EP2900037A1 - Circuit à capteur optique, panneau lumineux et procédé pour faire fonctionner un circuit de capteur optique - Google Patents

Circuit à capteur optique, panneau lumineux et procédé pour faire fonctionner un circuit de capteur optique Download PDF

Info

Publication number
EP2900037A1
EP2900037A1 EP14152147.6A EP14152147A EP2900037A1 EP 2900037 A1 EP2900037 A1 EP 2900037A1 EP 14152147 A EP14152147 A EP 14152147A EP 2900037 A1 EP2900037 A1 EP 2900037A1
Authority
EP
European Patent Office
Prior art keywords
signal
color
light
optical sensor
sensor
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP14152147.6A
Other languages
German (de)
English (en)
Inventor
Curd Trattler
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ams Osram AG
Original Assignee
Ams AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ams AG filed Critical Ams AG
Priority to EP14152147.6A priority Critical patent/EP2900037A1/fr
Priority to US14/276,960 priority patent/US9480122B2/en
Priority to US14/541,082 priority patent/US9451667B2/en
Publication of EP2900037A1 publication Critical patent/EP2900037A1/fr
Withdrawn legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/20—Controlling the colour of the light
    • H05B45/22—Controlling the colour of the light using optical feedback
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/32—Pulse-control circuits
    • H05B45/327—Burst dimming

