FR2850808A1 - Electronic touch switch for operating an electrical circuit uses low-tension detector with one branch in contact with sensitive article such as a plant - Google Patents

Abstract

Touch switch incorporates a low-tension detector based on an unstable multivibrator and contains a miniature electronic card (14) with printed circuit and a spring (15) ensuring contact with a metal tip (16). The detector is connected by a sheathed and earthed cable (13) to a power controller (18) containing a micro-controller that measures variations in oscillation frequency, and a power relay. The touch switch incorporates a low-tension detector based on an unstable multivibrator and containing a miniature electronic card (14) with a printed circuit and a spring (15) ensuring contact with a metal tip (16). The detector can be set in the soil in a plant pot or in water in a vase of cut flowers, and is connected by a sheathed and earthed cable (13) to a power controller (18) containing a micro-controller that measures variations in oscillation frequency over a fixed period, and a power relay. The power controller is connected to a socket (20) into which a lamp can be plugged, enabling it to be switched on by lightly touching the plant or flower.

Description

The present invention relates to the field of switches

electronic touch.

  Known switches in the state of the art operate on the basis of the detection of small potential differences between the earth and a contact zone connected to an electrical circuit. The contact area is generally formed by a metallic sensitive button. This type of switch is found in dimmers, bedside lamps, floor lamps or in elevators.

  Several solutions have been suggested and developed to use a vegetable in place of the metallic touch. In fact, plants and flowers are slightly conductive of electricity because of their water and mineral salt content. 15 The use of plants instead of switches or a remote control device is advantageous in certain situations, such as a dark room or for the physically disabled. Such examples have been suggested in the patents: GB 2,203,842A, US 4,152,629 and DE 196 28,891C.

  The first principle used is based on the detection of the leakage current to earth from the power supply network (50 or 60Hz) and an adapted electronic circuit type Siemens S576.

  Patents are also known which propose to activate a lamp according to a principle of variation of the frequency of a higher frequency oscillating circuit (450 KHz): US 4,701,676 and US 4,668,877.

  Among the limitations of these devices, note: the need to connect the sensitive part to the supply phase and not to neutral or earth where a weak alternating current which flows through the body, not dangerous, but that some sensitive individuals can feel.

  However, the use of a plant as a sensitive touch, with these principles, runs up against the impossibility of using a large plant or a plant whose leaves touch a wall or even a terracotta pot placed on the ground. Indeed, in this type of environment, too high a leakage current towards the earth activates the device permanently.

  To overcome these drawbacks, a first approach had been suggested in the patents: GB 2 203 842 and FR 9 805 555, 5 which consisted in modifying the sensitivity of the circuit by a variable divider bridge depending on the size of the plant and the type of vase, but this approach only works if the environment of the plant is stable, which is not the case when it is watered.

  The present invention aims to offer a solution that automatically adapts according to the size of the plant, the degree of insulation and the degree of humidity of the soil in the pot, which is low voltage, galvanically isolated from the network of food, therefore safe, and which no longer generates tingling to the touch.

  The present invention aims to also offer two modes of operation: a simple ON-OFF mode by short touch of the plant, a dimmer mode by a prolonged touch of the plant.

  The invention also makes it possible to measure the degree of humidity of the soil in which the plant is found and makes it possible to warn the user of a lack of water.

  The invention makes the device completely insensitive to low frequency electrical disturbances from the mains (50/60 25 Hz) or radio frequencies (RFI) as well as to micro-cuts in the supply network, and the device does not generate any radioelectric interference with the other devices.

  The invention uses the power of a microcontroller to detect the human touch of the plant, to visualize the lack of humidity M0, in addition to the basic function of power switch or dimmer.

  Finally, the present invention is based on the use of miniature technologies (digital CMS integrated circuit and microcontroller) which make its manufacture easy to perform, to miniaturize, and very economical, by current electronic production units.

