JPH03180000A - Reception circuit for infrared remote controller - Google Patents

Abstract

PURPOSE:To almost avoid the influence of fluorescent lamp noise by detecting timing for the periodical fluctuation voltage of a commercial power source to pass 0V and invalidating the output signal of a photodetecting circuit corresponding to the timing. CONSTITUTION:A rectifier circuit 41 to rectify the commercial power supply (AC100V) to a power supply part 30, a comparator circuit 43 to compare a rectify signal (a) with a reference voltage Vc and to output a component more than a prescribed voltage with inverted logic, an AND gate 45 to calculate AND between the inverted logic of a comparator circuit output signal (b) and a reception signal to be outputted from a photodetecting circuit 20 are provided. Thus, the timing for the fluorescent lamp noise to be increased before and after a direct current voltage to be periodically fluctuated passes 0V is defined as a dead area and the received signal of of the other time zone is made valid. Therefore, even when the photodetecting circuit 20 executes malfunction by the fluorescent lamp noise, the noise is not transmitted to a serial data input circuit in a rear step.

Description

[Detailed Description of the Invention] [Summary] The purpose of this invention is to improve the environmental resistance of the receiving circuit of an infrared remote control that performs input operations from a remote location with respect to the main unit. The commercial power supply monitoring means detects predetermined timing before and after passing 0V, and the control means disables the output signal of the light receiving circuit that receives infrared light according to the predetermined timing. .

[Industrial application field]

The present invention relates to a receiving circuit for an infrared remote control that performs input operations from a remote position relative to a main unit.

[Conventional technology]

Conventional infrared remote controllers transmit and receive signals using a configuration in which the infrared light is pulse-modulated and transmitted by a code, which is detected by a light-receiving element on the receiving side, amplified and detected, and sent to the serial data input circuit of the main unit. ing.

[Problems to be Solved by the Invention] By the way, there are many noise sources in the environment around which an infrared remote control is used for transmitting and receiving signals. In particular, when the light in the infrared region emitted from a fluorescent lamp fluctuates significantly, the light receiving circuit of the infrared remote control is affected by this and may cause malfunction.

In addition, the noise in the infrared wavelength range generated from fluorescent lamps is
As shown in FIG. 4, it is known that periodic fluctuation voltage of the commercial power supply often occurs before and after passing 0V. In other words, it can be said that fluorescent lamp noise is generated in synchronization with the AC frequency of the commercial power supply.

On the other hand, in order to avoid the effects of such noise and perform stable transmission and reception, measures are sometimes taken to set the output power on the transmitting side somewhat higher and adjust the sensitivity on the receiving side, but the power consumption This is not necessarily a good idea under the current situation where it is required to reduce battery consumption and reduce battery consumption as much as possible.

An object of the present invention is to provide a receiving circuit for an infrared remote control that can improve environmental resistance.

[Means to solve the problem]

FIG. 1 is a block diagram of the principle of the present invention.

In the figure, a commercial power supply monitoring means 11 detects a predetermined timing before and after the periodic fluctuation voltage of the commercial power supply passes 0V, and a control means 15 receives infrared light according to a predetermined timing. Control is performed to invalidate the output signal of the light receiving circuit 13.

[Function] In the present invention, since the fluorescent lamp noise that affects the reception operation of the infrared remote control is common before and after the periodic fluctuation voltage of the commercial power supply passes 0V, the commercial power supply monitoring means 11 detects the timing. By causing the control means 15 to invalidate the output signal of the light receiving circuit 13 in accordance with the timing, the influence of fluorescent lamp noise can be almost avoided.

Note that the received signal output by the light receiving circuit 13 is intermittent depending on the frequency of the commercial power supply, but this does not particularly affect the analysis of the received signal because a predetermined code is used.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 2 is a block diagram showing the configuration of an embodiment of the present invention.

In the figure, the light receiving circuit 20 includes a light receiving section 21 that receives infrared light and converts it into an electrical signal, an amplifying section 22 that amplifies this electrical signal, a detecting section 23 that detects the amplified signal and outputs a received signal, Waveform shaping section 2 that shapes the waveform of this received signal and sends it to a PC or other serial data input circuit.
Consisting of 4.

Here, the features of the present invention are as follows in this embodiment:
A rectifier circuit 41 that rectifies the commercial power supply (AClooV) supplied to the power supply unit 30, a comparison circuit that compares the rectified signal (a) with a reference voltage vc and outputs a component higher than a predetermined voltage (amplitude) using inverted logic. 43, it is configured to include an AND gate 45 which takes the logical product of the inverted logic of the comparison circuit output signal (b) and the received signal output from the light receiving circuit 2o. Note that the comparison circuit 43 includes a voltage dividing resistor 47 that determines the reference voltage vc.
．． 48 and a differential amplifier 49.

FIG. 3 shows the waveforms of the rectified signal (a) and the comparison circuit output signal (b).

The rectifier circuit 41 and comparison circuit 43 shown in this embodiment correspond to commercial power supply monitoring means (11 in FIG. 1), and the AND gate 45 corresponds to control means (15 in FIG. 1), and the frequency of the commercial power supply is This configuration controls whether or not the received signal output by the light receiving circuit 20 is valid or invalid depending on the (phase).

In other words, the timing where the fluorescent lamp noise increases before and after the periodically fluctuating AC voltage passes 0V is defined as the dead zone region,
By validating received signals at other times,
Even if the light receiving circuit 20 malfunctions due to fluorescent lamp noise,
The configuration is such that the data is not transmitted to the subsequent serial data input circuit.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to avoid a situation where the light receiving circuit malfunctions due to fluorescent lamp noise and leads to an incorrect reception operation (manual processing), thereby increasing the environmental resistance of the infrared remote control. I can do it.

In addition, the transmission level is the same as before (and it is easy to reduce power consumption.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the principle of the present invention. FIG. 2 is a block diagram showing the configuration of an embodiment of the present invention. FIG. 3 is a diagram explaining the operation of the embodiment of the present invention. FIG. 4 is a diagram illustrating the timing of occurrence of fluorescent lamp noise. 11... Commercial power supply monitoring means, 13... Light receiving circuit, 1
5... Control means, 20... Light receiving circuit, 21... Light receiving section, 22... Amplifying section, 23... Detecting section, 24...
・Waveform shaping section, 30... Power supply section, 41... Rectifier circuit, 43... Comparison circuit, 45... AND gate, 47
．． 48... Voltage dividing resistor, 49... Differential amplifier.

Claims (1)

[Claims] (1) Commercial power supply monitoring means (11) that detects predetermined timing before and after the periodic fluctuation voltage of the commercial power supply passes 0V
and a control means (15) for disabling an output signal of a light receiving circuit (13) for receiving infrared light according to the predetermined timing.
) A receiving circuit for an infrared remote control, comprising: