WO2017102573A1

WO2017102573A1 - Optical smart trunk opener

Info

Publication number: WO2017102573A1
Application number: PCT/EP2016/080373
Authority: WO
Inventors: Laurent Lamesch
Original assignee: Iee International Electronics & Engineering S.A.
Priority date: 2015-12-15
Filing date: 2016-12-09
Publication date: 2017-06-22
Also published as: LU92909B1

Abstract

A method of operating an optical proximity detection system (20) that comprises at least one light emitting member (24, 40) and at least one optical sensor (26) configured to generate a sensor signal indicative of light reflected by a scene. The method comprises the steps of operating the light emitting member (24, 42) in a first operational mode (reflectance mode), and if a sensor signal amplitude variation exceeds a predetermined threshold, operating at least one light emitting member (24, 42) in a second operational mode (time-of-flight mode). The method further comprises determining (64) and evaluating (66) data regarding distance between the at least one optical sensor (26) and at least one object of the scene from time-of-flight information, generating (68) a trigger signal (22) indicative of an occurrence of an event if at least one predetermined criterion is fulfilled.

Description

Optical Smart Trunk Opener

Technical field

[0001 ] The invention relates to a method of operating an optical proximity detection system with regard to generating a trigger signal indicative of an occurrence of an event, an optical proximity detection system for generating a trigger signal indicative of an occurrence of an event, a control system for controlling activation of a motor-driven vehicle door member, the control system comprising such optical proximity detection system, and a software module for carrying out such method.

Background of the Invention

[0002] Sensor-controlled automatic actuation of motor-displaceable closure elements of a motor vehicle is known in the art.

[0003] For instance, utility patent document DE 20 2005 020 140 U1 describes a motor vehicle door arrangement with at least one motor vehicle door and a drive for motorized movement of the motor vehicle door from the closed position into the open position and from the open position into the closed position. The arrangement further comprises a control for triggering the drive, the control being assigned an optionally actuatable mobile part which the user generally carries and which interacts with the control means over a wireless transmission link when the user approaches the motor vehicle, enhanced activation automatically carrying out opening and/or a closing as triggered by a predetermined process of use and without the necessity of activating the mobile part. In one embodiment, provision is made for a user-side operator control event, namely a user-side foot movement, to cause the motorized opening of the tailgate. With respect to enhanced activation, the control means, especially with the vehicle stopped, can be moved into the activated and deactivated states, and can be triggered by the predetermined usage process exclusively when the control means is in the activated state.

[0004] Further, a use of a combination of capacitive and optical sensors for sensor-controlled automatic actuation of motor-displaceable closure elements is known from, by way of example, patent application US 2015/0226870 A1 , which describes an electronic sensor unit for a motor vehicle that includes a housing and a control and evaluation device arranged in the housing, which can be coupled to a control system for the motor vehicle. The electronic sensor unit further includes at least one capacitive sensor electrode having a detection range. The capacitive sensor electrode is coupled to the control and evaluation system, and is disposed in the housing. A capacitance change of the capacitive sensor electrode can be detected by the control and evaluation system. The electronic sensor unit furthermore comprises a lighting system having a lamp that can emit an optical signal. The lighting system is likewise coupled to the control and evaluation system. A target region characterizing the detection range outside the housing can be marked using the optical signal. The lighting system can be disposed on or in the housing, in which case the housing must have an opening through which the optical signal can pass. The housing, the control and evaluation system, the at least one capacitive sensor electrode and the lighting system form an integral assembly. When an intrusion has been detected in the detection range by the control and evaluation system, and at the same time, a user is authorized to open the motor vehicle, a door or hatch located thereto can be opened via a control system.

Object of the invention

[0005] Using an optical sensor for detecting a user-intended control event, for instance a user-side foot movement ("kick") for a vehicle trunk opener, requires reliable kick detection and low power consumption at the same time. Proximity detection based on measurement of a change of reflectance of a scene has the advantage of requiring comparatively low power but is sensitive to a reemission factor of the object to be detected. The problem to be solved is the reduction of a dependence of an optical proximity detection system on the reemission factor, while keeping power consumption low, for applications in which the probability of object proximity is small.

