JPH01204397A - Lighting control device - Google Patents

Abstract

PURPOSE:To make it possible to control and stabilize the brightnesses of fluorescent lamps properly and individually by making it possible to individually detect the brightnesses of a plurality of fluorescent lamps without being affected by the fluorescent lamps other than the lamp individually detected. CONSTITUTION:When a plurality of fluorescent lamps 1 are actuated and lit at different frequencies, the output light of each fluorescent lamp 1 is received by a photoelectric sensor 2. The photoelectric sensor 2 converts the received light signal into an electric signal and outputs it, A filter 1 allows to pass only the signal component of a frequency corresponding to the lighting frequency of each fluorescent lamp 1. The filtered output is given to a lighting control circuit 5 and a brightness signal corresponding to the brightness of the fluorescent lamp 1 is produced. The lighting control circuit 5 controls the lighting voltage of the fluorescent lamp 1 based on the brightness signal, This arrangement enables to stabilize and maintain the brightness of each of the fluorescent lamps 1.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention provides a system for stably maintaining the brightness of a fluorescent lamp at a predetermined value, for example, in a system that images an object under illumination with a fluorescent lamp and processes the image. This invention relates to a lighting control device for use in lighting systems.

<Conventional technology> Conventionally, in order to maintain the brightness of a single fluorescent lamp at a predetermined value,
The output light of the fluorescent lamp is received by a photoelectric sensor and converted into an electrical signal, a brightness signal corresponding to the brightness of the fluorescent lamp is generated from this electrical signal, and the voltage of this brightness signal is compared with a reference voltage. There is a method of controlling the lighting voltage of a fluorescent lamp by controlling the lighting voltage of a fluorescent lamp.

By the way, if this control method is directly applied to the control of a lighting system equipped with multiple fluorescent lamps, a photoelectric sensor will be used for each fluorescent lamp to receive its output light, but each photoelectric sensor has other Since the output light of the fluorescent lamps is incident, it is difficult to accurately detect the brightness of each fluorescent lamp. Conventionally, the brightness of the entire illumination system from all fluorescent lamps was detected by using a single photoelectric sensor to receive the output light of multiple fluorescent lamps, or the brightness of the entire lighting system from all fluorescent lamps was detected by using a single photoelectric sensor, or by using a photoelectric sensor for each fluorescent lamp to detect the output light from other fluorescent lamps. A method is adopted in which the brightness of each fluorescent lamp is controlled individually by detecting the brightness of each fluorescent lamp while ignoring the input light from the fluorescent lamp.

<Problems to be solved by the invention> However, since deterioration of fluorescent lamps occurs and progresses individually, in any of the above control methods, if one of the fluorescent lamps deteriorates, other fluorescent lamps that have not deteriorated will As a result, control is performed to increase the brightness of the fluorescent lamp. As a result, the balance of brightness in each fluorescent lamp gradually collapses, causing uneven illumination, which is extremely inconvenient in image processing. Furthermore, in the case of the above control method, even if one of the fluorescent lamps malfunctions due to deterioration, the brightness of the lighting system as a whole is maintained at a predetermined value.
There are problems such as failure to discover poorly lit fluorescent lamps and delays in replacing them.

This invention was made with attention to the above problem, and by making it possible to detect the brightness of a plurality of fluorescent lamps individually without being affected by other fluorescent lamps, the brightness of each fluorescent lamp can be adjusted. The purpose of the present invention is to provide a novel lighting control device that can individually and appropriately control and stabilize the lighting.

<Means for Solving the Problems> In order to achieve the above object, the present invention provides a lighting control device that controls the lighting voltage of a plurality of fluorescent lamps to stably maintain the brightness of each fluorescent lamp. Multiple fluorescent lamps whose frequencies are set to different values, a photoelectric sensor to receive the output light of these fluorescent lamps and convert it into an electrical signal, and a frequency corresponding to the lighting frequency of each fluorescent lamp for the output of the photoelectric sensor. A lighting control circuit that generates a brightness signal corresponding to the brightness of each fluorescent lamp from the filter output and controls the lighting voltage of each fluorescent lamp based on this brightness signal. I decided to equip it.

