JPS595597A - Dimming 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 The present invention relates to a dimming control circuit that controls the dimming of artificial light generated by a lighting load and maintains the overall illuminance substantially constant regardless of the magnitude of daylight.

Conventional dimming control circuits have been developed that control the artificial light caused by the lighting load in the range of 100% to 20% so that the illuminance on the desk surface is constant due to the sum of the artificial light and daylight. . @1 Figure shows the operation of such a conventional example. In FIG. 1, (2) indicates the illuminance due to daylight, (H) indicates the illuminance due to artificial light, and (d F′i) indicates the overall desk surface illuminance. The lighting load is turned off when the illuminance becomes higher than the desired set illuminance of 8096.For this reason, when the illuminance due to daylight is greater than 80% and less than 100X, the lighting load is turned on or off. There was also the problem that it was extremely difficult to control the illuminance of artificial light within the range of 0% to 20% of the set illuminance without turning off the lighting load. The uninvented invention was made to solve such problems of the conventional example, and it is a situation where the lighting load repeats turning on and off until the illuminance due to daylight reaches the desired set illuminance. It is an object of the present invention to provide a dimming control circuit that can prevent this.

The configuration of the present invention will be described below with reference to illustrated embodiments. Second
Figures 4 to 4 show an embodiment of the invention. First, in FIG. 2, 11) is a lighting load, which is connected to an AC power source 13) via a dimming unit +21i. 14) is a control circuit that controls the light control unit z1 according to the amount of light detected by the sensor 161. Figure @3 is a circuit diagram showing the configuration of the control circuit (4), which compares the amount of daylight and artificial light detected by Seris 15) with the set illuminance on the desk surface, and calculates the difference component. and a comparison amplifier circuit (6) which has a steresis characteristic and which amplifies the lighting load Il+ according to the output of the comparison amplifier circuit (61).
A steresis circuit 17) for controlling on/off of the lighting load 11) and a lower limit illuminance holding circuit (8) for maintaining the lower limit of the illuminance of artificial light by the lighting load 11) at a predetermined level are located 1 km apart. Comparison amplifier circuit +61 is a differential amplifier (91 and variable resistor VR1
It consists of a resistor R+ and a capacitor CK.

Differential amplifier (variable resistor V is connected to the input terminal of 91)
A reference voltage divided by a series circuit of R and a resistor Rs is applied. By changing this reference voltage, the illuminance setting for the desk surface can be changed. The negative input terminal of the differential amplifier (9) is connected to 7ys161.
A voltage signal corresponding to the amount of light detected by the steresis circuit 1101 is applied to the steresis circuit 71. The steresis circuit 71 is composed of a comparator 1101, resistors R1 to R4, Ry and a transistor Q. Comparator 110
A reference voltage divided by resistors R and Ra is applied to the positive input terminal Llc of 1, and the output voltage of the comparison amplifier circuit (61) is input to the negative input terminal. When the output voltage of the comparison amplifier circuit (6) becomes equal to or lower than the reference voltage divided by the resistors R and Rs, the output of the cosciparator 110+ becomes H level.
Transistor Ql turns on and relay Ry turns on. The relay Ry is configured to turn off the lighting load (1) when the power of the dimming unit 12) is turned off. By the way, when the output of the comparator 11α becomes H level, the reference voltage applied to the positive input terminal of the comparator 11α via the resistor R4 rises, so the relay Ry is turned on and the bell control relay Ry is turned off. There is a difference in the level of operation. Furthermore, the lower limit illuminance holding circuit (8) is composed of a switch (11), resistors R1, R6, Rv, diodes Di, DI, and a transistor. The lower limit set voltage corresponding to the lower limit illuminance level of the resistor Rs and RgFi is divided into voltages, and the lower limit set voltage divided by the resistor island and I It is applied to the base of transistor Q8. Further, the output voltage of the comparison amplifier circuit (6) is applied to the base of the transistor via the diode D.