[0006] It is desirable to provide a method of operating an optical detection system for detecting an occurrence of an event that allows for low-power operation and reliable detection. General Description of the Invention

[0007] In one aspect of the present invention, the object is achieved by a method of operating an optical proximity detection system with regard to generating a trigger signal indicative of an occurrence of an event, in particular a user-intended control event. The optical proximity detection system comprises at least one light emitting member, at least one optical sensor that is configured to generate a sensor signal indicative of a change of incident light that has been emitted by the at least one light emitting member and has been reflected by a scene, and at least one control and evaluation unit for controlling an operation of the at least one light emitting member and for evaluating generated sensor signals.

[0008] The method comprises steps of operating at least one of the at least one light emitting member in a first operational mode,

acquiring, by said at least one optical sensor, sensor signals generated by emitted light which has been reflected by the scene,

comparing change of amplitude, i.e. an amplitude variation, obtained from acquired sensor signals to at least one predetermined threshold for a signal amplitude variation,

upon the amplitude variation of the acquired sensor signals exceeding the at least one predetermined threshold for a signal amplitude variation, commencing operating at least one of the at least one light emitting member in a second operational mode,

acquiring, by said at least one optical sensor, sensor signals generated by emitted light which has been reflected by at least one object of the scene, determining data regarding distance between the at least one optical sensor and the at least one object from time-of-f light information obtained from relations between the acquired sensor signals and the light emitted by the at least one light emitting member,

evaluating the determined data regarding the distance with regard to at least one predetermined criterion, and

generating a trigger signal indicative of an occurrence of an event if the at least one predetermined criterion is fulfilled. [0009] The phrase "operating at least one of the at least one light emitting member in a first operation mode", as used in this application, shall be understood as follows: If the detection system comprises only one light emitting member, then this light emitting member is operated in the first operation mode. If the detection system comprises more than one light emitting member, then at least one out of the more than one light emitting members is operated in the first operation mode. The main goal of the first operational mode is to detect changes in the amplitude of the reflected light.

[0010] Although the second operational mode (in the following also named "time- of-flight mode") requires more power than the first operational mode ("reflectance measurement mode"), the average power consumption is not substantially increased, as the probability of object proximity, and therefore the operation time of the time-of-flight mode, is small compared to the operation time of the reflectance measurement mode.

[001 1 ] The above-mentioned object is achieved by separating the detection of the occurrence of an event, for instance a kicking motion, into two measurements performed by the same optical sensor: a first continuous but low-power one, and a second one which is only started if a probable event is detected, but which consumes more power. The benefit compared to the conventional solutions lies in that operating an optical proximity detection system with regard to generating a trigger signal indicative of an occurrence of an event with low power consumption and accurate detection of the occurrence of an event can be enabled at the same time.

[0012] Preferably, the at least one light emitting member or the light emitting members are formed by light emitting diodes (LED).

[0013] Further, preferably the at least one light emitting member or the light emitting members are configured to emit light having a wavelength that lies in the near-infrared (IR-A) region of electromagnetic waves between 0.75 μιτι and 1 .4 μιτι.

[0014] In a preferred embodiment, the steps of the method are repetitively carried out. Preferably, the steps are periodically carried out. In this way, a sufficient availability for detecting potentially occurring events can be provided. [0015] If the steps of acquiring sensor signals comprise a step of digitally converting the acquired sensor signals, the benefits of methods that are well- known in the art of digital signal processing can be applied to the subsequent steps of the method.

[0016] In another preferred embodiment of the method, the step of commencing operating at least one of the at least one light emitting member in a second operational mode comprises a preceding step of halting operating the at least one of the at least one light emitting member in the first operational mode. This has the advantage of savings in hardware effort and an operation at a lower average power consumption.

