JPH0497696A - Remote controller - Google Patents

Abstract

PURPOSE:To reduce the effect of noise for an intermission period of a 1st modulated carrier frequency signal by inserting a 2nd carrier frequency signal whose frequency differs for the intermission period of a 1st modulated carrier frequency signal so as to prevent reception sensitivity at a receiver side from being unnecessarily increased. CONSTITUTION:A remote control signal modulator 3 of a transmission section 1 modulates a 1st carrier frequency signal set to A frequency tuned to a tuning circuit 8 of a reception section 5 by using a remote control signal generated corresponding to a key matrix 2. Simultaneously, the remote control signal modulator 3 modulates a 2nd carrier frequency signal set to a frequency not tuned to the tuning circuit 8 of the reception section 5 so as to send the result for a period equivalent to the intermission period of the 1st modulated carrier signal. Thus, the 2nd carrier frequency signal is inserted for the intermission period of the 1st carrier frequency signal to avoid the intermission period for the carrier frequency signal sent as the transmission signal. Thus, the reception sensitivity at the receiver side is not unnecessarily increased and then the effect of noise is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a remote control device such as an infrared remote control device used in a television receiver or the like.

[Prior Art] In a conventional device, as described in Japanese Patent Publication No. 59-26159, remote control was performed by intermittently transmitting a carrier frequency signal in response to a control signal. Note that related devices of this type include, for example, the remote control transmitter IC μPD1943G manufactured by NEC.

[Problems to be Solved by the Invention] The above-mentioned conventional technology does not take into consideration the automatic gain control characteristics on the receiving side, and the interruption period during the continuous carrier frequency signal period is longer than the automatic gain control holding time. If it is long, there is a problem that during this carrier frequency signal interruption period, the gain of the light receiving amplifier increases due to automatic gain control, which increases the receiving sensitivity and makes it susceptible to noise received in the transmission system. . Note that this automatic gain control holding time cannot be made too long because if it is made too long, the gain cannot be controlled in response to fluctuations in the amplitude of the transmitted carrier frequency signal.

An object of the present invention is to prevent the receiving sensitivity on the receiving side from becoming high even if the control signal has a long interruption period during continuous carrier frequency signal periods.

[Means for Solving the Problems] In order to achieve the above object, in the present invention, a second carrier frequency signal having a different frequency is inserted into a period corresponding to an interruption period in a continuous carrier frequency signal period. This is how it was done.

[Operation] By inserting the second carrier frequency signal into the interruption period of the first carrier frequency signal, the interruption period of the carrier frequency signal is completely eliminated. Therefore, because the receiving side receives the carrier frequency signal without interruption, even if the interruption period of the first carrier frequency signal becomes long, the reception sensitivity on the receiving side may become unnecessarily high. Therefore, the influence of noise during this period can be reduced.

[Example code] An embodiment of the present invention will be described below with reference to FIG.

The remote control signal modulator 3 of the transmitter 1 modulates a first carrier frequency signal set to a frequency tuned to the tuning circuit 8 of the receiver 5 by a remote control signal generated in accordance with the key matrix 2.

This waveform is shown in FIG. 2(a).

At the same time, the remote control signal modulator 3 transmits a second carrier frequency signal set to a frequency that is not tuned to the tuning circuit 8 of the receiving section 5.
The first carrier frequency signal is modulated so as to be transmitted for a period corresponding to the interruption period of the modulated first carrier frequency signal.

This waveform is shown in FIG. 2(b).

Here, the period other than the control signal period shown in FIG. 2 corresponds to the interruption period of the first carrier frequency signal, but it is not necessary to transmit it as in this embodiment.

The first and second carrier frequency signals modulated by these remote control signals are combined as shown in FIG. 2(c),
Transmission ■, transmitted by ED4.

In the receiving section 5 , a light receiving amplifier 7 equipped with an automatic gain control circuit (hereinafter referred to as AGC) receives and amplifies the first and second carrier frequency signals, and inputs the signals to a tuning circuit 8 . Tuning circuit 8
In order to tune to the first carrier frequency signal set to the frequency to be tuned again, only the first carrier frequency signal is sent to the detector 9.
tell. The detected remote control signal is sent to the waveform shaping circuit 1
0 to the microcomputer 11.

FIG. 3 shows the transmission signal waveform according to the prior art and the gain of a light receiving amplifier equipped with AGC when receiving the signal.

The period A in this figure is a long period in which the carrier frequency signal is interrupted, and the gain of the light receiving amplifier increases during this period, making it susceptible to noise.

According to this embodiment, as shown in FIGS. 2(c) and 2(d), there is no interruption period of the transmission signal during the control signal period, so the gain of the light receiving amplifier 7 does not become high, so it is not affected by noise. It is effective in making it difficult.

Furthermore, when the interruption period of the carrier frequency transmission signal is shorter than the gain response time constant of the light receiving amplifier 7 equipped with AGC (the third
Period B in Figure (b) and Period B in Figure 4(a) are
Since the increase in gain due to GC is small, there is no need to insert the second carrier frequency signal. The waveform of the second Wi transmission signal in this case is shown in FIG. 4(b).

Further, by inserting the second carrier frequency signal before and after the remote control signal transmission period as in period C in FIG. 4(c), the stable period of the gain of the light receiving amplifier 7 can be extended.

[Effects of the Invention] According to the present invention, by inserting the second carrier frequency signal into the interruption period of the first carrier frequency signal, there is no interruption period in the carrier frequency signal transmitted as the transmission signal. , 1st
Even if the interruption period of the carrier frequency signal becomes long, the receiving sensitivity on the receiving side will not become unnecessarily high.
Therefore, the influence of noise can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is an explanatory diagram showing an example of the waveform of the main signal in Fig. 1 and the gain of the light receiving amplifier, and Fig. 3 is a conventional remote control device. Explanatory diagram showing the waveform of the main signal and the gain of the light receiving amplifier in 5th
This figure is an explanatory diagram showing another example of the waveform of the main signal of FIG. 1 and the gain of the light receiving amplifier. Explanation of symbols 1... Transmitting unit, 2... Key matrix, 3... Remote control signal modulator, 4... Light emitting LED, 5... Receiving unit, 6
...Photodetector diode, 7...Photodetector amplifier equipped with AGC, 8...Tuning circuit, 9...Detector, 10...
Waveform shaping circuit, 1 microcomputer. 11th mouth 20 plant system wisdom weige

Claims (1)

[Claims] 1. In the transmitter, the first carrier frequency signal is modulated by intermittent the first carrier frequency signal according to the control signal, and the modulated first carrier frequency signal is In a remote control device, the control signal is transmitted from the transmitter to the receiver, the receiver demodulates the modulated first carrier frequency signal to obtain the control signal, and controls a controlled device using the control signal. , when transmitting the modulated first carrier frequency signal from the transmitting section to the receiving section, during an interruption period of the modulated first carrier frequency signal, a signal of a frequency different from that of the first carrier frequency signal is transmitted. A remote control device configured to transmit a second carrier frequency signal.