JPS6387916A - Illuminator for growing plant - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a lighting device for plant growth that supplies light necessary for plant growth, and more specifically, it relates to a lighting device for lighting a discharge lamp as a light source at a high frequency. The present invention relates to a lighting device for growing plants that allows plants to carry out photosynthesis efficiently by flashing the lighting device periodically.

[Prior Art] FIG. 4 is an output waveform diagram of a discharge lamp in a conventional plant growth lighting device disclosed in, for example, Japanese Patent Application No. 58-232422.

Generally, facilities that grow plants (mainly agricultural products) in an artificial environment require a device that irradiates the light necessary for growth, but the light reaction (photochemical reaction) and dark reaction (thermochemical reaction) in plant photosynthesis is required. This patent application No. 58-23242 relates to a device that blinks irradiated light at high speed.
Proposals have been made by No. 2 and others. This conventional device consists of a DC power supply, a discharge lamp, an inverter for lighting the discharge lamp at a high frequency, and a brightness control device for controlling the discharge lamp to blink at high speed.

Also, Japanese Patent Publication No. 58-43880 and Japanese Patent Publication No. 57-180
No. 897, etc., discloses a technology to supply power to an inverter near the center of the output voltage phase of an AC power supply for the purpose of lighting and dimming a discharge lamp at high frequency, but regarding light irradiated to plants. This is detailed in Japanese Patent Application No. 58-232422.

This will be explained below.

FIG. 4(a) is a waveform diagram showing the current flowing through the discharge lamp of this conventional device, and FIG. 4(b) is a diagram showing an outline of the light emission output waveform of the discharge lamp. and.

When this light emission output waveform was examined using a high-speed response sensor such as a photodiode, it was found that it was as shown in FIG. 4 (c).

That is, a peak output occurs at time A when the discharge lamp starts emitting light, and from time B when power supply to the discharge lamp stops, the light emission output gradually attenuates. The peak output at A was due to restriking of the discharge lamp, and the decay at B was due to afterglow of the phosphor used in the discharge lamp.

Here, the light emission output just before B is 100%, and the fall time is defined as the time taken until this value drops to 10%.

The inventors' investigation has revealed that when plants are grown using discharge lamps with various fall times t, there are considerable differences in the growth of the plants.

As shown in FIG. 4(d), if the phosphors have the same luminous efficiency, 1. It is thought that this is due to the fact that the shorter the value, the greater the luminous output immediately before B, and the mechanism of the light-dark reaction of photosynthesis.

[Problem that the invention seeks to solve]

Conventional lighting equipment for plant growth is configured as described above, so when using fluorescent lamps as discharge lamps, the fall characteristics due to the afterglow time of the phosphor are not properly set, resulting in high-speed lighting. When attempting to save power by blinking, there is a problem in that photosynthesis of plants may not be sufficiently promoted.

This invention was made to solve the above-mentioned problems, and it is possible to prevent a decrease in the efficiency of photosynthesis of plants when trying to save power by blinking a discharge lamp at high speed. The purpose of the present invention is to obtain a lighting device for plant growth that can provide a lighting system for growing plants.

[Means for solving problems]

The lighting device for plant growth according to the present invention is provided with a phase control means that can freely set the discharge start time and discharge stop time of the discharge lamp, and the ratio between the fall time and the discharge rest period when stopping the discharge is 0. .2 or less.

[Effect]

The discharge lamp of this invention achieves power-saving operation by one-phase control, but since the ratio of the fall time when the discharge is stopped to the discharge rest period is 0.2 or less, the relationship with the photosynthesis of plants is Uplifting can also efficiently save power.

[Example of sentry sentry]

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, 1 is an AC power supply, 2 is a rectifier circuit that performs full-wave rectification, and 3 is an inverter, which is constructed of a push-pull type transistor inverter that performs self-oscillation. 4 is a discharge lamp, 41 is a phosphor, and 5 is a blinking circuit as a phase control means, which is composed of a switch 51 and a control circuit 52 for controlling opening and closing thereof.

The blinking circuit 5 opens and closes the switch 51 so as to supply power to the discharge lamp for a period that includes a local maximum value corresponding to the maximum output voltage of the AC power source 1 or the inverter 3.

When the blinking circuit 5 operates, a discharge lamp current flows through the discharge lamp 4 as shown in FIG. 2 (b) with respect to the output voltage of the II flow circuit 2 shown in FIG. ) produces a luminous output like this.

Note that point C in FIG. 2(c) indicates the maximum value.

Here 1. is the fall time due to afterglow, T1 is the repetition period, T2 is the pause period of discharge, ]00XT, /
T1= is the lighting period ratio. Then, the light emission output A2 immediately before the power supply to the discharge lamp 4 is stopped is A2≧A1/2 with respect to the light emission output A1 near the center of the output voltage phase of the AC power source.
The plants will be irradiated so that The electric power supplied to the discharge lamp 4 was kept constant, T and T2 were set as shown below, and salad greens were used as plants for irradiation, and the living body weight of the plants was measured. The results are shown in Table 1 below.