[0017] In some embodiments of the method, the step of operating at least one of the at least one light emitting member in a first operational mode includes amplitude-modulating the light emitted by the at least one of the at least one light emitting member at a first modulation frequency, and the step of comparing an amplitude variation of acquired sensor signals includes a preceding step of demodulating the acquired sensor signals. In this way, an influence of background light can be reduced to a large extent.

[0018] Preferably, the acquired sensor signals generated by emitted light which has been reflected by the at least one object are synchronously demodulated by mixing the optical sensor signal with the modulation signal in order to suppress the influence of the background light.

[0019] In some embodiments of the method, the step of operating at least one of the at least one light emitting member in a second operational mode includes amplitude-modulating the light emitted by the at least one of the at least one light emitting member at a second modulation frequency. In this way, the hardware for modulating the at least one of the at least one light emitting member in the first operational mode can be laid out independent from the hardware for modulating the at least one of the at least one light emitting member in the second operational mode, enabling applying specific solutions for fulfilling requirements, by which in total a cost-efficient solution can be provided.

[0020] Advantageously and in order to keep a hardware effort as low as possible, the first modulation frequency is adapted to fulfill the requirements of a measurement in the reflectance mode, and the second modulation frequency is adapted to fulfill the requirements of a measurement in the time-of-flight mode. Preferably, the first modulation frequency is selected to have a fundamental frequency that lies within a frequency range between 1 kHz and 100 kHz, and the second modulation frequency is selected to have a fundamental frequency that is larger than 10 MHz, more preferable larger than 20 MHz, and, most preferably, larger than 30 MHz. The term "fundamental frequency", as used in this application, shall be understood particularly as a lowest sinusoidal frequency in a Fourier analysis of the light emitted at the modulation frequency.

[0021 ] In yet another preferred embodiment of the method, a duty cycle of the first operational mode is less than 5%, more preferably less than 2% and, most preferably, less than or equal to 1 %, by which the optical proximity detection system can be operated at a sufficient availability with very low average power consumption.

[0022] In some embodiments of the method, the event is formed by an operator- intended control event and the trigger signal is designed as an input to a control system for controlling an activation of a motor-driven vehicle door member. In this way, the method can, for instance, beneficially be employed for operating optical proximity detection systems for kick-triggered vehicle trunk or vehicle tailgate openers, and can provide low-power operation and reliable detection in combination with robustness regarding electromagnetic interference (EMI) to meet electromagnetic compatibility (EMC) requirements to a large extent.

[0023] In another aspect of the invention, an optical proximity detection system for generating a trigger signal indicative of an occurrence of an event is provided. The optical proximity detection system includes a light emitting member and at least one optical sensor that is configured to generate a sensor signal indicative of a change of incident light that has been emitted by the light emitting member and has been reflected by a scene. Furthermore, the optical proximity detection system comprises a control and evaluation unit for controlling an operation of the light emitting member and for evaluating the generated sensor signals, and at least one processor unit and at least one digital data memory unit. The at least one processor unit has data access to the at least one digital data memory unit. The at least one processor unit is configured to carry out the steps of an embodiment of the method disclosed herein.

[0024] In this embodiment, the light emitting member is at first operated in the first operational mode in order to detect changes in the amplitude of the reflected light, and, after the change of amplitude or the amplitude variation of the acquired sensor signals exceeded the at least one predetermined threshold, is then operated in the second operational mode.

[0025] The benefits of the described embodiments of the disclosed method as well apply to the optical proximity detection system.

[0026] In another embodiment, the optical proximity detection system further includes at least a second light emitting member. The control and evaluation unit is configured for operating the first light emitting member in the first operational mode and for operating the at least second light emitting member in the second operational mode.

[0027] In one embodiment, the control and evaluation unit is configured to halt the operation of the first light emitting member in the first operational mode before commencing operating the at least second emitting member in the second operational mode.

[0028] In one embodiment, the control and evaluation unit is configured to continue operating the first light emitting member in the first operational mode while operating the at least second light emitting member in the second operational mode.

[0029] In another aspect of the invention, a control system for controlling activation of a motor-driven vehicle door member, preferably a vehicle trunk or a vehicle tailgate, is provided. The control system comprises at least one processor unit and at least one digital data memory unit, wherein the at least one processor unit has data access to the at least one digital data memory unit. The control system further includes an embodiment of the optical proximity detection system disclosed herein for generating a trigger signal indicative of an occurrence of an event. The at least one processor unit is configured to receive the trigger signal from the optical proximity detection system and, upon and as long as receiving the trigger signal from the optical proximity detection system, to generate an output signal for at least initiating an activation of the motor-driven vehicle door member.

[0030] In this way, the benefits of the disclosed optical proximity detection system as well apply to the control system.

[0031 ] In another embodiment, the control system further includes a second optical proximity detection system. The control and evaluation unit of the first optical proximity detection system is at least configured for operating, controlled by the at least one processor unit of the control system, the at least one light emitting member in the first operational mode, and the control and evaluation unit of the second optical proximity detection system is at least configured for operating, controlled by the at least one processor unit of the control system, the at least one light emitting member in the second operational mode. In suitable embodiments that make use of appropriate data communication links, retro-fitting of existing optical proximity detection systems can be facilitated in this way.

[0032] In yet another aspect of the invention, a software module for controlling an execution of steps of an embodiment of the method disclosed herein is provided.

[0033] The method steps to be conducted are converted into a program code of the software module, wherein the program code is implementable in a digital memory unit and is executable by a processor unit. Preferably, the digital memory unit and/or processor unit may be a digital memory unit and/or a processing unit of the control and evaluation unit of the optical proximity detection system. The processor unit may, alternatively or supplementary, be another processor unit that is especially assigned to execute at least some of the method steps.

[0034] The software module can enable a robust and reliable execution of the method and can allow for a fast modification of method steps.

[0035] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

Brief Description of the Drawings

[0036] Further details and advantages of the present invention will be apparent from the following detailed description of not limiting embodiments with reference to the attached drawing, wherein: Fig.1 schematically illustrates in a partial view an arrangement of a control system for controlling activation of a motor-driven vehicle door member as installed in a vehicle;

Fig. 2 is a schematic illustration of the control system pursuant to Fig. 1 , comprising an optical proximity detection system in accordance with the invention;

Fig. 3 is a schematic illustration of the control system pursuant to Fig. 1 comprising an alternative embodiment of the optical proximity detection system in accordance with the invention;

Fig. 4 is a flow scheme of the method in accordance with the invention; and

Fig. 5 is a schematic illustration of an alternative control system, comprising two optical proximity detection systems in accordance with the invention.

Description of Preferred Embodiments

[0037] An arrangement of a control system 10 for controlling activation of a motor-driven vehicle door member 18 as installed in a vehicle that is designed as a passenger car is schematically illustrated in Fig. 1 . The vehicle door member 18 is formed as a vehicle trunk. The control system 10 comprises an optical proximity detection system 20 in accordance with the invention that is arranged at a location close to the vehicle trunk. The optical proximity detection system 20 is configured for generating a trigger signal 22 that is indicative of an occurrence of an event, in particular an operator-intended control event, which is formed by a user-side foot movement ("kick").

[0038] Fig. 2 schematically illustrates a setup of the control system 10. Besides the optical proximity detection system 20, the control system 10 further includes a processor unit 12 and a digital data memory unit 14 to which the processor unit 12 has data access. The processor unit 12 is configured to receive the trigger signal 22 from the optical proximity detection system 20 via data communication link 46. Upon and as long as receiving the trigger signal 22 from the optical proximity detection system 20, the processor unit 12 is configured to generate an output signal 16 for initiating an activation of the motor-driven vehicle door member 18, as will be described later on. The condition of the generated output signal 16 can be combined with another condition or other conditions that need to be fulfilled for activating the motor-driven vehicle door member 18. For instance, one additional condition may be the presence of a car key, which a user usually carries and which interacts with vehicle control means over a wireless transmission link, as is well known in the art.

