KR100752523B1 - An infrared-ray receiver - Google Patents

Abstract

The present invention relates to an infrared receiver including a gain adjusting unit for preventing noise from inside / outside of the receiver on an output. The present invention generates a respective pulse for an input noise and a signal and uses the pulse signal to generate a noise and After the signal is divided, fast gain attenuation for noise and sufficient time constant for the signal are secured.

Infrared receiver according to the present invention can reduce the area of the chip in the integrated circuit design by securing a sufficient time constant by charging and discharging only for a short time in response to the input signal, the continuous inside the chip by not using the oscillator It is advantageous to maintain a high sensitivity by removing the source of noise, in particular, it has the advantage of reducing the time that the error due to noise in the output can be induced by the fast charging for continuous noise.

Infrared receiver, noise reduction

Description

Infrared receiver

1 is a block diagram of a conventional infrared receiver.

2 and 3 is an operation waveform diagram showing a gain control method of a conventional gain control unit for removing noise components.

4 is a circuit diagram showing an infrared receiver with a conventional noise canceling function.

5 is a block diagram showing an infrared receiver according to the present invention.

Figure 6 is a schematic diagram showing a gain control unit of the infrared receiver according to the present invention.

FIG. 7 is a timing diagram illustrating signals of rising and falling edge detectors, a noise signal, and a pause detector of FIG. 6.

8A and 8B illustrate embodiments of setting a threshold voltage of the noise signal and the pause detector of FIG. 6;

9 is a circuit diagram illustrating a specific embodiment of FIG. 6.

10A and 10B show the relationship between the charge pump circuit portion and the automatic gain control amplifier.

11A, 11B and 11C are timing diagrams showing the signal types of the BPF outputs of the charge switch and the discharge switch of the charge pump circuit portion;

12A, 12B, and 12C are diagrams showing changes in automatic gain control amplifier voltages for respective noise signals and received signals.

<Explanation of symbols for main parts of the drawings>

110: input unit 120: ultra short amplification unit

130: automatic gain control amplifier 140: limit amplifier

150: band pass filter 160: gain control unit

161: rising and falling edge detector 162: noise signal and pause detector

163 control logic section 164 charge pump circuit section

170, 200: comparator 180, 210: demodulator

190: output unit

The present invention relates to an infrared receiver, and more particularly to an infrared receiver including a gain control unit for removing noise generated in the infrared receiver.

Infrared receivers are receivers that receive and process infrared signals from infrared data transmitters, such as infrared remote controls, typically used in home appliances such as TVs.

1 is a block diagram of a conventional infrared receiver which is commonly used, and is disclosed in Korean Patent Registration Publication No. 322520 filed and registered by the applicant of the present invention.

Referring to FIG. 1, an input unit including a photodiode first detects an infrared input signal received from the outside and converts an infrared signal into an electrical signal. The changed electrical signal is weak, so it is amplified to an appropriate value through the ultra short amplifier.

The signal once amplified from the ultrashort amplifier is again properly adjusted by the gain control amplifier designed to control the gain. The automatic gain control amplifier reduces the gain of the receiver as the voltage increases.

The signal through the automatic gain control amplifier is finally amplified once again via the limit amplifier. The output signal of the limit amplifier passes the band pass filter again to filter out the carrier frequency signal of the infrared signal.

The output of the band pass filter unit is input to the gain control unit and the comparator. The role of the gain control part is to generate a gain control current or a gain control voltage for the purpose of adjusting the gain of the automatic gain control amplifier according to whether the signal output from the band pass filter is noise or a normal signal.

The comparator is a circuit for comparing the output of the band pass filter unit with the reference DC voltage set as a reference. The output of the comparator is connected to the demodulator, and the output signal of the demodulator is output through the output unit.

However, the input signal input to the infrared receiver from the outside is not only an infrared component, but also unwanted unwanted light such as fluorescent light or sunlight. These disturbances are considered noise components because they are not intended by the designer.

