JPS61218092A - Photoelectric type flash control circuit - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a photoelectric blinking control circuit used in a photoelectric automatic blinker that automatically turns on and off a light source according to illuminance.

[Background technology]

This type of photoelectric blinking control circuit has a blinking operation that turns on light sources installed outdoors, such as street lights and security lights, when it gets dark in the evening and turns them off when it gets bright in the morning. It is often used when performing automatically. The state of automatic blinking control by this conventional photoelectric blinking control circuit (hereinafter abbreviated as "flashing control circuit" in this specification) is shown in Fig. 4, which shows the relationship between the temporal change in illuminance and the automatic blinking time. This will be explained with reference to. As shown in the illuminance curve (a) in Figure 4, as the day passes and evening approaches, the illuminance gradually decreases, and finally reaches the illuminance LA where natural light alone is insufficient to distinguish objects.
become. The blinking control circuit is equipped with a circuit that photoelectrically converts the illuminance using a photoconductive element such as CdS (cadmium sulfide), and the blinking is performed based on the output signal that this photoelectric conversion circuit outputs when the illuminance is LA. A control circuit automatically turns on the light source.

After that, the light source continues to be lit during the night, but in the morning, the illuminance increases again and reaches the illuminance LB, which is slightly higher than the illuminance LA, and the blinking control circuit at this time Automatically turns off the light source based on the output signal. The reason why the illuminance LB at the start of turning off the light source is higher than the illuminance LA at the start of turning on the light source is as follows. If you set the light to turn off immediately after the illuminance LA is exceeded, even if the light source turns on at the illuminance LA, immediately after that, the illuminance will be slightly higher due to fluctuations in the illuminance itself or due to the lighting operation of the light source itself. Sometimes the lights go back to the same direction, and in such cases the lights go out again. In some cases, such a blinking operation may be repeated many times when lighting starts. This repetition of continuous blinking of the light source is undesirable because it shortens the life of the light source and causes discomfort to people. Therefore, in order to prevent the light from turning off even if the illuminance returns to the original level for a while after being turned on (in other words, unless it returns to the illuminance LB or higher), the illuminance LA, L
By setting B as described above, the blinking control circuit is provided with hysteresis characteristics. usually,
The illuminance LB is set to a value that is approximately two to five times the illuminance LA.

However, even if the illuminance is the same in the evening and in the morning, human senses perceive the morning as brighter, so the illuminance LB with the lights off is higher than the illuminance LA with the lights on, and in the morning, the illuminance LA is still brighter. When it is lit, it becomes like a night light, giving a sense of strangeness to people passing by. In other words, in the conventional blinking control circuit, unnecessary lighting is performed for a certain period of time close to when the lights are turned off in the morning. Naturally, this unnecessary lighting not only makes people feel strange, but also shortens the life of the light source, and the light sources used in street lights consume a lot of electricity (and are placed in Since there are many of them, extra power is consumed.

[Purpose of the invention]

In order to solve the above-mentioned problems, this invention eliminates unnecessary lighting in the morning, prolongs the life of the light source, saves power consumption, and also enables blinking that does not cause any strange feeling to people passing by. The purpose is to provide a control circuit.

[Disclosure of the invention]

In order to achieve the above object, the present invention provides a photoelectric blinking control circuit including a switching element that blinks a light source based on a photoelectric conversion signal corresponding to illuminance, when the illuminance falls below a first level. A switching element control circuit is provided that controls the switching element to turn on the light source once and then turn off the light source when the illuminance is at least a second level lower than the first level. The gist of this paper is a photoelectric blinking control circuit.

