JP2008118312A - Receiving circuit of remote control signal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a receiving circuit of remote control signal capable of exhibiting satisfactory performance upon power-on and of dealing with high speed communication. <P>SOLUTION: The receiving circuit of remote control signal includes detection means for performing waveform shaping by comparing a comparison voltage and a waveform signal by a comparator 4. In the receiving circuit of remote control signal, a middle point of the amplitude of a waveform signal of a voltage change upon ordinary operation is stored as reference voltage and is used as a comparison voltage of the comparator 4. There are provided processings of steps S1, S2, S3 executed by a microcomputer 1, an A/D converter 2, and a D/A converter 3. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention belongs to the technical field of a remote control signal receiving circuit that receives and processes a signal from a remote controller associated with a main device.

Conventionally, waveform shaping is performed using a comparator to convert a demodulated signal received from a remote control signal into a digital signal. The received waveform is input to the comparator, and is input to the comparison side of the comparator via a capacitor to shape the digital waveform. In this receiving circuit, the quick charging circuit takes measures against a delay in the rise time of the comparison-side potential when the power is turned on by the capacitor (see, for example, Patent Document 1).
JP 2001-145171 A (page 2-9, full view)

  However, the conventional remote control signal receiving circuit does not have sufficient performance when the power is turned on when there is an interference wave. For this reason, there was a problem in dealing with high-speed communication.

  The present invention has been made paying attention to the above-mentioned problems, and an object of the present invention is to provide a remote control signal receiving circuit that has sufficient performance at power-on and can cope with high-speed communication.

  In order to achieve the above object, in the present invention, a frequency voltage converting means for converting a radio wave signal from a remote control from a frequency change to a voltage change signal, and a conversion from a voltage change waveform signal to a digital signal from which data can be extracted, In the remote control signal receiving circuit having a detecting means for performing waveform shaping by comparing the comparison voltage by the waveform signal with the waveform signal, the midpoint of the amplitude of the waveform signal of the voltage change during normal operation is stored as a reference voltage, and the comparison of the comparator A reference voltage setting unit used for the voltage is provided.

  Therefore, in the present invention, the performance at the time of power-on is sufficient, and it is possible to cope with high-speed communication.

  Hereinafter, an embodiment for realizing a remote control signal receiving circuit of the present invention will be described based on a first embodiment corresponding to the first and second aspects of the present invention.

First, the configuration will be described.
FIG. 1 is a block diagram of a waveform shaping portion of the remote control signal receiving circuit according to the first embodiment.
The waveform shaping portion of the remote control signal receiving circuit of the first embodiment is a circuit portion after the received signal is processed by the F / V converter 51, and includes the microcomputer 1, the A / D converter 2, and the D / A converter 3. The comparator 4 has a main configuration.

The microcomputer 1 processes the input signal, calculates a threshold value for waveform shaping, and outputs the threshold value.
The A / D converter 2 converts the analog signal received from the remote controller into a digital signal and outputs it to the microcomputer 1.

The D / A converter 3 converts the digital signal indicating the threshold value from the microcomputer 1 into an analog signal and outputs the analog signal to the comparator 4.
The comparator 4 performs shaping by comparing the received signal from the remote controller with the threshold signal from the D / A converter 3, and outputs the shaped waveform.

The operation will be described.
[When the power is turned on when there is an interference signal]
Here, a description will be given of power-on when there is an interference signal.
FIG. 2 is a block diagram showing a waveform shaping portion of a conventional remote control signal receiving circuit. FIG. 3 is a time chart when the power is turned on when there is an interference signal in the waveform shaping portion of the conventional remote control signal receiving circuit. FIG. 4 is an explanatory diagram showing F / V conversion and signal operation at power-on when there is an interference signal in the waveform shaping portion of the conventional remote control signal receiving circuit.

The waveform shaping portion of the conventional remote control signal receiving circuit shown in FIG. 2 mainly includes an F / V converter 51, a detection circuit 52, and a quick charging circuit 53.
The F / V converter 51 converts the frequency-modulated received signal as shown in FIG. 4A into a signal whose voltage amplitude changes.