Definitions

  • This invention relates to an optical sensor circuit, to a luminous panel and to a method for operating an optical sensor circuit.
  • Light emitting diodes or LEDs find increasing application in electric lighting.
  • flat light luminaries or panels comprise diffusers framed by an array of light emitting diodes (LEDs) to illuminate larger areas and are applied in back light illuminated displays and LED light guides.
  • Luminaries may support color tuning capabilities. This can be obtained by mixing together of different contributions of different types of LEDs, e.g. cold and warm white light LEDs, in order to achieve a desired correlated color temperature (CCT).
  • CCT correlated color temperature
  • a color sensor can be placed inside the luminaire in order to directly sample the light, e.g. color point x, y of the luminaire.
  • the color sensor is placed behind a light guide and a diffuser in order to measure the color temperature. Based on this color point, the CCT value (e.g. based on the McCamy formula) is calculated and transferred to a control loop (PID) to adjust the LEDs accordingly to obtain a constant correlated color temperature (CCT) over temperature and lifetime of the luminaire.
  • PID control loop
  • the object of this invention is to provide an optical sensor circuit, a luminous panel and a method for operating an optical sensor circuit which overcomes the above mentioned problems, and, in particular, improves the CCT measurement.
  • an optical sensor circuit comprises an optical sensor, a clock and a controller unit connected to both the optical sensor and to the clock.
  • the optical sensor is designed to provide a sensor signal indicative of incident light.
  • the sensor signal is indicative of a color of the incident light.
  • the clock provides a clocked control signal.
  • the clocked control signal comprises consecutive high and low states.
  • the clock may comprise a clock terminal in order to receive the clocked control signal from external means.
  • the clock is implemented on-chip.
  • the controller unit further comprises the control terminal which can be connected to a light-emitting device or to an array of light-emitting devices.
  • the optical sensor circuit can be implemented in at least two ways, which may be alternatives but can be combined as well.
  • the controller unit is designed to process the sensor signals.
  • the controller unit is designed to process the sensor signals depending on the control signal, i.e. whether the control signal is in its high or low state.
  • the controller unit processes a first sensor signal recorded during a high state of the control signal and a second sensor signal recorded during a low state of the control signal.
  • the assignment of low and high states is interchangeable, of course.
  • the optical sensor In operation the optical sensor is exposed to light which may originate from several sources. Depending on the properties of light incident on the optical sensor, e.g. its brightness and/or color, the sensor generates a sensor signal, which is recorded as the first or second sensor signal, for example. Via the connection to the controller unit the (first and second) sensor signal is provided to the controller unit.
  • the controller unit receives the clocked control signal.
  • the states, e.g. high or low at least two different modes of operation are set in the controller unit.
  • the controller unit performs signal processing of the (first and second) sensor signals with respect to different properties or origin of the incident light.
  • the controller unit is designed to process the sensor signal as a color signal in a first mode if the clocked control signal is in high state.
  • the sensor signal is processed as an ambient light signal in a second mode if the clocked control signal is in low state.
  • the first sensor signal corresponds to the color signal
  • the second sensor signal corresponds to the ambient light signal.
  • the color signal is indicative of a color of light emitted by a light emitting device to be connected at the control terminal.
  • the ambient light signal is indicative of an intensity of ambient light.
  • the controller unit is designed to process the sensor signal as a color signal in a first mode if the clocked control signal is in high state.
  • the sensor signal is processed as an ambient color light signal in a second mode if the clocked control signal is in low state.
  • the first sensor signal corresponds to the color signal
  • the second sensor signal corresponds to the ambient color light signal.
  • the color signal is indicative of a color of light emitted by a light emitting device to be connected at the control terminal.
  • the ambient color light signal is indicative of a color of ambient light.
  • the controller unit Depending on the processing, i.e. color or ambient light in the first implementation or color light signal and ambient color light signal in the second implementation, according to the first and second mode, respectively, the controller unit generates a driving signal which is used to drive the light-emitting device to be connected at the control terminal.
  • the driving signal depends on the color and ambient light signal or color light signal and ambient color light signal.
  • the term "light” hereinafter denotes electromagnetic radiation in the visible but can also include parts of the infrared and ultraviolet.
  • Ambient light refers to any source of light that is not explicitly controlled by the optical sensor circuit, i.e. when connected to a light emitting device.
  • the color of light, i.e. detected via the color signal is a function of wavelength.
  • the color signal can be an explicit function of wavelength or be integrated over a given spectral range.
  • a clocked signal hereinafter comprises at least one high and low state, typically a succession of these states.
  • the driving signal for example, can be a clocked driving signal as well.
