstand dy sowie
• – die ersten, die zweiten und die weiteren Ausdehnungen der organischen Photodetektoren in der ersten (x) und der zweiten Richtung (y) derart gewählt sind, dass
• – der Durchmesser d kleiner ist als die ersten, die zweiten und die weiteren Ausdehnungen und
• – der Durchmesser d größer ist als der erste Abstand dx und als der zweite Abstand dy.

there

• The further organic photodetectors in the first direction (x) each have certain further expansions,
• The first and the further organic photodetectors each have certain second expansions, as seen in a second direction (y),
• In the second direction (y), the first organic photodetectors are arranged at a second mutual distance dy from the first organic photodetectors, wherein
• The diameter d of the light beam at the location of the surface of the receiver,
• - The first dx and the second mutual distance dy as well
• - The first, the second and the further dimensions of the organic photodetectors in the first (x) and the second direction (y) are chosen such that
• - The diameter d is smaller than the first, the second and the other dimensions and
• - The diameter d is greater than the first distance dx and as the second distance dy.

The array can be a rectangular or a parallelogram-like array, with the first and the further organic photodetectors being arranged on the corners of the imaginary rectangle or of the imaginary parallelogram.

In an alternative embodiment, the transmitter and the receiver can be integrated in a common unit, wherein additionally a beam deflector, in particular a mirror, is provided, which deflects the light beam emitted by the transmitter onto the receiver.

The organic photodetectors may have a rectangular, circular or circular segmental shape.

The sensor arrangement can thus be used as a light barrier or as a button. In this case, a beam deflector can be provided which deflects the light beam which can be emitted by the transmitter onto the receiver.

• – großflächiger (bspw. 1–10 cm²), gleichzeitig kostengünstiger Empfänger durch den Einsatz organischer Sensoren an Stelle der Siliziumtechnologie;
• – einfache, wenig aufwändige Ausrichtung;
• – Möglichkeit der Bestimmung der Richtung, Geschwindigkeit und/oder Größe eines sich durch die Lichtschranke bewegenden Objektes durch Verwendung einer Empfängers mit mehreren sensitiven Bereichen;
• – keine Notwendigkeit des Einsatzes einer Optik; dadurch äußerst geringe Bauteiltiefe (bspw. < 1 mm);
• – Möglichkeit des Einsatzes der Lichtschranke bei verschiedenen Abständen zwischen Sender und Empfänger;
• – integriertes Emitter-Lasermodul mit kostengünstiger Strahlkollimation und geringer Bauteiltiefe (ca. 3 mm) durch die in-plane Montage des Emitters und die Nutzung einer flachen Umlenkeinrichtung (bspw. ein Kunststoff-Strangguss-Prisma mit Totalreflexion);
• – mögliche Anwendungen sind bspw. Einweg-Lichtschranken, Reflexionslichtschranken und Lichttaster.

An inventively constructed light barrier thus has the following advantages:

• - large area (eg 1-10 cm ² ), at the same time cost-effective receiver through the use of organic sensors in place of silicon technology;
• - simple, low-cost alignment;
• Possibility of determining the direction, speed and / or size of an object moving through the light barrier by using a receiver with a plurality of sensitive areas;
• - no need to use an optic; As a result, extremely low component depth (eg <1 mm);
• Possibility of using the light barrier at different distances between transmitter and receiver;
• - integrated emitter laser module with cost-effective beam collimation and small component depth (about 3 mm) by the in-plane mounting of the emitter and the use of a flat deflection device (eg a plastic continuous casting prism with total reflection);
• - Possible applications include, for example, disposable light barriers, reflection light barriers and light scanners.

Further advantages, features and details of the invention will become apparent from the embodiment described below and with reference to the drawings.

Showing:

1 a photocell with a transmitter and a receiver,

2 the transmitter in a side view,

3 the receiver in a first embodiment in a plan view,

4 the measuring principle for motion detection,

5 the receiver in a second embodiment in a plan view,

6 the receiver in a third embodiment in a plan view,

7 a light barrier with an integrated transmitter-receiver unit and the receiver unit in plan view,

8th a cross section of a sensitive area.

In the figures, identical or corresponding areas, components or component groups are identified by the same reference numerals.

The 1 does not show to scale a sensor arrangement according to the invention used as a light barrier 1 with a transmitter 100 and a receiver 200 , The recipient 200 points, as in the 3 is shown, several sensitive areas 210 . 220 . 230 . 240 which emit an output signal S210, S220, S230, S240 when illuminated.

The transmitter 100 sends a beam of light 300 out on the receiver 200 is directed. Ideally, there are stations 100 and receiver 200 aligned with each other such that the beam spot of the light beam 300 all sensitive areas 210 - 240 Recipient 200 at least partially covering (see 3 ).

Once an object 400 , which moves in the direction indicated by the arrow, in the light beam 300 arrives or interrupts, the receiver receives 200 or - depending on the extent and / or position of the object 400 - at least one of the sensitive areas 210 - 240 no signal, what about an electronics module 500 Recipient 200 that in the receiver 200 can be integrated and those with the sensitive areas 210 - 240 is registered. The consequence of this can be depending on the application of the light barrier, for example, the triggering of an alarm.

The 2 shows a possible execution of the transmitter 100 the photocell 1 in a schematic representation. The transmitter 100 has a light source 110 with simple, cost-effective beam expansion with a divergence of, for example, about 1-2 °. Suitable for this purpose is, for example, a commercially available laser diode. The wavelength of the transmitter 100 emitted light is in the visible, near-infrared or short-wave IR range. This can be the transmitter 100 operate in either continuous or pulsed mode. In pulsed operation, an additional coding can additionally be used.

To a small component depth of the transmitter 100 to be guaranteed in the 1 illustrated embodiment, a laser diode 110 together with a deflection device 120 For example, a mirror or a prism, on a plate 130 arranged. That of the laser diode 110 emitted light is transmitted through the deflector 120 in the direction of in the 2 not shown receiver 200 directed.

For the actual function of the transmitter 100 as a component of a light barrier is the deflection device 120 unnecessary. It only serves to increase the component depth of the transmitter 100 to reduce. Other light sources than said laser diode 110 Of course, they can also be used. A condition for selecting the light source is that the light that can be emitted by the light source is from the receiver 200 or detectable by the sensitive areas.

To the geometry of the light beam 300 be related to the 3 mentioned requirements with respect to the size ratios of the beam diameter d and the arrangement of the sensitive areas of the receiver 200 posed. The light beam 300 like in the 1 indicated to be a divergent light beam. Alternatively, a can collimated light beam can be used, which has a largely constant diameter.

The 3 shows the receiver 200 in a top view. The recipient 200 has several sensitive areas 210 . 220 . 230 . 240 on. The sensitive areas are each designed as organic photodetectors, for example organic photodiodes, which can advantageously be made very flat, so that the entire receiver 200 has a very small component depth.

Also in the 3 indicated is the beam spot S, ie the cross section of the transmitter 100 emitted light beam 300 at the location of the surface of the receiver 200 , The beam spot S is in the 3 centered on the receiver 200 aligned and covers each of the sensitive areas 210 - 240 at least partially. A perfect centering is not absolutely necessary for the function. In principle, it would be sufficient if each of the sensitive areas is hit by the light beam and thus emits a signal in the presence of the light beam.

The diameter d of the light beam 300 at the recipient's place 200 is greater than the distance dx, dy between two adjacent sensitive areas in the x and y directions and at the same time smaller than the extents of the individual sensitive areas 210 . 220 . 230 . 240 in the x and y directions. In 3 is, for example, the extent of the sensitive area 210 in the x-direction is referred to as ax210, while the extent of this region in the y-direction is referred to as ay210. The names of the extents of the other sensitive areas 220 - 240 are chosen in an analogous way (ax220, ay220, ax230, ay230, ax240, ay240), but are in the 3 for clarity not shown.

Typical orders of magnitude in the 3 represented receiver 200 are, for example, a length (y-direction) of about 9 cm, a width (x-direction) of about 4 cm and a depth (z-direction) of about 5 mm.

