DE102004049855B3 - Acquisition method for the solar irradiation and ambient temperature in a vehicle cabin comprises switching an anode of a photodiode towards a mass and the cathode via a resistor towards a supply voltage - Google Patents

Abstract

Method for acquiring the solar irradiation and ambient temperature in a vehicle cabin comprises connecting an anode of a photodiode (5) to a mass (6) and the cathode via a resistor (1) to a supply voltage (3) and feeding the light-dependent photo-voltage as a first input signal (15) to a control unit (4) for measuring the solar irradiation and feeding the light-dependent conducting state voltage as a second input signal (16) to the control unit for measuring the ambient temperature.

Description

The The invention relates to a method for detecting solar radiation and the ambient temperature in the passenger compartment of a vehicle below Use of an unventilated Temperature sensor.

The Air conditioning of vehicles, especially motor vehicles, serves both the comfort needs the vehicle occupants as well as road safety. The air conditioning system of motor vehicles includes in addition to the heating and Refrigeration circuit the air conditioner, the air distribution devices, but also the control unit for the air conditioning with the control device and the associated sensors.

The Sensors detect relevant state variables, such. Temperature, Moisture, pollutant load or solar radiation in and possibly also outside of the passenger compartment, and pass this information to the control device further. In the control device, the comparison of these state variables with Target sizes, where dependent on a determined deviation the air conditioning system necessary measures to achieve the desired Comfort conditions causes.

On the market sensors for detecting the interior temperature can usually be in ventilated Temperature sensors and non-ventilated Classify temperature sensors.

To the Operation of ventilated Temperature sensors is a ventilation motor that generates an airflow or fan necessary. About that generate ventilation motors or fan dependent on their design, the volume flow and the required pressure increase naturally a sound power, the possibly to an undesirable noise pollution leads.

Unventilated temperature sensors On the other hand, they indicate the exact temperature of an internal temperature Passenger compartment typically two measuring points. As the first measuring point Here is a photodiode for detecting solar radiation, and as a second measuring point is an NTC resistor for detecting the Temperature provided. These components are either separate Components, or as a combined, and therefore very expensive Component on a flexible circuit board in the housing front the control device arranged.

From the prior art is in this context the DE 37 22 000 A1 previously known, in which a device for measuring the temperature of a medium, in particular for measuring the interior temperature in a motor vehicle, is described. In this case, two temperature sensors are provided, of which the first, flowed by room air temperature sensor is placed in the vicinity of a wall or the roof space. The second temperature sensor provided for the purpose of correcting the first temperature measured by the temperature sensor is arranged directly on this wall and measures its temperature. By means of the difference between the temperature detected by the first temperature sensor and the second temperature sensor, which is determined by an evaluation device, the actual room air can be exactly determined and can be used to counteract disturbing influences, such as eg. B. driving speed changes to be quickly corrected. In this case, NTC resistors are provided for the parallel-connected temperature sensors, which are each interconnected via a partial resistance between the battery voltage and ground. The center taps of the parallel circuits are interconnected via series resistors and connected to the inverting input of an operational amplifier.

The DE 41 30 063 A1 discloses a device for measuring the interior temperature in motor vehicles with a temperature sensor having a first temperature sensor and a second temperature sensor. Using a control device, the temperature measured by the second temperature sensor is corrected by the temperature measured by the first temperature sensor. Characteristic of this invention is the fact that the temperature sensor has an insulating body whose surface quickly assumes the temperature of the medium surrounding it, wherein the first temperature sensor is arranged on the surface of the insulating material and measures the surface temperature, and the second temperature sensor is arranged on a grid is and measures the grid temperature, and that the lead wires for contacting the first temperature sensor and the second temperature sensor are arranged in the insulating body. In order to determine the best possible interior temperature, the signal corresponding to the grating temperature is supplied both to a subtractor and to an adder with a positive sign. The signal corresponding to the surface temperature is supplied to the subtractor with a negative sign. The subtractor forms the difference between the grating temperature and the surface temperature and supplies the difference value to the adder via a positive sign amplifier.