  • the clocked signal and the driving signal is a function of high and low state but does not necessarily have to be periodic.
  • the driving signal can be of pulse width modulation type.
  • the pulse width modulation can be used for driving the light-emitting devices.
  • the high and low states then correspond to on and off states of the light-emitting device.
  • light emitting diodes are used as light-emitting devices. However, other sources are possible as well, like fluorescent or incandescent lamps. If these light-emitting devices are light-emitting diodes, the pulse width modulation can be used to adjust brightness and/or color via a duty cycle of the modulation signal.
  • the described first implementation of the optical sensor circuit allows for ambient light measurement and color measurement using just a single optical sensor.
  • the controller unit evaluates the sensor signal as color signal or ambient light signal using just the single sensor unit.
  • the described second implementation of the optical sensor circuit has similar properties but allows for color light measurement of ambient light and color measurement of light emitted from connected light sources using just a single optical sensor.
  • the optical sensor circuit offers the possibility to measure the color point of ambient light and the color of the luminaire with only one color sensor which, for example, can be mounted behind a panel of a luminaire.
  • the color point does not only depend on the light of the light emitting device(s) but also on the surrounding ambient light entering the optical sensor or the luminaire.
  • the positioning of the color point and consequently the CCT value can be accounted for using the driving signal to drive the light emitting device. There is no need to switch off the light emitting device(s) in order to determine the color of ambient light.
  • the color measurements can be executed in a time frame not perceptible to human sight.
  • the clock is coupled to the control terminal such that the clocked control signal is synchronized to the clocked driving signal.
  • the first and second mode of operation of the optical sensor circuit make use of the timing differences of the clocked control signal wherein timing refers to the temporal succession of high and low states.
  • the states of the clocked signal indicate the controller unit to process the sensor signal as an ambient light signal or as color signal or, ambient color light signal and color signal.
  • the first mode starts with a low state of the clocked control signal and continues for a number of clock cycles, e.g. five successive high and low states.
  • the second mode then starts after the number of clock cycles has passed, e.g. with the first high state after the five successive high and low states.
  • a low state of the clocked control signal is assigned to ambient (color) light signal and a low state of the clocked control signal is assigned to color light signal.
  • the controller unit comprises a master clock in order to define the number of clock cycles.
  • the clocked control signal is via the driving signal provided at the control terminal.
  • This driving signal is a clocked signal.
  • the clocked control signal allows for separating the ambient light processing from the color light processing by synchronizing the detection via the optical sensor to the driving signal. Thereby the processing is synchronized to the state of the light emitting device, e.g. whether the light emitting device is turned on or off.
  • the light-emitting device is off. As no light is emitted in this state, and ambient light measurement or ambient color light measurement is synchronized, only light originating from the surroundings of the optical sensor circuit is recorded by the optical sensor.
  • the color processing of the color signal or ambient color signal is executed. During this time the light-emitting device is turned on. The sensor signals therefore record the light emitted by the light-emitting device and the light originating from the surroundings as ambient light signal or ambient color signal.
  • the clock is coupled to the optical sensor such that the clocked control signal is synchronized to the sensor signal.
  • the sensor signal can be used.
  • the light-emitting device is driven by the driving signal which is clocked into high and low states as well. Accordingly, the optical sensor will detect a low level and high level indicating that the light-emitting device is switched on and off, respectively. In turn, the succession of high and low states received in this manner can be used to generate the clocked control signal from the sensor signal. The operation of a controller unit can then be synchronized to this detected sensor signal.
  • the sensor signal indicates different brightness level of light emitted by the light-emitting device.
  • the optical sensor is a color sensor.
  • the color sensor can be a single device characterized by an overall spectral responsivity or can comprise several elements each being sensitive to a specific spectral range or wavelength.
  • the color sensor comprises at least two sensor elements, in particular three sensor elements. Each of these sensor elements is sensitive to a corresponding spectral range of light and/or connected to a corresponding optical filter.
  • the sensor elements can be constructed to be sensitive only to a certain spectral range of light.
  • the sensitivity can also be adjusted or additionally controlled by using optical filters which are attached to the individual sensor elements.
  • optical filters which are attached to the individual sensor elements.
  • red, green and blue spectral ranges can be selected and the respective sensor signals from the individual sensor elements contain spectral properties of the light incident on the optical sensor circuit.
  • a spectral response curve can thus be constructed.
  • the sensor elements can be photodiodes, charge coupled devices or avalanche photodiodes. Additional infrared filters can also be provided.
