Electric lamp and discharge devices: systems – Current and/or voltage regulation
Patent
1996-07-24
1999-12-14
Philogene, Haissa
Electric lamp and discharge devices: systems
Current and/or voltage regulation
315163, 3151693, 372 28, 372 38, G05F 100
Patent
active
060022124
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND
The present invention relates to a method and an according device for driving a radiation emitting device, such as light emitting diode (LED) which is to be used for a wide range of modulation frequency.
LEDs are generally known. These kind of diodes transmit electromagnetical radiation with a given wavelength (or colour), which depends on physical characteristics of the LED. Commonly known LEDs transmit light with e.g. red, green, yellow colour or infrared (IR) radiation. LEDs transmitting visible light can be used for for displaying information, such as a process parameter of a device, to a user.
In addition to this, all kinds of LEDs can be used for a system including a light transmitter and a light receiver. Such systems can also use a light wave conductor and can be used for the transmission of audio-, video- and/or data-information. A preferred application for such a system is a infrared- (IR-) remote control for any kind of devices, such as TV-sets, audio-receivers, videotape-recorders, etc. For transmitting the mentioned information it is necessary to modulate the radiation transmitted by the LED. This can be done e.g with the aid of a pulsed modulation wherein during the duration of a pulse the transmitted radiation is switched on and off with a given modulation frequency, which is called in the further description carrier frequency.
Known IR-remote control systems work in a wide range of carrier frequencies, normally from 30 kHz up to 500 kHz. Often a remote control transmitter is used just for the control of a single device, and thereby it works either in the carrier frequency range of --30 to 40 kHz, or --390 to 500 kHz.
From EP 289 625 B1 there is a remote commander known which can be used for controlling a number of devices by learning commands from other remote commanders.
From the elder (not yet published) German patent application P 43 08 441.9 is a learning remote commander known, which can be used for different kinds of carrier frequencies and which is also able to consider the presence of so-called togglebits.
We have found out that there occur problems, if a remote commander of the type mentioned includes just a single radiation emitting element, such as a LED, or a number of such elements which are driven simultaneously.
It is an object of the present invention to solve the above mentioned problem.
SUMMARY OF THE INVENTION
The basic idea of the present invention is, that for a "low" carrier frequency, e.g. lower than 50 kHz, a lower current is necessary for the same radiation intensity, as for a "high" carrier frequency, e.g. higher than 300 kHz. This means that a high current is sent through the LED during a short period of time and that a low current is sent through the LED for a long period. Thereby it is possible to avoid the destruction of the LED but having always a high efficiency.
According to the present invention the value of a current with which a single radiation emitting element, such as a LED, or a group of such elements, is driven depends on the carrier frequency of the transmitted signal. It is preferred to increase the current-value for higher carrier frequencies.
For the realization of a remote controller which is usable for a given distance, a minimum radiation intensity of the LED is necessary. That means, known systems, which drive the LED with the same current independent from the carrier frequency, must provide quite a high current to get over a given distance as well for a low carrier frequency as for a higher carrier frequency. This means that known systems use for the lower frequency a current which is higher than necessary. Contrarily to this the invention has the advantages that the life time of the driven radiation emitting element is increased and that power consumption of the remote commander is decreased which means that life time of a used battery is increased.
Further details, characteristics and advantages of the invention will be explained with the aid of the drawing in the following description of preferred embodiments. Therein
BRI
REFERENCES:
patent: 4488305 (1984-12-01), Claverie et al.
patent: 4577320 (1986-03-01), Yoshikawa et al.
patent: 4817097 (1989-03-01), Dufour
patent: 5099193 (1992-03-01), Moseley et al.
*Patent Abstracts of Japan, vol. 12, No. 207, 1988 and Japan Pt. 63-004726 (Mitsubishi).
**Patent Abstracts of Japan, vol. 10, No. 39, 1986 and Japan Pt. 60-194846.
Amstoutz Marc
Diehl Eric
Gagnot Dominique
Emanuel Peter M.
Philogene Haissa
Thomson Multimedia S.A.
Tripoli Joseph S.
Wein Frederick A.
LandOfFree
Method and device for driving a radiation emitting device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and device for driving a radiation emitting device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and device for driving a radiation emitting device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-866531