Based on 4 the measuring principle becomes the detection of a movement of the object 400 explained in x or y direction. For the sake of simplicity, in the 4 only the four sensitive areas 210 - 240 Recipient 200 represented, on which the beam spot S falls.

For this purpose, in the output signals S210, S220, S230, S240 of the individual sensitive areas using the electronics module 500 supervised. For in the 4 not shown case, that no object 400 interrupts the beam, gives each of the sensitive areas 210 - 240 in each case an output signal S210 = S220 = S230 = S240 = 1, as long as the transmitter 100 the light beam 300 sending out. It is assumed for the sake of simplicity that the output signals of the regions are identical, which in practice, for example, does not necessarily have to be the case depending on the centering of the light beam. Does not a sensitive area of the light beam 300 or hit by the beam spot S, the output signal of this area is equal to zero apart from any background signals and / or noise signals.

By simple mathematical operations, a movement can be determined, for example, in the x direction. In the electronics module 500 Recipient 200 For example, the outputs S210-S240 are combined in the following manner: x = (S220 + S240) - (S210 + S230) / S210 + S220 + S230 + S240 Y = (S210 + S220) - (S230 + S240) / S210 + S220 + S230 + S240

In the 4A is the case that shows the object 400 in the positive y-direction through the light beam 300 moves and therefore covers the beam spot S temporarily. For in the 4A displayed time is the object 400 in a position where the sensitive areas 210 and 220 no longer from the light beam 300 or be covered by the beam spot S. Accordingly, the output signals S210 = 0 and S220 = 0. The output signals of the other sensitive areas are S230 = 1 and S240 = 1.

From the equations listed above results for this case: X = (1 + 1) - (0 + 0) / 0 + 1 + 0 + 1 = + 1, Y = (0 + 1) - (0 + 1) / 0 + 1 + 0 + 1 = 0

This will be in the electronics assembly 500 interpreted as a movement of the object 400 in the positive x-direction.

For the 4B would be because of S210 = 1, S220 = 0, S230 = 1, S240 = 0 in an analogous manner X = -1, Y = 0, ie a movement in the negative x-direction. For the 4C respectively. 4D would result X = 0, Y = -1 or X = 0, Y = +1, ie a movement in negative or positive y-direction.

So it is possible with simple means a two-dimensional motion detection. Since the geometry of the arrangement is known, can simultaneously with time measurement in a simple manner, the speed and size of the object 400 be determined.

In the 3 is a square receiver 200 shown in which both the two-dimensional array passing through the four individual sensitive areas 210 . 220 . 230 . 240 is formed, so also the areas themselves are square. Other geometries, for example an arrangement of the sensitive areas on the corners of an imaginary parallelogram, and a different number of sensitive areas are naturally conceivable, depending on the desired application. If, for example, movement is to be detected in only one direction, for example only in the x direction, it would be sufficient to arrange only two sensitive regions in the x direction one behind the other and to dispense with the sensitive regions adjacent in the y direction. For a 2-dimensional detection in the x and y direction, it would in principle also be sufficient, as an alternative to in 3 illustrated embodiment with four arranged in square sensitive areas only three sensitive areas to be provided, which are arranged in a triangle, ie at the vertices of an imaginary triangle. This is purely exemplary for in the 5 shown receiver 600 shown, with its sensitive areas 410 . 420 . 430 also circular.

The sensitive areas may have a shape adapted to the beam cross section. Already mentioned were the rectangular or square shape ( 3 . 4 ) as well as the circular shape ( 5 ). Alternatively, the sensitive areas as in the 6 also indicated to have the shape of a circle segment.

The array with the plurality of sensitive areas or organic photodetector is ideally designed as a single component, for example, on a common glass substrate 206 With the aid of a structured electrode a plurality of detectors or sensitive areas are realized.