  • the at least two sensor elements each generate respective sensor sub-signals indicative of light incident on the optical sensor.
  • the controller unit comprises means to combine the sensor sub-signals as a function of wavelength of light. Then, the sensor sub-signals are processed by the controller unit as the color signal, e.g. indicating the color of light emitted by the light-emitting device.
  • the controller unit also comprises means to combine the sensor sub-signals into the ambient light signal.
  • the ambient light signal is processed, indicating the level of ambient light. For example, adding the sub-signals from the individual sensor elements results in an integral sensor signal which gives a measure of ambient light, e.g. brightness.
  • the color light signal and the ambient color light signal are sub-signals which are integrated by means of separated units, e.g. two signal-to-frequency converters.
  • the driving unit comprises a signal-to-frequency converter.
  • the sensor signal typically a photo current
  • the sensor signals are recorded for a given period of time.
  • the signal-to-frequency converter is used to accumulate the sensor signal depending on a frequency signal applied to the converter. The more counts the optical sensor generates the stronger the sensor signal, and vice versa.
  • a driver circuit is connected between the control terminal and the light-emitting device.
  • a DC/DC converter is used to supply a current to the light-emitting device.
  • a controller circuit is used to adjust brightness and/or color of the light-emitting device depending on the driving signal.
  • the driver circuit can either be an integral part of the optical sensor circuit and be integrated on the same die or connected externally.
  • the controller unit comprises a micro-controller and/or control logic.
  • the functionality of the optical sensor circuit as described herein can be realized by appropriate programming of the micro-controller. Alternatively, or in addition, some or all of the presented units can be realized by logical components.
  • the optical sensor circuit can be implemented as an application-specific integrated circuit (ASIC).
  • a luminous panel comprises a transparent luminary board, an array of light-emitting devices connected to the luminary board, an optical sensor circuit is also included according to the principles presented above and electrically connected to the array of light-emitting devices.
  • light-emitting diodes are used as light-emitting devices.
  • the array of light emitting diodes In the first implementation during the first mode of operation the array of light emitting diodes is turned on and, in addition to ambient light, light is emitted by the panel and reflected from nearby surfaces as reflected light back to the panel and the optical sensor. Consequently, the optical sensor detects both emitted light and ambient light as sensor signal.
  • the array of light emitting diodes In the second mode of operation the array of light emitting diodes is turned off and no light is emitted from the panel. The optical sensor in this mode only detects ambient light reflected from the surroundings into the panel as reflected light.
  • the array of light emitting diodes is turned on and, in addition to ambient light, light is emitted by the panel and reflected from nearby surfaces as reflected light back to the panel and the optical sensor. Consequently, the optical sensor detects both the color of emitted light and ambient light as sensor signal.
  • the array of light emitting diodes is turned off and no light is emitted from the panel. The optical sensor in this mode only detects ambient light reflected from the surroundings into the panel as reflected light.
  • the luminous panel preferably comprises a diffuser, a light guide, and a reflector which are connected with each other in a stacked fashion.
  • the light guide is framed with the array of light emitting diodes.
  • the light guide is adapted to guide light emitted from the light emitting diodes.
  • the guided light will predominately enter the diffuser.
  • the light will leave the panel as emitted light in a directed fashion. This happens either directly via the diffuser or indirectly after being reflected at reflector.
  • the light-emitting devices comprise red, green and blue light-emitting diodes.
  • white light-emitting diodes in particular light emitting diodes with different color temperature, e.g. cold and warm white light-emitting diodes, can be used. This way brightness and/or color of light emitted by the array can be altered by adjusting individual light-emitting diodes from the array, e.g. by changing the duty cycle of the driving signal.
  • red, green and blue light-emitting diodes do not result in a pleasant perception of the overall brightness and/or color of light emitted by the array.
  • other mixing schemes apart from red, green, and blue are employed.
  • mixing of green and blue light-emitting diodes with warm or cold white light-emitting diodes may lead to a more pleasant lighting.
  • the mixing generally depends on the desired effect, whether it is is applied to room lighting or product showcases, for example.
  • a method for an optical sensor circuit comprises the step of receiving light by means of an optical sensor and providing a sensor signal indicative of the incident light.
  • the sensor signal is indicative of a color of the incident light.
  • a clocked control signal is received comprising consecutive high and low states.
  • the sensor signal is selectively processed as a first sensor signal in a first mode if the clocked control signal is in a high state, or processed as a second sensor signal in a second mode if the clocked control signal is in low state.
  • a clocked driving signal is generated to drive a light-emitting device depending on the color and/or intensity of the first and second sensor signals.
  • the driving signal can be used to adjust a color point, for example.
  • the method for optical sensor circuit can be implemented in at least two ways which may be alternatives but can be combined as well.
  • the first sensor signal is a color signal and the second sensor signal is processed as an ambient light signal.
  • the first sensor signal corresponds to color signal and the second sensor signal corresponds to the ambient light signal.
  • the color signal is indicative of a color of light emitted by a light emitting device to be connected at a control terminal.
  • the ambient light signal is indicative of an intensity of ambient light.
  • the first sensor signal is a color signal and the second sensor signal is an ambient color light signal.
  • the first sensor signal corresponds to the color signal and the second sensor signal corresponds to the ambient color light signal.
  • the color signal is indicative of a color of light emitted by a light emitting device to be connected at a control terminal.
  • the ambient color light signal is indicative of a color of ambient light.
  • Measurement of ambient light measurement and color measurement in the first implementation and color measurement in the second implementation can be achieved by using just a single optical sensor.
  • the sensor signal can be processed both as color signal or ambient light signal or color signal and ambient color signal. This has the benefit of smaller size and reduced cost of the implementation in a circuit.
  • the sensor can be made non-visible so as to reside behind a diffuser and detect through the diffuser. An optical separation of an ambient light sensor from a luminary is therefore not required. This allows for improved freedom of design of the luminary panel as there is no need to take care of a light sensor by design.
  • the described second implementation of the optical sensor circuit has similar properties but allows for color light measurement of ambient light and color measurement of connected light sources using just a single optical sensor.
  • the optical sensor circuit offers the possibility to measure the color point of ambient light and the color of the luminaire with only one color sensor which, for example, can be mounted behind a panel of a luminaire.
  • the color point does not only depend on the light of the light emitting device(s) but also on the surrounding ambient light entering the optical sensor or the luminaire.
  • the positioning of the color point and consequently the CCT value can be accounted for using the driving signal to drive the light emitting device.
  • the method further comprises the step of synchronizing the clocked control signal to the driving signal.
  • the step of synchronizing the clocked signal is performed with respect to the sensor signal.
  • the control signal in the first mode, is processed so as to indicate a color of light emitted by the light-emitting device.
  • the ambient light signal is processed so as to indicate the level of ambient light in the first implementation.
  • the ambient light color signal is processed so as to indicate the color of ambient light.
  • a color point can be determined from both color light signal and ambient light color signal. These color points can be compared and, in turn, differences can be used to adjust the color of light emitted by the light-emitting device.
  • FIG. 1 shows an exemplary embodiment of an optical sensor circuit according to the principle presented.
  • the optical sensor circuit comprises a controller unit CU, an optical sensor DET, a clock, and several terminals.
  • the terminals comprise a first and a second control terminal OUT1, OUT2.
  • Other terminals can be provided but will not be described in further detail.
  • Such terminals can be related to additional functionality of the controller unit CU such as dimming, switching, occupancy detection and programming.
  • the controller unit CU is connected to the optical sensor DET. Furthermore, the controller unit CU is connected to the first and second control terminals OUT1, OUT2. All these components are preferably integrated into a common integrated circuit structure but may just as well be separate units.
  • the optical sensor DET can be integral part of an integrated optical sensor circuit or an external component connected to the remaining circuit.
  • the controller unit CU comprises a micro-controller or control logic.
  • the controller unit CU may be an application-specific integrated circuit or ASIC. The components and functionality will be described in more detail below and can be implemented as dedicated hardware components like control logic, or as programmed units of the micro-controller.
  • the optical sensor DET preferably is a color sensor.
  • the color sensor comprises a single or several sensor elements like photodiodes or charge coupled devices which are sensitive to visual light.
  • the color sensor generates a sensor signal which depends on wavelength.
  • the spectral response can be realized by a single sensor element, for example by recording several sensor signals each being spectrally separated by appropriate means such as filters, prisms or gratings.
  • the filters have characteristic spectral transmission curves.
  • several sensor elements can be used to generate respective sub-signals. Each sensor element can be sensitive to a different color or spectral range. Again, this can be implemented by filters, prisms or gratings being attached to the respective sensor element. Or the sensor elements already generate the sub-signals as a function of wavelength. In any of these cases the resulting sensor sub-signals are indicative of the color of light they detect and can be processed individually or be combined to a color signal.
  • the optical sensor circuit further comprises a driver circuit DRV which is connected to the first and second control terminals OUT1, OUT2. Furthermore, the driver circuit DRV is connected to an array of light emitting devices LED. A DC/DC converter is used to supply a current to light-emitting devices LED. A controller circuit is used to adjust brightness and/or color of the light-emitting device.