The detection circuit 52 mainly includes a comparator 521, resistors 522, 523, and 524, and a capacitor 525, and performs waveform shaping.
The quick charging circuit 53 includes a resistor 531, a capacitor 532, a comparator 533, and a switch 534, and rapidly charges the capacitor 525 of the detection circuit 52 when the power is turned on.
The operation of the waveform shaping portion of this conventional remote control signal receiving circuit will be described. In the circuit portion shown in FIG. 2, the voltage change signal output from the F / V converter 51 is caused to flow to the resistor 524 and the capacitor 525, whereby the midpoint of the amplitude of the voltage change signal determined by the bias voltage, the resistor 523, and the capacitor 525. Is output to the comparator 521.

Therefore, the comparator 521 performs circuit processing for extracting data from the radio signal by performing waveform shaping by comparing the midpoint of the amplitude of the voltage change signal with the voltage change signal.
An advantage of using the midpoint of the amplitude of the voltage change signal as the threshold value of the comparator 521 is when the F / V characteristic shown in FIG. 4A, that is, a frequency change is converted into a voltage change. In other words, since the entire change range of the frequency desired by the circuit (reference numerals 105 and 106 in FIG. 4 (a)) is actually shifted, if the midpoint of the voltage change corresponding to this is taken, correction is performed. The same effect as that performed can be obtained.

However, there is a problem in the waveform shaping portion of this conventional remote control signal receiving circuit. After the power is turned on, since the rise is delayed by the capacitor 525, the rise of the comparison voltage of the comparator 521 is delayed, and during this time, the operation of the determination circuit does not become normal.
Therefore, a quick charge circuit 53 is provided in the waveform shaping portion of the conventional remote control signal receiving circuit shown in FIG. The quick charging circuit 53 starts up the capacitor 525 at an early stage by flowing a voltage change signal output from the F / V converter 51 to the capacitor 525 without passing through the resistor 524.

However, when the jamming radio wave is received when the power is turned on, even the quick charging circuit 53 rises only to the midpoint of the voltage of the jamming radio wave.
As shown in FIG. 4 (a), the disturbing radio wave generally has only a low voltage when converted to a voltage (see reference numeral 107 in FIG. 4 (a)). In such a case, as shown in FIG. 4B, after the charging time by the quick charging circuit 53 has elapsed, the midpoint voltage input to the comparator 521 is sufficiently increased by charging the resistor 524 and the capacitor 525. Normal waveform shaping cannot be performed until it rises.

Specifically, with respect to the input waveform 108 to be processed shown in FIG. 4B, it takes time until the comparison voltage 109 that should be approximately in the center of the amplitude reaches the center.
That is, the voltages at the point d on the input signal side and the point e on the comparison voltage side of the comparator 521 in FIG. 2 are required to reach the levels of 103 and 104 in FIG. , 102 level, it is necessary to wait until the levels 103 and 104 are reached.

This is a problem in communications that are becoming faster year by year. Actually, in such a case, it is necessary to provide a dummy signal portion in front of the data portion of the data signal and wait for the rise.
The remote control signal receiving circuit according to the first embodiment solves such a problem.

[Threshold voltage setting process at power-on]
FIG. 5 is a flowchart illustrating the flow of threshold voltage setting processing executed by the microcomputer 1 in the detection portion of the remote control signal receiving circuit according to the first embodiment.

  In step S1, the voltage set as the initial reference voltage is read.

  In step S2, a process for storing the maximum value and the minimum value of the threshold voltage (reference voltage) of the comparator 4 in the normal operation state is performed. Specifically, the stored maximum value and minimum value are compared with the sampled threshold voltage, and when the maximum value is exceeded or below the minimum value, an update process is given as an example.

  In step S3, a half of the difference between the stored maximum value and minimum value is calculated, and the midpoint voltage is calculated.

  In step S4, the midpoint voltage calculated in step S3 is compared with the initial reference voltage in step S1, and it is determined whether or not the initial reference voltage registered in the initial range is within a predetermined range. If it is outside the predetermined range, the process proceeds to step S5.

  In step S5, the calculated midpoint voltage is registered as a new reference voltage.

