DD148424A1 - TOUCH SWITCH WITH INTEGRATED LIGHT MASTER CONTROL - Google Patents

Abstract

The invention relates to a contactless electronic switch, in which an LED with corresponding control circuit is integrated for optical display of the Schalterbetaetigung or the switching state. It was the object of the invention to develop on the basis of the technology for light emitting diodes such Berwärtung switches containing as a complex component Kontaktflaechen, light emitting diode and drive circuit. As a result, connection lines and space can be saved, as well as fine mechanical work on the front panel can be reduced. The essence of the invention is that in a housing which is at least one-sided transparent, LED and drive circuit are mounted side by side or on top of each other on a strip of stretcher bent in two directions. Contact pads are formed on one side and terminal pins on the other side , which can be fixed by Schwalloeten in a circuit board. The after the invent. Solution principle designed Beruehrungsschalter can be used in input devices of data processing systems, in electronic consumer goods as well as in the Mesz-, control and regulation technology.

Description

-4- 2 1822D

Title of the invention

Touch switch with integrated light emitter control

Field of application of the invention

The invention relates to a contactless electronic switch with integrated information display, which can be used in input devices of data processing systems, electronic consumer goods, as well as in the measurement and control technology.

Characteristic of the known technical solutions

There are a number of ways known to trigger a switching operation without direct contact. These known systems respond to the change of a physical quantity, such as temperature, pressure, radiation or especially an electrical variable such as inductance, capacitance or impedance.

Thus, the operating personnel can initiate a contactless switching operation on an electrical device by coupling the capacity or impedance which adheres to the human body into a corresponding system. For example, densely adjacent contacts must be bridged with the finger, as described above, with the finite skin resistance of approximately 20 k-fZr-100 k-Q of the base of the input stage being transcribed. a voltage is supplied to the gate.

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According to this principle of the sensor switch and integrated switching stages have been developed, which exploit the very high input impedance of MOS transistors.

Another integratable concept is known from DE-OS 2654575. In this case, the contact of the contact surfaces additionally connected capacity of the human body is processed to a switching operation.

For a secure operation of the electronic switch, the design of the contact surfaces is essential. They can be designed as desired, but unfavorable climatic conditions as well as dirt and dust deposits should not result in a fine closure. "Insulating substrates have proven to be dirt-repellent and moisture-repellent plastics such as piacrylic glass or polystyrene.

Other types of touch switches are described in DS-AS 2158172 and DE-OS 2256337. A sensor switch (DE-AS 21J8172) has perpendicular to the contact surfaces a cylindrical cavity which is provided for receiving a DC amplifier and corresponding connecting lines.

However, in many applications for touch switches, a visual indication of the switching state is desired. Control lamps or light emitter diodes are therefore arranged behind or next to the contact surfaces. The disadvantage here is that in addition precision mechanical work on the front panel are required and compared to conventional switches no space savings is achieved. In addition, additional connection lines must be made by the optical display circuit.

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Object of the invention

The aim of the invention is a touch switch, which contains as a complex component touch contact surfaces, light emitting device and drive circuit, so that in the application, connecting lines and

Saved space and fine mechanical work on the front panel can be reduced.

Explanation of the essence of the invention

The invention has for its object to produce an electronic switch based on the technology for light emitting diodes, which contains an integrated information display and any logic necessary for the switching process ·

The essence of the invention is that in a housing which is transparent at least on one side, a light emitting device and a drive circuit are arranged on a carrier strip. The carrier strip is designed so that a double function of the same as a switching element is thus guaranteed as a contact and as a carrier for the drive elements and the light emitter. The light-emitting device and the drive circuit are side by side or ', one above the other on a carrier strip fastened en, which is bent in two directions. On one side contact pads are formed, on the other side pins which can be fixed by means of wave soldering in a circuit board ·

'The electrical connections between carrier strip, circuit and LichtemitterdiodB be by bonding

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If the light emitting diode and drive circuit are not monolithically fabricated on GaAs, for example, the light emitting diode having the backside n-region may directly face to η-type silicon or polysilicon surfaces

be stuck to the drive chip, so that a bonding step is saved.

According to the invention, the contact contact surfaces consist wholly or partly of transparent conductive layers, for example of SiO or SnOp or TiO _2. In a further embodiment, the contact contacts may be formed as optical fibers, wherein the light is guided by the light emitter in the interior to the surface. According to the invention, the electronic switch is designed in such a way as: that it can be arranged individually or in line or matrix form.

With the device according to the invention can be realized depending on the desired switching operation and arrangement of the contact surfaces, the various touch switches using the technology for light emitting diodes.

embodiment

The invention will now be explained in more detail in exemplary embodiments. The accompanying drawing shows in Fig. 1-5 various integratable capabilities for triggering a switching operation. 6 shows the technological realization of the circuit example according to FIG. 1, FIG. u.

