JPS61131628A - Infrared ray remote control reception circuit - Google Patents

Abstract

PURPOSE:To select and discriminate a control signal of the major mode in a single tuning system by providing a resonance element having a resonance characteristic to an infrared ray having >2 carrier frequencies. CONSTITUTION:A specific resonance characteristic with respect to carrier frequencies f1, f2 is set to the resonance element 12. When an infrared-ray transmission signal in a carrier frequency f1 is received by a photodetector 10, a photodetection current flows to the photodetector 10 and is fed to an amplifier circuit 4. Since the resonance element 12 has the resonance characteristic to the carrier frequency f1, the amplifier circuit 4 selects the signal in the frequency f1. When the infrared-ray signal in the carrier frequency f2 is received by the photodetector 10, the photodetection current flows similarly to the amplifier circuit 4. Since the resonance element 12 has the resonance characteristic also to the frequency f2, the signal of the frequency f2 is selected similarly by the amplifier circuit 4.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to an improvement in the tuning system of an infrared remote control receiving circuit that is capable of receiving transmitted infrared rays having two or more carrier frequencies.

2. Description of the Related Art In general, infrared remote control receiving circuits are used for TV
It is installed in a remote control target device such as a television receiver, and is used for remote control operations such as tuning channel operation and volume adjustment.

In other words, infrared rays for remote control are transmitted toward the infrared receiving element of the infrared remote control receiving circuit, but in the infrared remote control receiving circuit, the infrared signal converted into an electrical signal by the infrared receiving element is transmitted with high gain. After being tuned amplified, it is detected. The detected output is waveform-shaped and then converted into a pulse-like output signal, which is applied to, for example, an operation control circuit of a TV receiver to perform desired operations such as channel operation.

Conventionally, such infrared remote control receiving circuits that support two or more carrier frequencies have used a parallel resonant circuit consisting of an inductor and a capacitor in the first stage amplification section to tune and amplify the output signal of the infrared receiving element. A tuned amplifier circuit is used and the frequency selection characteristic is set to a single carrier frequency.

Problems to be solved by the invention In such an infrared remote control receiving circuit,
It is difficult to support control in which two or more carrier frequencies are set and a wide variety of complex operation modes are set.

If two or more carrier frequencies are set, a tuning amplifier circuit having selection characteristics corresponding to each carrier frequency must be installed, which complicates the tuning system.

Therefore, the present invention attempts to obtain selection characteristics for two or more carrier frequencies in a simple tuning system.

Means for Solving the Problems That is, the present invention provides an infrared receiving element that receives transmitted infrared rays of two or more carrier frequencies, and a resonant element that has resonance characteristics of frequencies corresponding to the two or more carrier frequencies. and an amplifier circuit that amplifies and extracts the received signal of the infrared light receiving element for each carrier frequency.

Accordingly, the present invention resonates with each carrier frequency of the transmitted infrared rays of two or more carrier frequencies, and selects and discriminates the infrared signals of each carrier frequency.

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

FIG. 1 shows an embodiment of an infrared remote control receiving circuit according to the present invention.

In FIG. 1, a transmitting infrared 8
An infrared light receiving element 10 that receives light is connected. The transmitted infrared rays 8 are obtained by pulse modulating two or more carrier frequencies, and are transmitted from a transmitter (not shown) toward the infrared light receiving element 10.

Upon reception of the transmitted infrared rays 8, a light receiving current flows through the infrared light receiving element 10 and is applied to the amplifier circuit 4.

A resonant element 12 having resonance characteristics for two or more carrier frequencies is connected to the amplifier circuit 4 as a load. The resonant element 12 is formed by connecting in series a plurality of parallel resonant circuits of inductors and capacitors each having a unique resonant frequency corresponding to each carrier frequency.
Consists of frequency peak elements, etc. That is, the impedance of the resonant element 12 exhibits a peak value corresponding to each carrier frequency, and the amplifier circuit 4 outputs a frequency selection output corresponding to the peak value.

The output signal of this amplifier circuit 4 is applied to a limiter and level shift circuit 14, where unnecessary level portions thereof are captured and the level is set to a predetermined level.

The output of this limiter and level shift circuit 14 is applied to a detection circuit 16 and detected. This detection circuit 16
is composed of a peak value detection circuit that detects the peak value of the output signal of the limiter and level shift circuit 14, and a peak hold detection circuit that includes a capacitor that holds the peak value.

