WO2009057971A1

WO2009057971A1 - Control method and circuit for receiving signals in infrared receivier for remote control and infrared receiver having the control circuit

Info

Publication number: WO2009057971A1
Application number: PCT/KR2008/006433
Authority: WO
Inventors: Suki Kim; Joon-Jea Sung; Hee-Rang Jo
Original assignee: Silicon Communications Technology Co., Ltd.
Priority date: 2007-10-30
Filing date: 2008-10-30
Publication date: 2009-05-07
Also published as: KR20090043728A; KR100976404B1; CN101843013A

Abstract

Disclosed are a control method for receiving signals in an infrared receiver for remote control, the control method comprising: determining whether a signal input to the infrared receiver has N or more discontinuous sections each longer than a second time interval within a first time interval; and distinguishing between a data signal and a noise signal according to results from the determination, and a control circuit for carrying out the control method, in which discontinuous characteristics of the data signal and the noise signal are used to clearly distinguishing and eliminating the noise signal from the input signal.

Description

CONTROL METHOD AND CIRCUIT FOR RECEIVING SIGNALS IN INFRARED RECEIVIER FOR REMOTE CONTROL AND INFRARED RECEIVER HAVING THE

CONTROL CIRCUIT Technical Field

[1] The present invention relates to a control method and a control circuit which can eliminate a noise signal from signals received in an infrared receiver for remote control. Background Art

[2] Nowadays, many electronic appliances employ an infrared remote controller so that their functions can be remotely controlled at a close range. The infrared remote controller includes an infrared transmitter and an infrared receiver.

[3] A user can give various operation instructions to a main body of the electronic appliance through the infrared transmitter. That is, in response to a user's control instruction input, the infrared transmitter uses infrared as a carrier and sends information coded by a certain method to the infrared remote receiver provided in the main body. Aooording to the control instruction transmitted from the infrared transmitter, the infrared remote receiver controls the functions of the electronic appliance.

[4] In the infrared remote controller, a malfunction or the like due to an external noise causes a problem. R»r example, if noise which has a band similar to an infrared band used in the infrared remote controller is received from the outside, the infrared remote receiver recognizes a received noise signal as a data signal corresponding to a user's instruction, thereby causing the appliance to malfunction.

[5] As a representative source of generating noise, there is an illuminators such as a fluorescent lamp used in a room. Lately, various illuminators or the like generate a noise signal in a band similar to that a data signal of the infrared remote controller has, and therefore the appliance may malfunction if the infrared remote controller mistakes such a noise signal for the data signal transmitted from the infrared transmitter.

[6] Conventionally, an amplification gain control method has been used as a way of solving svch a problem. The amplification gain control method is as follows.

[7] Rg. 1 is a view for explaining that the noise is eliminated through a conventional amplification gain control method. As shown in Rg. 1, a received signal 11 transmitted from the outside to the infrared remote receiver includes a data section 12 and a discontinuous section 13 with regard to a time axis. The received signal has a feature of alternating between the data section and the discontinue section regardless of whether it is a data signal transmitted from the infrared transmitter or a noise signal generated by an illuminator or the like. [8] In the infrared remote receiver, an envelope curve of the received input signal is detected, and an amplitude of the detected signal is compared with a reference voltage V to thereby control an output gain as follows. ref

[9] An output gain control 15 is performed such that the output gain is decreased when the amplitude of the detected signal is higher than the reference voltage V , but the ref output gain is increased when the amplitude of the detected signal is lower than the reference voltage V . ref

[10] Without considering a white noise generated in an infrared receiving apparatus throughout a full band, most of a noise due to power or noises due to extraneous light are generally given in the form of a signal having a period of 4ms~10ms depending on a power period, and likewise a signal transmitted from the infrared transmitter has a format of a certain period.

[11] Further, noises due to the illuminator or the like have a shorter discontinuous section corresponding to no infrared signal as compared with the infrared data signal with respect to one period, and thus imch of the envelope curve of the received signal becomes higher than the reference voltage V . Accordingly, the section where the ref output gain decreases gets longer, so that the amplitude of an output signal continues to decrease when receiving only noise continuously. Finally, the amplitude of the output signal becomes equal to or lower than a reference output value, and therefore the output signal is not detected.