Table 1 Conditions: T1 = = 10 ms T, = 5 ms As described above, if the weight of the living body is 1 when a white fluorescent lamp is used, the efficiency of photosynthesis is clearly improved.

In addition, when the input DC voltage to the inverter 3 is a smooth DC voltage with little ripple, and the one period T1 and rest period T2 are changed, and the types of discharge lamps are changed, the results of the experiment are shown in Figure 3. . From the results shown in Figure 3, it can be generally concluded that t +/
It can be seen that a discharge lamp having the characteristics of Tx < 0, 2 is suitable.

Here, the main phosphor of a normal white fluorescent lamp is an antimony-manganese-activated calcium halophosphate phosphor.

On the other hand, the main phosphor of lamp 1 in Table 1 is a phosphor whose main components are europium-activated yttrium oxide, terbium-activated yttrium silicate, europium-activated strontium chlorophosphate, etc. The phosphor.

It is a phosphor whose main ingredients include europium-activated strontium borophosphate and tin-activated strontium/magnesium phosphate. Incidentally, the main component of the lamp 2 is one having properties intermediate to those of the main components of the lamps 1 and 3. By using phosphors with different afterglow times as described above, the required fall time can be adjusted to 1. is obtained.

In the above explanation, the light color of the discharge lamp was white, but it is also possible to use a monochromatic discharge lamp using a single phosphor, or a phosphor that emits light from a rare gas such as Ne*Ar. You can also use

In addition, in the case of a device using a phosphor, if the rest period T2 becomes short, the phosphor must have a very short afterglow time in order to maintain t4/T2 constant, which increases the difficulty. , T2 is generally desirable to be 2 ms or more. However, in the case of a monochromatic discharge lamp, sufficient characteristics can be obtained up to T2 of about 1 S.

In the above embodiment, the discharge lamp 4 is turned on during a predetermined phase period of the voltage of the AC power supply 1, but by providing the blinking circuit 5 on the AC power supply 1 side or the input side of the inverter 3, the inverter In addition, one blinking circuit 5 can control the lighting of a plurality of inverters or discharge lamps.

Moreover, this blinking circuit 5 uses a voltage that is not synchronized with the AC power supply and is obtained by smoothing the input DC voltage of the inverter.

It may be operated at an appropriate period T1.

Furthermore, it is possible to light two or more discharge lamps with one inverter, or divide an even number of discharge lamps of two or more into halves so that each discharge lamp is lit once per cycle of the AC power supply. can be turned on alternately during each half cycle of the AC power supply.

Regarding the configuration of the inverter, the means for restricting the discharge flow is not limited to that shown in the embodiments, and any means that can blink the discharge lamp at a predetermined period and perform high-frequency lighting may be used.

Regarding the discharge lamp, the electrodes may be preheated as necessary, and the means for preheating is not particularly limited, and the blinking circuit is not limited to the embodiments.

Even if a pulsating DC voltage obtained by rectifying an AC power supply is used as the input DC voltage to the inverter, a small capacity capacitor or the like should be installed on the input side of the inverter to reduce the high frequency impedance of the power supply. You can also connect it by

〔Effect of the invention〕

As described above, according to the present invention, the discharge lamp phase control means is provided so that the ratio of the falling time of the discharge stop operation of the discharge lamp to the discharge pause period is 0.2 or less. When performing power-saving operation of a discharge lamp, there is an effect that the efficiency of photosynthesis of plants can be improved to the maximum.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram showing a lighting device for plant growth according to an embodiment of the present invention, FIGS. 2 and 3 are characteristic diagrams for explaining the operation of the device in FIG. 1, and FIG. FIG. 2 is a characteristic diagram for explaining the operation of a conventional lighting device for plant growth. 1 is an AC power supply, 2 is a rectifier circuit, 3 is an inverter, 4 is a discharge lamp, and 5 is a blinking circuit (phase control means). In addition, in FIG. 1, the same reference numerals indicate the same or equivalent parts. Patent Applicant Mitsubishi Electric Corporation - 0.10.20.3 0.5
1.0 → tf/Tz

Claims (2)

[Claims] (1) A lighting device for plant growth in which a discharge lamp is lit via an inverter, further comprising a phase control means for setting a discharge start time and a discharge stop time per unit cycle regarding the discharge output of the discharge lamp; A lighting device for growing plants, characterized in that the ratio between the falling time of the discharge stop operation of the electric lamp and the discharge pause period is set to 0.2 or less. (2) The discharge output of the discharge lamp includes a local maximum value corresponding to the maximum output value of the inverter during the discharge period from the discharge start time to the discharge stop time. The plant growth lighting device described in Section 1.