CZ20004043A3 - Device for automatic control of illumination level - Google Patents

Abstract

An automatic lighting intensity regulating device or "dimmer" (DM), utilizable in particular for electronic reactors of fluorescent tubes, controlled by an electronic circuit for the partial closing of the conduction angle, in order to supply a lamp current (IL), for each cycle of the rectified network signal (IR) , only for a certain amount of time, so as to minimize the production and operating costs of the device (DM), with respect to those now offered on the market.

Description

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The device for automatic regulation of luminous intensity, particularly useful for electronic chokes of fluorescent tubes or fluorescent lamps, is controlled by an electronic circuit whose operation is based on at least a partial closing process of the line angle, so that a current signal (IL) is supplied to each cycle said tube for a predetermined period of time, said electronic circuit comprising at least one phototransistor (FT) light detecting device that monitors ambient light and emits an output signal (VE, IE) which, after filtration, is fed to a portion of the circuit to be compared with a predetermined value (P) such that a timing device synchronized with the rectangular waveform current signal (IR) is triggered by using a toothed signal (IS).

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01-3159-00-Eng

Device for automatic regulation of light intensity

Technical field

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic light intensity control device, in particular for electronic chokes and fluorescent lamps.

BACKGROUND OF THE INVENTION

It is known that most of the emitted light in fluorescent lamps is generated by the fluorescent substance that is coated with the fluorescent tube.

In addition, these fluorescent tubes usually exhibit a negative voltage to current ratio, so that in the absence of any other device, the current flow increases when lit up to a magnitude which leads to damage. It is therefore very important to provide a supply device, which usually consists of an electronic choke capable of limiting the current and output of the luminaire, depending on the design data provided by the manufacturer, to provide a suitable current intensity to preheat the cathodes and fluorescent tubes and to provide a suitable charge voltage. discharge.

The light intensity control device for fluorescent lamps is controlled and controlled by electronic circuits, which, however, are very expensive due to the relatively high light intensity. The complexity of their components, the relatively long wiring lengths between the source and the luminaire, and due to the necessity of monitoring the control measures on the basis of their electromagnetic compatibility and harmonic components of the current. In addition, the electronic chokes available on the market have other drawbacks related to high-frequency stray or stray currents.

SUMMARY OF THE INVENTION

SUMMARY OF THE INVENTION It is an object of the present invention to provide an automatic light intensity control device capable of providing all the control and regulating functions of a regulator by virtue of its new essential design and objectives in order to minimize circuit cost and associated load compared to prior art and taking advantage of all the available benefits.

It is a further object of the present invention to provide an apparatus for automatically regulating luminous intensity with appropriate efficiency, which will in particular be able to ensure compliance with current regulation in a given matter.

The foregoing and other objects have been achieved in accordance with the present invention by providing an automatic light intensity control device, particularly useful for electronic chokes of fluorescent tubes or fluorescent lamps, which is controlled by an electronic circuit based on at least partial shut-off. of the line angle process, so that in each cycle of the power signal (IR) a current signal (IL) is applied to said tube for a predetermined period of time, which in any case is " 9 9 "

at least half the period shorter than the waveform of said feed signal (IR).

Preferably, said feed signal (IR) is a network frequency current signal having a substantially sinusoidal or rectified waveform.

Preferably, said electronic circuit comprises at least one phototransistor (FT) light detecting device that monitors ambient light and emits an output signal (VE, ΙΕ), which, after filtration, is fed to a portion of the circuit intended to compare it with a predetermined value ( P), so that a timing device synchronized with the rectified waveform current signal (IR) by means of a toothed signal (IS) is triggered.

Preferably, said fluorescent tube is switched on and off by varying at least one operating frequency of the half-bridge circuit when activating and deactivating the capacitive element (C21) connected in parallel with the oscillating circuit (R20, R21, C20), and by distributing the compensation reaction signal (PR), wherein said reaction signal (PR) is sent to the control section of said oscillator (R20, R21, C20) by slightly increasing its frequency to provide a charging delay time.