2 and 3 show a gain control method of a conventional gain control unit for removing such unintended noise components.

2 illustrates a gain adjusting method of the gain adjusting unit disclosed in Korean Patent Registration Publication No. 322520.

According to FIG. 2, the gain control method uses a time ratio of burst and gap, which can be expressed as Burst: Gap = 1: N.

In the case of a signal, it becomes N> 1, in the case of noise, it becomes N <1, and in the case of a signal, it fully charges, and in the case of noise, gain control is performed continuously so that it may be discharged entirely.

However, this method has a problem in that the gain is reduced for the fluorescent lamp noise signal N <1 similar to the shape of the signal, thereby outputting noise.

Figure 3 shows a gain control method of the gain control unit disclosed in the Republic of Korea Patent Publication No. 2004-4030.

According to FIG. 3, the charging may be continued for a rest period to remove about 8 ms of fluorescent lamp noise, which is a problem of FIG. 2.

However, when the non-noise signal is applied, the overall charging period is long, so the gain reduction is large even when the signal is received. Therefore, a small current is required to increase the time constant or a relatively large capacitor is required in the circuit. .

FIG. 4 is a circuit diagram showing a conventional infrared receiver having a noise canceling function disclosed in Korean Patent Laid-Open Publication No. 2004-4031, which uses signals such as an oscillator, respective clock signal generators, a pause detector, a signal detector, and the like. After classifying the noise, an apparatus for removing the noise by using charging, discharging, and holding is shown.

Referring to FIG. 4, in processing an input signal of an infrared receiver, the gain of the amplification unit inside the infrared receiver is a noise signal unlike the conventional method in consideration of the difference between the characteristics of the input signal, that is, the noise signal and the normal input. In the case of the normal signal and the case can be adjusted differently.

However, since the circuit configuration of the clock generator requires a register, the amount of circuit is large, which is a big burden in the integrated circuit configuration, and since the oscillator always generates the clock, it acts as a noise generator in the integrated circuit. In the infrared receiver for amplifying the received signal has a disadvantage that acts as a factor for reducing the sensitivity.

The present invention has been proposed to solve the above problems. In order to prevent noise from inside / outside the receiver from occurring at the output, each pulse is generated for the input noise and the signal, and the pulse signal is used. It is an object of the present invention to provide an infrared receiver capable of securing an optimal receiver sensitivity by dividing a noise and a signal and then rapidly attenuating the noise and securing a sufficient time constant for the signal.

The infrared receiver including a gain control unit for adjusting the gain of the automatic gain control amplifier according to the output signal of the band pass filter unit according to the present invention for achieving the above technical problem to detect the infrared input signal received from the outside to convert the infrared signal into an electrical signal An input unit including a photodiode to be replaced with; An ultra-short amplification unit for amplifying the electrical signal changed by the input unit; An automatic gain control amplifier which amplifies the electric signal amplified from the ultra short amplifier and whose gain is adjustable; A limit amplifier for amplifying the electric signal amplified by the automatic gain control amplifier; A band pass filter for filtering the carrier frequency signal of the infrared signal from the electric signal amplified by the limit amplifier; A first comparator for comparing the signal filtered by the band pass filter with a first threshold voltage; A first demodulator for demodulating the signal output by the first comparator; An output unit for receiving an output of the demodulator and outputting the output to an outside of the infrared receiver; A second comparator configured to receive a signal filtered by the band pass filter and compare it with a second threshold voltage; A second demodulator for demodulating the signal output by the second comparator; And receiving a demodulated signal by the second demodulator, outputting falling and rising edge detection signals with respect to the second threshold voltage, and extracting time information of the burst period and the resting period from the falling and rising edge detection signals. And a gain control unit for adjusting the gain of the automatic gain control amplifier.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the accompanying drawings.

