DE8202355U1 - DEVICE FOR DETECTING FOREIGN SUBSTANCES ON A DISC - Google Patents

Description

Device for recognizing foreign bills on a disk

The invention relates to a device for detecting what is present on the outside of a window Foreign matter such as moisture, dirt or Snow. Such a device could, for example, be used in a motor vehicle to control the lilisnh-üJasch system the windshield or the Scheinmerfer to control automatically.

There are already devices for automatic control the windshield wipers of motor vehicles became known, what train! to be stuck on the outside of the windshield Have capacitor plates as a sensor. If moisture gets between the capacitor plates when it rains, this changes the dielectric and with it the capacitance of the capacitor. This change is called Measured value used to activate the windshield wiper.

The well-known facility only dissipates moisture, but not to recognize dirt. So she can't for automatic activation of the windscreen washer system used when the windshield is dirty 1st. Snow on the windshield, including the

The disc mixer must be switched on, can previously known device also not to be recognized. Apart from these deficiencies, it has been shown that the known device works very imprecisely. This is 10. in part because the adhesive layer between the

Condenser plates and the windshield, depending on Pressure force when sticking the capacitor plate, different is thick.

The invention is based on the object of a device of the type mentioned to develop the reliable is able to differentiate between moisture, snow and dirt and works accurately enough to be automatic Control of a wipe-wash system for a motor vehicle windshield to be used.

According to the invention, this object is achieved by the claims specified measures resolved.

Due to the optical scanning of the disk according to the invention moisture, dirt and snow can be reliably perceived and distinguished from one another. It is coming therefore not to incorrect measurements, so that, for example, with snowflakes on a windshield not erroneously the windscreen washer system is activated. The device according to the invention is relatively easy to manufacture and therefore to sell boxes that are still portable for the motorist, especially since it should be borne in mind that with In a vehicle with such a sensor, the interval switching for the windshield washer system can be dispensed with.

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D ^ in the device according to the invention, the sensor is to be attached on the inside of the window, it is protected from the effects of weathering and dirt. In addition, no electrical lines need to be led out of the vehicle to the outside.

Its installation is very easy and can also be done easily before. Lay people are made, which means the subsequent installation of such a device in a motor vehicle favored.

Thanks to the device according to the invention, the needs Motorists no longer have to determine the degree of soiling of the windshield themselves and accordingly switch on the LJisch-üJasch system. In addition, it is not applicable the constant switching on and off of the windshield wiper, which was previously necessary in light drizzle.

This means that the driver can keep up with the traffic situation Pay attention so that, thanks to the invention, road safety is increased overall.

The 2D embodiment of the invention specified in claim 2 is advantageous for detecting moisture on a pane. The existence of different refractive indices on dry and wet glass is cleverly exploited. Total reflection ^; occurs on the outer surface of the pane only when the pane is dry, as there is then an optically thinner medium on the outside of the pane. If the pane is wet, the refractive index changes in such a way that the total reflection is canceled and the light receiver no longer receives a signal.

In raindrops does not fall exactly on the sensitive 3D surface of the sensor, the total reflection is only partially canceled. The reflection is then still sufficient to generate a signal.

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In order to be able to recognize dust on a disc, the embodiment specified in claim 3 is the embodiment according to the invention Establishment makes sense. Dust diffusely reflects the light. Light from the light source can therefore from the dust on the pane to a light receiver be reflected for dust detection. This measuring beam path differs from the measuring beam path for water detection, which when the windshield is dry is deflected by total reflection, so fundamentally that a clear distinction between paler and Dirt becomes possible.

The light source for dirt detection is advantageous an infrared light source, uieil with increasing The wavelength of the light is reflected by the dust particles becomes more reflective, so that the light receiver has a sufficiently strong input signal in the case of an infrared light source receives.

To prevent the light source from being assigned to it Light receiver irradiated directly, it is appropriate between 'To arrange a shielding plate for the light source and the light receiver.