  • the driver circuit can either be an integral part of the optical sensor circuit and be integrated on the same die or connected externally.
  • the light emitting devices LED are connected to the driver circuit DRV.
  • the light emitting devices are light emitting diodes, for example a first string LED1 comprising cold white LEDs and a second string LED2 comprising warm white LEDs (tunable white) and/or colored LEDs such as red, green, and blue.
  • Figure 2A shows an exemplary timing diagram of an optical sensor circuit according to the principle presented.
  • the drawing shows a first driving signal PWM1 of the first string LED1 of light emitting diodes, a second driving signal PWM2 of the second string LED2 of light emitting diodes, an ambient color light enable signal aCTS_en, an ambient color light signal aCTS, a color enable signal CTS_en, and a color light signal CTS as functions of time t.
  • the light emitting devices LED1, LED2 are sketched with their electronic symbol.
  • the reference numeral ON indicates that a light emitting device is switched on and a reference numeral OFF indicates the light emitting device is switched off.
  • the operation of the optical sensor is synchronized to the timing of a clocked control signal to be provided by the clock.
  • the clocked control signal is used to define the driving signals PWM1 or PWM2 of the light emitting devices.
  • the drawing shows the driving signal PWM1, PWM2 comprising high and low states which correlate to the LEDs being switched on or off, respectively.
  • the operation of the controller unit CU is synchronized to the timing of the clocked control signal. Depending on the states of the clocked control signal the controller unit CU enters a first or second mode of operation in which the sensor signal from the optical sensor is processed differently.
  • the first and second mode of operation are defined with respect to the clock and the first and second driving signals PWM1, PWM2 are synchronized.
  • the first mode starts and the first and second driving signal PWM1, PWM2 are in a low state OFF, and continues for a number of clock cycles, e.g. five successive high and low states ON, OFF.
  • the second mode starts after the number of clock cycles has passed, e.g. with the first high state ON of the first or second driving signal PWM1, PWM2 after the five successive high and low states ON, OFF.
  • the light emitting devices LED1, LED2 are switched off and ambient color light signal aCTS can be recorded.
  • the controller unit CU comprises a master clock in order to define the number of clock cycles.
  • the first mode is depicted as light grey box 1 and the second mode is depicted as dark grey box 2.
  • first and the second mode can be defined differently.
  • first and second mode can switch synchronous to high and low states ON, OFF.
  • the controller unit CU issues the color enable signal CTS_en.
  • the sensor signal is processed as a color signal CTS.
  • the color signal CTS includes information of the light emitted by the LEDs as it is synchronized to states in which the LEDs are turned on.
  • the optical sensor also records ambient light which is present as well.
  • the color signal CTS can be corrected for ambient light, for example, by subtracting the ambient light signal aCTS to be recorded in the first mode.
  • the color light signal CTS includes information on the color of the light emitted by the LEDs as the optical sensor generates a wavelength dependent sensor signal or a number of wavelength dependent sensor sub-signals.
  • the controller unit CU evaluates these signals as an indication of color, or color temperature. For example, the controller unit CU comprises means to determine the color point.
  • the controller unit CU comprises means to adjust the driving signals PWM1, PWM2 to alter the color emitted by the LEDs. This can be achieved via the driving circuit DRV.
  • the driving signals PWM1, PWM2 are applied to the different LEDs such that only certain strands LED1, LED2 or individual LEDs from the array are used or partly used. For example, when using cold and warm white LEDs their respective colors can be mixed to result in a desired mix, e.g. tune-able white. If LEDs of different color are used a desired mixed color can be adjusted.
  • the controller unit CU issues the ambient light enable signal aCTS_en.
  • the sensor signal is processed as an ambient color light signal aCTS.
  • the ambient color light signal aCTS includes information on the light originating from the surroundings of the optical circuit it is synchronized to states in which the LEDs are turned off.
  • the controller unit CU comprises means process the sensor signal or the sensor sub-signals such as to indicate the color of ambient light.
  • the means to adjust the driving signals PWM1, PWM2 of the controller unit CU can be used to alter the brightness and/or color emitted by the LEDs. For example, this can be achieved by adjusting the duty cycle of the driving cycle, i.e. adjust the timing of high and low states or adjust the times during which the LEDs are turned on and off, respectively. This way the color point characterizing the emitted light can also be adjusted.
  • the clock is coupled to the optical sensor DET.
  • the clocked control signal can be synchronized to the sensor signal.
  • the optical sensor will detect a low level and high level indicating that the light-emitting device is switched on and off, respectively.
  • the succession of high and low states received in this manner is clocked.
  • the operation of a controller unit CU can then be synchronized to the sensor signal in the way described above, e.g. with respect to Figure 2A .
  • the sensor signal indicates different brightness level of light emitted by the light-emitting device.
  • This embodiment can also be used if the signal for driving of the LEDs is not available, e.g. the optical sensor is separated from the LED driving circuit.
  • the signal for driving of the LEDs is not available, e.g. the optical sensor is separated from the LED driving circuit.
