CN113905488A

CN113905488A - Lighting system for controlling the color temperature of artificial light under the influence of daylight levels

Info

Publication number: CN113905488A
Application number: CN202010641126.2A
Authority: CN
Inventors: 不公告发明人
Original assignee: Deng Yalan
Current assignee: Deng Yalan
Priority date: 2020-07-06
Filing date: 2020-07-06
Publication date: 2022-01-07

Abstract

The invention relates to a lighting system comprising at least one light source (100) for providing artificial light, and a control device (120) for controlling the light source. The light source (100) has an adjustable color temperature. The control means (120) comprises means for generating a control signal, the control signal being dependent on the daylight level. The control means (120) adjusts the color temperature of the light source in accordance with a predetermined relationship between the daylight level and the color temperature of the artificial light. Tests have shown that the tester selects a lighting system in which the predetermined relation between the daylight level and the color temperature of the artificial light means that the color temperature increases from approximately 3300k to 4300k when the daylight level measured on the desk increases approximately from 400 lux to 800 lux.

Description

Lighting system for controlling the color temperature of artificial light under the influence of daylight levels

Technical Field

The invention relates to a lighting system comprising at least one light source for providing artificial light, and control means for controlling the light source, the control means comprising means for generating a control signal, the control signal being dependent on the daylight level. The invention also relates to a control device for such a lighting system.

Background

Lighting systems of this type have become widely used, in particular for the illumination of office buildings. In known lighting systems, the means for generating a control signal (which signal depends on the daylight level) typically comprise a light sensor for determining the daylight level. Lighting systems of this type have also been used for street lighting systems, in which the artificial light is switched on by the control means when the measured daylight level falls below a predetermined minimum value, and, conversely, is switched off when the measured daylight level exceeds a predetermined maximum value. In particular, it is known that in office lighting systems, the control means regulate the intensity of the artificial light mainly in an inverse relationship to the daylight level.

Extensive studies have revealed that adequate lighting is greatly beneficial to the comfort of the office workers for 85% of them, and it is known that light can play both a visual and non-visual role in this regard. With respect to visual effects, it is clear that it is important to perform a particular task with the proper intensity and type of illumination, whereas for non-visual effects it is known that various effects in the human body are affected by illumination. Examples of these effects include the human sleep activity cycle and the 24 hour rhythm (circadian rhythm) of certain hormone production processes. Thus, the non-visual effect of light has an indirect impact on human behavior and efficiency.

The foregoing highlights the important role of light. In many environments, such as offices, factories and living rooms, light is generated by both incident sunlight and additional artificial light. In many cases, daylight is not controlled or has only a limited effect to a limited extent by the user, e.g. opening or closing curtains. This makes the control of the artificial light source more important.

Disclosure of Invention

It is an object of the invention to provide a lighting system of this type which takes into account human preferences.

In summary, the illumination system according to the invention is characterized in that the light source has a function of adjusting the color temperature, and the control means adjust the color temperature of the light source in accordance with a predetermined relationship between the daylight level and the color temperature of the artificial light.

The invention is based on the perception (obtained from the test) of the tester, i.e. the tester shows a preference for artificial light of a given color temperature, which depends on the intensity of the incident daylight. For example, by measuring the level of incident daylight through a light sensor, the controller can adjust the color temperature of the artificial light in accordance with the measured daylight level.

Detailed Description

An embodiment of the lighting system according to the invention is characterized in that the means for generating the control signal comprise a day counting means for determining the specific date of the year and for generating the control signal on the basis of a predetermined relationship between the date and the average daylight level. In a simple version of this embodiment, the estimation of the daylight level is done at the same time as the determination of the date with the day counting device. From the predetermined relationship between the date and the average daylight level, the daylight level can be estimated for adjusting the color temperature.

In a simpler form the embodiment is characterized in that the means for generating the control signal further comprise a clock and the control signal is generated on the basis of a predetermined relationship between the date and the specific time of day, respectively, and the average daylight level. Due to the adoption of the clock, the daylight level at any time in a day can be simply and accurately estimated, so that the color temperature of the artificial light can be better adjusted.

A further advantageous version of said embodiment is characterized in that the means for generating the control signal further comprise a light sensor for determining the actual daylight level, and in that the control means store at least two different predetermined relations between daylight level and color temperature, one of said relations being selected by the control means on the basis of the measured actual daylight level. For example, a better adjustment of the color temperature of the artificial light can be achieved by storing different relations for different types of weather (e.g. sunny, cloudy or cloudy in a sunny, cloudy in a cloudy), and selecting the most suitable one based on the measured daylight level.

An embodiment of the lighting system according to the invention is characterized in that the control device stores predetermined relations between at least two different daylight levels and color temperatures, and in that the control device comprises a first control member for selecting one of said relations. It is generally accepted that human preferences vary widely. This is also true for different preferences of the light background. Some people prefer "warm light" and others prefer "cool light". In order to meet the preferences of different persons in a simple manner, the latter embodiment of the system provides the user with a method of selecting from at least two predetermined relationships.

An embodiment of the illumination system according to the invention is characterized in that the control device comprises a correction device for correcting the predetermined relation between the light level and the color temperature. To better meet the requirements of the user, this embodiment of the system provides the possibility to fix the predefined relationship. As with the previously described embodiments, this embodiment, on the one hand, enables optimization of the control system for a particular office building, for example, taking into account the condition and overall layout of the building. On the other hand, if the offices are individually controllable, each office may adopt a relationship to suit the individual needs of the user. A development of this embodiment of the illumination system according to the invention is characterized in that the control device comprises a second control element for readjusting the adjusted color temperature and activating the correction device. In the previously described embodiments, the user can influence the color temperature control only indirectly by selecting or modifying a relation, whereas in the present embodiment the user can make a readjustment directly on the color temperature. On the basis of the readjustment, the system also makes a correction to the relation between the desired daylight level and the color temperature. Personal preferences can thus be better satisfied.

An embodiment of the illumination system according to the invention is characterized in that the predetermined relation between the number of daylight savings and the color temperature of the artificial light, which is adjusted by the user, is mainly characterized in that the color temperature increases with an increasing number of daylight savings. Tests have shown that there is a positive correlation between the daylight level and the artificial light color temperature, so that a lighting system meeting these requirements can also meet the needs of the average person.

An embodiment of the lighting system according to the invention is characterized in that the predetermined relation between the daylight level and the color temperature of the artificial light is such that the color temperature increases from approximately 3300k to 4300k when the daylight level measured on the office desk increases from approximately 400 lux to approximately 1800 lux. Tests have shown that such a relation properly reflects the requirements of the average tester. Lighting systems based on such relations can greatly meet the requirements of users regarding color temperature adjustment.

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

In the drawings:

FIG. 1 shows the relationship between the average daylight level and the average color temperature of artificial light selected by a tester;

FIG. 2 shows a schematic block diagram of the lighting system of the present invention;

FIG. 3 is a block diagram of a first embodiment of the lighting system shown in FIG. 2;

FIG. 4 is a block diagram of a second embodiment;

FIG. 5 is a block diagram of a third embodiment;

FIG. 6 is a block diagram of a fourth embodiment;

FIG. 7 is a block diagram of a fifth embodiment;

fig. 8 is a block diagram of a sixth embodiment.

Figure 1 shows the results of a test to determine a person's preference for artificial light background in an office environment. The test was conducted in two identical offices for 14 months. The preferred lighting background is measured from about 100 testers, each using an office for at least one day. The office was equipped as a normal office in which the tester worked normally. The tester can adjust the intensity of the artificial light and also adjust the color temperature. The intensity of the light can be adjusted in the range of about 400 to 2000 lux, and the color temperature can be adjusted in the range of about 2700 to 2400 k. But also the intensity and color temperature of the incident sunlight. The total intensity of light (including daylight and artificial light) is measured on a horizontal table. Similar measurements were made in a scaled-down model in which sunlight, i.e. incident light, was used, but no artificial light was used. After calibration, the daylight level in the office can be derived from the last measurement. In order to be able to determine the influence of daylight on the selected lighting background, the artificial light is switched off several times during the day, after which the tester has to adjust the artificial light again.