It is also favorable if according to a different embodiment According to the invention, a reference beam light receiver is assigned to each light receiver arranged in a measuring beam path Äst, whose measurement is in each case in a comparator with the The measured value of the assigned light receiver is compared in the measuring beam path. Through the reference beam light receiver can cause disturbances of temperature, voltage fluctuations and age of the send and receive elements

3G to be neutralized.

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The reference beam light receivers are expediently SD arranged to have both light from the assigned Receiving light source as well as outside light. This wsrdsn the reference beam light receiver, exactly like the measuring beam light receiver, for example of daylight, and moonlight or influenced by the cone of light from oncoming vehicles Light source are irradiated, the differences in the measured values are: between the reference beam light receivers and the 1C assigned light receivers exclusively on the effect of the measuring beam path back-i, so that all disturbance variables eliminated thanks to the reference beam light receiver will.

It is also right when the light source for water detection is arranged on a wedge made of a crystal-clear material . This also applies to the arrangement of the light receiver on a Heil made of crystal clear material. These configurations have the advantage that it is achieved in a simple manner that the light is guided in the correct circle 2D from the transmitter to the receiver.

The Lichtquellsn exercises inventive device are vortsilhafterwEisE emitting diodes. Compared to incandescent lamps, such luminescent diodes have the advantage of high reliability and service life, easy modulation of the emitted light and the absence of a starting current.

As a light receiver is used for the inventive Set up advantageously white photodiodes. Photodiodesn are relatively cheap as electronic components available 3D 'and are well suited for the high stress in motor vehicles. They are sufficiently temperature resistant to

the temperatures prevailing in a motor vehicle withstand between minus 25 degrees C and plus BD degrees C. to be able to and tolerate the vibrations occurring in the motor vehicle. Instead of the photodiodes however, phototransistors can also be used. It is also beneficial that Photodiodes the photocurrent linearly with the illuminance changes so that they allow quantitative radiation measurement. The high one should also be emphasized 1G cutoff frequency of photodiodes.

Another embodiment of the invention is also advantageous, according to which the sensor is attached directly to the inside of the pane. This is how the Sensor does not, if the window is fogging up from the inside or is frozen over. In these cases it also sulls not the windshield wipers or the Uli sch wash system to be activated.

It is advantageous if the sensor is arranged in a housing is. This ensures that the air 2G is inside the sensor, which means that the

Temperature is the same everywhere. This is for the elimination of the temperature dependence on the luminous and photodiodes in the sensor are crucial.

In order to eliminate disturbance variables acting through the air, it is advisable to manufacture the housing from metal.

The angle specified in claim 15 between kZ and 6D degrees towards the perpendicular, measured in the pane, has proven to be the optimum angle for the measuring beam path for moisture detection.

By the specified in claim 16 advantageous measure can easily prevent the reference beam photodiode from detecting dirt van the reflected radiation from the dirt particles is irradiated. Instead of the aluminum flood, you could Of course, you can also grind a film made of a different material, which of course has to be opaque.

It is also beneficial to run the sensor for detachable Attachment to the disc is formed. This ID allows the sensor to be repositioned when

shows that there are scratches in the crucial area of the disc.

The detachable fastening of the sensor is particularly easy and cheap to accomplish if it has a Has suction cup, as indicated in claim 1B.

Air inclusions between the ΚεϊΙεπ of the sensor and the Washer can be reliably and easily achieved through a silica washer between the wedges and the washer be avoided. You could of course also use ZD Dl or a disk made of something comparable to silicone

Achieve material.

It is also an advantage if every light source can be generated of a measuring beam input with high frequency (1D kHz) is clocked and uses the corresponding alternating voltage as measured values for the light receiver will. This configuration eliminates the influence of outside light in a simple manner. Since that Outside light changes very slowly, it can be as the same size. Even if the Ssnsar

3D for a short time from the headlight cone oncoming

Vehicles is detected, this change is clear below the clock frequency of the measuring beam. The outside light can therefore be used as a superimposed DC voltage of the changing measuring voltage can be viewed. If you take an AC voltage measurement, you have that Eliminates outside light in a simple way.