The output of this detection circuit 16 is applied to a waveform shaping circuit 18, where the waveform is shaped, and then taken out from an output terminal 20.

In such a configuration, as shown in FIG. 2, the resonance element 12 is set to have unique resonance characteristics for the carrier frequencies f, , f2. In this case, the sharpness of the resonance characteristic is increased,
In order to improve the selection characteristics of both resonance frequencies, the carrier frequency r,
, r, and the same resonant frequency f1″, f, are expressed as f,=
If it is 2f, then f + =20Kflz, f
Set z = 40KHz.

With this setting, when the transmitter sends an infrared transmission signal with a carrier frequency f1 as shown in A in FIG. A current flows and is applied to the amplifier circuit 4. Since the resonant element 12 has resonance characteristics with respect to the carrier frequency f1, the signal of the carrier frequency f1 is selected by the amplifier circuit 4, applied to the transmitter and level shift circuit 14, and subjected to predetermined signal processing. Thereafter, the signal is detected by the detection circuit 16, subjected to waveform shaping by the waveform shaping circuit 18, and then taken out from the output terminal 20.

Further, B in FIG. 3 indicates the carrier frequency f on the transmitter side.

This shows an infrared transmission signal obtained by dividing the transmission signal by two. When this infrared transmission signal is received by the light receiving element 10 and the received light current is applied to the amplifier circuit 4, the resonant element 12
has a resonance characteristic of the carrier frequency f2, so the amplifier circuit 4 selects a signal of 2 at the carrier frequency. The output of this amplifier circuit 4 is applied to a limiter and level shift circuit 14, and a desired signal is extracted from an output terminal 20 through similar processing.

In this case, since the carrier frequencies f, , f2 are set to fz =2f+, different carrier frequencies can be set on the transmitting side simply by installing a frequency divider. Therefore, in a transmitter that can transmit control signals in multiple (m) modes using a certain carrier frequency, one or more frequency dividers may be installed to transmit control signals in 2m mode or multiple mode.
By correspondingly setting a plurality of resonance frequencies in the resonance element 12, it is possible to select and discriminate control signals of multiple modes using a single tuning system and a simple configuration.

FIG. 4 shows a specific embodiment of the infrared remote control receiving circuit of the present invention, and the same parts as in the embodiment shown in FIG. 1 are given the same reference numerals.

In FIG. 4, the amplifier circuit 4 is composed of a transistor 21 with an emitter installed, and the resonant element 12 installed as a load of the amplifier circuit 4 includes an inductor 22a and a capacitor that have resonance characteristics with respect to the carrier frequency f1. 24
a parallel resonant circuit consisting of an inductor 22b and a capacitor 24b that have resonance characteristics with respect to the carrier frequency "2".
It consists of a parallel resonant circuit consisting of:

The resonant element 12 may be configured as a single element formed by serially connecting a plurality of parallel resonant circuits each having a unique resonant frequency, or as a resonant circuit in which such parallel resonant circuits are arbitrarily installed.

With this configuration, each of the carrier frequencies f, , fz can be efficiently selected and discriminated.

As described in detail, according to the present invention, a single tuning system can discriminate between transmission signals of two or more different carrier frequencies, and control signals of many modes can be selected. The operation control section of the device can be made smaller and lighter.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the infrared remote control receiving circuit of the present invention, FIG. 2 is an explanatory diagram showing the resonance characteristics of a resonant element, FIG. 3 is an explanatory diagram showing a transmission signal, and FIG. FIG. 2 is a circuit diagram showing a specific embodiment of the infrared remote control receiving circuit of the invention. 4... Amplification circuit, 10... Infrared light receiving element, 12.
...Resonant element.

Claims (2)

[Claims] (1) An infrared receiving element that receives transmitted infrared rays of two or more carrier frequencies, and a resonant element having resonance characteristics of frequencies corresponding to the two or more carrier frequencies are installed as loads and receive signals from the infrared receiving element. An infrared remote control receiving circuit comprising an amplifier circuit that amplifies and extracts each carrier frequency. (2) The infrared remote control receiving circuit according to claim 1, wherein the resonant element is constructed by connecting two or more parallel resonant circuits of an inductor and a capacitor in series.