Further, the DE 100 49 979 A1 a device for determining the temperature in the interior of a vehicle. Here is designed as a NTC or PTC resistor temperature sensor behind a wall adjacent to the interior and a processing unit is provided, which receives the measurement signal of the temperature sensor and outputs a temperature representing the interior of the vehicle output signal. Furthermore, the device has a heat conduction element for detecting the temperature of the air of the interior space within its wall region, wherein the heat conduction element is in Wärmeleitkontakt with the temperature sensor and is provided for extension through an opening in the wall. Furthermore, a sun sensor can also be provided on the temperature sensor receiving printed circuit board of the control unit in order to sufficiently take into account the additional heat input into the passenger compartment for determining an exact passenger compartment temperature.

The aforementioned solutions have in common that, on the one hand, by arranging several, considering the disturbances Temperature sensors whose output signals weighted against each other or linked together become, a representative Passenger compartment temperature is determined; the effort is, however not insignificant.

at other solutions become the possibilities a bidirectionally operable photodiode and the possibilities such a photodiode, both light output and temperature discussed to those of ordinary skill in the art, however, the current state of the art in this remains Knowledge stand.

So concerns the DE 199 12 463 A1 a method for stabilizing the optical output power of light-emitting diodes and laser diodes, with which the influence of temperature on the optical output power (light output) of light emitting diodes and laser diodes can be compensated, without the need for detection of temperature or light output is required. The method is based on the fact that the current flowing through a light emitting diode or laser diode and the decreasing forward voltage at constant light output, regardless of the temperature, are in an often linear functional relationship that can be determined.

In the DE 103 02 285 A1 a method for determining the interior temperature of a motor vehicle passenger compartment on the basis of a determined on a sensor size for solar radiation and / or a determined at a further sensor surface temperature at the measurement location is presented. The invention proposes to eliminate measurement errors resulting from an air circulation in front of a measuring location in that this circulation is determined as such. For this purpose, a signal is given to a heating element, which is read out by thermal coupling with a sensor as a step response. From the difference of the step response in comparison to the reaction, which is determined adaptively at the sensor, with stationary air, one or no air flow is determined. This information is weighted into account when determining the interior temperature.

The DE 44 31 117 C2 comprises a circuit for adjusting the operating point of at least one photodiode of a receiver of alternating light useful signals with a resistor circuit connected in parallel to compensate for uniform light signals. In this case, the resistance circuit has a self-regulating resistor, the voltage-dependent changes its resistance as soon as a certain voltage is exceeded below the saturation voltage, thereby loading the photodiode until the determined voltage is substantially reached.

The DE 199 07 972 A1 discloses an optoelectronic image cell having a photocurrent emitting photosensitive element and an impedance converter for the photocurrent. This has a feedback element between the output of the impedance converter and the photosensitive element. The device serves to shorten the settling and decay time of the image cell.

The DE 103 40 346 A1 describes a sensor device, which is preferably formed by photodetectors with optical elements arranged in front of it. It serves to generate an electrical output signal as a function of the position of a light source with respect to the sensor device. This has at least one sensor and is characterized in that the sensor device has at least two sensors, which are aligned in directions different from each other. As a result, a particularly simple geometric detection of the position of the light source, in particular the position of the sun for controlling an air conditioner, allows.

The The object of the invention is now a method for detection the solar radiation and the ambient temperature in the passenger compartment to develop a vehicle that is reliable and only under Using a small number of electronic components realized can be.

• [A] Messung der Solareinstrahlung im Fahrgastraum, wobei die Anode der Photodiode gegen Masse und die Kathode über einen Widerstand gegen die Versorgungsspannung geschaltet werden und die lichtabhängige Photospannung als erstes Eingangssignal der Regeleinrichtung zugeführt wird, und
• [B] Messung der Umgebungstemperatur im Fahrgastraum, wobei die Kathode der Photodiode gegen Masse und die Anode über einen Widerstand gegen die Versorgungsspannung geschaltet werden und die temperaturabhängige Durchlassspannung als zweites Eingangssignal der Regeleinrichtung zugeführt wird.