To reliably differentiate between dirt and snow to be able to, a threshold value circuit is useful, which as a distinguishing criterion the size of the the light reflection generated voltage value of light « recipient is taken into account. Such a threshold circuit can work very reliably, since the reflectivity of snow and dirt is very different. In this way it can be prevented that the windshield washer is automatically switched on by mistake, for example when there is snow drift.

It is also beneficial if the relay is controlled for the windshield wipers and washer-wiper systems have a switch-on delay is upstream. This prevents in a simple manner that when you switch on the ignition by a short impulse from the windshield wipers and the washer-wiper system activated briefly.

According to another embodiment of the invention, the device has a frost detection device which the activation of the relays for the windshield wipers and the wiper / washer system blocked in the event of frost. By this measure this prevents the windshield wipers or even the wiper / washer system from being operated in the event of frost.

The frost detection device advantageously has a temperature sensor arranged on the pane.

The temperature of the windshield of a motor vehicle is msisi higher than, for example, the air temperature at the level of the bumper, where there is often a sensor for black ice warning are attached. In addition, the windshield is usually also at low temperatures due to the vehicle heating Sub-zero temperatures are not yet in the frost range, so that the pane can still be sprayed with water.

It is expedient in the device according to the invention the comparator stage a pulse length conversion for lengthening downstream of the impulses. Since the comparator stage only supplies very short pulses, the pulse duration is sufficient not to control the relays. This can be remedied by changing the pulse length.

Appropriately, ήατ sensor of the device according to the invention in a motor vehicle in the middle of the

Windshield mounted just above the rest position of the windshield wiper in the working area of the windshield wiper. This location is favorable because the Disk is least curved in the middle, so that ZQ the curvature only has a negligible influence on the optical properties of the system.

In order to prevent a driver from being severely frightened when the disk mixer is switched on automatically it is advisable to provide a visual display device, which flash a few seconds before the wiper-washer system or the windshield wiper is activated begins what is specified in claim 27.

Since in motor vehicles a windshield is often used even as heavily soiled it can be -Yes, the driver 3D has to clean this manually, it is useful if

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the inventive device is designed so that it switches off automatically _r after several Uisch washing periods as indicated in claim 2B.

As is also advantageous, call the performance a Has measuring device, by means of which it is switched off, called the idasservDrrat of the wiping lilasch system is used up. This prevents the pump, which is usually operated by the water in the Wipe-wash system is cooled in the absence of water ΊΟ is damaged or destroyed as a result of overheating.

It is also advantageous if the device has means for determining the frequency of the disk hitting raindrops because it then it becomes possible to automatically switch the windshield wiper to a faster wiper level if more violent Rain that makes it necessary.

The invention can be implemented in numerous ways to. To clarify its basic structure, an embodiment is shown in the drawing and is described below. In this example it is assumed that the device is on the windshield of a motor vehicle is arranged and for controlling the wiper-washer system and the windshield wiper serves. The scope of the device according to the invention is by no means based on the Limited windshield of a motor vehicle.

Show in the drawing

Figure 1 - one on the inside of a disc

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attached sensor of the invention Device with the components for water detection;

Figure 2 - the one attached to the inside of the pane Sensor with the components

for dirt detection;

Figure 3 - the arrangement of one of the dirt detection

associated reference beam Liehtempfangets in the sensor according to the invention, from the front 1D seen;

FIG. U - the arrangement according to FIG. 3 seen from the side;

Figure 1 shows - in section a part of a disk 1, the components of a sensor 2 on the inside of the pane are shown, which are used to identify the oiler on the Outer side of the disc serve. These components include a light source 3, which is a luminescence

2D diode acts. This light source 3 is attached to an inclined surface h of a Heil 5 made of a crystal-clear material and is able to radiate obliquely through the wedge 5 into the disk 1. Here, the solder towards the measured Spelled is £ of extending in the disc 1 light so large that the inside occurs at the point marked with 6 disk outer surface Totalreflexj .. π on dry glass. Have proven to be suitable. Angle between U2. and GO degrees, measured towards the perpendicular, are set in the disc.

