JPH0983443A - Automatic transmission output controller for infrared ray transmitter-receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To send a signal with a proper transmission output in response to a distance with an opposite party transmitter-receiver. SOLUTION: An output of an AGC circuit 20 adjusting a gain of a preamplifier 16 and an output of a notch filter 28 to detect the magnitude of received noise are added by an adder 32 and the sum is given to a peak hold circuit 34. When the communication opposite party is resident at a remote location, the output of the peak hold circuit 34 is increased and when resident at a near location, the output of the peak hold circuit 34 is decreased. The output of the peak hold circuit 34 is given to a transmission drive circuit 22 to control a drive current of a light emitting section 24 depending on the output of the peak hold circuit 34.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an infrared transmitter / receiver,
In particular, the present invention relates to an automatic transmission output control device for controlling the transmission output of an infrared transceiver used for a communication port of a computer.

[0002]

2. Description of the Related Art Conventionally, there has been proposed an infrared transmitter / receiver which is used for a port of a computer or the like and performs data communication using infrared rays. FIG. 5 is a block diagram showing the configuration of a conventional infrared transceiver.

In the infrared transceiver 10 shown in FIG. 5, the infrared ray 14 is received by the light receiving section 12, and the light receiving section 1 is received.
The output of 2 is amplified by the preamplifier 16 and input to the bandpass filter (BPF) 18. The BPF 18 takes out only the received signal, demodulates the received signal, and takes out predetermined data. The AGC circuit 20 is connected to the output side of the preamplifier 16,
The gain of the preamplifier 16 is adjusted so that the output of the above-mentioned is at a constant level.

In the infrared transmitter / receiver 10, the transmission drive circuit 22 drives the light emitting section 24 based on the signal modulated by the predetermined data, and the infrared ray 26 for transmitting the predetermined data is emitted. .

The above infrared transmitter / receiver 10 performs infrared communication with the partner transmitter / receiver at various distances within the range of the maximum communicable distance. Normal communication is performed at a distance considerably shorter than the maximum communicable distance,
In this case, as described above, since the sensitivity of the receiving section is appropriately adjusted by the AGC circuit 20, it is expected that the received signal is always demodulated at an appropriate level and the noise resistance is improved. You can

[0006]

However, since no adjustment is made to the transmission output from the transmitter, the transmission is always performed with a constant output. For this reason, there is a problem in that energy for transmission is wastefully consumed particularly in communication with a partner at a short distance.

Further, there is also a problem that if high-power light is received at an excessively short distance, the light may be saturated and accurate reception may not be possible.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide an infrared transmitter / receiver capable of transmitting a signal with an appropriate transmission output according to the distance from the transmitter / receiver of the other party. An object is to provide an automatic transmission output control device.

[0009]

In order to achieve the above object, the invention according to claim 1 has an automatic transmission output control of an infrared transmitter / receiver which has a receiver and a transmitter and communicates within a predetermined distance. An apparatus, comprising: a reception level determination unit that determines a reception signal level in the reception unit; and a transmission output control unit that controls the transmission output from the transmission unit according to the output of the reception level determination unit. And

According to a second aspect of the present invention, in the automatic transmission output control device for an infrared transceiver according to the first aspect, the reception level determination section adjusts the reception sensitivity of the reception section.
C circuit, a notch filter for detecting noise components other than the received signal, an adder for adding the output of the AGC circuit and the output of the notch filter, a peak value of the output of the adder is held, and a predetermined attenuation is performed. A peak hold circuit that outputs while attenuating at a rate, wherein the transmission output control unit includes a transmission drive circuit that controls the transmission output from the transmission unit in proportion to the output of the peak hold circuit. To do.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an infrared transceiver 1 according to the present invention.
The 0 configuration is shown as a block diagram. In FIG.
The output of the light receiving unit 12 that receives the infrared light 14 is the preamplifier 1
6 is amplified by the AGC circuit 20, and the gain of the preamplifier 16 is demodulated by the demodulator through the BPF 18.
The configuration adjusted by is similar to the above-mentioned conventional example. Here, the light receiving unit 12, the preamplifier 16, and the BPF 1 described above are provided.
8. The AGC circuit 20 constitutes a receiver according to the present invention.

The structure in which the transmission drive circuit 22 drives the light emitting section 24 based on the modulated data signal and outputs the infrared ray 26 as a predetermined data signal is also similar to the above-mentioned conventional example. Here, the transmission drive circuit 22 and the light emitting unit 24 constitute a transmission unit according to the present invention.

A feature of the present invention is that the transmission output of infrared rays as a transmission signal output from the transmission unit is controlled according to the reception signal level in the reception unit.

In FIG. 1, the AGC circuit 20 feeds back its output to the preamplifier 16 so that the output of the preamplifier 16 becomes constant. Therefore, when the communication partner is distant and the communication distance is long, the light receiving unit 1
Since the intensity of the infrared ray 14 received by 2 is weak and it is necessary to increase the gain of the preamplifier 16, the output of the AGC circuit 20 becomes large. On the other hand, when the receiving party is in a short distance, on the contrary, the gain of the preamplifier 26 may be small, so that the output of the AGC circuit 20 is small. As described above, it is possible to determine the distance between the communication partner and the distance from the magnitude of the output of the AGC circuit 20.

Further, in FIG. 1, a notch filter 28 is connected in parallel with the BPF 18 on the output side of the preamplifier 16. FIG. 2 shows the filter characteristics of the BPF 18 and the notch filter 28. As shown in FIG. 2, the filter characteristic of the notch filter 28 is paired with the filter characteristic of the BPF 18, and the BPF 18 passes the received signal, whereas the notch filter 28 passes the noise component other than the received signal. It is configured to let.