[12] On the other hand, the data signal transmitted from the infrared transmitter has a longer discontinuous section corresponding to no infrared signal as compared with the noise signal with respect to one period. Thus, contrary to interference signals due to the illuminator or the like, the data signal has a long section where the output gain increases but a short section where the output gain decreases, so that it can be detected as the output signal.

[13] In detail, sich a method increases or decreases the gain of an internal amplifier by ch arging (or discharging) a current of a capacitor to decrease (or increase) a control voltage, thereby controlling a total gain of the receiver. At this time, the infrared data signal and the noise signal are distinguished on the basis of an amount ratio between the currents charged to and discharged from the capacitor.

[14] However, the foregping amplification gain control method used in eliminating the noise has the following problems.

[15] The infrared remote controller uses various kinds of data formats in sending an in- stnction, so that a ratio between the data section and the discontinuous section within one period varies. Thus, if the amplitude of the output signal is controlled on the basis of a gain value determined according to results from being compared with the reference voltage V , not only it is difficult to obtain a stable output signal of which ref the noise is eliminated after a predetermined time, but also an output pulse width may be affected.

[16] In other words, various kinds of used infrared data formats are all different in the ratio between the section corresponding to the infrared signal and the section corresponding to no infrared signal within one period. Therefore, if the constant ratio between the currents charged to and discharged from the capacitor is applied, the gain of the amplifier stabilized after a certain time is varied depending on the infrared data formats even though the infrared data are received having the same amplitude, thereby affecting the output pulse width. Also, although certain codes are transmitted from the remote controller, they may not be detected as the data signals since the gain control lowers them into the reference output value or less.

[17] Meanwhile, the kind and the function of the illuminators have recently become various, and thus noise sources have increased with various properties. Further, the infrared remote controller has provided various data formats ad the kind thereof becomes diverse. In result, if the amplification gain control method based on the ratio between the data section and the discontinuous section within one period is used, there is increased probability that the infrared receiver will mistake a control signal for a noise or a noise for a control signal, thereby causing a problem of ensuring no reliability of the infrared remote receiver. Disclosure of Invention Technical Problem

[18] To solve the above described problems, an aspect of the present invention is to provide a control method and a control circuit of an infrared remote controller which can have reliability of clearly distinguishing between a data signal and a noise signal of a signal received in an infrared receiver. Technical Solution [19] A control method for receiving signals in an infrared receiver for remote control may include: determining whether a signal input to the infrared receiver has N or more discontinuous sections ea±t longer than a second time interval within a first time interval; and distinguishing between a data signal and a noise signal according to results from the determination.

[20] A control method for receiving signals in an infrared receiver for remote control may include: generating a first signal having information about whether an outline signal of an input signal exceeds a reference level; generating a second signal having information about whether a discontinuous section exceeds a second time interval on the basis of the first signal; generating a third signal which indicates whether the discontinuous section appears N or more times within a first time interval on the basis of the second signal; and determining the input signal as a data signal if the discontinuous section appears N or more times within the first time interval on the basis of the third signal.

[21] A control circuit for receiving signals in an infrared receiver for remote control may include: a signal determiner which determines whether a signal input to the infrared receiver has N or more discontinuous sections eash longer than a second time interval within a first time interval; and a squelch circuit which outputs the input signal if the discontinuous section longer than the second time interval appears N or more times within the first time interval, but otherwise breaks the input signal, on the basis of results from the determination of the signal determiner.

[22] An infrared receiver may include the control circuit for receiving the signals.

Advantageous Effects

[23] The present invention employs discontinuous characteristics of a data signal and a noise signal, and thus has an effect on clearly distinguishing and eliminating the noise signal from a received signal. Further, a determining time section value and a discontinuous section reference value are properly controlled according to characteristics of the data signal, so that the reliability of eliminating the noise signal can be enhanced. Brief Description of the Drawings

[24] Hg. 1 is a view for explaining that the noise is eliminated through a conventional amplification gain control method.

[25] Rg. 2 is a view for explaining a form of noise generated by an illuminator or the like.

[26] Hg. 3 is a view for explaining a form of a data signal transmitted from an infrared transmitter.

[27] Rg. 4 is a view for explaining an intensity level of a signal axording to an exemplary embodiment.

[28] Rg. 5 is a flowchart of distinguishing between a data signal and a noise signal according to an exemplary embodiment.