This object is achieved in that the method for detecting the solar radiation and the ambient temperature in the passenger compartment of a vehicle, in which using a A / D converter having control device receives and processes two different input signals of a bidirectionally operable photodiode and at least one Out output signal, comprising the following substeps:

• [A] measurement of the solar irradiation in the passenger compartment, wherein the anode of the photodiode to ground and the cathode are connected via a resistance to the supply voltage and the light-dependent photovoltage is supplied as a first input signal to the control device, and
• [B] Measurement of the ambient temperature in the passenger compartment, wherein the cathode of the photodiode to ground and the anode are connected via a resistor to the supply voltage and the temperature-dependent forward voltage is supplied as a second input signal to the control device.

at the measurement of solar radiation, the photodiode is backwards, so in their reverse direction, operated, the light-dependent photo voltage unreinforced the Analog input of the A / D converter of the control device is supplied. When measuring the ambient temperature in the passenger compartment, however does the photodiode move forward, ie in the forward direction, operated, the temperature-dependent forward voltage using a differential amplifier amplifies the analog input of the A / D converter supplied to the control device becomes.

With According to the present method, only a single, formed as a photodiode optical sensor or detector two independent from each other Parameters, namely the solar radiation and the temperature of the sensor, recorded and forwarded for evaluation to the control device. The information obtained from the solar radiation measurement used to reduce the influence of solar radiation, which causes greater warming of the solar energy Caused the surrounding area of the photodiode at darker locations, to be considered when determining an exact ambient temperature.

The two preferably sequentially detected signals form a measurement; Several measurements are taken after a program in the control device processed and form a measuring cycle.

The The output signal supplied by the control device is preferred a signal representing the cabin temperature.

• • Minimierung der Offsetspannung,
• • Verstärkung der temperaturabhängigen Durchlassspannung innerhalb des Bereiches der Eingangsspannung des A/D-Wandlers sowie
• • Unterdrückung von Gleichtaktstörsignalen gegenüber Differenzsignalen.

In order to keep the output voltage of the amplifier required in the temperature measuring device in the range of the input voltage of the analog input of the A / D converter of the control device, it is necessary to provide a differential amplifier. The advantages of the differential amplifier in detail are:

• Minimizing the offset voltage,
• • amplification of the temperature-dependent forward voltage within the range of the input voltage of the A / D converter as well
• • Suppression of common-mode interference signals compared to differential signals.

in the Temperature measuring operation [B] is the temperature-dependent forward voltage of Photodiode using this differential amplifier whose high offset voltage due to a highly accurate reference voltage largely is compensated, amplified.

Of the differential amplifier preferably has a constant gain factor that is made up of the size and the Interconnection of additional required resistors determined.

The Reference voltage is supplied by a reference voltage diode. For the purpose of stabilizing the reference voltage, the reference voltage diode connected with upstream resistance to the supply voltage and the reference voltage is lowered by means of a voltage divider and subsequently routed to the negative input of the differential amplifier.

In a preferred embodiment of the invention is additionally a between the supply voltage and the negative input of the differential amplifier itself extending circuit provided with a resistor to the Fluctuations of the supply voltage in temperature measuring operation [B] to map to the reference voltage or to compensate for these fluctuations.

In In practice, the inventive method for detection the solar radiation and the ambient temperature with an electronic circuit realized, in which the photodiode is operated in an H-bridge. The H-bridge includes two parallel circuits, each one against the supply voltage switched resistor and each one connected to ground Have switch. While the cathode of the circuits connected in parallel between the two placed photodiode directly to the analog (positive) input of the A / D converter of the control device, the anode of the photodiode indirectly using the differential amplifier against the analog (positive) Input of the A / D converter of the control device out. By a mutual opening or Close the two switches can thus successively or alternately the Solar radiation and the ambient temperature by means of the photodiode be recorded.

In a first switching position of the switches operated in parallel, the cathode of the photodiode switched to ground. In this state, the photodiode operates as a temperature meter, wherein the forward voltage of the photodiode is amplified by means of the differential amplifier and the A / D converter of the control device is supplied. In a second switching position of the parallel operated switch, however, the anode of the photodiode is connected to ground. In this state, the photodiode operates as a solar radiation meter, wherein the reverse voltage of the photodiode is fed directly to the A / D converter of the control device.