It is also conceivable, the transmitter and the receiver in a common unit 600 to integrate. In place of the transmitter 100 in the 1 then occurs a beam deflector 700 For example, a mirror, the of the integrated transceiver unit 600 emitted light beam 300 to the transceiver unit 600 reflected back. This is in the 7A shown (not to scale). The 7B shows an example of a plan view of possible embodiment of the transmitter-receiver unit. The sensitive areas 210 - 240 are like in the 3 demonstrated arranged. The light source 110 In the example shown, it is arranged centrally between the sensitive areas. Alternatively, it may also be arranged above, below or next to the sensitive areas (not shown). Is purely exemplary in the 7C a further embodiment of the integrated transceiver unit 600 shown where the light source 110 has a larger area.

The structure of a receiver 200 in the form of an organic photodetector capable of realizing the sensitive areas 210 . 220 . 230 respectively. 240 is suitable in the 8th shown schematically. It consists of a mixture called "bulk heterojunction" (BHJ) consisting of electron donors and electron acceptors as well as an intermediate layer 204 (so-called interlayer) from an organic semiconductor. Donor and acceptor may be a polymer or a small organic material. The intermediate layer 204 can be used as a filter to filter out certain unwanted wavelengths of the background light (eg visible light).

The BHJ is preferably prepared by a spray or spray coating process. Here is just a lithographic step for the production of the so-called "bottom electrode" 205 necessary. This is typically a transparent conductive oxide (TCO), for example composed of indium tin oxide (ITO). The other layers 201 to 203 are applied unstructured.

The organic photodetector has a substrate 206 for example, may be made of glass, a passivated metal film or a diffusion barrier printed circuit board material (eg, a metal film or an oxide film). Right on the substrate 206 is the bottom electrode 205 on which the interlayer 204 is applied. Above the intermediate layer. follow first a photoactive layer 203 , then a so-called "top electrode" (layer 202 ) and an encapsulation (layer 201 ).

The encapsulation (layer 201 ) may, for example, from glass, a metal or other oxidic material.

• – eine Bandlücke eines polymeren Absorbers für sichtbares oder nahinfrarotes Licht, bspw. P3HT oder PCPDTBT,
• – eine Bandlücke von ”Small Molecule Absorber” (bspw. Squarainderivate),
• – hybride Dioden mit organischer Halbleitermatrix und anorganischem Absorber (bspw. Quantenpunkte wie PbS),
• – hybride Dioden mit metallischen Nanopartikeln.

The photoactive layer 203 is an organic semiconductor with adjustable spectral sensitivity. This is characterized, for example, by

• A bandgap of a visible or near-infrared polymer absorber, for example P3HT or PCPDTBT,
• A band gap of "Small Molecule Absorber" (eg squaraine derivatives),
• Hybrid diodes with organic semiconductor matrix and inorganic absorber (eg quantum dots such as PbS),
• - Hybrid diodes with metallic nanoparticles.

An ambient light filter can be replaced by a polymeric interlayer. Such an ambient light filter may be an organic semiconductor with high absorption in the visible region and low absorption in the near-infrared spectrum. For example. P3HT can be used as filter and PCPDTBT as absorber.

Claims (9)