  • the LED light signal can distinguish ambient color light signal from the LED light signal by level. For example, the light brightness is measured every 1ms. If the measured sensor signal is low, this level is used as ambient light signal. Once the signal is high this sensor signal is used as color signal. Any measurements which have a level in-between, e.g. caused by 50% ambient light and 50% LED light are discarded. For example, due to the concept of the sensor placement close to a luminary it can be assumed that the signal from the light emitting device is substantially higher compared to the signal from the ambient light. Therefore, the above approach can separate these two levels easily.
  • Figure 2B shows an exemplary chromaticity diagram of an optical sensor circuit according to the principle presented, for example, according to the CIE 1976 standard (CIE: International Commission on Illumination).
  • CIE 1976 standard CIE: International Commission on Illumination
  • the drawing shows a cutout of a color space which can be characterized by chromaticity coordinates x, y (or, in a different representation by coordinates u', v').
  • Line 11 indicates the chromaticity of black-body radiation sources of various temperatures, e.g. 3500 K to 6000 K.
  • the control unit CU comprises processing means to process the ambient color light signal aCTS and the color light signal CTS.
  • the determined first color point color1 corresponds to the color of the ambient light only (color(ambient)).
  • the determined second color point color2 corresponds to the color of the light emitting devices LED1, LED2 and the ambient light.
  • color(LED1, LED2) is the color produced by the LEDs themselves. Therefore, the correct color point and consequently the correct CCT value can be obtained.
  • Figure 2B shows the mixing of the luminaire light and the surrounding light sources.
  • surrounding light generates a CCT value of 5700K
  • the luminaire generates 4000K.
  • the mixed result gives a wrong CCT value of 4470K (see line 12).
  • the correct CCT value can be calculated.
  • Figures 3A and 3B show exemplary embodiments of a current-to-frequency converter according to the principle presented.
  • the drawings show too alternative implementations of a current-to-frequency converter which is used as part of the controller unit to acquire the sensor signal from the optical sensor DET.
  • the optical sensor DET is connected to a switchable integrator INT and a reference circuit REF.
  • the integrator INT is further connected to a flip-flop FLP via a comparator COMP.
  • An output of the flip-flop FLP is connected to the reference circuit REF and to a logic gate AND.
  • the logic gate AND comprises an enable input to be provided with an enable signal.
  • the current-to-frequency converter is basically used to acquire the sensor signal which, for example, is a photocurrent generated in a photodiode, for a given period of time. From Figure 2A it is apparent that the sensor signals aCTS and CTS are accumulated with each measurement initiated by the enable signals aCTS_en and CTS_en. The so acquired sensor signals are translated into counts per time using the current-to-frequency converter.
  • the sensor signals are integrated by means of the integrator INT.
  • the integrated sensor signal ramps up and is provided at an input of the comparator COMP. There it is compared with a reference vref. Every time the integrated sensor signal reaches the level of the reference the comparator COMP is set to its high state.
  • the flip-flop FLP generates a measure of such high states per time.
  • a time reference is applied to the flip-flop FLP via a clock signal clk'.
  • the flip-flop FLP outputs a count signal fOUT which is indicative of the measured sensor signal as counts per time, the time being set by the clock signal clk'.
  • the count signal fOUT is fed to the reference circuit REF in order to initiate a reset to a reference level.
  • the count signal fOUT is also fed to the logic gate AND.
  • the count signal fOUT is read out if the enable signal is set at the enable input.
  • the embodiment of Figure 3B is similar to the one described above.
  • the logic gate AND is replaced by a switch SW connected between the optical sensor DET and the integrator INT.
  • the enable signal aCTS_EN, CTS_EN controls the switch SW such as to enable current-to-frequency conversion only when it is applied to the circuit.
  • Figures 4A and 4B show an exemplary embodiment of a luminous panel according to the principle presented.
  • the drawings show a section of the planar luminous panel during the first ( Figure 4B ) and second mode ( Figure 4A ) of operation of the optical sensor circuit (implied by the dashed box in the drawings).
  • the luminous panel comprises a diffuser DF, a light guide LG, and a reflector RF which are connected with each other in a stacked fashion.
  • the light guide LG is framed with an array of light emitting diodes LED as indicated by individual diode electrical symbols.
  • the light guide LG is adapted to guide light emitted from the light emitting diodes LED.
  • the guided light will predominately enter the diffuser DF.
  • the light will leave the panel as emitted light EL in a directed fashion. This happens either directly via the diffuser DF or indirectly after being reflected at reflector RF.
  • Figure 4A shows the situation during the second mode of operation. During this mode the light emitting diodes LED are turned off no light EL is emitted from the panel.
  • the optical sensor DET in this mode only detects ambient light AL reflected from the surroundings into the panel as reflected light RL.
  • Figure 4B shows the situation during the first mode of operation.
  • the light emitting diodes LED are turned on and, in addition to ambient light AL, light EL is emitted by the panel and reflected as reflected light RL back to the panel and the optical sensor DET. Consequently, the optical sensor DET detects both emitted light EL and ambient light AL as sensor signal.