Tests have shown that the tester only slightly readjusts the intensity of the artificial light in the presence of the incident sunlight. The artificial light increases only about 800 lux on average, regardless of the number of daylight levels. In the case of very strong daylight, for example, greater than 2000 lux, incident on the table, the artificial light is often not turned off, but rather its intensity is increased. Conversely, if there are high daylight levels, the intensity of the artificial light is reduced by partially closing the blinds.

It was surprisingly found that the tester did indeed readjust the color temperature of the artificial light to a large extent under the influence of incident sunlight. It has been found that the number of levels of incident light plays an important role in the tuning of the color temperature of artificial light. However, the color temperature of sunlight has not been found to play a significant role. Thus, from the measurements, the relation between the average number of incident daylight levels and the color temperature of the artificial light can be derived, as chosen by the tester.

Fig. 1 shows this relationship. The assays shown in the figures were completed during months 1-1994 to 2-1994. In order to obtain a perception (insight) of a color temperature background (color temperature setting), which is a function of the weather type and the specific date of the year, each measurement is represented in groups. For each measured day, its weather type may be expressed as clear, cloudy, or a mixture of both (cloudy in clear or cloudy in clear). Measurements taken throughout the month can be integrated for each weather type. In principle, this forms three bars per month, the center of which represents the mean value of the selected color temperature and the height of which represents twice the standard deviation, and therefore also constitutes an indicator of personal preference differences and background settings (settings) dispersion.

In fig. 1, the average effect of daylight on the illumination intensity E (in lux) is listed on the horizontal axis, while the average color temperature Tk (in k) of the artificial light is listed on the vertical axis. It can be derived from the measurements that the required color temperature of the artificial light increases as the daylight level increases. It is clear that the color temperature increases from about 3300k to 4300k as the daylight level increases from approximately 400 lux to 1800 lux. In many lighting systems, a linearly increasing relationship between daylight level and color temperature of artificial light is suitable to meet the requirements of the average person. Many people dislike too high color temperatures, e.g. above 4200 k. It can be derived from fig. 1 that the required color temperature does not increase beyond a point close to 4000k for a daylight level of 1500 lux. In some cases it may even happen that the required color temperature decreases when the daylight level exceeds approximately 1800 lux. An illumination system using the relationship between the daylight level and the color temperature represented by curve 10 in fig. 1 can better meet the requirements of the average person.

This type of lighting system can be used for artificial lighting of spaces where people are staying, such as offices, factory halls, schools and public buildings. Daylight can also enter these houses, for example through windows or skylights. The house is not shown in the figure.

Fig. 2 shows a general block diagram of the illumination system of the present invention based on the above-described viewpoint. The lighting system comprises at least one light source 100 for providing artificial light, the light source being of the type having an adjustable color temperature. The light sources are used to illuminate the corresponding parts of the room, such as desks, platforms and walls. Such a light source with adjustable color temperature can be manufactured, for example, by combining at least two obscurable light sources, each having a fixed and different color temperature. A suitable lamp for the combination is the Philips fluorescent lamp, model HFD (high frequency obscurable) TLD. When a lamp with a fixed color temperature of 2700k (e.g. TLD color 82) and a lamp with a fixed color temperature of 6500k (e.g. TLD color 86) are combined, the color temperature can be adjusted over a wide range. It is desirable to adjust the color temperature by changing the luminous flux ratio of the lamp while keeping the total luminous flux constant. It is clear that in many applications a small range of regulation (e.g. from 3500k to 4000k) is sufficient. Obviously, the combined lamps can be assembled into one lamp. Other light sources with adjustable color temperature are known from European patent applications EP-A439861, EP-A439862, EP-A439863, EP-A439864, EP-A504967 and German patent application DE-A4200900.

The lighting system further comprises means 110 for generating a control signal dependent on the daylight level. The apparatus 110 may include: for example a photoreceptor (photoreceptors are known per se) and further comprises a signal processor for converting signals provided by the photoreceptor into control signals suitable for other components of the illumination system. The photoreceptor is preferably mounted in such a way that it is representative of the incident light it measures. Photoresistors and photodiodes are known examples of photoreceptors.

The present lighting system further comprises a control device 120 for controlling the light source (or light sources). The control device adjusts the color temperature of the light source in accordance with a predetermined relationship between the daylight level and the color temperature of the artificial light. The relation between the daylight level and the color temperature of the artificial light is preferably as described above. The Philips control device 800-IFS is an example of a control device suitable for use in the present invention. The program of the control device can be adjusted to perform the above-described control operation, and the relationship between the daylight level and the color temperature is stored in a ROM (or RAM) memory of the control device.

Fig. 3 shows a block diagram of an embodiment of the lighting system according to the invention, in which the means 110 for generating a control signal depending on the daylight level comprises a day counter 130, the day counter 130 being arranged to determine a specific day of the year, the means 110 further comprises a signal processor 135 which generates the control signal depending on a predetermined relationship between the specific day of the year and the average daylight level, the day counter being adapted to determine the specific day of the year being generally known, the day counter 130 being operatively connected to the clock function of a microcontroller when the control means 120 comprising a microcontroller is used, the further advantage is obtained by combining the signal processor 135 with the control means 120, whereby a control means may be used which is arranged to generate a control signal depending on a predetermined relationship between the specific day of the year and the artificial light temperature (on the one hand the relationship between the specific day of the year and the average daylight level, another aspect is a combination of the two relations between the average daylight level and the color temperature of the artificial light).

Fig. 4 is a block diagram of another embodiment wherein the means for generating a control signal (dependent on the daylight level) 110 further comprises a clock 140 for determining a specific time of day. The signal processor 135 generates the control signal on the basis of a predetermined relationship, i.e. on the one hand a specific date of the year and a specific time of day, and on the other hand an average daylight level, i.e. a relationship between them. Clocks suitable for determining a particular time of day are generally available. When the control device 120 including a microcontroller is employed, the clock function of the microcontroller can effectively be regarded as the clock 140. The signal processing means 135 can be combined with the control means 120 to achieve a better result. Therefore, a control device for adjusting the color temperature of the light source in accordance with a predetermined relationship between the color temperature of the artificial light and the color temperature of the light source on a specific date of the year and a specific time of day, respectively, may be employed.

Fig. 5 is a block diagram of another embodiment, wherein the means 110 for generating a control signal (dependent on the daylight level) further comprises a light sensor 180 for determining the actual daylight level. A signal processing means 135 is also arranged for converting the signal provided by the photoreceptor into a second control signal suitable for the rest of the illumination system. The control means 120 stores a predetermined relationship between at least two different daylight levels and color temperatures. For example, three relationships may be stored, corresponding to weather types of "sunny", "cloudy", and their "mixed" as shown in fig. 1. The control means 120 is arranged for selecting one of said relations in dependence on the second control signal.

Fig. 6 is a block diagram of an embodiment of the device according to the invention, wherein the control means 120 stores at least two different predetermined relations between daylight level and color temperature. The control device 120 further comprises a first control member 150 for selecting one of said relationships. The control 150 may be provided with a knob (for example) that indicates the selected relationship. Alternatively, it is possible to add a display screen to the control device 120 to display the relationship to be selected, and in that case, the control member 150 is provided with a keyboard or mouse. It will be apparent that control 150 may also be equipped with a remote control or switch.

Fig. 7 is a block diagram of another embodiment of the device according to the invention, wherein the control means 120 comprise a correction device 160 for correcting the predetermined relation between the daylight level and the color temperature. There are many known methods for correcting this relationship. For example, in this respect, the same increase or decrease of the color temperature for each daylight level may be considered. If this relationship is stored in the ROM or RAM memory of the control device, it is sufficient to store an offset value (offset) in a permanent memory, such as an EEPROM. In particular, if the relationship is linear, another modification method may only need to modify the color temperature at the initial point (e.g., 400 lux, 3300k) and/or the end point (e.g., 200 lux, 4300 k). That is, it is sufficient to store the color temperatures of the initial point and the end point in the permanent memory.