[29] Rg. 6 is a block diagram of a signal determining module of an infrared remote receiver according to an exemplary embodiment. Best Mode for Carrying Out the Invention

[30] The present invention described above will be more apparent through the following detailed descriptions related to accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[31] Rg. 2 is a view for explaining a form of noise generated by an illuminator or the like.

As shown in Rg. 2, most noise signals generated by the illuminator and the like and received in an infrared remote receiver are characterized in that they have a period of 4ms~10ms according to a power period, and a discontinuous section where a receiving intensity of the noise signal is equal to or less than a reference voltage does not exceed a maximum of 10ms within one period.

[32] Rg. 3 is a view for explaining a form of a data signal transmitted from an infrared transmitter. As shown in Rg. 3, an infrared data signal transmitted from an infrared transmitter to an infrared remote receiver generally has a period of 40ms~200ms, and a discontinuous section corresponding to no infrared signal ranges from 20ms to 100ms within one period.

[33] Referring to the received noise and signal shown in Rgs. 2 and 3, the noise generated by the illuminator, etc and the signal transmitted from the infrared transmitter are different in the period and the discontinuous section. Therefore, the present invention provides a method of distinguishing between the signal and the noise in the infrared remote receiver by employing the period and discontinuous characteristics of the received noise or signal.

[34] Rg. 4 is a view for explaining an intensity level of a signal according to an exemplary embodiment. As shown in Rg.4, a reference level for distinguishing the intensity of the received signal includes a signal level, an output level, and a noise level.

[35] Below, a method of distinguishing between the noise signal and the data signal will be described on the basis of the forms of the received noise signal and data signal shown in Hgs. 2 and 3 and the intensity levels of the signals shown in Hg. 4.

[36] If the signal received and amplified by the infrared remote receiver has a voltage higher than the output level, the received signal is first regarded as a data signal and thus a squelch circuit is turned off, thereby outputting the currently received signal. Accordingly, the initially received signal having an intensity higher than the output level is output like a data signal regardless of whether it is the noise signal or the data signal.

[37] From the moment when the squelch circuit is turned off, the infrared signal input to the infrared remote controller is observed for a predetermined time, so that it is determined whether the infrared signal is the noise signal or the data signal. The signal received during the observation is first determined as the data signal, and the infrared signal received continuously is output while controlling a gain of an amplifier such that a peak voltage of this signal corresponds to a signal level higher than the output level.

[38] If the currently received signal is an actual infrared data signal, the amplified infrared signal is maintained to have the signal level regardless of the amplitude of the received infrared data signal, so that a variation in a pulse width of an output signal can be largely decreased. After a predetermined time, if the currently received signal is determined as a noise signal, the squelch circuit is turned on to break the output of the noise signal from the infrared remote receiver, and as shown in Rg. 2 the gain of the amplifier is gradually decreased so that the peak voltage of the noise signal corresponds to a noise level lower than the output level.

[39] To distinguish between the noise signal generated from the illuminator or the like and the data signal received from the infrared transmitter, the discontinuous characteristics of the noise signal and the data signal are used.

[40] In other words, since a noise signal generally has a period of 4ms~10ms according to a period of a power signal, most discontinuous sections where the signal intensity is lower than or equal to the reference value do not exceed a maximum of 10ms within one period. On the other hand, the infrared data signals have many kinds of formats, but most of them have a period of 40ms~200ms and their discontinuous section corresponding to no infrared data signal ranges from 20ms~ 100ms within one period.

[41] Accordingly, a time of the discontinuous section corresponding to no infrared signal is counted within one period with regard to the received signal. If a signal of which the counted time does not exceed 10ms continues on for 200ms or more, this signal can be determined as a noise signal. The reason why the time of 200ms or more is taken for the determination is because one period of the longest infrared data signal is about 200ms.

[42] On the basis of that the noise signal and the data signal are generally different in the discontinuous characteristics, they can be distinguished as follows.

[43] That is, the data signal and the noise signal can be distinguished according to whether the discontinuous section each longer than a second time interval exists N or more times within a first time interval. Preferably, the first time interval is 200ms, the second time interval is 20ms, and N is 1.