U_TEMP

= Eingangsspannung an der Auswert- und Steuereinheit am Port IN1,

OFFSET_20,D

= Ausgangsspannung des Verstärkers bei 20°C und Dunkelheit,

k

= Verstärkungsfaktor des Differenzverstärkers,

TK_SENSITIV

= Temperaturkoeffizient der Vorwärtsspannung in [V/°C] (Temperaturturmessbetrieb),

T_COMP

= lichteinstrahlungskompensierte Temperatur,

T_NOCOMP

= nichtlichteinstrahlungskompensierte Temperatur,

U_SUPPLY

= Versorgungsspannung,

U_LIGHT

= Eingangsspannung an der Auswert- und Steuereinheit am Port IN2,

KF_LIGHT

= Verstärkungsfaktor des Differenzverstärkers in [°C/V],

S₁

= Steuerregister für Schaftelement S1,

S₂

= Steuerregister für Schaltelement S2, wobei für S1 und S2 gilt: 0 = offen bzw. hohe Impedanz und 1 = geschlossen und niedrige Impedanz.

The determination of the non-light- _{irradiation-compensated} temperature T _NOCOMP (temperature measurement) and the light-irradiation-compensated temperature T _COMP (solar irradiation measurement) in the control device takes place taking into account the following parameters:

U _TEMP

= Input voltage at the evaluation and control unit at port IN1,

OFFSET _{20, D}

= Output voltage of the amplifier at 20 ° C and darkness,

k

= Amplification factor of the differential amplifier,

TK _SENSITIVE

= Temperature coefficient of the forward voltage in [V / ° C] (temperature measuring operation),

T _COMP

= light radiation compensated temperature,

T _NOCOMP

= non-light irradiation-compensated temperature,

U _SUPPLY

= Supply voltage,

U _LIGHT

= Input voltage at the evaluation and control unit at port IN2,

KF _LIGHT

= Amplification factor of the differential amplifier in [° C / V],

S ₁

= Control register for shaft element S1,

S ₂

= Control register for switching element S2, where S1 and S2 are: 0 = open or high impedance and 1 = closed and low impedance.

The non-light-irradiation-compensated temperature or the light-irradiation-compensated temperature are then determined according to the following equations (1) and (2): T NOCOMP = 20 ° C + (U TEMP - OFFSET 20 ) / (K · TK SENSITIVE )respectively. (1) T COMP = T NOCOMP + (U SUPPLY - U LIGHT ) · KF LIGHT (2)

• Normalbetrieb: S₁ = 0 und S₂ = 0
• Schleifenstart: S₁ = 1 und S₂ = 0, U_TEMP = Analogeingang IN1 des AD-Wandlers, S₁ = 0 und S₂ = 1, U_LIGHT = Analogeingang IN2 des AD-Wandlers, S₁ = 0 und S₂ = 0, T_NOCOMP = 20 + (U_TEMP – OFFSET₂₀)/(k·TK_SENSITIV), T_COMP = T_NOCOMP + N_SUPPLY – U_LIGHT·KF_LIGHT, Warte bis nächste Messung, Schleifenende.

For alternately detecting the solar irradiation and the ambient temperature by means of the photodiode connected in accordance with the invention, a nightly loop is processed in the control device:

• Normal operation: S ₁ = 0 and S ₂ = 0
• Loop start: S ₁ = 1 and S ₂ = 0, U _TEMP = analog input IN1 of the AD converter, S ₁ = 0 and S ₂ = 1, U _LIGHT = analog input IN2 of the AD converter, S ₁ = 0 and S ₂ = 0, T _NOCOMP = 20 + (U _TEMP - OFFSET ₂₀ ) / (k · TK _SENSITIVE ), T _COMP = T _NOCOMP + N _SUPPLY - U _LIGHT · KF _LIGHT , wait until next measurement, loop end.

Due to the fact that the forward voltage of the photodiode due to production very strong scatter, a calibration of the photodiode is necessary. The calibration of the photodiode is done at a known temperature. Preferably, therefore, the output voltage of the differential amplifier is read in the dark and 20 ° C reference temperature via the port IN1 in the A / D converter of the controller and stored in the non-volatile memory cell OFFSET _{20, D.}

According to the invention, in case that the photodiode is placed in the controller, the calibration factory done at the end of the line of ECU production.

at A further embodiment of the invention provides that the photodiode is used as an external solar radiation sensor, which first wired in the context of vehicle production and in the Vehicle is placed. Since the assembly of the vehicles is usually in a building takes place, the photodiode is not undesirable heated by sunlight. For calibration of the photodiode then the reference temperature is the temperature of the temperature sensors placed in the exhaust nozzles used and adjusted to this temperature.

