JPH0246274Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a lighting device used for artificial lighting for growing plants using a high-pressure discharge lamp as a light source.

BACKGROUND OF THE INVENTION Recently, attempts have been made to grow plants using artificial light sources instead of natural light. The lighting method used is the continuous lighting method used for general lighting, or the flashing method that repeatedly turns on and off.

Problems that the invention aims to solve The conventional continuous lighting method has high electricity costs, while the flashing method has drawbacks such as high equipment costs, and has been limited from an economic standpoint.

Means for Solving the Problems The present invention connects a series circuit of a high impedance element, a low impedance element, and a high pressure discharge lamp to both ends of an AC power supply, and connects a bidirectional silicon-controlled rectifier (hereinafter referred to as This device connects a triax (called a triax) and turns on the triax after a predetermined phase within each half cycle of the AC power supply.When the triax is off during each half cycle of the AC power supply, the optical output is lowered and the triax is turned on. By increasing the light output when it is on, lighting equipment costs and running costs are significantly reduced.

Embodiments Hereinafter, details of the present invention will be explained with reference to illustrated embodiments.

FIG. 1 is a circuit diagram showing an embodiment of a lighting circuit according to the present invention, in which an AC power source 1 is connected to a series circuit of a high impedance element 2, a low impedance element 3, and a high pressure discharge lamp 4. In addition, a triax 5 is connected in parallel with the high impedance element 2,
Connected to the gate pole G of the triax 5 is a gate circuit 6 which generates a gate pulse at a predetermined phase within each half cycle of the AC power supply 1. 7 is a capacitor for power factor correction, which is connected in parallel with the AC power supply 1.

Next, the operation of the embodiment of the present invention will be explained. First, when the AC power supply 1 is turned on, the high pressure discharge lamp 4
lights up, and a discharge lamp current flows through the high-impedance element 2 and the low-impedance element 3. At this time, within each half cycle of the AC power supply 1, a current is applied to the gate pole G of the triax 5 from the gate circuit 6 at a predetermined phase. When applying a trigger pulse,
The triax 5 is off until a predetermined phase, and then remains on until the start of the next phase when the triax 5 is turned on and the current flowing through the triax 5 becomes zero. During the period when Triack 5 is off,
Since the discharge lamp current flows through the high impedance element 2 and the low impedance element 3, the discharge lamp current value is small. During the period when the triax 5 is on, the high impedance element 2 is short-circuited by the triax 5, and the discharge lamp current has a current waveform with a large peak value. Such operation is repeated in each half cycle of the AC power supply 1. FIG. 2 shows the waveforms of the triax current in A, the discharge lamp current in B, and the light output of the discharge lamp in C. The period _T0 is a half cycle of the AC power supply 1, of which the triax 5 is off during the period _T1 and on during the period _T2 . As can be seen from the light output waveform in (c), the light output has a waveform with a large difference between the maximum and minimum values, which is perceived as flickering to the human eye, but does not pose any problem in growing plants.

Next, the high pressure discharge lamp 4 according to the embodiment of the present invention shown in FIG.
A high-pressure sodium lamp was used as the lamp, and was lit at the following constants.

Power supply voltage 200V 60Hz Impedance value of element 2 300Ω Element 3 〃 9Ω Triac 5 on time 5.7ms Lamp output 450W At this time, the on-duty cycle D of the triac, that is, in Fig. 2, D = (T ₂ × T ₀ ) ×100=(5.7/8.67)×100=65.7
(%).

When growing salad vegetables by lighting a high-pressure sodium lamp using such a lighting device, we found that a high-pressure sodium lamp with a lamp output of 660W was used using a conventional ballast 8 consisting of a chiyoke coil 9 and a capacitor 10 as shown in Fig. 3. The same growth effect as when the light was turned on continuously was obtained. Furthermore, even when a so-called metal halide lamp filled with sodium halide, mercury halide, etc. was used as the high-pressure discharge lamp 4, it was possible to grow salad vegetables with the same power saving rate. Experiments have shown that if the circuit is designed so that the on-duty cycle D of the triac 5 is 40% or more and 70% or less, and the impedance ratio of the high impedance element 2 and the low impedance element 3 is 20 or more and 40 or less, power can be saved. It was found that it can be used as a highly effective lighting device for growing plants.

Effects of the Invention As detailed above, according to the present invention, light output is achieved by passing a current with a large peak value through a high-pressure discharge lamp only during a predetermined phase period within each half cycle of an AC power source using a simple circuit configuration. The difference between the maximum value and the minimum value of can be increased, and as a result, it is possible to significantly reduce lighting power costs and equipment costs, and moreover, it is possible to obtain the same effect as the conventional continuous lighting for growing plants. In addition, by reducing the electric power of the discharge lamp, it is possible to reduce the amount of heat released from the high-pressure discharge lamp and the lighting device, and it is possible to reduce air conditioning costs in the cultivation room or to make the high-pressure discharge lamp and the lighting device more compact. In addition, the lighting method according to the present invention has the advantage that it has almost no effect on lamp life, etc., compared to the single-carrier lighting method, and lamps for single-carrier lighting can be used as they are.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing one embodiment of the lighting circuit of the discharge lamp for plant cultivation of the present invention, and Fig. 2 shows the tri-ac current, discharge lamp current, and FIG. 3 is a diagram showing an example of the waveform of discharge lamp light output, and is a circuit diagram showing a lighting circuit using a conventional ballast. 1... AC power supply, 2... High impedance element, 3... Low impedance element, 4... High pressure discharge lamp, 5... Bidirectional silicon controlled rectifier (triac).

Claims (1)

[Claims for Utility Model Registration] (1) A series circuit of a high-impedance element, a low-impedance element, and a high-pressure discharge lamp is connected to both ends of an AC power source, and a bidirectional silicon-controlled rectifier is connected in parallel with the high-impedance element. In high-pressure discharge lamp lighting devices, the on-duty cycle of bidirectional silicon-controlled rectifiers is increased by 40% or more to 70%.
A lighting device for a discharge lamp for growing plants, characterized by the following: (2) The lighting device for a discharge lamp for growing plants according to claim (1), characterized in that the impedance ratio of the high impedance element and the low impedance element is 20 or more and 40 or less.