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Through this tütal reflection, the light comes from the Light source 3 through a second ΚξϊΙ 7 made of crystal clear Material for a light receiver B, which can be a photodiode. To clarify ung are the main beam path and the upper one Edge ray of the measuring beam path in the drawing registered.

If the outer surface of the disc 6 is paler in shape of RegEntrDpfen or even an Idasserfilm is located, then the total reflection is on the inside on the outer surface of the pane 6 partially or completely canceled, so that the light receiver B less or no light receives more from the light source 3 and thus a signal for moisture on the outer surface of the pane G der Disk 1 is given.

In order to be able to eliminate disturbance variables from the sensor 2, a reference beam light receiver is located above the light source 3 9 arranged, the light from the light source 3, but also, just like the light receiver B, outside light receives. The evaluation of the signals from the reference beam light receiver 9 and the light receiver B will be later still explained.

The cheapest place to attach the ES according to the invention Sensor 2 is the center of the window just above the rest position of the wiper in the working area of the Wipers.

Those components of the sensor 2 will now be described with reference to FIG. 2 which are used for dirt detection to serve. The drawing again shows the disk 1 on which a second light source 1D is arranged is. This light source 10 is

preferably an infrared light source. In contrast to the light source 3, this is arranged so steeply in relation to the pane 1 that its light shines outwards through the pane 1 when the pane 1 is not soiled. However, are on the disk 1 dirt particles or even a dirt layer 1 ^Λ, as is dargestBllt in Figure 2, then this dirt particles or the layer of dirt, the light of the second light source 10 s · rEflektierBn: that it passes to a second light receiver 12, 1D which is able to generate an electrical signal indicating the layer of dirt or the dirt particles.

To prevent light from the second light source 1D reaches the second light receiver 12 directly . A shielding plate 13 is arranged between these components.

Exactly how to the components for the water recognition also belongs to the components for dirt detection a reference beam light receiver 14, the exact arrangement of which is ...; Figures 3 and 4 results. This second reference ctrl light

2D receiver 14 is laterally next to the second light source 1D arranged and sits on an aluminum foil 15, which to the second light source 10 over the contour of the second Reference beam light receiver 14 protrudes. The figure 4 leaves furthermore the shielding plate already explained with reference to FIG 13 .recognize ..

To eliminate disturbance variables, the complete sensor 2, apart from its active side, it is enclosed by a housing 16 made of metal, but this is only shown in FIG became.

A device is not shown in the drawing • for frost detection. This has είηεη temperature sensors

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on the outside of the rear shield. The establishment is designed so that at sub-zero temperatures on the windshield the operation of the windshield wiper as well as the LJisch-hJasch system is prevented.

It is also not shown that the sensor 2 can be seen as a whole, for example with a suction cup can be so that it can be releasably attached to the disc 1. Around air inclusions between the disc 1 and ^ den To avoid wedges 5 and 7, it is advisable to place a silicone disk between the 1D of the healing points and the disk, uieil these on the one hand deformable, on the other hand however, it is sufficiently translucent.

Let us now consider the overall function of the device according to the invention -described. The coming from the sensor 2 Signals are processed in an electronic circuit. A logic is used to determine whether There is dirt, rain, snow or a layer of ice on the windshield 1 and, depending on the », the windshield wiper The Wisch-Idasch system switched on.

The light receivers 8, 12, which are switched in the reverse direction receive to one the radiation of the assigned Light sources 3, 1D and on the other hand the outside light, which made up of sunlight, street lights, the headlights oncoming vehicles and other light sources. So the outside light comes in as a disturbance and must therefore be eliminated. In order to be able to separate the measuring beam from the outside light the measuring beam clocked. That happens with an astsbilen Multivibrator. The clock frequency is 1D kHz. There

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the outside light changes very slowly, it can conceived as equal sizes. Self uisnn the Sensor E briefly from the headlight of oncoming people Vehicle is detected, this change is well below the clock frequency of the measuring beam. That Outside light can be used as είπε superimposed equal voltage the changing measuring voltage. If you take an alternating voltage measurement, you have the outside light already eliminated.