A comparable procedure for calibrating the photodiode can as part of the maintenance and / or inspection of vehicles in an auto repair shop or service point if, for example, the as external Solar radiation sensor used photodiode or the Photodiode containing control device must be replaced.

The path of the inventive concept is not abandoned even if one of the zones to be air-conditioned in the vehicle corresponding number of photodiodes are provided, the light-dependent photovoltage or temperature-dependent forward voltages supplied as input variables of the control device of a multi-zone air conditioning be led. Thus, differently tempered environmental regions of the placed photodiodes-which are produced by a relative movement of the vehicle to the sun-can be purposefully detected and subsequently used to determine a "true" climate zone temperature.

• • unter Verwendung eines einzigen als Photodiode ausgebildeten optischen Sensors bzw. Detektors können die Solareinstrahlung und die Umgebungstemperatur erfasst werden,
• • die Schwankungen der Versorgungsspannung werden zusätzlich mittels eines sich zwischen der Versorgungsspannung und dem negativen Eingang des Differenzverstärkers sich erstreckenden Stromkreises mit einem Widerstand auf die Referenzspannung abgebildet und
• • zur Stabilisierung der Referenzspannung wird zusätzlich eine Referenzspannungsdiode eingesetzt.

The significant advantages and features of the invention over the prior art are essentially:

• Using a single optical sensor or detector designed as a photodiode, the solar radiation and the ambient temperature can be detected,
• • The fluctuations of the supply voltage are additionally mapped by means of a between the supply voltage and the negative input of the differential amplifier extending circuit with a resistance to the reference voltage and
• • A reference voltage diode is additionally used to stabilize the reference voltage.

Further Features and advantages of the invention will become apparent to those skilled in the art from the following detailed description of a preferred embodiment with regard to the attached drawings; in this show:

1 : Circuit arrangement with a photodiode used for solar radiation measurement, state of the art

2 : Circuit arrangement with a photodiode used for temperature measurement, state of the art

3 : Circuit arrangement with a photodiode used for solar radiation and temperature measurement and

4 : Circuit arrangement with a photodiode used for solar radiation and temperature measurement with mapping of the fluctuations of the supply voltage to the reference voltage and stabilization of the reference voltage.

The 1 illustrates a circuit arrangement with a photodiode used for solar radiation measurement 5 , The circuit includes one between the supply voltage 3 and mass 6 switched photodiode 5 , in addition to the supply voltage 3 switched resistance 1 as well as an output signal 17 generating control device 4 which has an A / D converter, not shown. The photodiode 5 is operated in its reverse direction, respectively backward, with the anode of the photodiode 5 against mass 6 and the cathode of the photodiode 5 about a resistance 1 against the supply voltage 3 are switched. The first input signal, respectively the light-dependent photovoltage 15 , becomes directly the analog input, here IN 2, of the A / D converter of the control device 4 fed. The light-dependent photovoltage 15 is inversely proportional to solar radiation.

The 2 shows a circuit arrangement with a photodiode used for temperature measurement 5 , The circuit includes one between the supply voltage 3 and mass 6 switched photodiode 5 , one against the supply voltage 3 switched resistance 2 , one an output signal 17 Generating control device 4 which has an A / D converter, not shown, as well as a differential amplifier 7 trained operational amplifier. The photodiode 5 is operated in the forward direction, respectively forward, with the cathode of the photodiode 5 against mass 6 and the anode of the photodiode 5 about a resistance 2 against the supply voltage 3 are switched. Using the differential amplifier 7 becomes the now signal-amplified temperature-dependent forward voltage 16 as a second input signal to the positive analog input, here IN 1, of the A / D converter of the control device 4 fed. The differential amplifier 7 forms the difference between the reference voltage, not shown, which is the negative input of the differential amplifier 7 and the temperature-dependent forward voltage and amplifies this difference by a fixed amplification factor. The temperature-dependent forward voltage is inversely proportional to the solar irradiation, provided the photodiode 5 is acted upon by a constant solar radiation.

