DE102010003055A1 - Sensor for determination of type of dominant light source e.g. fluorescent lamp, has evaluation unit deriving type of light source from results, where photodiodes, calculation unit and evaluation unit are realized by realized circuit - Google Patents

Abstract

The sensor (1) has a calculation unit (30) deriving a quotient result (23) and a frequency result (13) from output signals (11, 21), where the frequency result indicates information about presence or absence of signal components in a given frequency range, where the signal components are contained in electromagnetic radiation. An evaluation unit (40) derives a type of a dominant light source from the quotient result and the frequency result. Photodiodes (10, 20), the calculation unit and the evaluation unit are realized by an integrated switching circuit. An independent claim is also included for a measuring method for determining a type of a dominant light source in electromagnetic radiation incident on the unit.

Description

The present invention relates to a sensor for determining the type of dominating light source from a plurality of light sources of various kinds. In addition, a measuring method is given.

Sensors, in particular color sensors, which perform a complete spectral analysis are known from the prior art.

It is problematic that these sensors are expensive and therefore expensive to manufacture.

This problem is solved by a sensor and a measuring method for producing a sensor according to independent claims 1 and 15, respectively.

Further developments and advantageous embodiments of the sensor are specified in the dependent claims.

Exemplary embodiments

Various embodiments include a unit for determining the type of dominant light source in an electromagnetic radiation incident on the unit. The electromagnetic radiation is generated from a plurality of light sources of various types. The unit has at least one first photodetector, designed to detect electromagnetic radiation in the visible spectral range and to generate a first output signal. The unit has at least one second photodetector, designed to detect electromagnetic radiation in the infrared spectral range and to generate a second output signal. The unit has at least one calculation unit, designed to derive a quotient result and a frequency result from the first and the second output signal. The frequency result indicates information about the presence or absence of signal components contained in the electromagnetic radiation in a predetermined frequency range. The unit has an evaluation unit, designed to derive the type of dominating light source from the quotient result and the frequency result.

Knowing the nature of the dominant light source is helpful in reconstructing the light spectrum and optimizing the exposure in photography to accurately reflect the color impression. This can z. B. eliminates the filtering of IR light in a camera. The color representation of displays and projectors is corrected depending on the dominant light source.

Both photodiodes are based on silicon diodes.

The first photodiode has a photopic filter, which means that the photodiode is adapted to the spectral sensitivity of the human eye. Such a photodiode is also called an ambient light diode. This photodiode has its maximum sensitivity at a wavelength of about 550 nm and measures between about 400 nm and 700 nm. The sensitivity of the first photodiode is adjustable by the number and type of dielectric layers.

The second photodiode has an infrared filter. The photodiode has its maximum sensitivity at a wavelength of about 860 nm and measures between about 800 nm and about 900 nm. The sensitivity of the infrared sensor is adjusted either by the number and type of dielectric layers or by the use of a daylight blocking filter.

In a preferred embodiment, the first and the second photodiode, the calculation unit and the evaluation unit are realized by a single integrated circuit. This has the advantage that the sensor can be realized in the smallest space.

In a preferred embodiment, the calculation unit has a first subunit configured to derive the frequency result in such a way that it indicates information about the presence or the absence of portions of the first output signal in a predetermined frequency range.

In a preferred embodiment, the first subunit has a first determination unit that has a predefined electrical filter. The electrical filter is designed to divide the DC components of the first output signal by a low-pass filter, the frequency components of the first output signal at 50 Hz and / or 60 Hz by a bandpass filter and the frequency components of the first output signal in the kHz range by a high-pass filter. The use of an electric filter is particularly advantageous because this is easy and inexpensive to implement.

In an alternative preferred embodiment, the first subunit has a first determination unit configured to integrate the first output signal.

In a preferred embodiment, the first determination unit is designed to carry out several integrations with different time constants. From the dependence of the signal level of the integration time can be determined with which frequency the signal was modulated. The integrations can take place simultaneously or serially one after the other.

In a preferred embodiment, the first determination unit is designed to carry out a first integration with a first time constant in such a way that the frequency magnitude has information about whether the first output signal has a spectral component around 0 Hz.

In a preferred embodiment, the first determination unit is designed to carry out a second integration with a second time constant in such a way that the frequency variable has information about whether the first output signal has a spectral component at 50 or 60 Hz.

In a preferred embodiment, the first determination unit is designed to carry out a third integration with a third time constant in such a way that the frequency variable has information as to whether the first output signal has a spectral component in the kHz range, in particular around 300 kHz.

