DE19857084C2 - Infrared tester without battery and rechargeable battery, powered by a solar cell - Google Patents

Description

Current infrared testers that work electronically always have a primary or secondary energy source as a power supply. There is also a certain dependency and environmental impact on it Form of energy supply.

The invention specified in claim 1 is based on the problem operate an electronic circuit (infrared tester) without a battery, to be always ready and available, as already shown in principle in GB 2 292 995 A and in US 5 012 113.

The solution to the problem is with the features listed in claim 1 reached.

The use of a solar cell in conjunction with a high-capacity storage capacitor and a diode, which prevents the capacitor from being discharged via the solar cell, ensures that the power supply is independent and always ready. The device has an almost unlimited lifespan and is 40 thanks to its small dimensions. 25th 12 mm and only 16 g weight always available.

Once charged and with the following darkening, the IR tester is several weeks ready for use. If it is exposed to the light every now and then, it charges Storage capacitor again and again and an extra "charging" is not necessary. For charging, the device with the solar line is sufficient for 1 to 2 minutes to hold a light bulb (60 W, o. a.) at a distance of about 20-30 cm, or it exposed to direct sunlight during this time.

The remaining energy and thus the operational readiness can be checked, in which the IR tester is held in the light with the IR diode and by hand is darkened. After removing the hand, the IR diode receives daylight or the like, then the red LED lights up briefly. The device is ready for use.  

With the infrared tester, the economical electronics are very useful low power u. Quiescent current consumption through the use of CMOS and low-current components as well as by operating an IR transmitter diode IR receiving diode reached.

The IR diode is switched in the reverse direction and thus the cause of the very low quiescent current consumption of the IR tester. A switch is accordingly not mandatory.

When operating the IR transmitter diode as an IR receiver diode, the properties of the semiconductor material used here, gallium arsenide (GaAs), are used. When there is light, especially infrared light, positive and negative charge carriers are released in the GaAs semiconductor chip, which is only 0.09 mm ^{2 in} size, and a voltage is created.

An exemplary embodiment of the invention is explained with reference to FIGS . 1 to 4.

Show it:

Fig. 1 shaft plan and component list

Fig. 2 construction and assembly

Fig. 3 housing construction

Fig. 4 IR tester, fully assembled

On the basis of the circuit diagram and the component list in Fig. 1, all details of the invention can be seen precisely.

The heart of the circuit consists of an IC in the DIL-14 housing, the 74HC14. This circuit contains six Schmitt trigger gates with negated output. Only three are used in the IR tester. The unused gates are lying input side to ground.

R1 and D1 form a high-resistance voltage divider. With the IC at pin 13, about half of the operating voltage, against ground, must be measured.

The IR diode D1 reacts with incidence of light with a decreasing resistance value. The values on the voltage divider change accordingly.  

TV-IR remote controls send out impulses in packets. If pulsating infrared light strikes D1 from such a remote control, its internal resistance is also reduced in pulses. A negative pulse voltage arises at pin 13 .

The Schmitt trigger gate between pin 13 u. 12 converts these negative impulses into packets with positive rectangular impulses.

These rectangular pulses reach the RC network C1 and R2, a high-pass filter, where low-frequency interference signals are blocked. This prevents the indicator LED D2 from permanently lighting when the IR source emits constant light.

As already described, a quick test of the operational readiness of the IR testers possible. (Previously covered IR diode for bright daylight or the like. suspend, then the red indicator LED lights up only briefly).

After the RC element, a square wave voltage must be obtained again from the strongly deformed signal. The Schmitt trigger gate between pin 11 u. 10, so it serves for the signal -u. Pulse shaping.

The last gate between pin 9 u. 8, with its negated logic, converts the negative pulse packets back into positive ones.

It is also used to power up the display LED D2. The LED D2 represents the pulse packets as individual pulses because that is too slow for the human eye to differentiate each individual pulse in the packets to distinguish. The frequency of the individual pulses is too high for this. The red indicator LED flashes or flickers in rhythm with the pulse packets. The combination of a gold cap capacitor C1 is used as the power supply from Philips, a solar cell from Panasonic and a Schottky diode D1 for Application.

To achieve an optimal function of the IR tester, only one fits completely certain combination of the three power supply components together! The residual current of the Schottky diode and the storage properties of the gold cap must be carefully observed.  

A possible assembly can be seen from FIG . Because of the miniaturization, no circuit board was used.

The circuit is placed on the back, pins 2 , 4 , 6 u. 12 pinched off and the rest bent inwards. Pins 1 , 3 , 5 u. 7 are connected with a bare wire, as a common ground connection. Pin 9 u. 10 are soldered together. The SMD components, the LED and IRD are shown in FIG. 1 and FIG. To solder. 2 Now the wiring is done with the solar cell, Schottky diode and gold cap.

Then all parts are inserted into a prefabricated plastic module housing, a well-known electronics shipping company, as shown in FIG. 3.

One side of the housing ( 1 ) is open when delivered. An opening ( 2 ) must be worked out for the solar cell, as well as a hole for the red LED ( 3 ) and the IR diode ( 4 ).

The electronics are inserted with the diodes in the corresponding holes, then the solar cell fitted and the storage capacitor and Schottky diode embedded in the remaining cavity.

Now the housing is from the side (1) with a suitable sealing compound poured out. The surface of the solar cell is covered with a transparent Cast resin sealed.

All parts and materials used here are commercially available.

Finally, the completely assembled IR tester can be seen in FIG. 4. Here, ( 1 ) the side sealed with sealing compound, ( 2 ) the sealed solar cell, ( 3 ) the display LED, ( 4 ) the IR diode and ( 5 ) a small chain around the IR tester as a keychain pendant use.

Finally, it should be noted that the problem solution presented and one possible product, a remarkable contribution to resource conservation and Relieved the environment. The applications of the IR tester are diverse. All infrared emitting sources can be checked for function. The IR tester at a distance of up to max. Aligned 50 cm to the IR source must become. Use in the service area (TV remote controls), private or Computer industry and a. is given. Due to the waterproof construction Applications under these conditions are also conceivable.

Claims (2)

1. Infrared test device, as a small electronic device, with

• a power supply comprising a solar cell, a diode (D1) and a capacitor (C1),
• - And an IR diode switched in the reverse direction and an LED (D2), both of which are connected to one another via three Schmitt trigger gates.

2. Infrared test device according to claim 1, wherein

• a CMOS circuit with six Schmitt trigger gates represents the basic component and an RC element prevents the influence of daylight,
• - And an infrared transmitter diode is used as the receiving diode.