1D Since the light sources 3, 1D are light emitting diodes and

If only have a very low differential internal resistance VDn, they should only be fed from a voltage source with a high internal resistance. This can be achieved by selecting the supply voltage high enough and setting the desired current via a V / resistor. A better solution is to supply the luminescent diodes from a constant current source, which also has the advantage that voltage changes have no effect on the

2D DurchlaßstrDm and thus habsn to the radiation intensity.

The luminescent diodes are connected in series in order to have as few lines as possible from the Ξεπξογ 2 to the circuit. Also, you only need one transmission circuit. Since the circuit in the motor vehicle temperatures van minus 25 to plus Brad G is ausgesstzt BD degrees C, observed must uerden, DAO uerden the maximum power dissipation is not exceeded. The pulsing of the luminescence diodes is achieved by periodically interrupting the Uoruiartsstromes.

iilie from the sensor description can be seen, arbsiten Water and

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2D The cutoff frequency of the high pass must be set so high

be that, for example, when driving through εϊπε city at night, the 1OD Hz oscillation won fluorescent lamps not reinforced. The operational amplifier is connected in the inverting B circuit and is designed for a gain of 100 .. The The gain in this circuit is proportional to the resistance ratio of the feedback to the Input resistance.

To convert the amplified AC voltage into a DC voltage To make it, a sample and hold circuit can be used, for example.

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Dirt detection each with a measuring and a reference beam path. The reference beam path is necessary the disturbance variables of temperature and voltage fluctuations and to neutralize aging of the sending and receiving elements. Since the circuit for the four MeßsingängE • The explanation follows until the comparators are almost the same up to there only for the first input, the measured value of the water detection.

The light receiver B of the sensor 2 receives, as already described, the measuring beam and the outside light. The measuring beam is an alternating quantity, the outside light almost an equal size. To separate these, a Alternating voltage amplification made. she will realized by a high-pass filter at the input of the circuit. It is a simple high pass in which. |

the input resistance of the operational amplifier already is used as an R-member. With the inverting wiring of the operational amplifier, the input resistance is equal to the upstream resistance.

An essential component of the circuit is the camarator stage. In it, the difference between the voltage ■ UJErtEn is formed of the light receiver and the respective light receiver Referenzstrahl- are sd that disturbances eli- b miniert.

The SchnEe discovery takes place via the second, dar Dirt detection αίεπεηαεη light receiver mittsls εϊπεγ SchujElluj switch-on. There the beautiful light It is much more reflective than dirt, it creates 1G dsr Corresponding light receiver in snow είπε IDEALLY higher tension g sharp with dirt, what can be determined by the school switch can.

Since the KomparatDrstufε is not ΓÜckgεkDppelt, there are it only emits 8 signals for a very short time. To εΓΓΕΐοπεπ that the wipe-wash system remains switched on long enough after activation is the kcmparatorstufε είπε pulse length change after switching. Είπε yourself Subsequent switch-on delay prevents that 2G automatically initially when the ignition is switched on the üJisch-liJasch plant and the disc mixer be akbiwiart.

After the switch-on delay, the control is OK the R8lais for the windshield wiper and the LJischüJasch system. This control is in addition to the actuation by dan SansDr by means of a manual Activate actuation. A device for frost detection is able to block the control.

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To make particularly effective use of the light source 3 emitted light beams can be reached by the 4 of the wedge 5 can also be designed as a convex lens. This leads to the fact that the individual ones emanating from the light source 3 are not Rays running parallel to one another are deflected by the convex lens into rays running parallel to one another. The resulting lower scattered light and the better utilization of light make it possible to use the light source 3 with less To train fruit starch.

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Claims (1)

UDD Adolf Schindling AB Graefstrasse 1D3 GDOO Frankfurt / Main G-S Kl-kl / 1641 G 82 02 355.7 December 10, 1982 Claims * 1. A device for detecting existing on the outside of a Sr.i.eibe impurity en uiie moisture, dirt or snow, characterized by a sensor (2) of a light source '3, 10) and converting a light into an elec ^L generic size Light receiver (S, 12), the sensor is arranged on the inside of the pane (1) and the light source (3, 1D) and the light receiver (8, 12) are arranged to one another in such a way that the light rays emitted by the light source are on the disc (1) to the light receiver (8, 12) are reflected. . 2. Device according to claim 1, characterized in that the light source (3) and the LichtEUipf anger (8) are arranged to one another in such a way that when it is dry \ Disk (1) the light from the light source through total reflection \ inside the disc (1) on its outer surface (G) directed from the light source (3) to the light receiver (8) is. 3, device according to claim 1 or one of the following, characterized in that the light source and light receiver (12) are arranged relative to one another in such a way that the light from the light source (10) reflected by the dirt particles on the pane (1) is directed towards the light receiver. ^. Device according to claim 3, characterized in that the light source (1D) is an infrared light source, 5. Device according to claims 3 ader k, characterized in that a shielding plate (13) is arranged between the light source OD) and the light receiver (12). 6. Device according to claim 1 or one of the following, characterized in that a reference beam light receiver (9, 1h) is assigned to each light receiver (β, 12) arranged in a measuring beam path. 7. Device according to claim 1 or one of the following, characterized in that the reference beam LichtEmpf ängEr (9, 1 * t) are arranged so that soiJDhl light from the associated light source (3, 1D) as well as outside light is directed to them . B. Device according to claim 1 or one of the following, characterized in that the light source (3) for Ulasser detection on a Heil (5) bus is arranged a crystal clear material. 9. Device according to claim 1 Dder one of the following, characterized in that the light receiver (6) for UlasserErkEnnung JEurils is arranged on a wedge (7) made of a crystal clear material. 1D. Device according to Claim 1 of one of the following, characterized in that the light source (3, 1D) is in each case a luminescent diode. 11. Device according to claim 1 or one of the following, characterized in that the light receiver (8, 9, 12, 1 * O is each εϊπε photodiode. 12. Device according to claim 1 DdET one of the following, characterized in that the sensor (2) is attached directly to the inside of the disk (1). 13. Device according to claim 1 or one of the following, characterized in that the sensor (2) is arranged in a housing (16). 1 * t. Device according to Claim 13, characterized in that the housing (1G) is made of metal. 15. Device according to claim 2 Dder one of the following, characterized in that the angle dss Heiles (5) sd is measured that one is upon him perpendicular incident light beam with a Angle between h2. Degree and SD degree measured towards the perpendicular in the disc * (1). 16. Device according to claim 1 Dder one of the following, characterized in that the reference beam light receiver (1 * O for dirt detection with his sensitive surface to the light source (1D) directed next to the light source (1D) on a sensitive to dsr Protruding from the side of the light receiver (14) Aluminum foil (15) is provided. 17- Device according to claim 1 or one of the following, characterized in that the sensor (2) is designed for releasable attachment to the pane (1). 16. Device according to claim 1 duet one of the following, characterized in that the Ξεπξογ (Z) for releasable fastening with εϊπεγτι suction cup is provided. 19. Device according to claim 1 DdEr one of the following, characterized by gskEnnzEichnst, · that between the ΚεϊΙεπ (5, 7) made of crystal clear DerkstDff and the disk (1) είπε silicon disk is vargE See. 2G. Device according to claim 1 DdEr εϊπεπι öeT faIgEnds, characterized in that a frost detection device είπεπ on the disk (1) has associated temperature sensors. 21. Device according to claim 1 or εϊπεπι the following characterized in that the Ξεπβογ (2) is attached to a motor vehicle in the middle of the windshield just above the rest position of the windshield wiper in the working area of the windshield wiper.