<Operation> When multiple fluorescent lamps are lit at different lighting frequencies,
The output light of each fluorescent lamp is received by a photoelectric sensor. The photoelectric sensor converts the received light signal into an electric signal and outputs it, and the filter passes only the signal component of the frequency corresponding to the lighting frequency of each fluorescent lamp in the output of the photoelectric sensor. The filter output is fed to a lighting control circuit to generate a brightness signal corresponding to the brightness of each fluorescent lamp.Furthermore, this lighting control circuit controls the lighting voltage of each fluorescent lamp based on this brightness signal. Maintains stable brightness of fluorescent lights.

According to this invention, the brightness of each fluorescent lamp is detected without being affected by the output light of other fluorescent lamps, so even if one of the fluorescent lamps deteriorates, the brightness of that fluorescent lamp can be increased. control is carried out. Therefore, the brightness balance of each fluorescent lamp is always maintained, and uneven illumination does not occur. In addition, since control is performed for each fluorescent lamp without being affected by other fluorescent lamps, if any fluorescent lamp malfunctions due to deterioration, this can be easily detected and the fluorescent lamp can be replaced quickly.

<Embodiment> Fig. 1 shows the overall configuration of a lighting control device according to an embodiment of the present invention, and Fig. 2 (1) to (4) show signal waveforms of each part of the circuit in this device example. It shows. Although the illustrated example controls the brightness of an illumination system 1 consisting of two fluorescent lamps 1a and lb, the present invention is not limited to this, and the brightness of an illumination system consisting of a large number of fluorescent lamps can be controlled. It can also be applied to equipment that uses

The illustrated lighting control device includes two fluorescent lamps 1a.

two control systems A for individually controlling the brightness of 1b;
Each control system A, B includes a photoelectric sensor 2a,
2b, amplifiers 3a, 3b, bandpass filters 4a, 4
b and two lighting control circuits 5a and 5b.

Each fluorescent lamp 1a, lb is lit at a high frequency at a different lighting frequency f, , f2 to eliminate the influence of other fluorescent lamps, and in the case of this embodiment, the value is f I = 10 (
kHz) and f2 = 50 (kHz).

Each photoelectric sensor 2a, 2b corresponds to a fluorescent lamp la, lb.
They are placed at equal distances and positions from each other, and receive the output light from each of the fluorescent lamps 1a and 1b and convert it into an electrical signal (see FIG. 2 (2)) corresponding to the amount of received light. Each bandpass filter 4a.

4b allows only signal components of frequencies corresponding to the lighting frequencies f, f2 of each fluorescent lamp 1a, lb to pass for each sensor output amplified by each amplifier 3a, 3b.

FIG. 3 shows the frequency characteristics of each bandpass filter 4a, 4b together with the harmonic components of the sensor output, and one bandpass filter 4a has a center frequency of 2.
By setting f I (-20 (kHz)),
By passing only the signal component due to the output light of one fluorescent lamp 1a, and by setting the center frequency of the other bandpass filter 4b to 2f2 (-100 (kHz)), the signal component due to the output light of the other fluorescent lamp 1a is passed. Only signal components are passed through.

Output of each bandpass filter 4a, 4b (Fig. 2 (3)
) are rectifier/smoothing circuits 6a and 6b.

Error amplifiers 7a, 7b, drivers 8a, 8b.

Lighting control circuit 5a, '5 consisting of inverters 9a, 9b
b, respectively.

The rectifier/smoothing circuits 6a, 6b are for rectifying and smoothing each filter output to extract a voltage corresponding to the brightness of each fluorescent lamp 1a, lb.
(see Figure (4)) are error amplifiers 7a and 7 as brightness signals.
b and is compared with a reference voltage. As a result, each error amplifier 7a, 7b is driven by a driver 8 so that both type pressures match.
By controlling the operations of a, 8b and inverters 9a, 9b, the lighting voltage of each fluorescent lamp 1a, lb (see Fig. 2 (1))
is controlled by feedback.