Landscapes

  • Circuit Arrangement For Electric Light Sources In General (AREA)
EP14152147.6A 2013-05-15 2014-01-22 Circuit à capteur optique, panneau lumineux et procédé pour faire fonctionner un circuit de capteur optique Withdrawn EP2900037A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
EP14152147.6A EP2900037A1 (fr) 2014-01-22 2014-01-22 Circuit à capteur optique, panneau lumineux et procédé pour faire fonctionner un circuit de capteur optique
US14/276,960 US9480122B2 (en) 2013-05-15 2014-05-13 Optical sensor circuit, luminous panel and method for operating an optical sensor circuit
US14/541,082 US9451667B2 (en) 2013-05-15 2014-11-13 Optical sensor circuit, luminous panel and method of operating an optical sensor circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP14152147.6A EP2900037A1 (fr) 2014-01-22 2014-01-22 Circuit à capteur optique, panneau lumineux et procédé pour faire fonctionner un circuit de capteur optique

Publications (1)

Publication Number Publication Date
EP2900037A1 true EP2900037A1 (fr) 2015-07-29

Family

ID=50002524

Family Applications (1)

Application Number Title Priority Date Filing Date
EP14152147.6A Withdrawn EP2900037A1 (fr) 2013-05-15 2014-01-22 Circuit à capteur optique, panneau lumineux et procédé pour faire fonctionner un circuit de capteur optique

Country Status (1)

Country Link
EP (1) EP2900037A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109470328A (zh) * 2019-01-04 2019-03-15 智恒科技股份有限公司 一种多点感应式正反转识别的智能水表光脉冲传感器
WO2021170455A1 (fr) * 2020-02-24 2021-09-02 Tridonic Gmbh & Co Kg Détection de lumière ambiante au moyen de deux capteurs de lumière disposés à l'intérieur d'un luminaire

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090167195A1 (en) * 2007-12-28 2009-07-02 Sony Corporation Light source system
US20100207531A1 (en) * 2009-02-19 2010-08-19 Microsemi Corp. - Analog Mixed Signal Group Ltd. Color management for field-sequential lcd display

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090167195A1 (en) * 2007-12-28 2009-07-02 Sony Corporation Light source system
US20100207531A1 (en) * 2009-02-19 2010-08-19 Microsemi Corp. - Analog Mixed Signal Group Ltd. Color management for field-sequential lcd display

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109470328A (zh) * 2019-01-04 2019-03-15 智恒科技股份有限公司 一种多点感应式正反转识别的智能水表光脉冲传感器
WO2021170455A1 (fr) * 2020-02-24 2021-09-02 Tridonic Gmbh & Co Kg Détection de lumière ambiante au moyen de deux capteurs de lumière disposés à l'intérieur d'un luminaire
AT17491U1 (de) * 2020-02-24 2022-06-15 Tridonic Gmbh & Co Kg Umgebungslichterfassung mittels zweier innerhalb einer Leuchte angeordneten Lichtsensoren

Similar Documents

Publication Publication Date Title
US9451667B2 (en) Optical sensor circuit, luminous panel and method of operating an optical sensor circuit
US7923935B2 (en) Illumination control system for light emitters
US9706619B2 (en) Lighting fixture with image sensor
US9686477B2 (en) Lighting fixture with image sensor
US7709774B2 (en) Color lighting device
JP5160620B2 (ja) 色空間の限られた領域で光を発する効率的な固体光源
CN101632113B (zh) 具有空间可变背光的显示器的校准
CN100490595C (zh) 发光二极管控制装置
KR101452519B1 (ko) 고상 조명 패널들의 조정 시스템들 및 방법들
EP2168404B1 (fr) Systèmes et procédés pour étalonner des panneaux d'éclairage à semi-conducteurs au moyen de mesures de sorties lumineuses combinées
US20100171429A1 (en) Method of LED dimming using ambient light feedback
US7649161B2 (en) Light source utilizing light pipes for optical feedback
US20060018118A1 (en) Spectrum matching
CN109690264B (zh) 用于基于摄像机的环境光估计的方法和系统
EP2804047A1 (fr) Circuit à capteur optique, panneau lumineux et procédé pour faire fonctionner un circuit de capteur optique
US9480122B2 (en) Optical sensor circuit, luminous panel and method for operating an optical sensor circuit
CN114097307A (zh) 多通道颜色调节的时间切片
JP6799804B2 (ja) 照明装置及びそれを備えた照明システム、移動体
EP2900037A1 (fr) Circuit à capteur optique, panneau lumineux et procédé pour faire fonctionner un circuit de capteur optique
JP2017162571A (ja) 照明システム及びそれを備えた移動体
JP2011107234A (ja) 液晶ディスプレイ装置および発光装置
USRE49705E1 (en) Interference-resistant compensation for illumination devices using multiple series of measurement intervals
KR101489741B1 (ko) Ｌｅｄ 색온도 제어 방법 및 시스템

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 20140122

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

AX Request for extension of the european patent

Extension state: BA ME

17P Request for examination filed

Effective date: 20160128

RBV Designated contracting states (corrected)

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

17Q First examination report despatched

Effective date: 20171206

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20180619