In both embodiments described above, further advantages are obtained by using light sources that can be adjusted over a large range, for example from 2700k to 5400k, which facilitates the correction or selection of the relationship, so that the full range of light sources can be used. Thus, the individual's preference for "warm light" or "cool light" may also be better met.

Fig. 8 is a block diagram of another embodiment of the lighting system of the present invention wherein the control device includes a second control 170. The second control member 170 is used to make a further adjustment of the adjusted color temperature and to operate the correction device 160. The second control 170 may be of the same type as the first control 150. The second control member is preferably fitted with a shutter for easy readjustment of the color temperature.

It is clear that the lighting system of the invention can be combined with a lighting system in which the artificial light intensity is controlled by the daylight level. Such a lighting system also comprises at least one light source with adjustable light intensity. In addition, the system comprises control means for adjusting the intensity of the light source in accordance with a predetermined relationship between the daylight level and the artificial light intensity. In such an illumination system, it is advantageous to use a light source with adjustable intensity and color temperature. Then, control means may be provided for controlling the intensity and the color temperature of the artificial light in dependence on the daylight level.

For the control of the illumination, it is important to consider human perception. Whereas human perception can be expressed on a quantitative scale, e.g. "artificial light gets stronger and warmer if it gets darker outdoors". Therefore, using a scale-oriented control unit (rule-oriented control unit), such as a "fuzzy logic" controller, is highly suitable for use in the illumination system of the present invention. The fuzzy logic control means provide major advantages, in particular in advanced embodiments of the inventive lighting system. This is also valid, for example, for lighting systems that also take into account seasonal or weather conditions (e.g. sunny or cloudy days, with occlusion and cloud cover variations) in order to achieve a specific setting of the color temperature or intensity of the artificial light. Such ｃA lighting system for controlling the intensity of light is described in the non-prepublished application EP- ｃA-0652692 (PHF 93.577). It is particularly advantageous to combine the known illumination system with the illumination system of the invention.

Claims

1. A lighting system comprising at least one light source for providing artificial light, and control means for controlling the light source, the control means comprising means for generating a control signal in dependence on the daylight level, characterized in that:

the type of the light source is of a kind having an adjustable color temperature, and the control means adjusts the color temperature of the light source in accordance with a predetermined relationship between the daylight level and the color temperature of the artificial light.

2. The lighting system of claim 1 wherein the means for generating the control signal includes a date counter for determining a particular date of the year and generating the control signal based on a predetermined relationship between the particular date of the year and the average daylight level.

3. The lighting system of claim 2 wherein the means for generating the control signal further comprises a clock and the control signal is generated based on a predetermined relationship between a specific date of the year and a specific time of day, respectively, and the average daylight level.

4. An illumination system as claimed in claim 3, characterized in that the means for generating the control signal further comprise a light sensor for determining the actual daylight level, the control means storing at least two different predetermined relations between daylight level and color temperature, and the control means selecting one of said relations on the basis of the measured actual daylight level.

5. An illumination system as claimed in any one of claims 1 to 3, characterized in that the control means store at least two different, predetermined relationships between daylight level and color temperature, the control means comprising a first control member for selecting one of said relationships.

6. An illumination system as claimed in any one of the preceding claims, characterized in that the control means comprise correction means for correcting the predetermined relationship between the daylight level and the color temperature.

7. An illumination system as claimed in claim 6, characterized in that the control means comprise second control elements for readjusting the adjusted color temperature and for operating the correction means.

8. An illumination system as claimed in any one of the preceding claims, characterized in that the predetermined relationship between the daylight level and the color temperature of the artificial light is such that the color temperature increases mainly with increasing daylight level.

9. The illumination system of claim 8, wherein the predetermined relationship between the daylight level and the color temperature of the artificial light means that the color temperature increases from about 3300k to about 4300k as the daylight level measured on the desk increases from about 400 lux to about 800 lux.