  The invention is described below, in more detail, through exemplary embodiments and the following figures: FIG. 1 gives the block diagram of a control device according to the present invention; FIG. 2 illustrates a practical embodiment in a control box for an electrical outlet and in a pen tube for the detector part .; Figure 3 gives the electronic diagram of the detector part which is placed in the plant pot; Figure 4 gives the electronic diagram of the control part which is placed in the socket; FIG. 5 gives the flow diagram of the processing program 15 in the microcontroller; FIG. 6 gives an example of an embodiment of the dimmer control part with a static power switch; Figure 7 gives an exemplary embodiment of a vase lighting support according to the present invention; FIG. 8 gives the electronic diagram of the embodiment of FIG. 7.

  The principle which is used in the present invention is based on the detection of small variations in the oscillation frequency of an electronic oscillating circuit RC, knowing that a part of the capacitor fixing the frequency is connected to the plant and that this capacity varies when an individual touches the plant.

  The low voltage detector 4, which includes this oscillator, is in contact with the plant 7, in the pot 6, by the ground 5. The 30 pulses of the detector are continuously analyzed by the microcontroller which is in the control unit 2, connected to the mains supply 1. When a person touches the plant, the equivalent capacity of the RC oscillator increases due to the return to earth by the individual, and therefore the frequency of the oscillator decreases. The microcontroller then detects the drop in the number of pulses. It activates or deactivates the lamp 3 or any other electrical equipment.

  Periodically, the microcontroller's program measures the number of pulses from the detector in a fixed time interval. Therefore, changes in the electrical environment of the plant (water, contact of the leaves with a wall, air humidity) can be taken into account. By measuring variations over short intervals (up to a few seconds) the device is very reliable and self-adapting.

  By measuring the duration of touch of the plant, the microcontroller can also detect the control mode that the user wants: a short touch, say less than one second, is interpreted as an ON-OFF command of the controlled electrical equipment. , a long touch, let's say greater than the second, is interpreted as a power variation command, that is to say that the microcontroller will vary the width of the command pulse of a conventional device triac control (dimmer function).

  In addition, when the humidity of the earth decreases, the capacity of the plant decreases and the number of pulses of the oscillator increases, which the microcontroller can detect, by blinking, for example an LED diode to warn the user that the plant probably lacks water or even order a water supply in order to automatically restore the right degree of humidity.

  The variations in capacity of the plant are very small, of the order of 2%, therefore, to avoid nuisance tripping, the supply of the detector must be particularly stable.

  In the embodiment of FIG. 2, the detector comprises a miniature electronic card 14 in CMS technology, 35 a spring 15 ensuring contact with the metal tip 16 of the pen, which can be made of plastic covered with a varnish aluminum and a LED diode 17 used to indicate the lack of water. The control card 18 with the components and the power supply of the detector is mounted in a standard housing 21 remote controlled socket. The printed circuit 14 of the detector is connected to the control card 18 by a standard shielded audio cable 13. This cable can have several meters which makes it possible to place the detector easily away from the control unit. The shielding of the cable ensures the immunity of the device 10 to external electromagnetic disturbances (RFI), as well as to the low frequencies of the sector. This shield being connected to electrical ground, provides total protection for the user. Finally, a small mains transformer provides the essential galvanic isolation for this type of device. 15 The wire 9 (phase) of the male connector 19 supplies the card 18. The wire 11 (neutral) of the male connector supplies the card 18 and the pin (neutral) of the female connector 20. The wire 12 coming from the output of the relay supplies the pin (phase) of the socket 20. Finally, the ground wire 10 makes it possible to fix the potential of the detector, and therefore allows the device to more easily meet the safety standards on this type of electrical switches .

  The control unit is, of course, protected by a cover 22 which is, in general, fixed to the base 21 by hidden screws 25, so that the user cannot easily open the device and the manufacturer can more easily provide warranty.