[Operation using set threshold when power is turned on]
In the detection part of the remote control signal receiving circuit according to the first embodiment, the reference voltage used in the comparator 4 is set in advance by performing the processing of steps S1 to S5 during normal operation. As soon as the detection part of the circuit starts normal circuit operation, it is possible to perform processing for shaping the waveform of the received signal from the remote controller.
This preset reference voltage is only read out what is stored inside or outside the microcomputer 1, and the value of the reference voltage is not affected by the value of the received signal at that time.

For this reason, even when starting up while receiving an interference signal, normal waveform shaping processing can be performed immediately, and a conventional rise delay is not caused.
Therefore, a dummy part (dummy code) provided before the data part of communication data can be eliminated. Not having to provide a dummy portion shortens the communication time. It also reduces the current consumption of the receiver.

Further, since there is no rise delay as in the prior art, waveform shaping can be performed immediately when the power is turned on, so that high-speed communication can be handled.
In addition, in the detection part of the remote control signal receiving circuit of the first embodiment, the reference voltage is sequentially updated, so that it can cope with the receiver temperature, aging, etc. and the remote controller temperature / aging, etc. Therefore, waveform shaping (conversion to digital signal) of the signal can be performed reliably.

Next, the effect will be described.
The remote control signal receiving circuit according to the first embodiment can obtain the effects listed below.

  (1) An F / V converter 51 that converts a radio signal from a remote control from a frequency change to a voltage change signal, and a conversion from a voltage change waveform signal to a digital signal from which data can be extracted. In a remote control signal receiving circuit having detection means for performing waveform shaping by comparison with a signal, a microcomputer that stores the midpoint of the amplitude of a waveform signal of a voltage change during normal operation as a reference voltage and is used as a comparison voltage of the comparator 4 1. Since the processing of steps S1, S2, and S3 executed by the A / D converter 2 and the D / A converter 3 is provided, the performance at the time of power-on is sufficient and high-speed communication can be handled.

  (2) Step S4 executed by the microcomputer 1, the A / D converter 2 and the D / A converter 3 for updating the reference voltage with the midpoint of the amplitude of the waveform signal of the voltage change during the subsequent normal operation. Since the processing of S5 is provided, the reference voltage is sequentially updated, and it can cope with receiver temperature, aging, etc. and remote controller temperature, aging, etc., and waveform shaping of the signal reliably from the beginning of the data (to digital signal) Conversion).

  As described above, the remote control signal receiving circuit of the present invention has been described based on the first embodiment. However, the specific configuration is not limited to these embodiments, and the invention according to each claim of the claims is described. Design changes and additions are allowed without departing from the gist.

  For example, the processing content realized by the microcomputer 1 in the first embodiment may be based on a circuit configuration or a program.

FIG. 3 is a block diagram of a waveform shaping portion of the remote control signal receiving circuit according to the first embodiment. It is a block diagram which shows the waveform shaping part of the conventional remote control signal receiving circuit. It is a time chart at the time of power-on when there is an interference signal in the waveform shaping portion of the conventional remote control signal receiving circuit. It is explanatory drawing which shows F / V conversion at the time of power activation, and operation | movement of a signal when there exists an interference signal in the waveform shaping part of the conventional remote control signal receiving circuit. 6 is a flowchart illustrating a flow of threshold voltage setting processing executed by the microcomputer 1 in a detection portion of the remote control signal receiving circuit according to the first embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Microcomputer 2 A / D converter 3 D / A converter 4 Comparator 51 F / V converter 52 Detection circuit 521 Comparator 522 Resistor 523 Resistor 524 Resistor 525 Capacitor 53 Quick charge circuit 531 Resistor 532 Capacitor 533 Comparator 534 Switch

Claims (2)

Frequency-voltage conversion means that converts the radio signal from the remote control from a frequency change to a voltage change signal, and the conversion of the voltage change waveform signal to a digital signal from which data can be extracted. In the remote control signal receiving circuit having detection means for shaping,
Storing the midpoint of the amplitude of the waveform signal of the voltage change during normal operation as a reference voltage, and providing a reference voltage setting means used for the comparison voltage of the comparator;
A remote control signal receiving circuit. In the remote control signal receiving circuit according to claim 1,
Provided with a reference voltage update means for updating the reference voltage with the midpoint of the amplitude of the waveform signal of the voltage change during the subsequent normal operation;
A remote control signal receiving circuit.

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