This invention will be described below with reference to FIG. 1, which shows a block diagram of a blinking control circuit according to an embodiment of the invention, and FIG. This will be explained with reference to the figures. As the evening approaches and the illuminance decreases, the photoelectric conversion output (2) of the photoelectric conversion circuit (1) decreases, as shown in the output waveform (b) shown in FIG. The output of this photoelectric conversion circuit 1 is input to a first level detection circuit 2 and a second level detection circuit 3. Then, when the photoelectric conversion output V falls below the level E1, the first level detection circuit 2 detects this decrease in illuminance, and the output is reversed from the L level to the H level, as shown in FIG. (The period during which the lighting signal is inverted to the H level side becomes the output period of the lighting signal.) Immediately upon receiving this inversion to the H level, the switching element drive circuit 6
(hereinafter abbreviated as "switching circuit 6") is the light source 7
It operates to light up. The output of the first level detection circuit 2 is also input to a time width signal generation circuit 4 (hereinafter abbreviated as "time width circuit 4"), and when this input is received, the first level detection circuit 2 Time T5 after a certain time width TM from time T1 when the output shifts from L level to H level
Until then, the output of the time width circuit 4 is low as shown in FIG.
level. Then, after time T5, it automatically returns to the H level. Although the output of the time width circuit 4 shown in FIG. 3 is at L level before time T1 and after time T4, it may be at H level. In short, it is sufficient to remain at the L level only during the period TM. On the other hand, the output of the second level detection circuit 3 is
As shown in FIG. 3, although the illuminance is still at H level at the lighting start time TI, the illuminance further decreases at time T2.
When the photoelectric conversion output ■ falls below level E2, the second level detection circuit 3 detects this and the output inverts from H level to L level, and in the morning, the photoelectric conversion output falls to level 82 again. At time T3, when the level is higher than that, the level returns from the L level to the H level. This second level detection circuit 3
Both the output of the time width circuit 4 and the output of the time width circuit 4 are inputted to the lights-off control circuit 5. The lights-off control circuit 5 is a time width circuit 4
and the output of the second level detection circuit 3, it operates as follows. First, only during the period when both outputs are at H level, that is, from time T3 to time T4.
As shown in FIG. 3, the output of this lights-off control circuit 5 is:
The switching circuit 6 is operated so that the light source 7 is turned off even when the output of the first level detection circuit 2 is at H level. However, the output of the lights-off control circuit 5 does not invert to the lights-off level side while the output of the time span circuit 4 is at L level even if the second level detection circuit 3 is at H level. to time T2,
The light source 7 remains lit. In other words, while the output of the second level detection circuit 3 is at H level, the light-off signal is output, but the time width circuit 4 outputs the light-off signal at L level for a certain period of time TM from the start of generation of the light-on signal. During this period, the light-off control circuit 5 is operated to prevent the light-off control circuit 5 from generating the light-off signal so that the light source 7 will not be turned off even if the light-off signal is output. Therefore, as a result,
As for the light source blinking operation, as shown in FIG. 3, the light source 7 is turned on at time T1 in the evening, and is turned off at time T3 in the morning when the illuminance is lower than the illuminance at the time of lighting.

At time T4, the output of the first level detection circuit 2 becomes L level, and at the same time, the output of the lights-off control circuit 5 also ceases to be at the lights-off level. However, the output of the lights-off control circuit 5 is at time T4.
Thereafter, the light may remain at the off level. Normally, the inversion operation levels of the first level detection circuit 2 and the second level detection circuit 3 are adjusted and set so that the illumination intensity when the lights are turned on is 1.5 to 5 times the illumination intensity when the lights are turned off. Note that the first level detection circuit 2 may have a hysteresis characteristic so that once the light-off signal is output, the light-on signal does not disappear even if the illuminance increases a little.

The above-mentioned time width circuit 4 is an integrated circuit configured to start time measurement in response to a change in the input level at time TI.
A C timer circuit or a one-shot multivibrator that generates a relatively long pulse is used. Of course, the present invention is not limited to the configuration shown in the block diagram of FIG. 1 described above. Therefore, the switching control circuit turns on the light source once when the illuminance falls below the first level, and then
Any switching control circuit may be used as long as it controls a switching element that blinks the light source so as to turn off the light source when the light source is at least a second level lower than the second level. Further, it goes without saying that the switching element may be an electronic switch such as a silice or a transistor, or may be a switch such as a relay contact.

Next, a more detailed explanation will be given based on FIG. 2, which shows a circuit example in which each block of the blinking control circuit shown in FIG. 1 is made more specific. The photoelectric conversion circuit 1 is made of, for example, CdS.
A photoconductive element D1 such as (cadmium sulfide) and a resistor R
It consists of 1. As the illuminance decreases, the resistance value of the photoconductive element Di increases, so the photoelectric conversion output (2) of the 71 points decreases as the illuminance decreases. The second level detection circuit 2 is composed of a comparator CPI that performs an inverting operation based on the 72-point voltage that provides the photoelectric conversion output level E1 at which the light source 7 starts to turn on, and the second level detection circuit 3 is composed of a comparator CPI that operates in reverse when the light source 7 starts to turn off. Gives photoelectric conversion output level E2 ■
Comparator CP that operates inverted based on 3-point voltage
It consists of 2. The output terminal of this comparator CP1 is connected to the gate of thyristor S1. When the comparator CPI is inverted and a lighting signal is generated at its output, the thyristor S1 becomes conductive, and current flows through the resistor R5 and the full-wave rectifier circuit D2, so the triac (bidirectional thyristor) S2, which is a switching element, becomes conductive. do.