When the other party of communication is at a long distance, the received noise component increases and the output of the notch filter 28 increases. On the contrary, when the communication partner is in a short distance, the output of the notch filter 28 is small because the noise component is small. From the above, the notch filter 2
Also from the output of 8, it is possible to determine the distance to the communication partner. Since the output of the notch filter 28 is an alternating current (AC) signal, it is converted to direct current (DC) by the rectifying means 30 such as a diode.

As described above, it is possible to determine the distance to the other party of communication from the outputs of the AGC circuit 20 and the notch filter 28.
The output from the peak hold circuit 34, which is obtained by adding 2 and inputting the output to the peak hold circuit 34, is a signal for determining the reception signal level of the infrared transceiver 10. That is, when the output from the peak hold circuit 34 is small, it means that the distance from the other party is short and the signal level received by the infrared transceiver 10 is high.
When the output is large, it means that the distance to the other party is large and the signal level received by the infrared transceiver 10 is low.

The peak hold circuit 34 has a structure as shown in FIG. 3, for example. In FIG. 3, the peak value of the signal input to the peak hold circuit 34 is stored in the capacitor 38 via the diode 36 as electric charge corresponding to the peak value voltage. The electric charge stored in the capacitor 38 is discharged through the resistor 40, and the voltage thereof is gradually attenuated. This decay rate is
8 and the resistance value of the resistor 40. next,
When the peak value of the input signal becomes higher than the voltage across the capacitor 38, the voltage of the capacitor 38 is charged to the peak value voltage. As described above, the peak hold circuit 34 holds the peak value voltage of the input signal and outputs it while attenuating it at a predetermined attenuation rate.

The AGC circuit 20, the notch filter 28, the diode 36, the adder 32, and the peak hold circuit 34 described above constitute a reception level determination unit according to the present invention.

In the reception level determination section described above, the AGC circuit 20 and the notch filter 28 are used as means for determining the reception signal level in the reception section, but either one of them is used. The received signal level may be determined by. At that time, the peak hold circuit 34 is directly input from either one, and it is not necessary to use the adder 32.

The output of the peak hold circuit 34 is input to the transmission drive circuit 22. Transmission drive circuit 22
Has a circuit configuration as shown in FIG. 4, for example. In FIG. 4, the output of the peak hold circuit 34 is
It is input to the gate of the first FET 42. As a result, depending on the magnitude of the output of the peak hold circuit 34, the first FE
The current between the source and drain of T42 is controlled.

That is, when an N-channel FET is used as the first FET 42, the source-drain current increases when the output of the peak hold circuit 34 increases, and the source-drain current decreases when the output decreases.
As a result, the current supplied to the light emitting unit 24 is controlled, and the drive current of the light emitting unit 24 is determined in proportion to the output of the peak hold circuit 34 which is the output of the reception level determination unit.

The second FET 44 of the transmission drive circuit 22 is connected to the downstream side of the light emitting section 24.
A signal modulated by the data to be transmitted is input to the gate of the FET 44 of. Therefore, the second FE
Depending on the gate input signal of T44, the light emitting section 24 is turned on and off.
The FF is controlled and infrared rays are output as a predetermined transmission signal. The transmission drive circuit 22 configured as described above
Constitute a transmission output control unit according to the present invention.

[0025]

As described above, according to the present invention,
Since the transmission output of the transmission unit is controlled based on the reception signal level in the reception unit, it is possible to drive the light emitting unit with an appropriate transmission output according to the distance to the communication partner. As a result, it is possible to prevent wasteful consumption of energy for transmission.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an automatic transmission output control device for an infrared transceiver according to the present invention.

FIG. 2 is a diagram showing filter characteristics of a BPF and a notch filter.

FIG. 3 is a circuit diagram showing a configuration example of a peak hold circuit of the embodiment shown in FIG.

FIG. 4 is a circuit diagram showing a configuration example of a transmission drive circuit of the embodiment shown in FIG.

FIG. 5 is a block diagram showing the configuration of a conventional infrared transceiver.

[Explanation of symbols]

10 infrared transmitter / receiver, 12 light receiving part, 14, 26 infrared, 16 preamplifier, 18 BPF, 20 AGC
Circuit, 22 Transmission drive circuit, 24 Light emitting part, 28
Notch filter, 30 rectifying means, 32 adder, 34
Peak hold circuit, 36 diode, 38 capacitor, 40 resistance, 42 1st FET, 44 2nd
FET.

Claims (2)

[Claims] 1. An automatic transmission output control device for an infrared transmitter / receiver, which has a receiving section and a transmitting section and communicates within a predetermined distance, and a receiving level determining section for determining a received signal level in the receiving section. An automatic transmission output control device for an infrared transceiver, comprising: a transmission output control unit that controls a transmission output from a transmission unit according to an output of the reception level determination unit. 2. The automatic transmission output control device for an infrared transmitter / receiver according to claim 1, wherein the reception level determination unit adjusts the reception sensitivity of the reception unit, and a notch for detecting a noise component other than the reception signal. A filter; an adder that adds the output of the AGC circuit and the output of the notch filter; and a peak hold circuit that holds the peak value of the output of the adder and outputs the value while attenuating it at a predetermined attenuation rate. An automatic transmission output control device for an infrared transceiver, wherein the transmission output control unit includes a transmission drive circuit that controls the transmission output from the transmission unit in proportion to the output of the peak hold circuit.