In a preferred embodiment, the first subunit has a first comparison unit. The first comparison unit is designed to compare the frequency magnitude with at least one threshold value and to derive a frequency result therefrom.

In a preferred embodiment, the calculation unit has a second subunit with a second determination unit, which is designed to derive the quotient size from a DC component of the first output signal and a DC component of the second output signal.

In a preferred embodiment, the second subunit has a second comparison unit, which is designed to compare the quotient size with at least one threshold value and to derive therefrom a quotient result.

In a preferred embodiment, the evaluation unit is designed to read a final value from a memory unit for each possible value of the frequency result and each possible value of the quotient result. The final value indicates the type of dominating light source, which is derived from the value of the frequency result and the quotient result.

In a preferred embodiment, the evaluation unit has a two-dimensional decision matrix that includes assignments of frequency results and quotient results to the types of different light sources.

The invention relates to a measuring method for determining the type of dominant light source in an electromagnetic radiation incident on the unit, which is generated from a plurality of light sources. It is detected electromagnetic radiation in the visible spectral range and generates a first output signal. It is detected electromagnetic radiation in the infrared spectral range and generates a second output signal. Subsequently, a quotient result and a frequency result are determined from the first and the second output signal, which indicates information about the presence or the absence of signal components contained in the electromagnetic radiation in a predetermined frequency range. Subsequently, the type of dominating light source is derived from the quotient result and from the frequency result.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the solution according to the invention are explained in more detail below with reference to the drawings.

1 shows the spectra of different light sources;

2 shows a comparison of the spectrum of a white LED with the spectral sensitivity of the human eye;

3 shows the frequencies of different light sources;

4 shows a unit according to the invention;

5 shows a first matrix;

6 shows a second matrix derived from the first matrix.

EXEMPLARY EMBODIMENTS OF THE OPTOELECTRONIC COMPONENT

The same, similar or equivalent elements are provided in the figures with the same reference numerals. The figures and the proportions of the elements shown in the figures with each other are not to be considered to scale. Rather, individual elements may be exaggerated in size for better presentation and better understanding.

1 shows spectra of different light sources. The spectrum of a fluorescent lamp 100 shows a high intensity in the visible spectral range, ie between wavelengths of 390 nm and 780 nm. In the infrared spectral range, ie for wavelengths greater than 780 nm, the spectrum of a fluorescent lamp 100 almost disappearing intensities. The spectrum of sunlight 101 shows a high intensity in the visible spectral range and a lower intensity in the infrared spectral range. The spectrum of a thermal radiator 102 at a temperature of 2856 Kelvin continuously increases to wavelengths of about 1000 nm. The spectrum of a lightbulb 103 runs essentially parallel to the spectrum of the thermal radiator 102 ,

2 shows a comparison of the spectrum of a warm white emitting LED 200 with the curve 201 the spectral sensitivity of the human eye. The main maximum of the spectrum of warm white emitting LEDs 200 is at a wavelength of about 590 nm; a secondary maximum lies in the blue spectral range at a wavelength of 460 nm.

3 shows the frequencies of different light sources. The light of a flashlight 300 , a DC powered LED 301 and an optical bench 304 is unmodulated, so the frequency is 0 Hz. The light of a fluorescent lamp 302 , a light bulb 303 and an energy-saving lamp 305 is modulated with a frequency of 50 Hz.

4 shows the unit 1 to determine the type of dominant light source in a unit 1 incident electromagnetic radiation 2 which is generated from a variety of light sources of various kinds. The unit has a first photodiode 10 which is designed to detect electromagnetic radiation in the visible spectral range and a first output signal 11 to create. Further, the unit points 1 a second photodiode 20 configured to detect electromagnetic radiation in the infrared spectral range and a second output signal 21 to create. The unit has a calculation unit 30 on which is formed, a quotient result 23 and a frequency result 13 from the first one 11 and the second 21 Derive output signal. The frequency result 13 provides information about the presence or absence of signal components contained in the electromagnetic radiation in a given frequency range. The unit 1 has an evaluation unit 40 on, trained to get off the quotient score 23 and the frequency result 13 derive the nature of the dominant light source.