5 shows an infrared receiver according to the present invention, which includes an input unit 110, an ultra-short amplifier 120, an automatic gain control amplifier 130, a limit amplifier 140, a band pass filter 150, and a gain. The controller 160, the first and second comparators 170 and 200, the first and second demodulators 180 and 210, and the output unit 190 are included.

The operation of the infrared receiver will be described in the present invention based on the components of FIG. 5.

The input unit 110 includes a photodiode to convert the input signal of light into an electrical signal, and the ultra-short amplifier 120 amplifies the converted electrical signal.

The automatic gain control amplifier 130 receives the output of the ultra-short amplifier 120, the gain is adjustable, the limit amplifier 140 amplifies the signal passed through the automatic gain control amplifier 130 once again, The band pass filter unit 150 filters only electric signals of a specific frequency included in the output of the limit amplifier 140.

The first comparator 170 compares the predetermined first threshold voltage Vth1 with the output of the bandpass filter unit 150 and outputs a signal when the output of the bandpass filter unit 150 is higher than the first threshold voltage Vth1. The first demodulator 180 demodulates the output signal of the first comparator 170, and the output unit 190 outputs the output signal of the first demodulator 180 to the outside of the infrared receiver.

When the output of the band pass filter unit 150 is lower than the first threshold voltage Vth1, the output of the band pass filter unit 150 does not go out to the output and is input to the second comparator 200 to be compared with the second threshold voltage Vth2 to compare the second demodulator 210. Demodulated through and is output to the gain control unit 160.

The gain adjusting unit 160 receives the output of the second demodulator 210 and outputs falling and rising edge detection signals with respect to the second threshold voltage Vth2, and bursts and rest periods by falling and rising edge detection signals. The gain is adjusted to extract the time information of the automatic gain control amplifier 130 to adjust the gain.

The threshold voltages of the first and second comparators 170 and 200 are arbitrarily determined, and the second threshold voltage Vth2 is set to a voltage that is several tens of mV lower than the first threshold voltage Vth1.

6 shows a configuration of the gain control unit 160 of the infrared receiver according to the present invention, and the rising and falling edge detection unit 161, the noise signal and the pause detector 162, the control logic unit 163 and the charge pump It consists of a circuit part 164.

Based on the components of Figure 6 will be described the operation of the gain control unit of the infrared receiver according to the present invention.

The rising and falling edge detection unit 161 receives a delay circuit for delaying the output signal of the second demodulator 210, an output signal of the second demodulator 210, and an output signal of the delay circuit so that the rising edge detection signal ( Vr) and a gate portion outputting the falling edge detection signal Vf, and the falling edge detection signal of the predetermined section by the falling edge at the time when a large signal starts with respect to the second threshold voltage Vth2 signal. (Vf) and a rising edge detection signal Vr of a predetermined section by a positive edge at the time when a large signal ends with respect to the second threshold voltage Vth2 signal.

The falling and rising edge detection signals Vf and Vr pass through a noise signal and a pause detector 162 for extracting time information of a burst section in which a carrier signal is loaded and a pause section in which a carrier signal is not loaded.

The noise signal and pause detector 162 includes a latch, a third comparator, and a fourth comparator.

The latch sets the reference voltages of the first and second reference voltages Vref1 and Vref2. When the output voltage Vd of the demodulator is at the falling edge, the latch-gap voltage Vbg is equal to the first reference voltage Vref1. In the rising edge, the control voltage of the first switch SW1 and the second switch SW2 is toggled so that the burst-gap voltage Vbg is compared with the second reference voltage Vref2. Let it be.

The third comparator compares the burst-gap voltage Vbg with the first or second reference voltage, and the fourth comparator compares the burst-gap voltage Vbg with the third reference voltage.

FIG. 7 is a timing diagram illustrating signals of rising and falling edge detectors, a noise signal, and a pause detector of FIG. 6.

Extraction of Burst section and Gap section is reset state (0V) if any one of falling edge detection signal (Vf) and rising edge detection signal (Vr) is Low, and both signals are High At this time, the capacitor is charged with current to change the time information into a burst-gap voltage (Vbg).