• Schleifenstart: S₁ = 1 und S₂ = 0, U_TEMP = Analogeingang Port IN 1 des AD-Wandlers, S₁ = 0 und S₂ = 1, U_LIGHT = Analogeingang Port IN 2 des AD-Wandlers, S₁ = 0 und S₂ = 0, T_NOCOMP = 20°C + (U_TEMP – OFFSET₂₀)/(k·TK_SENSITIV), T_COMP = T_NOCOMP + (U_SUPPLY – U_LIGHT)·KF_LIGHT, Warte bis nächste Messung, Schleifenende.

3 illustrates a circuit arrangement with a photodiode used for solar radiation and temperature measurement 5 , More specifically illustrated 3 the combination of two circuit arrangements, as these each individually 1 and 2 can be seen. The circuit arrangement in turn comprises the bidirectional photodiode 5 , which is operated in a H-bridge. The H-bridge comprises two parallel circuits, each with a resistor connected to the supply voltage 1 . 2 and in each case a switch connected to ground 18 . 19 exhibit. The mentioned linkage takes place by means of three nodes, which are represented as a dot, which show the two transverse taps for the temperature-dependent forward voltage and the light-dependent photovoltage 15 connect to the H-bridge. As can be seen, the cathode carries the photodiode placed between the two parallel circuits 5 immediately to the ana logen positive input of the A / D converter of the control device 4 , The anode of the photodiode 5 however, indirectly using the differential amplifier 7 against the analog positive input of the A / D converter of the control device 4 , By a mutual opening or closing of the two switches 18 . 19 can thus successively or alternately the solar radiation and the ambient temperature by means of the photodiode 5 be recorded. In the first switching position, the switch S1 18 closed (low impedance) and the switch S2 19 (high impedance) opened. Thus, the cathode is the photodiode 5 against mass 6 connected. In this state, the photodiode works 5 as a temperature meter, the forward voltage of the photodiode 5 by means of the differential amplifier 7 is amplified and the A / D converter of the control device 4 is supplied. In the second switching position of the parallel operated switch 18 . 19 on the other hand, the switch S2 19 (low impedance) closed and the switch S1 18 (high impedance) and thus the anode of the photodiode 5 against mass 6 connected. In this state, the photodiode works 5 as a solar radiation meter, the reverse voltage of the photodiode 5 directly to the A / D converter of the control device 4 is supplied. The two switch positions of the switches 18 . 19 are taken consecutively and continuously, with one measurement both signals, ie the temperature-dependent forward voltage and the light-dependent photovoltage 15 , includes. Several measurements forming a measuring cycle are made according to the following loop in the control device 4 processed:

• Loop start: S ₁ = 1 and S ₂ = 0, U _TEMP = Analog input Port IN 1 of the AD converter, S ₁ = 0 and S ₂ = 1, U _LIGHT = Analog input Port IN 2 of the AD converter, S ₁ = 0 and S ₂ = 0, T _NOCOMP = 20 ° C + (U _TEMP - OFFSET ₂₀ ) / (k · TK _SENSITIVE ), T _COMP = T _NOCOMP + (U _SUPPLY - U _LIGHT ) · KF _LIGHT , wait until next measurement, loop end.

The output signal 17 the control device 4 is a passenger compartment representative signal resulting from the temperature detection of the photodiode 5 as well as the solar irradiation caused heating of the surrounding areas of the placed photodiode 5 is generated.

The 4 shows a circuit arrangement with a photodiode used for solar radiation and temperature measurement 5 with a picture of the fluctuations in the supply voltage 3 to the reference voltage and stabilization of the reference voltage. The basic structure of this circuit arrangement corresponds to that of 3 , In addition, two circuits were added, the first of which depicts fluctuations in the supply voltage 3 is provided to the reference voltage and the second for stabilizing the reference voltage. The first opposite the 3 supplemented circuit supplies the reference voltage, which from a reference voltage diode 8th is generated. For the purpose of stabilizing the reference voltage, the reference voltage diode 8th with upstream resistor 11 against the supply voltage 3 switched, and the reference voltage by means of the voltage divider, resistance 12 and resistance 13 , reduced and subsequently to the negative input of the differential amplifier 7 guided. The interconnected resistor 14 represents the feedback branch. Immediately before the negative input of the differential amplifier 7 a node is provided at which the second opposite 3 supplemented circuit is integrated. This the resistance 10 and thus having voltage drop circuit extends between the supply voltage 3 and just this point. Thus, the fluctuations of the supply voltage 3 in the temperature measuring mode [B] to the reference voltage or these fluctuations are compensated. The constant gain k of the differential amplifier 7 is determined from the amount of resistors R 10, R12, R13 and R14 according to equation (3) as follows: k = 1 + R14 / (R10 + R12 + R13) (3)

It will be understood by those skilled in the art that using two photodiodes 5 in independent circuits, for example as in the 1 and 2 are shown, the temperature-dependent forward voltage and the light-dependent photovoltage 15 detected simultaneously and by the regulator 4 can be processed. Although contemporary, a hochtaktenden microcontroller having control devices 4 being able to perform a large number of arithmetic operations in parallel, the method according to the present invention for detecting the solar irradiation and the ambient temperature in the passenger compartment of a vehicle will, for practical purposes, only be carried out using a single photodiode 5 like these in the 3 and 4 interconnected, realized.

1

resistance

2

resistance

3

supply voltage

4

control device

5

photodiode

6

Dimensions

7

differential amplifier

8th

Reference voltage diode

9

resistance

10

resistance

11

resistance

12

resistance

13

resistance

14

resistance

15

first input signal of the control device 4

16

second, amplified input signal of the control device 4

17

Output signal of the control device 4

18

first Switch (S1)

19

second Switch (S2)

Claims (4)

Method for detecting a solar irradiation and an ambient temperature in a passenger compartment of a vehicle, in which, using a control device having an A / D converter ( 4 ), the two different input signals ( 15 . 16 ) of a bidirectionally operable photodiode ( 5 ) receives and processes and at least one output signal ( 17 ), a. for measuring the solar radiation in the passenger compartment, the anode of the photodiode ( 5 ) against mass ( 6 ) and the cathode via a resistor ( 1 ) against the supply voltage ( 3 ) and the light-dependent photovoltage as the first input signal ( 15 ) of the control device ( 4 ), and b. for measuring the ambient temperature in the passenger compartment, the cathode of the photodiode ( 5 ) against mass ( 6 ) and the anode via a resistor ( 2 ) against the supply voltage ( 3 ) and the temperature-dependent forward voltage as a second input signal ( 16 ) of the control device ( 4 ) is supplied. Method for detecting a solar irradiation and an ambient temperature according to claim 1, characterized in that a non-light-irradiation-compensated temperature in the control device ( 4 ) is determined as follows: T NOCOMP = 20 ° C + (U TEMP - OFFSET 20 ) / (K · TK SENSITIVE ) where: T _NOCOMP = non-light-irradiation-compensated temperature, U _TEMP = input voltage to the evaluation and control unit ( 4 ), OFFSET ₂₀ = output voltage of the differential amplifier ( 7 ) at 20 ° C and darkness, k = amplification factor of the differential amplifier ( 7 ) and TK _SENSITIV = temperature coefficient of the forward _voltage in [V / ° C] (temperature _{measuring mode} ). Method for detecting a solar irradiation and an ambient temperature according to claim 1 or 2, characterized in that a light irradiation-compensated temperature in the control device ( 4 ) is determined as follows: T COMP = T NOCOMP + (U SUPPLY - U LIGHT ) · KF LIGHT . where: T _COMP = light- _{radiation-compensated} temperature, T _NOCOMP = non-light- _{radiation-compensated} temperature, U _SUPPLY = supply voltage ( 3 ), U _LIGHT = input voltage at the control device ( 4 ) and KF _LIGHT = amplification _{factor of} the differential amplifier ( 7 ) in [° c / V]. Method for detecting a solar irradiation and an ambient temperature according to one of claims 1 to 3, characterized in that the control device ( 4 ) delivered output signal ( 17 ) is a signal representing the cabin temperature.