The first 10 and the second 20 Photodiode, the calculation unit 30 and the evaluation unit 40 are realized by a single integrated circuit. The calculation unit 30 has a first subunit 31 on, trained, the frequency result 13 derive such that there is information about the presence or absence of portions of the first output signal 11 indicating in a given frequency range. The first subunit 31 , has a first determination unit 31a which has a predefined electrical filter. The electrical filter is designed to match the DC components of the first output signal 11 through a low-pass filter, the frequency components of the first output signal 11 at 50 Hz or 60 Hz through a bandpass filter and the frequency components of the first output signal 11 in the kHz range by a high-pass filter separable from each other. Alternatively, the first subunit 31 , a first determination unit 31a formed, the first output signal 11 to integrate. The first determination unit 31a is designed to perform multiple integrations with different time constants. A first integration with a first time constant is to be performed such that the frequency size 12 has information about whether the first output signal 11 has a spectral component around 0 Hz. A second integration with a second time constant is to be performed such that the frequency size 12 has information about whether the first output signal 11 has a spectral component at 50 or 60 Hz. A third integration with a third time constant is to be carried out such that the frequency size 12 has information about whether the first output signal 11 a spectral component in the kHz range, in particular by about 300 kHz.

The first subunit 31 has a first comparison unit 31b formed, the frequency size 12 to compare with at least one threshold and from this a frequency result 13 derive.

The calculation unit 30 has a second subunit 32 with a second determination unit 32a on. The determination unit 32a is designed to the quotient size 22 from a DC component of the first output signal 11 and a DC component of the second output signal 21 derive.

The second subunit 32 has a second comparison unit 32b which is formed, the quotient size 22 to compare with at least one threshold and from this a quotient result 23 derive.

The evaluation unit 40 is designed for any value of the frequency result 13 and any value of the quotient result 23 a final value 60 from a storage unit 50 read. The final value 60 indicates the type of dominating light source that results from the value of the frequency result 13 and the quotient result 23 results.

The evaluation unit 40 has a decision matrix 41 on, the assignments of frequency results 13 and quotient results 23 to the types of different light sources.

5 shows the values for the DC components of the first output signal for different light sources 11 in the visible spectral range, for the DC components of the second output signal 21 in the infrared spectral range, for the ratio of DC components of the second output signal 21 to the DC components of the first output signal 11 , here called quotient result, and for the frequency result.

6 shows the two-dimensional decision matrix 41 containing the assignments of frequency results 13 and quotient results 23 to the types of different light sources. The quotient result 23 is formed from the DC component of the second output signal 21 divided by the DC component of the first output signal 11 , The quotient results 23 can be very low, low and high. The frequency results 13 can be in the kHz range, at 50 Hz or 60 Hz or at 0 Hz. Sunlight has the quotient result 23 low and the frequency result 13 0 Hz. An incandescent lamp has the quotient result 23 high and the frequency result 13 50 or 60 Hz. A flashlight has the quotient result 23 high and the frequency result 13 0 Hz. A fluorescent lamp has the quotient result 23 very low and the frequency result 13 50 or 60 Hz. A white LED, which is operated pulsed, has the quotient result 23 very low and the frequency result 13 in the kHz range, in particular around 300 kHz. A white LED, which is operated with direct current, has the quotient result 23 very low and the frequency result 0 Hz.

The unit has been described to illustrate the underlying idea using some embodiments. The embodiments are not limited to specific feature combinations. Although some features and configurations have been described only in connection with a particular embodiment or individual embodiments, they may each be combined with other features from other embodiments. It is also conceivable to omit or add in individual embodiments illustrated features or special embodiments, as far as the general technical teaching is realized.

Although the steps of measuring a sensor are described in a particular order, it is to be understood that any of the methods described in this disclosure may be performed in any other meaningful order, including but not limited to, method steps Deviated from the basic idea of the technical teaching described.

LIST OF REFERENCE NUMBERS

1

Unit / Sensor

2

incident electromagnetic radiation

10

first photodiode

11

first output signal

12

frequency size

13

frequency result

20

second photodiode

21

second output signal

22

quotient size

23

quotient result

30

calculation unit

31

first subunit

31a

first determination unit

31b

first comparison unit

32

second subunit

32a

second determination unit

32b

second comparison unit

40

evaluation

41

decision matrix

50

storage unit

60

full scale

100

Spectrum of a fluorescent lamp

101

Spectrum of sunlight

102

Spectrum of a thermal radiator at 2856 K.