Preferably, said electronic control circuit comprises a light detecting section and a section for generating and synchronizing a control signal capable of operating under favorable light conditions.

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The automatic control device (DM) of the present invention further preferably provides an additional signal (PR1) capable of keeping said luminaire lit during the on-time of said electronic control circuit and allowing some suitable preheating and charging phases.

Furthermore, the automatic control device (DM) of the present invention also advantageously provides at least three different frequency values of at least one signal corresponding to the charging, preheating and trip phases of said control device (DM).

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a control circuit for an automatic light intensity control device (luminance attenuator) for electronic inductors ("load") of fluorescent tubes or fluorescent lamps based on partial closing of the line angle. This means that during each 50 Hz rectified current signal cycle, the luminaire current is only applied for a certain period of time.

The system is created through the use of a light detector (“phototransistor”), which takes care of monitoring and monitoring ambient light. After suitable filtering, the signal is sent to a circuit that compares it to a preset value that activates the synchronized timing device via a toothed signal with a 50 Hz rectified line current signal.

The tube is switched on and off by varying the operating frequency of the half cross member from the low frequency when the tube is switched on to the high • ·

• Frequency values when switching them off. The purpose of the control circuit is therefore to activate or deactivate the capacitive element connected in parallel with the oscillator output and to distribute the compensation reaction. This additional signal is fed to the control section of the oscillator by slightly increasing its frequency to provide a time delay in its charging process.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be explained in more detail by way of examples of specific embodiments thereof, the description of which will be given with reference to the accompanying drawings, in which:

Fig. 1 is a graph in orthogonal coordinates that illustrates the timing of a rectified supply current signal with a corresponding luminaire current signal according to the present invention;

Fig. 2 shows a first light detection section of an electronic control circuit of an automatic light intensity control device, in particular for fluorescent tubes according to the invention;

Fig. 3 shows a second section for generating and synchronizing the control signal of the electronic control signal according to the preceding figure according to the present invention;

Fig. 4 is a graph of orthogonal coordinates showing the time course of three output signals of the electronic circuit of Fig. 2 in accordance with the present invention;

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Fig. 5 shows a graph in orthogonal coordinates showing the time course of three additional electronic output signals. 2 according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the above drawings, the electronic control circuit of the automatic light intensity control device for the electronic chokes of the fluorescent tubes or fluorescent tubes of the present invention, as shown in Figures 2 and 3, is based on partial closing of the conductivity angle so that during each 50 Hz rectified supply current cycle, which is generally indicated by the reference numeral IR in Fig. 1, the luminous current indicated by the reference numeral IL in Fig. 1 is applied only for a certain period of time.

This is achieved by using two sections of the electronic circuit, one relating to light detection and the other relating to the generation and synchronization of the control signal.

FIG. 2 shows a portion of an electronic circuit that relates to light detection based on a phototransistor FT.

In accordance with a preferred and exemplary but not limiting embodiment, the FT phototransistor is comprised of a NPN phototransistor based on the Siemens SFH309 Silicon unit, which guarantees high efficiency at low cost.

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FT phototransistor provides operating temperature range from -55 ° C to + 100 ° C _r collector-emitter voltage in vacuum of 35 V, collector current of 15 mA, collector peak current of 75 mA, power dissipation of 165 mW at 25 ° C and a thermal resistance of 450 K / W.

The wavelength range varies from 380 to 1 150 pm in a radiation-sensitive area of about 0,045 mm ² and relative to an angle of ± 12 °.

The phototransistor FT is connected to the terminal J4, the emitter facing the resistor R51 and the collector connected to the diode D10 so that the ambient light can be monitored. In the presence of light, the phototransistor FT then generates a current signal IE which causes the potential VE at the emitter output to rise to a value equal to the product of the output current IE and the resistance R51.

A suitably filtered signal is then applied to a circuit that compares it to a preset value and that activates the timing device by utilizing a toothed signal that is synchronized with the IR current signal.

Consequently, whenever the output signal from the IC3A buffer is such that it commutes the second comparator IC3B, the MOSFET Q17A is activated. The comparator IC3B consists of a hysteresis comparator whose commutation thresholds are 3.2 V and 2 V, while the transistor Q17A activates a voltage divider formed by resistors R2Q and R21 to maintain the non-inverting input of comparator IC2B at a high level up to this point.

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Activation of MOSFET Q17A brings comparator input IC2B to a predetermined value of about 4 V (signal P at the resistor output R20 and R21), whose retention via a toothed IS output signal from R25, C21 generates a digital ID signal 100 at IC2B output Hz with a duty cycle of 70%.

Under these conditions, the power consumption of the 100 W choke circuit is from 100 W to about 70 W.

The resistor R25 acts as a current generator and charges capacitor C21, which is periodically discharged by an IC2A comparator, which acts as an output diode when the collector is open.

The output signal from the electronic circuit section shown in FIG. 2 is represented by the output digital signal ID from comparator IC2B and is at a high level when the lamp is turned on, but at a low level whenever the toothed signal 15 exceeds a predetermined value of the signal P with the aid of a divider R20 and R21, as clearly shown in FIG. 4. This brings the operating frequency of the oscillator to such a high level that the luminaire is switched off.

Therefore, switching the lamp on and off is done by varying the operating frequency of half bridge Q1 and Q2. The task of the control circuit is to activate and deactivate the capacitor C17 in parallel with the oscillator consisting of R1 + P1 and C7 and to divide the compensation reaction using R61, R62 and Q7A.

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In fact, the continuous current PR signal that controls the MOSFET Q17A is also fed to the control section of the oscillator Q7A, as shown in Figure 3, by slightly increasing its frequency to provide a time delay during the charging process.

The PR signal is used to control the MOSFET Q7A because it splits the response of the transistors Q14 and Q15 through R61 and R62, and corrects the protective circuit via R3 due to the light intensity of the regulator or dimmer DM or dimmer.

The PR1 signal is applied to ensure the start of the control circuit as soon as possible after switching on and to keep the lamp in operation for a certain period of time so as to allow the fluorescent tube of the lamp to overheat and charge properly.

About one second after the preheater phase, when the PR1 signal is switched to logic zero, is C37 charged and the inverse of the IC3B compares from the supply value to the value depending on the resistances R55 and R28, allowing the control circuit to start working when light conditions are preferred.

In order to synchronize the output of the comparator IC2B with the 50 Hz mains voltage signal, as indicated by the RT letters in the figure of FIG. 5, a portion of the electronic circuit is set to detect the mains voltage RT passing through the zero point. The D13, D14, D3, and D4 diodes are, in fact, "D", "D", "D", "D", "D" and "D4".

The bridges are charged by a divider consisting of resistors R4 + R5 and R38.

The resistor R38 controls the power supply of the RT via diode 15 and serves as a double function in supplying the IC1 closing process via resistors R4 and R5 and limiting the voltage of resistor R38 to a value corresponding to the supply current and a threshold value of diode D15 of about 0.7 V.

Comparator IC2A compares the signal flowing in resistor R38 with a reference signal proportional to resistor divider R34 and R35, and adjusts its own output downward each time the signal on resistor R38 drops below a predetermined value represented by the passage of the incoming signal RT over the zero point, as clearly shown in the illustration of Fig. 5.

The output of comparator IC2A (arranged as an "open collector") therefore discharges capacitor C21, as a result of which the toothed signal IS is synchronized with the network signal RT 50 Hz.

As a result, switching off the fluorescent tube of the fluorescent tube is achieved by increasing the operating frequency of the IC1 unit with the help of the MOSFET Q7A through a continuous signal and causing a time delay in the charging process by splitting the reaction network of transistors Q14 and Q15 and MOSFET Q6A with 100 Hz and upstream a designated duty cycle designed to switch capacitor C17 to the on and off position.

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Whenever the lamp is on, the pre-heating phase of the cathode is performed by keeping the transistor Q6A in an activated state and putting the capacitor C8 in series with the capacitor C7.

At the end of the preheating phase, capacitor C8 is short-circuited via transistor Q12, allowing operation at a frequency close to the charging frequency, and hence operation at a higher preheating value. The use of three different frequency values makes it possible in practice to achieve the charging, preheating and tripping conditions of the dimmer or DM dimmer.

The above description illustrates the characteristics of an automatic light intensity control device, in particular for electronic fluorescent tube or fluorescent tube chokes as an object of the present invention, as well as the related advantages, which consist in particular in a substantial reduction in manufacturing and operating costs compared to the prior art. as a result of the advantages provided in this way, in combination with a reduction in the number of components used and thus achieving less complexity compared to known control devices.

Finally, it will be appreciated that the automatic luminous intensity control device for the fluorescent tubes or fluorescent lamps of the present invention is capable of many other variations without departing from the principles of novelty and inventive idea. It will be appreciated that, in the practice of the present invention, the materials, shapes and dimensions of the various details and components may be of any type, depending upon

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4 • 4 44 requirements, these details and components may be replaced by other elements of equivalent type.

PATENT CLAIMS

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Claims (7)

• * • · · · «V »···· • · · ·· «# · · • · • · · ♦ ·  · · «·· ·· regulating a light electronic inductor indicative An apparatus for automatic intensities, particularly useful for fluorescent tubes or fluorescent lamps, characterized in that it is controlled by an electronic circuit whose operation is based on at least a partial closing process of the line angle, so that a current signal (IL) is applied in each cycle ) into said tube for a predetermined period of time, which in any case is at least half the period shorter than the waveform of said feed signal (IR). The automatic control device (DM) of claim 1, wherein said feed signal (IR) is a line frequency current signal having a substantially sinusoidal or rectified waveform. An automatic control device (DM) according to claim 2, characterized in that said electronic circuit comprises at least one phototransistor (FT) light detecting device that monitors ambient light and emits an output signal (VE, ΙΕ), which after filtration it is fed to a portion of the circuit intended to be compared to a predetermined value (Ρ), so that a timing device synchronized with a rectified waveform current signal (IR) is triggered by using a toothed signal (IS). An automatic control device (DM) according to claim 1, characterized in that the said control device (DM) is characterized in that The fluorescent tube or lamp is switched on and off by varying at least one operating frequency of the half-bridge circuit when activating and deactivating the capacitive element (C21) connected in parallel with the oscillating circuit (R20, R21, C20), and dividing the compensation reaction signal (PR), wherein said reaction signal (PR) is sent to the control section of said oscillator (R20, R21, C20) by slightly increasing its frequency to provide a charging delay time. The automatic control device (DM) of claim 1, wherein said electronic control circuit comprises a light detecting section and a section for generating and synchronizing a control signal capable of operating under favorable light conditions. An automatic control device (DM) according to claim 4, characterized in that it provides an additional signal (PR1) capable of keeping said luminaire lit during the switching-on period of said electronic control circuit and allowing certain suitable preheating and charging phases. An automatic control device (DM) according to claim 6, characterized in that it provides at least three different frequency values of at least one signal corresponding to the charging, preheating and trip phases of said control device (DM). • 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 · · · 000 · · · · * 00 00 00 00 00 00 00 00 00 00 00 00 00 00 GIANT. 1 IL GIANT. 4 at AND η . 1 -IS / - / j / / OF OF OF OF OF ř— GIANT. aaa aa a a e a a a a a a a a a a a a a a a a a a a a a a a a a