In the above configuration, each of the two fluorescent lamps 1a.

When the lbs are lit at different lighting frequencies f, , f2, the output light of each fluorescent lamp 1a and lb is transmitted to the photoelectric sensor 2a and 2b.
The sensor outputs are received by the sensor and converted into electrical signals, and the outputs of each sensor are applied to bandpass filters 4a and 4b via respective amplifiers 3a and 3b.

Each of the band pass filters 4a, 4b passes only signal components having frequencies 2f, 2f2 which are twice the lighting frequency f+, fz of each fluorescent lamp 1a, lb for these input signals, and these filter outputs are sent to the lighting control circuit. 5a, 5b.

Each lighting control circuit 5a, 5b generates a brightness signal corresponding to the brightness of the fluorescent lamp 1a, lb, and controls the lighting voltage of each fluorescent lamp 1a, lb based on this brightness signal,
The brightness of each fluorescent lamp 1a, lb is maintained at a predetermined value.

When one of the fluorescent lamps 1a deteriorates and its output light decreases, the lighting control circuit 5a in the control system A generates a brightness signal corresponding to the decreased output light, and the brightness of the fluorescent lamp 1a decreases. Control is performed to increase the On the other hand, in the control system B of the other fluorescent lamp 1b, the brightness signal generated by the lighting control circuit 5b is not affected by the fluorescent lamp 1a whose output has decreased at all, and therefore its own brightness control is performed. It will be done. Therefore, the brightness of each of the fluorescent lamps 1a and 1b is always maintained at a predetermined value, the brightness of both is balanced, and uneven illumination does not occur.

Note that in the above embodiment, two photoelectric sensors are used, but
Not limited to this, - photoelectric sensors are connected to two fluorescent lamps 1a,
The photoelectric sensor may be arranged at a position equidistant from 1b, and the output of this photoelectric sensor may be provided to each bandpass filter 4a, 4b.

<Effects of the Invention> As described above, the present invention provides a plurality of fluorescent lamps whose lighting frequencies are set to different values, a photoelectric sensor for receiving the output light of these fluorescent lamps and converting it into an electrical signal, and a photoelectric sensor. A filter is used to extract only the signal component of the frequency corresponding to the lighting frequency of each fluorescent lamp, and a brightness signal corresponding to the brightness of each fluorescent lamp is generated from the filter output. A lighting control device is comprised of a lighting control circuit that controls the lighting voltage of the fluorescent lamp.

According to the device of this invention, the brightness of each fluorescent lamp is detected without being affected by the output light of other fluorescent lamps, so even if any of the fluorescent lamps deteriorates, the brightness of the deteriorated fluorescent lamp will be reduced. Control is performed to increase the Therefore, the brightness balance of each fluorescent lamp is always maintained, and uneven illumination does not occur.

In addition, since each fluorescent lamp is controlled individually without being affected by other fluorescent lamps, if any fluorescent lamp malfunctions due to deterioration, it can be easily detected and the fluorescent lamp can be replaced quickly. It has achieved remarkable effects.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the overall configuration of a lighting control device according to an embodiment of the present invention, Fig. 2 is a time chart of the example of the device in Fig. 1, and Fig. 3 explains the frequency characteristics of a bandpass filter. FIG. la, lb...Fluorescent lamps 2a, 2b...Photoelectric sensors 4a, 4b...Band pass filters 5a, 5b...
・Lighting control circuit

Claims (1)

[Claims] A lighting control device that controls the lighting voltage of a plurality of fluorescent lamps to maintain stable brightness of each fluorescent lamp, comprising: a plurality of fluorescent lamps whose lighting frequencies are set to different values; A photoelectric sensor that receives the output light of the fluorescent lamp and converts it into an electrical signal, a filter that extracts only the signal component of the frequency corresponding to the lighting frequency of each fluorescent lamp from the output of the photoelectric sensor, and a filter that extracts each signal component from the filter output. A lighting control device comprising: a lighting control circuit that generates a brightness signal corresponding to the brightness of a fluorescent lamp and controls the lighting voltage of each fluorescent lamp based on this brightness signal.