[44] Rg. 5 is a flowchart of distinguishing between a data signal and a noise signal according to an exemplary embodiment. Referring to Rg. 5, a timer is initialized (S51), and a current time of the timer is compared with the first time interval (S52). If the time of the timer is shorter than the first time interval, it is determined whether an input signal has N or more discontinuous sections each longer than the second time interval (S53). When the input signal has N or more discontinuous sections each longer than the second time interval, the input signal is determined as a data signal (S54). On the other hand, if the input signal has less than N discontinuous sections each longer than the second time interval, the current time of the timer is compared again with the second time interval (S52). When the time of the timer is longer than the first time interval, the input signal is determined as a noise (S55).

[45] A circuit for distinguishing between the data signal and the noise signal as shown in

Rg. 5 can be implemented by various methods. R>r example, the circuit may be carried out as follows.

[46] A first signal, which indicates whether an outline signal of the input signal exceeds a reference level, is generated. Here, the reference level may be the noise level, and a section where the input signal does not exceed the reference level is regarded as the discontinuous section. A second signal, which indicates whether this discontinuous section exceeds the second time interval, is generated. Further, a third signal, which indicates whether the second signal has N or more discontinuous sections within the first time interval, is generated. Thus, the squelch circuit is turned on when the input signal is determined as the noise signal on the basis of the third signal, but turned on when the input signal is determined as the data signal, thereby outputting only the data signal.

[47] Rg. 6 is a block diagram of a signal determining module of an infrared remote receiver according to an exemplary embodiment. Referring to Rg. 6, when the signal received in the infrared receiver is input to a signal determiner 61 via the amplifier, the signal determiner 61 determines whether the input signal is the data signal or the noise signal.

[48] That is, the signal determiner 61 determines whether the signal input to a signal determining module 60 has N or more discontinuous sections each longer than the second time interval within the first time interval. According to determination results, the squelch circuit 62 outputs the input signal only if there is N or more discontinuous sections each longer than the second time interval within the first time interval, but otherwise breaks the input signal.

[49] Preferably, the first time interval is 200ms, the second time interval is 20ms, and N is 1.

[50] As described above, various exemplary embodiments have been described with the drawings and the specifications. For reference, terms employed herein are not used for narrowing the meaning and limiting the scope of the invention. Accordingly, it will be appreciated by those skilled in the art that changes may be made in these exemplary embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

[51]

Industrial Applicability

[52] The present invention may be applied to an infrared receiver which has been widely used as a remote controller for electronic appliances, and additionally applied to other control methods for eliminating a noise.

[53]

[54]

Claims

[1] A control method for receiving signals in an infrared receiver for remote control, the control method comprising: determining whether a signal input to the infrared receiver has N or more discontinuous sections each longer than a second time interval within a first time interval; and distinguishing between a data signal and a noise signal according to results from the determination.

[2] The control method axording to claim 1, wherein the first time interval comprises 200ms.

[3] The control method axording to claim 1, wherein the second time interval comprises 20ms.

[4] The control method according to claim 1, wherein the N comprises 1.

[5] A control method for receiving signals in an infrared receiver for remote control, the control method comprising: generating a first signal having information about whether an outline signal of an input signal exceeds a reference level; generating a second signal having information about whether a discontinuous section exceeds a second time interval on the basis of the first signal; generating a third signal which indicates whether the discontinuous section appears N or more times within a first time interval on the basis of the second signal; and determining the input signal as a data signal if the discontinuous section appears

N or more times within the first time interval on the basis of the third signal.

[6] The control method according to claim 5, wherein the first time interval comprises 200ms.

[7] The control method according to claim 5, wherein the second time interval comprises 20ms.

[8] The control method axording to claim 5, wherein the N comprises 1.

[9] A control circuit for receiving signals in an infrared receiver for remote control, the control circuit comprising: a signal determiner which determines whether a signal input to the infrared receiver has N or more discontinuous sections each longer than a second time interval within a first time interval; and a squelch circuit which outputs the input signal if the discontinuous section longer than the second time interval appears N or more times within the first time interval, but otherwise breaks the input signal, on the basis of results from the determination of the signal determiner.

[10] The control method according to claim 5, wherein the first time interval comprises 200ms.

[11] The control method aaoording to claim 5, wherein the second time interval comprises 20ms.

[12] The control method axording to claim 5, wherein the N comprises 1.

[13] An infrared receiver comprising the control circuit for receiving the signals axording to any one of claims 1, 5 and 9.