  Figure 3 gives the electronic diagram of the detector part. A Timer 28 integrated circuit is mounted as an astable multivibrator with a duty cycle of 50%. Its working frequency is defined by the resistance 29 (R3) and the equivalent capacity of the circuit 27 (C2), 26 (Cl), 25 (Rl), the resistance 23 (Rp) and the capacity 24 (Cp) of the plant. . The condenser 26 (Cl) ensures the connection with the plant. Resistor 25 (R1) reduces the input potential to ground and earth 27. The plant with its vase behaves like an RC circuit 23-24 and its capacity 24 of the order of 700 pF varies when an individual touches the plant or the pot, if it is terracotta, slightly conductive. For a maximum of 5 sensitivity, a working frequency between 2 and 5 KHz is chosen. It eliminates disturbances (50 or 60 Hertz) from the supply network. For higher frequencies, the plant has its impedance which increases significantly, which reduces the sensitivity of the device. The circuit must be supplied with a constant voltage of the order of a few volts, and therefore without any danger, which comes from the control box by the supply wire 31. The resistor 32 prevents the pulses which are transmitted by the conductor 33 are disturbed by electromagnetic fields. The cable (4 15 conductors) must be shielded with the earth grounded.

  LED 34 alerts the user that the humidity of the earth has reached a limit value. This diode can be placed on the detector board or on the control board.

  FIG. 4 gives the electronic diagram of the control card, in the relay version. The male socket 19 supplies the mains supply which, through the relay 38, comes out on the female socket 20. A low power transformer (0.5 Watt) 39, conventional rectifying diodes and a filtering capacitor supply the supply, unregulated, 25 in DC voltage, from the card and from the relay. A first voltage regulation stage with transistor 37 and zener diode makes it possible to pre-stabilize the supply of the integrated regulation circuit 36, so that the variations of continuous voltage when the relay switches has no effect on the voltage 30 output 31.

  The microcontroller 35 counts the pulses arriving from the detector at 33. It controls by a transistor T1 the relay 38 and the LED 34 which flashes when the humidity measured by 35 crosses the detection threshold.

  The program which is given by way of example for this embodiment is given in FIG. 5. After stabilization of the supply voltage in 1, the program will activate the relay twice in 2 to indicate to the user that the circuit is 5 under pressure. The program fixes the pulse counting parameters at 3 before counting them for a certain time to check at 5 its oscillation frequency. If this is not good, a permanent flashing every 2 seconds will indicate to the user in 6 and 7 a crippling fault. If 10 all goes well, the program initializes the internal variables at 8 and enters the work loop.

  In this loop, the program begins at 9 by updating an indicator every 20 seconds, the device's refresh period. The subroutine 10 provides the comparison between the average number of pulses and the value measured in the last period. It is this subroutine that detects the touch of the plant and the decrease in humidity. The subroutine 11 controls the relay, when the dimmer function is included, the subroutine 12 ensures the variation of the duration of the control pulse, finally, the subroutine 13 ensures the periodicity of the loop every 10 milliseconds.

  Another operating mode is obtained Fig. 6 using a program routine of the microcontroller which delivers a control pulse of variable width to an opto-triac and a triac coupler, which makes it possible to make a variant product incorporating a dimmer function. A long touch then varies the width of the control pulse.

  According to another particular embodiment given in FIG. 30 7, the detector and the microcontroller are placed on the same electronic card 41 with, in place of the relay, LED diodes, all in a non-conductive support 40 covered with a metal plate 42, connected to the detector input by a spring 44 and a screw 43. the circuit is supplied by a standard 12 Volt DC power supply via a female plug 45.

  The support is placed under a glass or transparent Plexiglas vase 46 filled with water and a bouquet of flowers. The 5 LEDs can be the same color or different colors.

  The device allows the LEDs to be turned on or off by a short touch of the bouquet of flowers. A dimming effect is obtained if the touch is long, by a variation of the duty cycle of the LED control pulses.

  This version of the invention uses the same principle as that described above for earthen flower pots.

  The electrical capacity of the vase with its flowers and water and the earth leakage capacity of the 12 Volt 15 power supply vary when the user touches the flowers. The high sensitivity of the device makes it possible to detect a touch of one of the leaves or of one of the flowers in the bouquet.