The burst-gap voltage Vbg is again compared with the three reference voltages Vref1, Vref2, and Vref3 by the third and fourth comparators and used for the detection of noise and signals.

The three reference voltages Vref1, Vref2, and Vref3 are the first reference voltage Vref1 for determining noise exceeding the continuous threshold voltage Vthr in the case of the burst signal, and the predetermined idle period Gap after the burst ends. When the second reference voltage (Vref2) and the rest period (Gap) interval for detecting whether the excess exceeds the second reference voltage (Vref2) is composed of a third reference voltage (Vref3) for making a signal for increasing the gain for a predetermined time have.

8A and 8B illustrate an example of setting the reference voltages of the noise signal and the pause detector of FIG. 6.

Using a constant current and a capacitor, the burst-gap voltage (Vbg) increases linearly after reset, yielding an accurate time function as shown in Equation (1).

Here, the first reference voltage Vref1 and the first reference time T1 indicate a reference voltage and a reference time for detecting the burst as continuous signal noise when a burst occurs. The first reference time T1 is a continuous burst noise detection reference time and is set to about 14 ms longer than the longest burst of the general infrared signal (usually the head bit of the signal).

The second reference voltage Vref2 and the second reference time T2 indicate a reference voltage and a reference time for detecting a rest period after the burst ends. The second reference time T2 is set to about 20 ms, which is larger than 16 ms, which is twice the period of 8 ms, in order to attenuate a signal similar to a fluorescent lamp signal.

Here, since the third reference voltage Vref3 and the third reference time T3 are recognized as signals after the rest period is detected from the second reference voltage Vref2, a reference for detecting a signal for increasing a gain for a predetermined time period Voltage and reference time, and the third reference time T3 is about several ms.

The control logic unit 163 is a signal Vch for finally reducing the gain and a signal Vdis for increasing the gain of the signal of the rising and falling edge detection unit 161 and the output signal of the pause signal detection unit 162. Output

The charge pump circuit unit 164 is composed of a constant current source and a switch, and the automatic gain control amplifier unit is configured to charge, discharge, and maintain the capacitor in three ways: a signal attenuating the gain (Vch) and a signal increasing the gain (Vdis). Adjust the gain.

9 is a circuit diagram illustrating a specific embodiment of FIG. 6.

9, the configuration of the rising and falling edge detection unit 161 is composed of a delay circuit, Nor, NAND, and INV to generate the falling edge detection signal Vf and the rising edge detection signal Vr.

In the noise signal and pause detector 162, the latch sets the reference voltages of the first reference voltage Vref1 and the second reference voltage Vref2, and the burst-gap voltage Vbg when the output voltage Vd of the demodulator is at the falling edge. The first reference voltage Vref1 may be compared with the first reference voltage Vref1, and the rising edge of the voltage bus-gap voltage Vbg may be compared with the second reference voltage Vref2 so that the first switch SW1 and the second switch SW2 are compared. Maintains the control voltage of the toggle.

The control logic unit 163 uses the third comparator output voltage V1, the fourth comparator output voltage V2, the falling edge detection signal Vf, and the output voltage Vd of the demodulator, and the charge pump circuit unit 164. A charge switch (SWch) signal and a discharge switch (SWdis) signal, which are signals for controlling the signal, are made.

10A and 10B show the relationship between the charge pump circuit unit 164 and the automatic gain control amplifier.

10A and 10B will be described with reference to FIGS. 11A, 11B, and 11C, which show comparisons between the signal types of the BPF outputs of the charge switch SWch and the discharge switch SWdis of the charge pump circuit section. .

According to FIG. 11A, a charge signal is generated in the ON state by closing the charge switch SWch for a predetermined time Tch at the time when the signal burst starts when the signal burst is greater than the second threshold voltage Vth2. do.