Photocell with a sensor arrangement ( 1 ), wherein the sensor arrangement ( 1 ) with a transmitter ( 100 ) for emitting a light beam and a receiver ( 200 ) with an electronic module ( 500 ), whereby transmitters ( 100 ) and receiver ( 200 ) are arranged to each other such that the light beam ( 300 ) on a surface of the receiver ( 200 ) and generates a beam spot S there, wherein - the receiver ( 200 ) at least two first organic photodetectors ( 210 . 220 ) for detecting the light beam ( 300 ) which emit an output signal (S210, S220) when illuminated and which are on or at the surface of the receiver ( 200 ) are arranged side by side in a first direction (x) at a first mutual distance dx, so that the beam spot S is at least when no object ( 400 ) the light beam ( 300 ) interrupts each of the organic photodetectors ( 210 . 220 ) at least partially covers, - the organic photodetectors ( 210 . 220 ) with the electronics module ( 500 ) and the output signals (S210, S220) of the organic photodetectors ( 210 . 220 ) with the help of the electronic assembly ( 500 ), wherein - the first organic photodetectors ( 210 . 220 ) in the first direction (x) have respective first expansions (ax210, ax220), and - the diameter d of the beam spot S at the location of the surface of the receiver ( 200 ), the first distance dx and the first dimensions (ax210, ax220) are selected such that on the one hand the diameter d is smaller than the first dimensions (ax210, ax220) and on the other hand the diameter (d) is greater than the first mutual one Distance (dx). Photocell according to claim 1, characterized in that the receiver ( 200 ) at least one further organic photodetector ( 230 ) for detecting the light beam ( 300 ) which emits an output signal (S230) when illuminated, wherein - the further organic photodetector ( 230 ) in a second distance (dy) from one of the first organic photodetectors as seen in a second direction (y) different from the first direction (x). 210 . 220 ), so that the beam spot S is at least when no object ( 400 ) the light beam ( 300 ) interrupts, also the further organic photodetector ( 230 ) at least partially covers, - the further organic photodetector ( 230 ) with the electronic assembly ( 500 ) and the output signal (S230) of the further organic photodetector ( 230 ) with the help of the electronic assembly ( 500 ) is monitored. A light barrier according to claim 2, characterized in that the first organic photodetectors ( 210 . 220 ) and the further organic photodetector ( 230 ) on or on the surface of the receiver ( 200 ) are arranged so that they lie at the vertices of an imaginary triangle. Photocell according to claim 1, characterized in that the receiver ( 200 ) at least two further organic photodetectors ( 230 . 240 ) for detecting the light beam ( 300 ) which emit an output signal (S230, S240) when illuminated, wherein - the first ( 210 . 220 ) and the other organic photodetectors ( 230 . 240 ) Recipient ( 200 ) in a two-dimensional array on or at the surface of the receiver ( 200 ) are arranged so that the beam spot S at least when no object ( 400 ) the light beam ( 300 ) interrupts the first ( 210 . 220 ) and the other organic photodetectors ( 230 . 240 ) at least partially covers, - the two other organic photodetectors ( 230 . 240 ) with the electronic assembly ( 500 ) and the output signals (S230, S240) of the two further organic photodetectors ( 230 . 240 ) with the help of the electronic assembly ( 500 ) be monitored. Photocell according to claim 4, characterized in that - the further organic photodetectors ( 230 . 240 ) in the first direction (x) each have further expansions (ax230, ax240), - the first ( 210 . 220 ) and the other organic photodetectors ( 230 . 240 ) in a second direction (y) have respective second expansions (ay210, ay220, ay230, ay240), - the first organic photodetectors ( 210 . 220 ) in the second direction (y) at a second mutual distance dy from the first organic photodetectors ( 230 . 240 ), wherein - the diameter d of the light beam ( 300 ) at the location of the surface of the receiver ( 200 ), - the first mutual distance dx and the second mutual distance dy, and - the first, second and further dimensions (ax210, ay210, ax220, ay220, ax230, ay230, ax240, ay240) of the organic photodetectors ( 210 . 220 . 230 . 240 ) in the first (x) and the second direction (y) are selected such that - the diameter d is smaller than the first, second and further dimensions (ax210, ay210, ax220, ay220, ax230, ay230, ax240, ay240) and - the diameter d is greater than the first distance dx and the second distance dy. A light barrier according to claim 4 or 5, characterized in that the array is a rectangular or parallelogram-like array, the first ( 210 . 220 ) and the other organic photodetectors ( 230 . 240 ) on the corners of the imaginary rectangles or the imaginary parallelogram are arranged. Photocell according to one of the preceding claims, characterized in that the transmitter ( 100 ) and the recipient ( 200 ) in a common unit ( 600 ), wherein in addition a beam deflector ( 700 ) provided by the transmitter ( 100 ) emitted light beam ( 300 ) to the recipient ( 200 ) redirects. Photocell according to one of the preceding claims, characterized in that the organic photodetectors ( 210 . 220 . 230 . 240 . 410 . 420 . 430 ) have a rectangular shape, circular shape or circular segment shape. Photocell according to one of the preceding claims, characterized in that a beam deflector is provided which blocks the light beam ( 300 ) to the recipient ( 200 ) redirects.

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