103

Spectrum of a lightbulb

200

Spectrum of a white LED

201

Spectral eye sensitivity

300

Frequency of a flashlight

301

Frequency of an OSTAR LED

302

Frequency of a fluorescent tube

303

Frequency of a lightbulb

304

Frequency of an optical bench (Tungsten lamp at constant current)

305

Frequency of an energy saving lamp

Claims (15)

Unit ( 1 ) for determining the nature of the dominant light source in a unit ( 1 ) incident electromagnetic radiation ( 2 ), which is generated from a plurality of light sources of various types, - with at least one first photodiode ( 10 ), adapted to detect electromagnetic radiation in the visible spectral range and a first output signal ( 11 ) to create, With at least one second photodiode ( 20 ), adapted to detect electromagnetic radiation in the infrared spectral range and a second output signal ( 21 ) - with at least one calculation unit ( 30 ), designed to produce a quotient result ( 23 ) and a frequency result ( 13 ) from the first ( 11 ) and the second ( 21 ) Derive output signal, wherein the frequency result ( 13 ) Indicates information about the presence or the absence of signal components contained in the electromagnetic radiation in a predetermined frequency range and - with at least one evaluation unit ( 40 ), designed to determine from the quotient result ( 23 ) and the frequency result ( 13 ) deduce the nature of the dominant light source. Unit according to claim 1, wherein the first ( 10 ) and second ( 20 ) Sensor, calculation unit ( 30 ) and evaluation unit ( 40 ) are realized by a single integrated circuit. Unit according to one of the preceding claims, wherein the calculation unit ( 30 ) a first subunit ( 31 ), configured, the frequency result ( 13 ) such that there is information about the presence or absence of portions of the first output signal ( 11 ) in a given frequency range. Unit according to claim 3, wherein the first subunit ( 31 ), a first determination unit ( 31a ), which has a predefined electrical filter, formed around the DC components of the first output signal ( 11 ) by a low-pass filter, frequency components of the first output signal ( 11 ) at 50 Hz or 60 Hz through a band-pass filter and frequency components of the first output signal ( 11 ) in the kHz range by a high-pass filter separable from each other. Unit according to claim 3, wherein the first subunit ( 31 ), a first determination unit ( 31a ), which is designed to receive the first output signal ( 11 ) to integrate. Unit according to claim 5, wherein the first determination unit ( 31a ) is designed to perform multiple integrations with different time constants. Unit according to claim 6, wherein the first determination unit ( 31a ) is adapted to perform a first integration with a first time constant such that the frequency size ( 12 ) has information about whether the first output signal ( 11 ) has a spectral component around 0 Hz. Unit according to claim 6 or 7, wherein the first determination unit ( 31a ) is configured to perform a second integration with a second time constant such that the frequency size ( 12 ) has information about whether the first output signal ( 11 ) has a spectral component at 50 or 60 Hz. A unit according to any one of claims 6 to 8, wherein the first determination unit ( 31a ) is adapted to perform a third integration with a third time constant such that the frequency size ( 12 ) has information about whether the first output signal ( 11 ) has a spectral component in the kHz range, in particular by about 300 kHz. Unit according to one of the preceding claims, wherein the first subunit ( 31 ) a first comparison unit ( 31b ), which is formed, the frequency size ( 12 ) with at least one threshold value and from this a frequency result ( 13 ). Unit according to one of the preceding claims, wherein the calculation unit ( 30 ) a second subunit ( 32 ) with a second determination unit ( 32a ), which is designed to determine the quotient size ( 22 ) from a DC component of the first output signal ( 11 ) and a DC component of the second output signal ( 21 ). Unit according to one of the preceding claims, wherein the second subunit ( 32 ) a second comparison unit ( 32b ), which is formed, the quotient size ( 22 ) with at least one threshold value and from this a quotient result ( 23 ). Unit according to one of the preceding claims, wherein the evaluation unit ( 40 ) is formed, for each possible value of the frequency result ( 13 ) and every possible value of the quotient result ( 23 ) an end value ( 60 ) from a storage unit ( 50 ), which indicates the nature of the dominant light source. Unit according to one of the preceding claims, wherein the evaluation unit ( 40 ) a two-dimensional decision matrix ( 41 ), the assignments of frequency results ( 13 ) and quotient results ( 23 ) to the types of different light sources. Measuring method for determining the type of dominating light source in a unit ( 1 ) incident electromagnetic radiation ( 2 ), which is generated from a plurality of light sources, with the following method steps: - Detection of electromagnetic radiation in the visible spectral range and generating a first output signal ( 11 ), - detection of electromagnetic radiation in the infrared spectral range and generation of a second output signal ( 21 ), - deriving a quotient result ( 23 ) and a frequency result ( 13 ) containing information about the presence or absence of electromagnetic radiation ( 2 ) in a given frequency range, from the first ( 11 ) and the second ( 21 ) Output signal, - deriving the type of dominating light source from the quotient result ( 23 ) and from the frequency result ( 13 )

Images