According to FIG. 11B, when a continuous burst occurs for a predetermined time after the charging signal is generated, the charging signal is regarded as a power supply noise or an incandescent lamp noise, and the charging signal is changed from a Tch to a demodulator signal and continuously charged until the burst ends.

Referring to FIG. 11C, when there is no burst for a predetermined time after the burst signal having a shape larger than the second threshold voltage Vth2 is regarded as a signal, the discharge switch SWdis for a predetermined time Tdis after the gap time Tgap ) Is closed and a discharge signal is generated in the ON state.

12A, 12B and 12C show changes in the automatic gain control amplifier voltage Vagc for each noise signal and the received signal.

FIG. 12A is a variation of the automatic gain control amplifier voltage (Vagc) for a random continuous signal in the form of general power supply noise or incandescent lamp noise, and is in a suppressed state. FIG. 12B is also a noise signal shape of a fluorescent lamp. 12C is a non-suppression state for the type of signal received at the receiver.

The technical spirit of the present invention has been described above with reference to the accompanying drawings. However, the present invention has been described by way of example only, and is not intended to limit the present invention. In addition, it is apparent that any person having ordinary knowledge in the technical field to which the present invention belongs may make various modifications and imitations without departing from the scope of the technical idea of the present invention.

Infrared receiver according to the present invention can reduce the area of the chip in the integrated circuit design by securing a sufficient time constant by charging and discharging only for a short time in response to the input signal, the continuous inside the chip by not using the oscillator It is advantageous to maintain high sensitivity by eliminating noise sources.

In addition, the infrared receiver according to the present invention has the advantage of reducing the time that the error due to noise in the output by inducing rapid charging for continuous noise.

Claims (11)

In the infrared receiver including a gain control unit for adjusting the gain of the automatic gain control amplifier receiving the output signal of the band pass filter, An input unit including a photodiode for detecting an infrared input signal received from the outside and converting the infrared signal into an electrical signal; An ultra-short amplification unit for amplifying the electrical signal changed by the input unit; An automatic gain control amplifier which amplifies the electric signal amplified from the ultra short amplifier and whose gain is adjustable; A limit amplifier for amplifying the electric signal amplified by the automatic gain control amplifier; A band pass filter for filtering the carrier frequency signal of the infrared signal from the electric signal amplified by the limit amplifier; A first comparator for comparing the signal filtered by the band pass filter with a first threshold voltage; A first demodulator for demodulating the signal output by the first comparator; An output unit for receiving an output of the demodulator and outputting the output to an outside of the infrared receiver; A second comparator configured to receive a signal filtered by the band pass filter and compare it with a second threshold voltage; A second demodulator for demodulating the signal output by the second comparator; And Receiving the demodulated signal by the second demodulator, outputting falling and rising edge detection signals with respect to the second threshold voltage, and extracting time information of the burst period and the resting period from the falling and rising edge detection signals; And a gain control unit for adjusting the gain of the automatic gain control amplifier. The method of claim 1, wherein the second threshold voltage Vth2 is Infrared receiver, characterized in that the voltage is about tens of mV lower than the first threshold voltage (Vth1). The method of claim 1, wherein the gain control unit Receiving the output signal of the second demodulator and outputting the falling edge detection signal (Vf) of a predetermined section by the falling edge (falling edge) at the time when the signal starts, and at the end of the fixed signal by the positive edge (positive edge) Rising and falling edge detection unit for outputting the rising edge detection signal (Vr) of the section; Noise for extracting time information of a burst section in which a carrier signal is loaded and a gap section in which a carrier signal is not loaded by the rising and falling edge detection signals Vr and Vf output by the rising and falling edge detectors Signal and pause detection unit; A signal Vch and a gain that finally attenuates the gain by using the falling edge detection signal Vf of the rising and falling edge detectors, the output voltage Vd of the second demodulator, and the output signal of the noise signal and the pause detector. A control logic unit outputting the signal Vdis to increase the value of the control logic unit; And A charge pump circuit that controls the gain of the automatic gain control amplifier, which consists of a constant current source and a switch, and charges, discharges, and maintains the capacitor with a signal attenuating the gain (Vch) and a signal increasing the gain (Vdis). Infrared receiver comprising a. The method of claim 3, wherein the rising and falling edge detection unit A delay circuit for delaying an output signal of the demodulator; And And a gate unit configured to input an output signal of the demodulator and an output signal of a delay circuit to output a rising edge detection signal Vr and a falling edge detection signal Vf. The method of claim 3, wherein the noise signal and the pause detection unit The reference voltages of the first reference voltage Vref1 and the second reference voltage Vref2 are compared with the burst-gap voltage Vbg when the output voltage Vd of the demodulator is at the falling edge, so as to be compared with the first reference voltage Vref1. On the rising edge, the latch maintains the control voltage of the first switch SW1 and the second switch SW2 in a toggle manner such that the burst-gap voltage Vbg is compared with the second reference voltage Vref2. (latch); A third comparator comparing the burst-gap voltage Vbg with the first or second reference voltage; And And a fourth comparator for comparing the burst-gap voltage (Vbg) with the third reference voltage. The time information of the burst section and the idle section is If any one of the falling edge detection signal Vf and the rising edge detection signal Vr is Low, it is in a reset state. When both signals are high, the capacitor is charged with a current to the burst-gap voltage Vbg. Infrared receiver characterized in that the change. The method of claim 6, wherein the burst-gap voltage (Vbg) is And a plurality of reference voltages which are used by the third and fourth comparators to detect noise and signals. The method of claim 7, wherein the plurality of reference voltages are compared with a burst-gap voltage Vbg. A first reference voltage Vref1 for discriminating noise when the burst-gap voltage Vbg exceeds the second threshold voltage Vth2 by the continuous burst signal; A second reference voltage Vref2 for detecting whether the burst ends and the burst-gap voltage Vbg exceeds a predetermined rest period Gap; And And a third reference voltage (Vref3) for generating a signal for increasing a gain for a predetermined time when the burst-gap voltage (Vbg) exceeds the second reference voltage (Vref2). The method of claim 8, wherein the first reference voltage Vref1 is Time function using constant current and capacitor