  Because the capacity of the vase is quite low, of the order of a hundred pF, the quiescent frequency of the multivibrator 20 must be increased around 30 KHz.

  The diagram of the electronic card in this exemplary embodiment is given in FIG. 8. The same detection circuit is found with the same microcontroller 35. The device is powered by the socket 45 and a power supply unit 12 25 Volts-lOOmA from trade. To ensure good stability of the detector supply, there are two regulation stages 49 (12 Volts) and 36 (5 Volts). The LEDs can be activated directly by the outputs of the microcontroller or by two transistors 47 and 48. The color change can be done by a switching program of the microcontroller, for example when passing through the lighting minimum. These LEDs can be replaced by low-voltage lamps such as halogen lamps or even a mini fluorescent tube.

  The present invention is based on the use of a low voltage detector, based on an astable multivibrator, one of the branches of the oscillating circuit RC of which is in contact with the sensitive part. This detector sends its pulses to a micro5 controller which measures the variation of the oscillation frequency over a fixed period and activates a power relay. The detector is connected by a cable to electrical ground. The detection of the touch by the microcontroller is done by comparison, over a fixed measurement period, between the mean value and the instantaneous value of the number of pulses.

  The measurement of the duration of the touch makes it possible to differentiate a short touch from a long touch, which allows the microcontroller to know whether the user control is of the on-off type or of the power variation type. Whenever the microcontroller detects a short touch, it can activate the power relay for starting or stopping. When the touch is long, the microcontroller delivers a pulse of variable width to a static electronic power switch controlled by an opto-triac coupler.

  To ensure the operating stability of the detector, it is preferable to have two levels of cascade voltage regulation.

  In the case where the detector is in contact with the plant soil, the microcontroller can detect a drop in the humidity of this soil by observing, over several days, an increase in the number of pulses of the astable multivibrator. In this case, the microcontroller can flash an LED diode.

  In the case of using the present invention for a vase lighting support, made of glass or plexiglass, the microcontroller can control LEDs or a low voltage lamp, the control being done by touching the vase or bouquet of flowers. . During a long touch, two LEDs of different colors can be activated separately by the micro35 controller, at the end of each dimming cycle.

Claims (10)

  1.Electronic touch control device, characterized in that it comprises a low-voltage detector based on an astable multivibrator, one of the branches of the 5 RC circuit of which is in contact with the sensitive part, such as plant soil , this detector being connected by a shielded cable connected to electrical ground to a power control device, comprising a microcontroller which measures the variation of the oscillation frequency over a fixed period and a power relay.   2. Device according to claim 1 characterized in that the frequency variation is analyzed, over a fixed period, by comparison between the average value and the instantaneous value of the number of pulses by a microcontroller.   3. Device according to claim 1 and 2 characterized in that the microcontroller measures the duration of the touch to differentiate a short touch from a long touch.   4. Device according to claim 1 to 3 characterized in that two levels * of cascade voltage regulation are used to ensure the operating stability of the detector.   5. Device according to claim 1 to 4 characterized in that the microcontroller detects the humidity of the soil in the pot by comparing the increase in the number of pulses of the astable multivibrator over a period of several days.   6. Device according to claim 1 to 5 characterized in that the microcontroller causes an LED to flash when the increase in the number of pulses exceeds a certain threshold.   7. Device according to claim 1 to 6 characterized in that the microcontroller controls an ON / OFF power relay each time the touch is short.   8. Device according to claim 1 to 6 characterized in that the microcontroller delivers a pulse of variable width to a static power switch controlled by an opto-triac coupler, to increase or reduce the power of the device controlled when the touch of the plant is quite long.   9. Device according to claim 1 to 6 characterized in that one uses LEDs or a low voltage lamp to light a glass or plexiglass vase and use the vase and the bouquet of flowers as a sensitive control key.   10. Device according to claim 9 characterized in that two LEDs of different color are used which are alternately activated at the end of each dimming cycle, during a long touch.