Therefore, if the output voltage of the comparison amplifier circuit (61) is better than the lower limit setting voltage formed by the resistors Rm and R@, the output voltage of the comparison amplifier circuit (6) is applied to the base of the transistor (h). However, the comparison amplifier circuit 16)
When the output voltage is lower than the lower limit setting voltage, the lower limit setting voltage is applied to the base of the transistor Cb via the diode Dsf. The transistor Q1 is connected as a follower, so the transistor Q! is connected to both ends of the resistor R7. The voltage applied to the base of the circuit is output with low impedance. This output voltage is not supplied to the dimming unit (2) as a filter signal.

Next, to explain the operation of the Taimei Example, first, sensor 1
When the combined light amount of daylight and artificial light (! The amount of artificial light due to the illumination load (11) increases.On the other hand, when the amount of light detected by the sensor (6) is greater than the set illuminance, the comparison amplifier circuit (6) increases the amount of artificial light due to the illumination load (11). )
The output of the lighting load is reduced, which reduces the amount of artificial light due to the lighting load. Therefore, as shown in FIG. 4 (al), the entire desk surface illuminance to Vi, which is the illuminance due to daylight □ (Al and the illuminance due to artificial light (8)), is maintained at the set illuminance. However, when the illuminance due to daylight becomes 80% or more of the set illuminance, the illuminance due to artificial light is maintained at 20% of the set illuminance by the lower limit illuminance holding circuit (8).The illuminance due to daylight increases further. When the illuminance on the desk reaches 120% or more of the set illuminance, the relay Ry of the steresis circuit (7) turns on, the power of the dimmer unit (2J) turns off, and the lighting load (1) turns off. As a result, the illuminance on the desk surface becomes low and almost equal to the set illuminance, but the steresis circuit (
7) Since Norishi-Ry does not turn off until the desk surface illuminance falls to 80% or less of the set illuminance, relay Ry will not repeatedly turn on and off. In addition, Fig. 4 (bl shows the change in illuminance of lighting load (1) with respect to the change in illuminance due to daylight, and the symbols ■ to ■ in the same figure represent the order in which the illuminance changes. (Corresponding to the symbols ■ to ■ of al.

The present invention is configured as follows, and detects the illuminance that is the sum of the illuminance due to artificial light from the lighting load and the illuminance due to daylight. means for controlling the lighting load t-dimmer so that the illuminance detected by the sensor substantially matches the desired set illuminance, and maintaining the lower limit of the illuminance due to artificial light from the lighting load at a predetermined value that is not zero. lower limit illuminance holding means,
Since the lighting device has a means for turning off the lighting load when the illuminance due to daylight reaches the desired set illuminance, the lighting load is turned on until the illuminance due to daylight reaches the desired set illuminance. It has the advantage that there is no need to repeatedly turn off and turn off the lights, and there is no need to control the dimming of the illuminance of the lighting load in a low illuminance area where it is close to zero level, so the method of controlling the dimming of the lighting load is simplified. It has the advantage of being able to

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the operation of the conventional example, Fig. 2 is a diagram showing the overall configuration of an uninvented embodiment, Fig. 3 is a circuit diagram of the main part of the same as above, Fig. 4 It is an operation explanatory diagram. ill Iri lighting load, 12) is a dimming unit, 14
) is a control circuit, 16) is a sensor, (6) is a comparison amplifier circuit, (7) is a steresis circuit, and a +81 Vi lower limit illuminance holding circuit. Agent Patent Attorney Ishi 1) Choshichi

Claims (1)

[Claims] 11) A sensor that detects the illuminance that is a combination of illuminance due to artificial light and daylight from the lighting load, and dimming control of the lighting load so that the illuminance detected by the sensor approximately matches the desired set illuminance. means for maintaining the lower limit of illuminance due to artificial light from the lighting load at a predetermined value other than zero; and means for turning off the illumination load when the illuminance due to daylight reaches a desired set illuminance. A dimming control circuit comprising: