NO885508L - BRIGHTNESS LIGHT CONTROL CIRCUITS AND CONNECTOR NETWORKS. - Google Patents

Description

The invention relates to a brightness control circuit for incandescent lamps and switching network components according to the preamble of claim 1.

Especially in recent times, there has been an increasing demand for brightness control circuits in connection with switching network components for the operation of halogen lamps.

There are already attenuable switching network parts where the operating point of a self-oscillating half-bridge connection is shifted within the half-wave by means of a potentiometer. However, these dimmable connecting network parts are only applicable when the connecting part is inserted into a lamp housing, when the potentiometer can also be attached to this lamp housing and when the lamp itself (e.g. table lamp, floor lamp, wall lamp) can be placed in an easily accessible position for the person using it . In cases where it concerns single ceiling lights or groups of ceiling lights, lights in a track system, etc., this solution is no longer acceptable, as the necessary supply lines to the user-accessible built-in potentiometer must be routed separately from the normal house installation and as further changes at the group connection must be carried out with a view to the connection network parts so that additional supply lines are necessary. Here, the principle of series connection of dimmer and load would be the most meaningful and expedient method. However, in the same way as the normal dimmer, the switching network requires spark arrestors, as it transforms the mains voltage of 220 Volts into a low voltage of 12 or 24 Volts with a higher frequency.

In this connection, problems arise with the used spark noise dampening devices which, when connecting the switching network part and the dimmer, form a main series resonance and several partial resonances which lead to malfunctions at the triac in the dimmer and likewise also to unwanted sound noise formations as a result of magnetostriction in those affected by the load current coils.

By dampening the series swing circuit with a resistor, respectively an incandescent lamp, an attempt has been made to limit the resonance voltages. However, this results in disadvantages due to the necessary adaptation to the cargo in question and due to the briefly consumed power in the resistance which clearly reduces the degree of efficiency.

It would be an alternative if spark noise damping devices were generally dispensed with in order to eliminate the oscillating circuit character. In practice, it is not possible to waive these in the switching network part (transformer), as here too the HF operating frequency must be unblocked by spark noise dampening devices.

In principle, the only remaining option is to dispense with spark damping devices in the dimmer, as the series resonance circuit is thus broken. Spark noise occurs with the normal dimmer above all because the triac, depending on the brightness level, is switched on a few times earlier or later in each mains half-wave and consequently suddenly allows a high current to flow and thus produces a jump function with corresponding over-oscillations. It automatically switches off again when the mains voltage drops to zero again. The purpose of the invention is therefore to develop a brightness control both for incandescent lamps and switching network parts, with which one can dispense with the usual, in phase controls in connection with triacs used spark noise damping means and despite this achieve a sufficient suppression of spark noise voltage with a simultaneously provided silent control circuit.

This purpose is achieved by the features specified in patent claim 1's characteristics.

Consequently, instead of the triac, a self-blocking field-effect transistor is used. As the transistor can only work with one polarity, a rectifier is required above all. As is known, the transistor only works when and while it receives a control voltage. When this control voltage is interrupted, it switches off even when mains voltage is still present.

With the triac, disconnection is not immediately possible if mains voltage is present. This special feature, combined with the triac, is exploited by the fact that the field-effect transistor already receives control voltage at the beginning of each mains voltage half-wave, i.e. is switched on.

Sooner or later, depending on the desired brightness, the control voltage is switched off, disconnecting the field effect transistor and breaking the current. It turns out that the current is no longer switched on suddenly, but rises slowly during the course of the mains voltage half-wave until it is switched off at a time corresponding to the desired brightness. It is also switched off with a control voltage that falls with respect to time.

Thus, the spark noise does not occur to the extent that with the connection with a triac and, in particular, the sub-resonance circuits in the switching network part are also dampened through the connected load (halogen or incandescent lamp). Therefore, you can also dispense with spark noise dampening devices apart from a small coil so that the main series resonance is thus eliminated.

An embodiment of the invention is explained in more detail with the help of the drawing.

Fig. 1 shows a principle core of a known kind, by which

preferably the series resonance is illustrated.

Fig. 2 shows a connection core for brightness control connection ling for incandescent lamps and switching mains parts. Fig. 3 shows a diagram of various functions that can be measured in the work area according to fig. 2:

a - for U dimmer,

b - for I load,

c - for U port.

Fig. 4 shows the device with two MOS field effect transistors

in series connection.

Fig. 5 shows the device with two MOS field effect transistors

in parallel connection.

Fig. 6 shows a connection core for one as an example

illustrated control circuit.

Fig. 7 shows a device according to fig. 2 for a secondary device control. Fig. 8 shows a diagram where various functions that are measurable in the work area according to fig. 8:

a - U-dimmer,

b - negative synchronization voltage,

c - negative output pulse,

d - gate voltage of the MOS field effect transistor.

Fig. 9 shows a device according to fig. 4 for one

secondary device management.

By that in fig. 2, the self-blocking field-effect transistor Tl is switched on at the beginning of the half-wave. This means hardly any noise voltage. Thus, no large noise dampening elements are required in the circuit which form a resonant circuit over the entire branch (with load). Large values for the noise dampener should, as already discussed at the outset, mean that sound is generated by magnetostriction. The edge steepness at the cut-off of the field-effect transistor Tl is determined by corresponding selection with regard to R and C (fig. 2), by digital control from the control circuit CO, i.e. square-shaped signals at the control circuit's output terminals.

The control circuit CO receives from the half-wave voltage the current through the charging of the buffer capacitor Cp, limited by the parallel-connected zener diode Z serves as operating voltage Ug for the control circuit. In addition, the voltage Ul in front of the rectifier diode is applied to the control circuit CO, so that the mains voltage's zero crossings can be registered.

For the control circuit, only three functions should be considered:

1. It must, at the time of the AC voltage's zero crossing, emit a control signal which is connected so that the self-blocking field-effect transistor Tl switches on the collector-emitter section; 2. The duration of this signal must be adjustable within a half-wave and 3. Signals with suitable flank steepness must go towards zero when they are switched off (in the example given at the RC link).

For the invention, for example, a control circuit according to fig. 6 suitable. In this connection, it is a monoflip-flop which is set when a voltage is present at input 1, and which at output 2 emits a square voltage with the height of the voltage UB during the duration of the set time for the monostable flip-flop.

The diagrams in fig. 3a-c clarify the functions of the circuit according to fig. 2. In fig. 3a is U-dimm the voltage occurring on the dimmer in the first half-wave when the field-effect transistor Tl is switched off, after which there follow two further half-waves with a short switching time (low brightness) and then two half-waves with medium brightness. Fig. 3b - I-load - shows the current through the load with the damped, falling cut-off edge. Fig. 3c - U-Tl - gate - shows the control voltage at the gate of the field effect transistor Tl.

As already mentioned at the outset, this connection can also be used for an incandescent lamp load and can be used without problems instead of a mechanical switch in house installations. If you want to increase the power that can be connected, i.e. allow greater maximum current, devices must be selected according to fig. 4 and 5. In this connection, fig. 4 the device with two MOS field effect transistors Tl and T2 in series connection and fig. 5 the device with two MOS field effect transistors T3 and T4 in parallel connection. According to fig. 2, the current in each half-wave goes via two diodes in the rectifier bridge GL and the MOS field-effect transistor Tl. Consequently, a power reduction is obtained in the coupling according to I-load (2 x U diode + U trans).

In fig. 4, the current across DC1 and DC2 can be omitted, as it only concerns the control circuit CO's supply voltage supply. The diodes Dl and D2 are the integrated inverse diodes for MOS field effect transistors with isolated gates or to high-injection MOS. For each half-wave, the load current flows through a transistor and a diode, e.g. in the first half-wave Tl and D2 and in the second half-wave T2 and Dl, i.e. as a power reduction I-load is obtained (UT + UD) and the power loss is lower than in the circuit according to fig. 2.

If the MOS field effect transistors Tl and T2 in the switching device according to fig. 4 is connected in series, then in the one in fig. 5 proposed the connection transistors T2 and T4 connected in parallel and the power balance is the same as in the connection according to fig. 4, as the transistors, even without an integrated inverse diode, must be protected against reverse polarity and flashover through a diode. The effect therefore also in this case, like the connection according to fig. 4, I-load (UT + UT), which reduces the loss effect in the brightness regulator. In fig. 6 shows, as an example, a control circuit which consists of a potentiometer POT and a further switch with regard to time which can be set, as well as a switch-on and switch-off timer. In accordance with patent claim 4, a specially developed for this purpose integrated timer CO is also used which is affected by a key and whose functions - damping and switching on/off - are invoked at various long key times. If this control link is also to be influenced via an auxiliary device, then in the circuit according to fig. 2 an optocoupler or plus transformer to produce a galvanically isolated connection from the part of the circuit which is galvanically connected to the secondary device to the part of the circuit which is potentially connected to the transistors. The actual control circuit is simplified as the potentiometer is naturally omitted, as the switch-on time is set via the key and each last called function in the control body is always carried out until a call that changes.

A circuit according to this embodiment with e.g. pulse transformer is shown in fig. 7. In fig. 8, the principle of operation is shown using diagrams a-d. The above-mentioned circuit is just an example of a brightness regulator for incandescent lamps and switching network parts with current feed-through starting with the zero crossing of the mains voltage sine curve and ending with a cut-off edge with an appropriate rise. In the case of a control device with a positive operating voltage, it is also possible to galvanically connect control devices and interface coupling on the DC voltage side of the bridge rectifier and allow the key and the auxiliary device key to act on an octocoupler of the simplest kind.

The circuit just described has a control part with a secondary device key and a key on the device, can in practice be similarly integrated in the circuits according to fig. 4 and 5. If this is realized in fig. 4, the coupling device according to fig. 9.

Claims (4)

1. Brightness control coupling for incandescent lamps and switching network components without the noise dampening devices required for the triac dimmer, characterized in that a self-blocking field effect transistor (Tl) in the diagonal of a bridge rectifier (GL) is controlled through a control circuit (CO) in such a way that the field effect transistor (Tl) conducts at the zero crossing of the alternating voltage and in accordance with an adjustable time in the control circuit (CO) for a desired section of the mains half-wave remains in the conducting state and then with a suitably set edge switches off before the next zero crossing is reached (Fig. 2). 2. Brightness control connection according to claim 1, characterized in that the power switch instead of being formed by a MOS field effect transistor in the bridge diagonals is formed by two MOS field effect transistors in series or parallel connection for connecting the load to the AC voltage in such a way that at series connection of such transistors, one transistor (Tl) with an integrated anti-parallel diode (Dl) is connected in series with the opposite polarity with another identical transistor (T2) with an integrated anti-parallel diode (D2) (fig. 2), as in parallel connection, a series connection of a diode (D3) and a MOS field-effect transistor (T3) is connected anti-parallel with an identical transistor (T4) in series with a diode (D4) (fig. 5). 3. Brightness control connection according to claims 1 and 2, characterized in that the operating DC voltage (Ul) for supplying the control circuit (CO) is obtained from the half-wave voltage in the non-connected section of the half-wave. 4. Light intensity control circuit according to claims 1, 2 and 3, characterized in that the control circuit (CO) can consist of both a timer that can be adjusted with regard to time and can be switched off and on by means of a potentiometer and complementary switch, as well as a integrated, with memory and calculation unit equipped timer that emits pulses at the set time, with associated interface that during the time period for a signal resulting from an affected key with regard to time is adjustable and can also be switched off and on, since, in parallel with the key on the device, one pole of which is connected to a conductor in the alternating voltage source, additional buttons can be connected as secondary devices (fig. 6, 7, 8 and 9).