[0039] The optical proximity detection system 20 includes a light emitting member 24 formed by an infrared LED that is designed to emit light in the near- infrared region, in particular at a wavelength of about 850 nm, when being energized. The light emitting member 24 is arranged to illuminate the ground underneath the vehicle trunk, as indicated in Fig. 1 . Then, the optical proximity detection system 20 comprises an optical sensor 26 that is configured to generate a sensor signal indicative of a change of incident light that has been emitted by the light emitting member 24 and has been reflected by a scene which in this specific embodiment includes the space between a lower side of the vehicle under the vehicle trunk and the ground. The optical sensor 26 is formed by a phototransistor, but other light-sensitive sensors that appear to be suitable to those skilled in the art are also contemplated, for instance a photodiode.

[0040] Combinations of an infrared LED and a phototransistor with the option of amplitude modulation are nowadays commercially available and can therefore readily be obtained. One example is the proximity sensor SFH 7741 by OSRAM Licht AG.

[0041 ] Moreover, the optical proximity detection system 20 includes a control and evaluation unit 28 for controlling an operation of the light emitting member 24. The light emitting member 24 is connected to an output port 34 of the control and evaluation unit 28, and the optical sensor 26 is operatively connected to an input port 36 of the control and evaluation unit 28 (typically via a not shown transimpedance amplifier), as is schematically indicated in Fig. 2. The input port comprises an analog-to-digital converter (ADC, not shown).

[0042] The control and evaluation unit 28 is equipped with a processor unit 30 and a digital data memory unit 32 of its own. The processor unit 30 has data access to the digital data memory unit 32 and is configured for acquiring and evaluating the generated sensor signals. To this end, the control and evaluation unit 28 includes a software module 44 for carrying out a method of operating the optical proximity detection system 20 with regard to generating a trigger signal 22 indicative of an occurrence of the user-side foot movement carried out underneath the vehicle trunk.

[0043] The trigger signal 22 is designed as an input to the processor unit 12 of the control system 10. The method steps to be conducted are converted into a program code of the software module 44, wherein the program code is implemented in the digital data memory unit 32 of the control and evaluation unit 28 and is executed by the processor unit 30 of the control and evaluation unit 28.

[0044] In the following, an embodiment of the method will be described. A flowchart of the method is illustrated in Fig. 4. In preparation of operating the optical proximity detection system 20, it shall be understood that all involved units and devices are in an operational state and configured e.g. as illustrated in Figs. 1 and 2.

[0045] In a first step 48 of the method, the light emitting member 24 is being operated in a first operational mode by the control and evaluation unit 28. The first operational mode includes an amplitude-modulation of a driving current through the light emitting member 24, and, by that, of the light emitted by the light emitting member 24 at a first modulation frequency. The amplitude-modulation is carried out by providing a driving current by the control and evaluation unit 28 that has a square wave shape with a fundamental frequency that lies within a frequency range between 1 kHz and 100 kHz, namely of 30 kHz.

[0046] In next steps 50, 54 of the method, sensor signals generated by emitted light which has been reflected by the scene are acquired and digitally converted. Amplitudes are obtained from the acquired sensor signals by carrying out an interim step 52 of synchronously demodulating the acquired sensor signals by mixing the phototransistor output signals with the amplitude-modulation signal of the first modulation frequency in order to suppress the influence of the background light. In another step 56 then, the change or variation of the obtained amplitudes is compared to a predetermined threshold for a signal amplitude variation. The predetermined threshold is chosen large enough in order to prevent undesired false activation by electronic noise or very small objects that happen to approach the optical sensor 26 by chance, such as leaves that are moved by the wind. [0047] The reflectance detection is switched on only periodically, namely each 100 ms, for a specified time of 1 ms, resulting in a duty cycle of the first operational mode of only 1 %. In-between the cycles of reflectance detection, the light emitting member 24 may be switched off in order to save power.

[0048] If the predetermined threshold for the signal amplitude variation is not reached or exceeded, the control and evaluation unit 28 continues with the step 50 of acquiring sensor signals.

[0049] Upon the change of amplitude of the acquired sensor signals exceeding the predetermined threshold for the signal amplitude variation, operating the light emitting member 24 in a second operational mode is commenced in the next step 60, which also includes a preceding step 58 of halting operating the light emitting member 24 in the first operational mode. The second operational mode includes an amplitude-modulation of a driving current through the light emitting member 24, and, by that, of the light emitted by the light emitting member 24, at a second modulation frequency. The amplitude-modulation is carried out by providing a driving current having a square wave shape with a fundamental frequency that is selected to have a fundamental frequency that is larger than 10 MHz, namely 30 MHz.

[0050] In another step 62, sensor signals generated by emitted light which has been reflected by the at least one object of the scene are acquired and digitally converted. Then, in the next step 64, data regarding distance between the optical sensor 26 and the at least one object are determined from time-of-f light information obtained from relations between the acquired sensor signals and the light emitted by the light emitting member 24. This is carried out by a mixer (not shown), for instance the mixer that had been carrying out the synchronous demodulation, or another mixer, that is operated in four different sequential phases. In the first phase, the mixer is using the modulation signal as local oscillator input. In the second phase, the mixer is using the modulation signal shifted by 90 degrees phase shift. In the third phase, the mixer is using the modulation signal shifted by 180 degrees, and in the fourth phase the mixer is using the modulation signal shifted by 270 degrees. The mixer output signal for each of the four phases is recorded, for instance with a microcontroller, using an analog-to-digital converter (ADC). The output signal of the first phase is assigned to a variable A, the second one to variable B, the third one to variable C, and the fourth one to variable D. Then, a value of the expression

is indicative of the distance between the optical sensor 26 and the at least one object. This measurement sequence and distance evaluation is repeated continually, with a repetition rate of 1 kHz, and for the duration of 1 s.

[0051 ] In another step 66, the determined data regarding the distance are evaluated with regard to a predetermined criterion, which is given by a duration of a close proximity to the optical sensor 26.

[0052] Optionally, the calculated values indicative of the distance between the optical sensor 26 and the at least one object can be further evaluated, for instance by the microcontroller, to reliably detect a user-side foot movement ("kick"). For instance, features in a temporal development of the determined data regarding the distance, such as a rising time of the mixer output signal or a falling time, a valley duration, or a rising time of the distance indication that are found to be characteristic for a human foot moving sideways back and forth in close proximity to the optical sensor 26, can be extracted in order to reliably discriminate between a valid kick movement and a false alarm.

[0053] If the predetermined criterion is fulfilled, a trigger signal 22 that is indicative of an occurrence of the event is generated by the processor unit 30 of the optical proximity detection system 20 in a next step 68. If the predetermined criterion is not fulfilled, the optical proximity detection system 20 resumes step 48 of operating the light emitting member 24 in the first operational mode, and the disclosed steps are repeated.

[0054] Fig. 3 is a schematic illustration of the control system 10 pursuant to Fig. 1 comprising an alternative embodiment of the optical proximity detection system 20 in accordance with the invention. For distinction purposes, the alternative control system is denoted by 10' and the alternative optical proximity detection system by 20'. For brevity, only differences to the embodiment disclosed beforehand will be described. [0055] The optical proximity detection system 20' comprises a second light emitting member 42. The control and evaluation unit 28 includes a second output port 36 and is configured for operating the first light emitting member 24 in the first operational mode and for operating the second light emitting member 42 in the second operational mode.

[0056] In a method of operating the alternative embodiment of the optical proximity detection system 20', the step 60 of commencing operating the second light emitting member 42 in the second operational mode may or may not include the preceding step 58 of halting operating the first light emitting member 24 in the first operational mode. The former has the advantage of a lower average power consumption. The latter has the advantage of providing additional information that can further be used for discriminating between a valid kick movement and a false alarm.

[0057] Fig. 5 is a schematic illustration of an alternative control system 10", comprising two optical proximity detection systems 20ι, 2Ο₂ in accordance with the invention. The two optical proximity detection systems 20ι, 2Ο₂ are identically designed to the optical proximity detection system 20 pursuant to Fig. 2. The control and evaluation unit 28i of the first optical proximity detection system 20i is at least configured for operating, controlled by the processor unit 12 of the control system 10", the light emitting member 24i in the first operational mode, and the control and evaluation unit 28₂ of the second optical proximity detection system 2Ο₂ is at least configured for operating, controlled by the at least one processor unit 12 of the control system 10", the light emitting member 24₂ in the second operational mode. If the upper part of Fig. 5 was an existing control system for controlling activation of a motor-driven vehicle door member already installed in a vehicle, retro-fitting would be possible in the way shown in Fig. 5.

[0058] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments.

[0059] Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting scope.

List of Reference Symbols

10 control system

12 processor unit

14 digital data memory unit

16 output signal

18 vehicle door member

20 optical proximity detection system

22 trigger signal

24 light emitting member

26 optical sensor

28 control and evaluation unit

30 processor unit

32 digital data memory unit

34 output port

36 output port

38 input port

40 control and evaluation unit

42 light emitting member

44 software module

46 data communication link steps of:

48 operate light emitting member in 1 st operational mode

50 acquire sensor signals

52 demodulate acquired sensor signals

54 digitally convert demodulated sensor signals

56 compare change of amplitudes to predetermined threshold

58 halting operating light emitting member in 1 st operational mode

60 operating light emitting member in 2nd operational mode

62 acquire sensor signals

64 determine data regarding distance sensor-object

66 evaluate determined distance data in view of criterion

68 generate trigger signal

Claims

1 . A method of operating an optical proximity detection system (20) with regard to generating a trigger signal (22) indicative of an occurrence of an event, the optical proximity detection system (20) comprising at least one light emitting member (24, 42), at least one optical sensor (26) that is configured to generate a sensor signal indicative of a change of incident light that has been emitted by the at least one light emitting member (24, 42) and has been reflected by a scene, and at least one control and evaluation unit (28; 40) for controlling an operation of the at least one light emitting member (24, 42) and for evaluating generated sensor signals, the method comprising steps of

- operating (48) at least one of the at least one light emitting member (24, 42) in a first operational mode,

- acquiring (50), by said at least one optical sensor (26), sensor signals generated by emitted light which has been reflected by the scene,

- comparing (56) an amplitude variation obtained from acquired sensor signals to at least one predetermined threshold for a signal amplitude variation,

- upon the amplitude variation of the acquired sensor signals exceeding the at least one predetermined threshold for a signal amplitude variation, commencing operating (60) at least one of the at least one light emitting member (24, 42) in a second operational mode,

- acquiring (62), by said at least one optical sensor (26), sensor signals generated by emitted light which has been reflected by at least one object of the scene,

- determining (64) data regarding distance between the at least one optical sensor (26) and the at least one object from time-of-flight information obtained from relations between the acquired sensor signals and the light emitted by the at least one light emitting member (24, 42),

- evaluating (66) the determined data regarding the distance with regard to at least one predetermined criterion, and

- generating (68) a trigger signal (22) indicative of an occurrence of an event if the at least one predetermined criterion is fulfilled.

2. The method of operating an optical proximity detection system (20) as claimed in claim 1 , wherein the steps are repetitively carried out.

3. The method of operating an optical proximity detection system (20) as claimed in claims 1 or 2, wherein the steps (50, 62) of acquiring sensor signals comprise a step (54) of digitally converting the acquired sensor signals.

4. The method of operating an optical proximity detection system (20) as claimed in any one of the preceding claims, wherein the step (60) of commencing operating at least one of the at least one light emitting member (24, 42) in a second operational mode comprises a preceding step (58) of halting operating the at least one of the at least one light emitting member (24, 42) in the first operational mode.

5. The method of operating an optical proximity detection system (20) as claimed in any one of the preceding claims, wherein the step (48) of operating at least one of the at least one light emitting member (24, 42) in a first operational mode includes amplitude-modulating the light emitted by the at least one of the at least one light emitting member (24, 42) at a first modulation frequency, and wherein the step (56) of comparing an amplitude variation of acquired sensor signals includes a preceding step (52) of demodulating the acquired sensor signals.

