Dimming method of indoor white LED
A white light and dimming technology, applied in the field of LED communication, can solve problems such as LED flickering, low energy utilization rate, and communication rate drop
Active Publication Date: 2016-11-09
南通固威机械科技有限公司
View PDF3 Cites 2 Cited by
- Summary
- Abstract
- Description
- Claims
- Application Information
AI Technical Summary
Problems solved by technology
If the traditional OOK and PPM modes are used, at the cost of sacrificing the symbol bandwidth, the bandwidth occupied by the signal is reduced, and the impact of the signal on the lighting is reduced. However, the energy utilization rate of this encoding method is low, and when the transmission rate is low, There will be LED flickering phenomenon
In summary, these methods all have a drawback, the communication rate will decrease significantly with the increase or decrease of the light level
Method used
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View moreImage
Smart Image Click on the blue labels to locate them in the text.
Smart ImageViewing Examples
Examples
Experimental program
Comparison scheme
Effect test
Embodiment Construction
[0051] Below in conjunction with accompanying drawing, technical scheme of the present invention is described in further detail:
[0052] The M-PAM encoding method is aimed at distinguishing multi-ary signal symbols by marking different pulse amplitudes in the linear area of the LED. It can be seen that the higher the binary level M is, the more effective bits are carried by each symbol, and the bandwidth utilization rate increases. However, too high M will also bring problems: ①Due to the limitation of the LED linear region, the difference in electrical signal waveforms is small, resulting in a higher precision for the A / D converter; ②The receiving end needs a larger SNR when reading the signal, The bit error rate increases and the sensitivity decreases; ③The tiny voltage difference is easily lost in the background noise. Therefore, choosing an appropriate M has an important impact on the performance of PAM encoding.
[0053] The M-PAM of the present invention has M volta...
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More PUM
Login to View More Abstract
The invention discloses a dimming method of an indoor white LED. The light intensity is adjusted through a method of combining the signal element probability and amplitude dimming. The method comprises the steps as follows: a variable Eta is taken as a scale factor of DC compensation D<shift> in analogue dimming; DC compensation D<shift> is as shown in the specification; Epsilon is the dimming level; A is a rated value of the light intensity of an LED linear region; when the dimming level is below 50%, the light intensity is adjusted through increasing of the probability of a signal element with a low light intensity amplitude and reducing the probability of the signal element with a high light intensity amplitude; when the dimming level is 50%, the DC compensation D<shift> is avoided and the light intensity is adjusted by changing the probabilities of the signal elements with the high light intensity amplitude and the low light intensity amplitude; and when the dimming level is over 50%, the light intensity is adjusted by reducing the probability of the signal element with the low light intensity amplitude, increasing the probability of the signal element with the high light intensity amplitude and reducing D<shift> compensation. Compared with a traditional digital dimming method, the dimming method disclosed by the invention has higher bandwidth utilization ratio; and the condition that the communication rate is not reduced along with the change of the dimming level is ensured.
Description
technical field [0001] The invention relates to the technical field of LED communication, in particular to a dimming method of an indoor white LED. Background technique [0002] White light LED communication systems mostly use baseband modulation. Currently, the modulation methods suitable for white light LED communication are: on-off keying (OOK); pulse position modulation (PPM); multi-pulse position modulation (VPPM); pulse width modulation (PWM); Pulse Interval Modulation (DPIM); Dual Head Pulse Interval Modulation (DH-PIM) and Color Keying (CSK). The purpose of these modulation methods is to obtain higher power utilization ratio and lower bit error rate under relatively narrow bandwidth. In addition, the indoor white light LED communication system also needs to take into account the dual needs of lighting and communication. In order to save energy, it is necessary to adjust the brightness of the light source at any time according to different background light intensitie...
Claims
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More Application Information
Patent Timeline
Login to View More Patent Type & Authority Applications(China)
IPC IPC(8): H05B33/08H04B10/116H05B44/00
CPCH04B10/116H05B45/10
Inventor 洪文昕钱晨朱晓叶王希琪李绍瑜
Owner 南通固威机械科技有限公司