8 the capping of the component.

In Fig. 1, a cascade formwork of two emitter follower (Darlington circuit) is shown.

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The current gains of both npn transistors multiply, and a minimum current path across contact pads 1 and 2 is sufficient to drive the follower transistor to illuminate the LED, thereby checking whether, when touched, a switching operation has actually taken place Terminal 3 can be supplied as potential jump to an evaluation circuit.

2 shows the circuit diagram of an integrated semiconductor structure comprising npn bipolar transistor and p-channel field-effect transistors. In this case, the sinking zone of the field effect transistor 4 is at the same time the base space of the

y | c bipolar transistor. This switching arrangement has a very high input resistance through the field-effect transistors and, because of the bipolar transistor connected as an emitter-follower, a sufficiently high output current for the LED. If the contact surfaces 1 and 2 are passed over like a sliding switch of a mechanical nature, the circuit remains in the position whose contact surfaces were last bridged. It can therefore assume two stable states. The LED lights up when the contact surfaces of 1 and 2 have been painted over. At the end. 3, the level can be forwarded to an evaluation circuit. In order to avoid a coupling of alternating voltages, which can lead to a faulty circuit, the input field effect transistor must be loaded capacitively to ground in the dimensioning. At the same time, a forced state is achieved when the operating voltage is switched on.

Fig. 3 shows an LED drive circuit constructed entirely of field effect transistors. It becomes LSI circuit technology, such as η-channel silicon gate. with depletion load transistors and enhancement switching transistors.

In this circuit example, the LED goes off when -. the contact surfaces 1 and 2 are bridged. The final stage transistor uence 5 ^ a the current through the LED corresponds t- speaking have long channel length. This variant is perfectly suitable to expand the circuit according to the user requirements as desired, for example, to achieve a mutual coupling or locking individual switching points.

Another circuit example is shown in FIG. In order to operate a shift register (D flip-flop) as a memory or divider flip-flop, the negated output must be fed back to the input. The negated output signal is available at the parallel output A provided for LED. If this signal is fed back to the D input, the low level must be less than 0 ,? V be. This is only with ohmic, but not guaranteed under load with a LED That is why the first. Shift register cell, which acts as a divider, a second, which controls the LED, downstream. The circuit takes after high-ohmic bridging of the contact surfaces 1 and 2 stable states according to the truth table. purely a safe function of the circuit, the sensor should be protected by a capacitor 6 against bounce and a trigger 7 required for the clock processing 8 steep flanks yeast.

By doubling the number of shift register cells, a sequential switching on and off of 2 LEDs can be achieved (FIG. 5). A further extension 2Q of the number of LEDs requires measures for a defined setting of the shift register. In Fig. 6, the technological realization of the circuit example shown in FIG. 1 is shown.

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On a highly doped η-type silicon wafer 9, an η-type epitaxial layer 10 is constructed. Subsequently, p regions 11 and n regions 12 are diffused so that the two transistors are formed. At the point where the LED 15 of GaAsP or GaP is to be glued later, a highly doped n-type region 14 is generated.

According to the circuit example, the connection lines between the components, terminals and contact surfaces are bonded or vapor-deposited as aluminum.

The terminals 1 and 2 are contact surfaces, the emitter of the follower transistor is grounded and the operating voltage is applied to the LED anode. At the same time the evaluation circuit can be connected to the contact surface 1. Figs. 7 and 8 show two embodiments for the capping of the arrangement. The contact surfaces 1, 2 can either limit the component laterally (FIG. 7) or be completely embedded in the potting compound. The light emitted by the LED I5 light can be scattered so that it also exits the side of the device.

It is possible, if necessary, to form the contact contacts in or around the plastic as a light guide

Furthermore, it is possible to let the touch contacts leak in transparent vapor-deposited conductive layers, for example made of tin oxide.

Claims (1)

-β - 2 18220 " invention claim 1 · touch switch with integrated light emitter drive, characterized in that in a housing which is at least one side transparent, a light-emitting device and a drive circuit are arranged on a carrier strip, wherein the carrier strip is constructed so that it both as a touch contact as well serves as a carrier for the drive elements and the light-emitting component. Touch switch according to item 1, characterized "Net, that the light-emitting device and the Anip» control circuit are arranged side by side or one above the other on the carrier feeder · 5e touch switch according to item 1 and 2, characterized in that the light-emitting component with at least one contact surface is electrically conductively mounted on the drive chip. 4-, touch switch according to item 1 and 2, characterized in that the drive circuit is monolithically integrated in the light-emitting device. p ". Touch switch according to item 1, characterized in that the contact contacts consist wholly or partly of transparent conductive layers. 6. Touch switch according to item 1, characterized in that the contact contacts are designed as light guides. __Simple drawings