(T1: continuous burst noise detection reference time, Cbg: burst-gap charge amount, Iref: reference current) Infrared receiver, characterized in that represented by. The method of claim 1, wherein the gain control unit A rising and falling edge detector configured of a delay circuit and Nor, NAND, and INV to generate falling edge detection signals Vf and rising edge detection signals Vr; In the internal latch, when the output voltage Vd of the demodulator is at the falling edge, the burst-gap voltage Vbg is compared with the first reference voltage Vref1. When the rising edge is at the rising edge, the burst-gap voltage Vbg is second A noise signal and a pause detector configured to toggle the control voltages of the first switch SW1 and the second switch SW2 in a toggle manner so as to be compared with the reference voltage Vref2; A charge switch SWch signal and a discharge switch SWdis using the third comparator output voltage V1, the fourth comparator output voltage V2, the falling edge detection signal Vf, and the demodulator output voltage Vd. A control logic unit generating a signal; And And a charge pump circuit unit configured to receive a charge switch (SWch) signal and a discharge switch (SWdis) signal from the control logic unit to charge and discharge a capacitor. The method of claim 10, wherein the charge pump circuit portion When the signal burst (Signal Burst) starts when a signal greater than the second threshold voltage (Vth2) is input, the charge switch (SWch) is closed for a predetermined time to generate a charging signal in the ON state, When burst occurs continuously for more than a certain time after the charging signal is generated, it is regarded as power noise or incandescent lamp noise. When there is no burst for a predetermined time after the burst signal having a shape larger than the second threshold voltage Vth2, the discharge switch SWdis is closed for a predetermined time after the gap time Tgap, which is regarded as a signal and discharged in the ON state. An infrared receiver, characterized in that the signal is generated.

Images