6. The method of operating an optical proximity detection system (20) as claimed in any one of the preceding claims, wherein the step (60) of operating at least one of the at least one light emitting member (24, 42) in a second operational mode includes amplitude-modulating the light emitted by the at least one of the at least one light emitting member (24, 42) at a second modulation frequency.

7. The method of operating an optical proximity detection system (20) as claimed in claim 5 or 6, wherein the first modulation frequency is selected to have a fundamental frequency that lies within a frequency range between 1 kHz and 100 kHz, and the second modulation frequency is selected to have a fundamental frequency that is larger than 10 MHz.

8. The method of operating an optical proximity detection system (20) as claimed in any one of the preceding claims, wherein a duty cycle of the first operational mode is less than 5%.

9. The method of operating an optical proximity detection system (20) as claimed in any one of claims 1 to 8, wherein

- the event is formed by an operator-intended control event, and

- the trigger signal (22) is designed as an input to a control system (10) for controlling an activation of a motor-driven vehicle door member (18).

10. An optical proximity detection system (20) for generating a trigger signal (22) indicative of an occurrence of an event, comprising

- a light emitting member (24),

- at least one optical sensor (26) that is configured to generate a sensor signal indicative of a change of incident light that has been emitted by the light emitting member (24) and has been reflected by a scene, and

- a control and evaluation unit (28) for controlling an operation of the light emitting member (24) and for evaluating the generated sensor signals,

- at least one processor unit (30) and at least one digital data memory unit (32), wherein the at least one processor unit (30) has data access to the at least one digital data memory unit (32),

wherein the at least one processor unit (30) is configured to carry out the steps of the method as claimed in any one of claims 1 to 9.

1 1 . The optical proximity detection system (20) as claimed in claim 10, further comprising at least a second light emitting member (42), wherein the control and evaluation unit (40) is configured for operating the first light emitting member (24) in the first operational mode and for operating the second light emitting member (42) in the second operational mode in accordance with the steps of the method as claimed in any one of claims 1 to 9.

12. A control system (10) for controlling activation of a motor-driven vehicle door member (18), the control system (10) comprising - at least one processor unit (12) and at least one digital data memory unit (14), wherein the at least one processor unit (12) has data access to the at least one digital data memory unit (14), - an optical proximity detection system (20) for generating a trigger signal (22) indicative of an occurrence of an event as claimed in claim 10 or 1 1 ,

wherein the at least one processor unit (12) is configured to receive the trigger signal (22) from the optical proximity detection system (20) and, upon and as long as receiving the trigger signal (22) from the optical proximity detection system (20), to generate an output signal (16) for at least initiating an activation of the motor-driven vehicle door member (18).

13. The control system (10) as claimed in claim 12, further comprising a second optical proximity detection system (2Ο₂), wherein the control and evaluation unit (28i) of the first optical proximity detection system (20i) is at least configured for operating, controlled by the at least one processor unit (12) of the control system, the at least one light emitting member (24) in the first operational mode, and

the control and evaluation unit (28₂) of the second optical proximity detection system (2Ο₂) is at least configured for operating, controlled by the at least one processor unit (12) of the control system, the at least one light emitting member (24₂) in the second operational mode.

14. The control system (10) as claimed in claim 12 or 13, wherein the motor-driven vehicle door member (18) is designed as a vehicle trunk or a vehicle tailgate.

15. A software module (44) for carrying out the method as claimed in any one of claims 1 to 9, wherein the method steps (48 - 68) to be conducted are converted into a program code of the software module (44), and wherein the program code is implementable in a digital data memory (32) and is executable by a processor unit (30).

16. Use of the optical proximity detection system (20) for generating a trigger signal (22) indicative of an occurrence of an event as claimed in claim 10 to 12 in a control system (10) for controlling activation of a motor-driven vehicle door member (18) as claimed in claim 13 or 14.