Due to the conduction of the triac S2, a current flows through the light source 7, so that the light source 7 lights up. As the time width circuit 4,
As mentioned above, for example, an IC timer is used in which the output is reset at the generation of the output of the comparator CP1, the output is at the L level until a certain time width TM is counted, and the output is at the H level after the time measurement is completed. . Lights-off control circuit 5
As shown in the figure, AND5a inputs the output of the time width circuit 4 and the output of the comparator CP2, and the
The transistor 5b has an emitter and a collector connected between the gate of the AND5a and a common line CM of the entire circuit, and a transistor 5b whose base is connected to the output of the AND5a.

When both inputs of AND5a are at H level,
The output becomes H level, and transistor 5b becomes conductive. Due to the conduction of this transistor 5a, the thyristor S1
Since the gate of is short-circuited to the common line CM, the thyristor Sl becomes non-conductive and the light source 7 is turned off. In addition, if the circuit is configured so that the signal outputs of the second level detection circuit 3 and the time width signal generation circuit 4 are at levels completely opposite to those described above, NAN is used instead of AND5a.
D is used. Note that a DC power supply is formed by the diode D3, the resistor R6, and the capacitor C2, and the Zener diode D4 further stabilizes the voltage of this DC power supply. In addition, in the switching circuit 6, the tritic S2, which is a switching element, is controlled via the thyristor S1, the full-wave rectifier circuit D2, etc., but depending on the capacity of the light source 7, etc. Alternatively, it may be driven.

〔Effect of the invention〕

As detailed above, the photoelectric flashing control circuit according to the present invention turns on the light source once when the illuminance falls below the first level, and then turns on the light source when the illuminance falls below the first level. A switching element control circuit is provided to control the switching element so as to turn off the light source at certain times. Because of this configuration, in this blinking control circuit, the lights are turned off in the morning at a lower illuminance than the illuminance at which the lights are turned on in the evening, unlike the conventional ones. Therefore, the light source does not stay on for an unnecessarily long time in the morning, so it does not make people feel strange, and furthermore, power consumption can be saved and the life of the light source can be extended.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a blinking control circuit according to an embodiment of the present invention, FIG. 2 is a specific circuit diagram of a blinking control circuit according to an embodiment of the present invention, and FIG. 3 is a block diagram of the blinking control circuit according to an embodiment of the present invention. FIG. 4, a time chart showing changes over time and changes over time in the light source blinking operation, is an explanatory diagram of the relationship between changes over time in illuminance and automatic blinking time in a conventional blinking control circuit. 8...Power supply Dl...Photoconductive element D4...Zener diode CPI, CP2...Comparator
Sl...Thyristor S2...Triac 5a
...AD Agent Patent Attorney Takehiko Matsumoto Figure 2 Figure 3

Claims (4)

[Claims] (1) In a photoelectric blinking control circuit including a switching element that blinks a light source based on a photoelectric conversion signal corresponding to illuminance, the light source is turned on once when the illuminance falls below a first level, and then, A photoelectric flashing control circuit comprising a switching element control circuit that controls the switching element to turn off the light source when the illuminance is at a second level or higher that is lower than the first level. (2) The switching element control circuit includes a first level detection circuit that outputs a lighting signal for operating the switching element when the illuminance is lower than the first level, and a first level detection circuit that outputs a lighting signal for operating the switching element when the illuminance is lower than the first level, and a switching element control circuit that outputs a lighting signal for operating the switching element when the illuminance is lower than the first level. A second level detection circuit outputs a light-off signal for turning off the element, and a time-width signal generation circuit outputs a signal with a fixed time width from the start of the light-on signal generation, and this time width signal is output. 2. The photoelectric blinking control circuit according to claim 1, further comprising a lights-off control circuit that prevents the switching element from turning off the light while the lights are turned off based on the lights-off signal. (3) The photoelectric blinking control circuit according to claim 2, wherein the time width signal generating circuit is a timer circuit. (4) The photoelectric blinking control circuit according to claim 2, wherein the time width signal generating circuit is a one-shot multivibrator.