JPH0241300B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an artificial lighting device that supplies light necessary for plant growth, and uses a discharge lamp as a light source to achieve high efficiency.

[Prior art]

In facilities for growing plants (mainly agricultural products) in which the growth environment is controlled, methods have been proposed in which the light necessary for growth is supplied by artificial lighting, or by using sunlight as the main source and supplementing it with artificial lighting. This type of lighting device was developed in Japanese Patent Application Laid-Open No. 1983-1981, which was able to provide appropriate lighting by taking into account the light-dark rhythm corresponding to night and day, based on research into the growth mechanism of plants.
No. 29991. This device allows cultivated plants to pass through a high-illuminance position directly below a ceiling lamp and a low-illuminance position midway between these lamps at intervals roughly corresponding to daytime and nighttime.

As mentioned above, this is based on the principle that photosynthesis is promoted at high illuminance corresponding to daytime, and photosynthetic products are translocated at low illuminance.

However, in this conventional device, lighting power costs accounted for a large portion of cultivation costs.

In addition, a lighting device that lights a discharge lamp at a high frequency and lights it up with periodic off periods was developed in Japanese Patent Application Laid-Open No. 47.
21979, but this is merely a matter of dimming a discharge lamp.

On the other hand, regarding photosynthesis, photosynthesis in plants is carried out through photochemical reactions and thermochemical reactions, as described in publications such as Yozo Iwanami's ``The World of Photosynthesis'' (Kodansha). The former reaction requires light, but the latter does not.
Although these reactions vary depending on the conditions, photochemical reactions take several tens of microseconds, and thermochemical reactions take several tens of microseconds.
It is known to have a response time of ms, which is completely different from the light-dark rhythm corresponding to daytime and nighttime.

[Summary of the invention]

This invention utilizes the principle revealed by the elucidation of the photosynthesis mechanism described above to provide a device that can achieve significant power savings by illuminating plants. That is, according to the above principle, during the "light" period, the discharge lamp is operated at a high frequency and the instantaneous power is greater than the rated power of the discharge lamp,
The "dark" period is a device that turns off the discharge lamp or keeps it on with less power than the rated power.

[Embodiments of the invention]

The present invention will be explained in detail below with reference to Examples.
FIG. 1 is a diagram showing the concept of a lighting device in a plant growing facility. In the figure, 1 is a plant cultivation facility;
2a...2c is a lighting fixture equipped with a discharge lamp; 3
is a cultivated plant.

FIG. 2 shows an embodiment of the lighting device according to the present invention. In the figure, 4 is a DC power source, 5 is a high frequency power source for lighting the discharge lamp 7 at high frequency,
The coil 51, the transistors 52 and 53, the base resistors 54 and 55 of the transistors 52 and 53, the capacitor 56, the output transformer 57, its secondary winding 58, and the feedback winding 59 constitute a push-pull type transistor inverter. 6 is a brightness/darkness control device that controls brightness and darkness, and includes a full-wave rectifier 61;
It consists of a transistor 62 and a drive circuit 63, and when the transistor 62 is turned on, the discharge lamp 7 enters a lighting state, that is, a "bright" state.

FIG. 4 is a diagram for explaining the operation, in which A schematically represents the current of the discharge lamp 7, and B schematically represents the light output of the discharge lamp 7.

In the apparatus shown in FIG. 2, when the DC power source 4 is turned on, the high frequency power source 5 undergoes self-oscillation as is well known by the action of the feedback winding 59 of the output transformer 57, and generates high frequency output power. Here, if the transistor 62 of the bright/dark control device 6 is in the ON state, a current flows through the discharge lamp 7, and a light output is generated as shown in the "bright" portion of FIG. 4B. Further, when the transistor 62 is turned off, the current of the discharge lamp 7 is stopped, and the light output disappears as shown in the "dark" part in FIG. 4B. Here, the ratio of the "light" and "dark" periods t ₁ and t ₀ can be set to about 1:100 to 1:1000 for photosynthetic reaction alone, but for convenience of explanation, t ₁ and t ₀ = 1: 9, and the rated power of the discharge lamp 7 is 100W.
Then, in the "light" period, even if the power consumption of the discharge lamp 7 is 10 times the rated power (1000W), the average power consumption of this discharge lamp is 100W, which does not exceed the rated power. In this way, by increasing the instantaneous power over the rated power during the "light" period, the discharge lamp 7
As shown in Figure 4 (b), obtaining a higher F ₁ than the value F ₀ when lit at rated power without a "dark" period means that the average power consumption of the discharge lamp can be reduced by reducing the average power consumption of the discharge lamp. Try to keep power consumption below
In other words, the discharge lamp can be realized without being overloaded in terms of average power consumption.

In addition, the period ratio t ₁ /T of the “light” period t ₁ is as a result of the experiment.
Unless it was set at t ₁ /T0.8, there would be little economic effect. This is because the lighting device used in the present invention is different from lighting used for general lighting and requires a brightness control device and the like.

From the principle of photosynthetic reaction, the period ratio t ₁ /T of the "light" period t ₁ may be very small, but from a practical evaluation, such as when the morphology of cultivated plants becomes elongated,
t ₁ /T0.1 was preferred.

Next, other embodiments will be described.

In the above example, no current is passed through the discharge lamp during the "dark" period, but it may be possible to pass a small amount of current to maintain the discharge, especially as a discharge lamp.
Appropriate when using HID lamps. An example of a device that achieves this is as shown in Figure 5.
There is a method in which the auxiliary impedance 8 is connected in parallel with the brightness control device 6 in the device shown in FIG.

Next, another embodiment will be described. FIG. 3 shows another embodiment, in which a single high-frequency power source supplies power to a plurality of discharge lamps. In the figure 6a
. . . 6c is a light/dark control device, and 7a . . . 7c is a discharge lamp. In this device, as mentioned above, the "light" period t ₁ is much shorter than the "dark" period t ₀ , so by operating the light/dark control device so as not to supply power to multiple lamps at the same time, the capacity of the high-frequency power source can be increased. There are hardly any.

Next is the setting of “light” period t ₁ and “dark” period t ₀ , but t ₁
It is difficult to perform stable discharge unless the output current of the high frequency power supply 5 is passed through the discharge lamp for at least one cycle.
The minimum period is determined by the fact that the frequency of high-frequency lighting must be 2 to 3 kHz or higher in order to take advantage of the advantages of high-frequency lighting, but even if the frequency is high, it is generally not
Approximately t ₁ ≧100 μs is appropriate. In addition, the dark period t ₀ is several tens of milliseconds required for a thermochemical reaction in conventional research. If this t ₀ is made longer, such as several tens of seconds, the discharge lamp becomes equivalent to repeating blinking.
There is a risk that the lifespan will be shortened. Therefore, although it differs depending on whether the discharge lamp is a low-pressure discharge lamp or a high-pressure discharge lamp, in a device that completely cuts off the current during the "dark" period, t ₀ is several 100 ms even for a low-pressure discharge lamp.
The following are suitable:

However, the repetition period T is f from the point of view of avoiding the effect on the human body working in the breeding facility (unpleasant flickering).
=1/T is not preferably 5 to 20 cycles/sec.
Furthermore, if f > 50 cycles/sec, the flicker will normally be difficult to perceive, so it may be set to T < 20 ms, which corresponds to this.

The electric power when lighting the discharge lamp is F ₁ in Figure 4 B.
It is preferable to set the illuminance during lighting to be at least F ₁ /F ₀ 2 or more in order to increase the illuminance during lighting, which affects how much higher than F ₀ can be obtained, and to save on the number of lighting equipment. For example, twice or more power may be supplied during lighting.

In the explanation of the embodiment, a push-pull type transistor inverter was used as the high frequency power source, but this may be any device that can operate the discharge lamp to be used at high frequency. It is fine as long as it can be set. Further, if the discharge lamp is a low-pressure discharge lamp such as a fluorescent lamp, electrode preheating means may be added. Further, in the case of a high-pressure discharge lamp, means such as applying a high voltage when starting the lamp may be added.

Further, since the device of the present invention corresponds to the daytime period for photosynthesis in plants, a device may be added that operates on a 24-hour cycle, for example, to provide a nighttime period and keep the lights off for a long time.

〔Effect of the invention〕

As described above, according to the device of the present invention, the discharge lamp alternately provides a high output that promotes photochemical reactions in photosynthesis and a dark period that facilitates thermochemical reactions, and a high output during the dark period. Since the period is longer than the light period in which light occurs, it has the advantage that the lighting power required for growing plants can be significantly reduced, and the number of installed illuminators can also be saved.

[Brief explanation of drawings]

Fig. 1 is a conceptual explanatory diagram of a plant growing facility, Fig. 2 is a circuit diagram showing one embodiment of the present invention, Fig. 3 is a block diagram showing another embodiment, Fig. 4 is a diagram for explaining the operation, and Fig. 4 is a diagram for explaining the operation. FIG. 5 is a circuit diagram showing still another embodiment. In the figure, 5 indicates a high frequency power supply, 6 indicates a brightness control device, and 7 indicates a discharge lamp, and the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A high-frequency power source that outputs high-frequency power, a discharge lamp that is lit by the output of the high-frequency power source, and the power of the high-frequency power source is controlled in two ways, large and small, and the large and small power is alternately supplied to the discharge lamp. a brightness/darkness control device for controlling the brightness/darkness of the discharge lamp, and the brightness/darkness control device controls the period t ₁ of the power supplied to the discharge lamp, and the power of the period (bright period t ₁ ) of the power supplied to the discharge lamp. P ₁ , when the rated power of the discharge lamp is P, and the high frequency lighting frequency of the discharge lamp is 1/K, t ₁ K, t ₁・100 μs and
A lighting device for growing plants, characterized in that the condition of P ₁ /P2 is satisfied and the average power consumption of the discharge lamp at this time is controlled so as not to exceed the rated power consumption of the discharge lamp.