CN1719488A

CN1719488A - Infrared remote control anti interference detection method

Info

Publication number: CN1719488A
Application number: CN 200510021403
Authority: CN
Inventors: 胥成祥; 周国立
Original assignee: Sichuan Changhong Electric Co Ltd
Current assignee: Sichuan Changhong Electric Co Ltd
Priority date: 2005-08-03
Filing date: 2005-08-03
Publication date: 2006-01-11
Anticipated expiration: 2025-08-03
Also published as: CN100373418C

Abstract

The present invention provides an infrared remote control anti-interference detection method. It can effectively reduce influence of interference signal on the remote control command. Said invention includes the following steps: a. cyclically detecting received signals; and b. if the continuous brevity codes are detected, considering that the key is continued; if the continuous brevity codes are not detected, considering that the key is released; the detection cycle is greater than cycle of two brevity codes.

Description

Infrared remote control anti interference detection method

Technical field

The present invention relates to electronic technology, particularly infrared remote control technology.

Background technology

At present, the remote control of general household electrical appliances receives emission, reception has the NEC sign indicating number of NEC Corporation and the RC-5 sign indicating number dual mode of PHILIPS company.For the RC-5 sign indicating number when the user by volume+/-, CH+/CH-etc. arbitrarily continuously during key, whenever press primary key, all have a command code to send, and know what the order of this time button is after the CPU reception, so say on the principle that the strong interference immunity of RC-5 sign indicating number is a little.For the NEC sign indicating number, simply set out for remote control cost and control, its transmitter code mode for when the user by volume+/-, CH+/CH-etc. are arbitrarily continuously during key, whenever press primary key, for the first time there is a command code to send, just have only duplication code to send later on, no command code when having disturbing pulse to scurry into during having only duplication code to send, has upset normal duplication code and has received, because do not have command code and send this moment, CPU does not just know how to operate, and the deadlock phenomenon occurs, and the user shows as remote control pause, the ineffective phenomenon of button.

Summary of the invention

Technical matters to be solved by this invention is, provides a kind of infrared remote control anti-detection method, can effectively reduce the influence of undesired signal to guidance command.

The technical scheme that the present invention solve the technical problem employing is that infrared remote control anti interference detection method may further comprise the steps: a, the periodic signal that receives that detects; B, if detect continuous brevity code, think that then button continues; If do not detect continuous brevity code, think that then button unclamps; It is characterized in that sense cycle is greater than two brevity code cycles.

Further, sense cycle is less than switching time.Be meant the time of people's quick switching key described switching time, is generally 500ms.Further, sense cycle is 400ms.Signal among the described step a is a NEC form coded signal.

The invention has the beneficial effects as follows, can under different interference environments, improve the infrared remote control receptivity of household appliances such as TV greatly, greatly improve the anti-interference adaptability that infrared remote control receives, can solve the ineffective problem of straighforward operation.And the present invention realizes by software programming, need not increase the hardware cost of circuitry.

The invention will be further described below in conjunction with the drawings and specific embodiments.

Description of drawings

Fig. 1 is the substandard all-key synoptic diagram of NEC.

Fig. 2 is the presentation format of NEC substandard " 0 " and " 1 ".

Fig. 3 is the ultimate principle figure of NEC continuation code.

Fig. 4 has suffered the main process flow diagram of processing for infrared remote control.

Fig. 5 is the disturbing pulse synoptic diagram.

Fig. 6 is the sense cycle synoptic diagram of prior art to the NEC continuation code.

Fig. 7 is the sense cycle synoptic diagram of the present invention to the NEC continuation code.

Embodiment

General Infrared Ray Remote Control Technology mainly contains RC-5, technology such as NEC.Here be example with the NEC technology mainly: at first we know that the NEC technical standard is (being example with upd6122): the frequency of remote control carrier wave is 38KHz; When certain button was pressed, system at first launched a complete all-key, launched a series of brevity codes again through time-delay then, unclamped up to button, promptly stopped emission.Brevity code repeats the 108ms that delays time, and the interval between per two pilot pulse rising edges all is 108ms.A complete all-key as shown in Figure 1.Wherein, preamble code high level 9ms, low level 4.5ms; 16 of systematic codes, 8 of numeric data codes, 8 of data radix-minus-one complements, totally 32; Data 0 usefulness " high level 0.5625ms+ low level 0.5625ms " expression, data 1 usefulness " high level 0.5625ms+ low level 1.6875ms " expression, as shown in Figure 2: radix-minus-one complement+stop bit (0.5625ms) high level of a brevity code=preamble code+systematic code position 0.Preamble code is used for notifying receiver to be remote-control data thereafter.It is the data of which type that systematic code is used for distinguishing, and receiving end judges according to this whether follow-up data are the instruction that must carry out.It is which key is pressed that numeric data code is used for distinguishing, and receiving end is made the judgement that carry out what action according to numeric data code.Brevity code is the sign indicating number that sends when continuing button.It informs receiving end, certain key whether by continuously according to.

In the prior art, one that receive that sense cycle software does is 200ms, if system during this 200ms does not find continuation code because there is interference code to occur, the operation of continuation code will be interrupted, because do not have command code and send this moment, CPU does not just know how to operate, and the deadlock phenomenon occurs, and the user shows as remote control pause, the ineffective phenomenon of button.Special signal wire ground connection when user family in some cases is bad, when the power supply EMC design of complete machine is not fine, the power supply interference of 50Hz can interfere with remote control and receive head, because it is relatively sensitiveer that remote control receives head, the oscillating impulse that it is the cycle that remote control reception head is easy to generate a 20ms is because this impulse magnitude is the same with normal burst, and frequency is very low, is difficult to filter out with hardware mode.When we know the NEC remote-control transmitting by top principle, crack it open behind button and always launch a complete all-key, even disturbing pulse is arranged, it can not occur interrupting at once.So if we do not put by next key, it launches a brevity code in the time interval of 108ms so, judge whether the appearance of continuation code with this, if but inside has disturbing pulse to occur, we are to survey interference waveform, and approximately disturbing pulse of 20ms (the roomy about 2ms of pulse) (as Fig. 4) appearance (annotating: relevant with the interval with the width of pulse) is an example:

In the prior art, as Fig. 5, it is to be a time interval of detecting brevity code with 200ms (because timer internal is into being that multiple carries out: 100ms, 200ms, 400ms, 800ms) that actual software is write, promptly we judge the appearance that none continuation code is arranged in 200ms, but this moment is because every 20ms of internal random has the appearance of a disturbing pulse to interrupt this brevity code pulse.Experiment finds that the probability that recognizes a continuation code is very little, is very big so indignant rate that continuation code interrupts occurs.If filtering a disturbing pulse of this every 20ms appearance with circuit is not all right, because the frequency of TV is 50Hz, if so adopt circuit to filter this disturbing pulse, that will be carrier frequency that the remote control mode of 38KHz filters out together, so can only start with from software;

The key that addresses this problem is to improve the probability of discovery brevity code (if there is not disturbing pulse certainly, during this be 100% can be found to continuation code, but because the appearance of disturbing pulse is arranged, through experiment with calculate indignant rate that discovery can be found to continuation code and disturbing pulse: the time interval of pulse width, pulse, the reference position of pulse are relevant; Relevant with the external interference coefficient; Relevant with the time interval of finding brevity code; ), because external interference coefficient, the pulsewidth of disturbing pulse, disturb the time interval of affectionately dashing, the reference position of disturbing pulse can't change, just can only increase interval detection time of finding brevity code so improve this probability, in the longer time, find continuation code, promptly can not continue to use this time interval of the 200ms that ultimate principle adopted of NEC standard again, the time interval that the present invention will detect brevity code changes 400ms into, as Fig. 6, during this, increased the number of emission continuation code pulse, through experimental demonstration, find that the probability of a continuation code just becomes bigger, can occur the interruption of continuation code hardly again this moment.

In addition, change 800ms into if will detect the time interval of brevity code, as Fig. 7,, experimental results show that though the probability of finding a continuation code finds that the probability of continuation code is bigger during than 400ms, the phenomenon of error code appears this moment possibly, because during 800ms,, work as the user so and in 800ms, press another key if do not put by next key, it still can think a continuation code, has promptly become error code; And error code can not appear in 400ms, be because artificial quick switching key time at least more than 500ms.Therefore, detect the time interval of brevity code, i.e. sense cycle can not be greater than artificial quick switching key time, i.e. 500ms.

Claims

1, infrared remote control anti interference detection method may further comprise the steps:

A, the periodic signal that receives that detects;

B, if detect continuous brevity code, think that then button continues; If do not detect continuous brevity code, think that then button unclamps;

It is characterized in that sense cycle is greater than two brevity code cycles.

2, infrared remote control anti interference detection method as claimed in claim 1 is characterized in that, sense cycle is less than switching time.

3, infrared remote control anti interference detection method as claimed in claim 2 is characterized in that, sense cycle is 400ms.

4, infrared remote control anti interference detection method as claimed in claim 2 is characterized in that, the signal among the described step a is a NEC form coded signal.