JPH0246273Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a power supply circuit 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 disadvantages such as high equipment costs, and has been limited from an economical perspective.

Means for Solving the Problems The present invention is equipped with a ballast and a current-limiting element in series with the discharge lamp, and a diode is connected in parallel with the current-limiting element. In order to achieve full-light lighting in both positive and negative cycles, a simple circuit configuration is provided, such as providing a delay circuit that shorts the current-limiting element when the discharge lamp starts, and repeats full-light lighting and dimmed lighting every half cycle. In this way, 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 the power supply circuit according to the present invention, in which 1 is an AC power supply, 2 is a ballast, and the ballast 2 is composed of a power factor correction capacitor 3 and a chiyoke coil 4. 5 is a high-pressure discharge lamp (hereinafter simply referred to as a discharge lamp); 6 is a current-limiting element; the current-limiting element 6 is connected in series with the discharge lamp 5; and a diode 7 is further connected to the current-limiting element 6. ing. A current detection circuit 8 that detects lamp current when it flows is connected to both ends of the chiyoke coil 4.
consists of a resistor 9 and a capacitor 10 connected in series, and a relay 11 connected in parallel with the capacitor 10. Further, a series circuit of the normally open contact 12 of the relay 11 and the timer 13 is connected in parallel to the AC power supply 1. Further, the normally closed contact 14 of the timer 13 is connected in parallel with the current limiting element 6, forming a timer circuit 15. The current detection circuit 8 and the timer circuit 15 constitute a delay circuit that short-circuits the current-limiting element 6 for a predetermined period of time after starting the discharge lamp.

Next, the operation of the embodiment of the present invention will be explained. First, when the AC power source 1 is turned on, the discharge lamp 5 is started. At this time, a lamp current flows through the chiyoke coil 4, and a voltage is generated across the chiyoke coil 4. This voltage causes the capacitor 10 to have a resistor 9
A divided voltage is generated and operates the relay 11. At this time, the normally open contact 12 of the relay 11 is closed, and the timer 13 starts operating. If the timer 13 is set to the time required for the discharge lamp 5 to stabilize, for example, about 2 minutes, the normally closed contact 14 of the timer 13 will remain closed during that time, and the AC power source 1 will cycle through both positive and negative cycles. Tomo discharge lamp 5
will be fully lit. When the set time of the timer 13 has elapsed, the normally closed contact 14 is opened, and thereafter, during the positive half cycle of the AC power supply 1, the diode 7 is conductive, the current limiting element 6 is shorted, and the discharge lamp 5 is fully lit. In the negative half cycle, the diode 7 becomes non-conductive and the lamp current flows through the current limiting element 6, so that the discharge lamp 5 is dimmed.
By operating in this manner, no direct current flows through the ballast 2 during the period when the equivalent impedance of the discharge lamp 5 is low, and therefore the chiyoke coil 4 is biased to direct current, resulting in a large current that flows into the ballast 2 and the ballast 2. The discharge lamp 5 will not be damaged. When the lighting of the discharge lamp 5 becomes stable, the equivalent impedance increases, so
Even if the normally closed contact 14 of the timer 13 is opened and a DC component flows, the current is also suppressed in the discharge lamp 5.
No large current flows.

FIG. 2 shows an example of an optical output waveform during stable lighting when the power supply circuit shown in FIG. 1 is used.

In addition, in the embodiment of the present invention shown in Fig. 1, a high-pressure sodium lamp is used as the discharge lamp 5, and the output is 400W,
When growing salad greens by lighting at Hz,
At an output of 660W, the same effect as a continuous high-pressure sodium lamp was obtained. Furthermore, even when a so-called metal halide lamp filled with sodium halide, mercury halide, etc. was used as the discharge lamp 5, it was possible to grow salad vegetables with the same power saving rate. Furthermore, after starting the discharge lamp, the time required for the discharge lamp to reach the equivalent impedance required to suppress the DC current varies depending on the type of high-pressure discharge lamp and the output power, but it is sufficient to expect it to be between 30 seconds and 3 minutes. It was confirmed through experiments that this is the case. Therefore, timer 13
The set time, that is, the delay time of the delay circuit that short-circuits the current-limiting element 6 at the time of startup until the discharge lamp stably lights up, may be set to 30 seconds or more and 3 minutes or less.

Effects of the invention As detailed above, according to the invention, a high-pressure discharge lamp can be lit with a simple circuit configuration such that the light output increases and decreases every half cycle, and as a result, the lighting power It is possible to significantly reduce costs and equipment costs, and to achieve the same effect as 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 discharge lamp and the ballast, thereby reducing air conditioning costs in the cultivation room or making the discharge lamp, ballast, and lighting equipment 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.

As described above, great effects can be obtained by lighting a discharge lamp for plant growth using the power supply circuit according to the present invention.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the power supply circuit of the discharge lamp for growing plants of the present invention, and Fig. 2 is an example of the waveform of the light output of the discharge lamp when the embodiment of the invention shown in Fig. 1 is turned on. . 1... AC power supply, 2... Ballast, 5... High pressure discharge lamp, 6... Current limiting element, 7... Diode, 8...
...Current detection circuit, 15...Timer circuit.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) In a high-pressure discharge lamp power supply circuit that repeats full lighting and dimmed lighting so that the light output increases and decreases every half cycle of the AC power supply, together with a ballast in series with the discharge lamp. For plant cultivation, comprising a current-limiting element, a diode connected in parallel with the current-limiting element, and a delay circuit that short-circuits the current-limiting element at the time of starting until the discharge lamp stably lights up. Discharge lamp power supply circuit. (2) Utility model registration claim No. (1) characterized in that the delay circuit comprises a current detector that detects discharge lamp current and a timer circuit that short-circuits the current limiting element for a predetermined time after detecting the current. A power supply circuit for a discharge lamp for growing plants as described in Section 1. (3) The power supply circuit for a discharge lamp for plant cultivation according to claim (1), wherein the delay time of the delay circuit is 30 seconds or more and 3 minutes or less.