JPH0923190A - Infrared-ray communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the demodulation of an abnormal pulse signal and to demodulate and use only a correct pulse signal. SOLUTION: An infrared-ray signal from an opposite device which is not shown is received by a light receiving element 2 and converted into an electric signal, which is amplified by an amplifier circuit 3, shaped to a prescribed level pulse signal by a waveform shaping part 4 and inputted to a demodulation part 5 and a counter 10. The counter 10 starts counting, and when its count value is more than a 1st prescribed value and less than a 2nd prescribed value larger than the 1st prescribed value, judges the pulse signal as a normal pulse signal and data demodulated by the demodulation part 5 are stored in a control part 6. The other pulse signal is judged as an abnormal signal, the data demodulated by the demodulation part 5 are canceled and a resending request signal is transmitted to the opposite device through a modulation part 7, a driving circuit 8 and a light emitting element 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared communication device that wirelessly communicates using infrared rays.

[0002]

2. Description of the Related Art Conventionally, a wireless communication device for spatially transmitting information by radio waves has been generally known, but recently, a wireless communication device using infrared rays has appeared. In this infrared communication device, appropriate modulation is applied to transmit information as infrared rays, and in particular, a pulse modulation method, in which a modulation / demodulation circuit can be realized by a logic circuit at a relatively low cost, is receiving attention.

This pulse modulation system is a system in which data to be transmitted is converted into a short pulse signal according to a predetermined rule, and the pulse signal received by the receiver is restored to the original data. For example, as shown in FIG. , (A) transmit data is modulated into a pulse signal according to a prescribed rule to obtain a pulse modulated signal of (b), and this pulse modulated signal of (b) is received and demodulated according to a prescribed rule, and (c) This is the received data.

Here, the predetermined rule means, for example, that the modulation side is for 1 bit of the signal which is "1" in the transmission data,
One pulse signal having a predetermined time width is transmitted. Then, when the receiving side receives the pulse signal, it sets 1 bit to “1” according to the predetermined bit rate, and when receiving the pulse signal again, it similarly sets the next 1 bit to “1” and the pulse If no signal is received, it is set to "0".

[0005]

However, in the above-mentioned conventional example, as shown by the broken line in FIG. 10 (d), if pulse-like noise occurs due to external noise from a fluorescent lamp or other factors, reception It becomes impossible to distinguish from the pulse that should be made, and the signal that should originally be set to "0" is "1".
However, there is a disadvantage that the demodulated (e) data becomes an erroneous data different from the transmitted data of (a).

An object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide an infrared communication device which prevents abnormal pulse signal demodulation and demodulates and uses only correct pulse signals.

[0007]

An infrared communication device according to the present invention for achieving the above object comprises a converting means for converting transmission data into a pulse signal having a predetermined pulse width, and the pulse signal being converted into infrared rays. Light emitting means for converting and sending to space, light receiving means for receiving infrared rays from the space and converting into an electric signal, amplifying means for amplifying the electric signal, and pulse signal amplified by the amplifying means in a predetermined data format In an infrared communication device having a restoring means for restoring to, a measuring means for measuring a pulse width of a received pulse signal from the amplifying means, and a measurement result by the measuring means are determined to be equal to or longer than a first predetermined time. A first determining means for determining and a second determining means for determining whether or not the measurement result is equal to or shorter than a second predetermined time longer than the first predetermined time are provided. .

The infrared communication device having the above-mentioned structure receives the infrared light transmitted through the space from the other device, converts it into an electric signal into a pulse signal, measures the pulse width of this pulse signal, and measures the pulse width. Is equal to or longer than a first predetermined time, and further is equal to or shorter than a second predetermined time longer than the first predetermined time, and only normal pulse signals falling within the predetermined range are demodulated. It is used and the other abnormal pulse signals are not used for demodulation.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS. FIG. 1 shows a block circuit configuration diagram of an infrared communication device according to a first embodiment. In the infrared communication device 1, photoelectric conversion for receiving infrared light spatially transmitted from a partner device (not shown) and converting it into an electric signal. Light-receiving element 2 having a function, such as a PIN photodiode
Is provided, and the output of the light-receiving element 2 is an amplifier circuit 3 for amplifying the converted electric signal, and the waveform of the pulse signal is shaped so that the output signal of the amplifier circuit 3 is adapted to a predetermined level signal such as TTL level or CMOS level. A waveform shaping section 4, a demodulation section 5 that demodulates the pulse signal output from the waveform shaping section 4 into a desired data format, for example, an NRZ signal according to a predetermined rule, and data that is received and transmitted to a partner device. The control unit 6 that outputs the NRZ signal is sequentially connected.

The output of the control unit 6 is a modulation unit 7 which modulates the transmission data into a pulse signal having a predetermined pulse width according to a predetermined rule, and a drive which generates a current for sending infrared rays according to the modulated signal. The circuit 8 is sequentially connected to a light emitting element 9 such as an infrared LED that emits infrared rays according to the output current of the drive circuit 8. Also,
A part of the output of the waveform shaping section 4 is connected to the counter 10 for measuring the pulse width of the pulse signal and the control section 6, and the output of the counter 10 is connected to the control section 6.

FIG. 2 shows a circuit diagram of the counter 10.
It is composed of a clock generation circuit 11 and a general-purpose IC counter 12. For example, when the output signal of the waveform shaping section 4 changes from a low level to a high level, the counter 10 starts counting with a clock sufficiently fast with respect to a predetermined pulse width, and while the output signal of the waveform shaping section 4 is at a high level. Repeats counting with a clock, and stops counting when the output signal of the waveform shaping section 4 changes from high level to low level.

FIG. 3 is a flow chart showing that the partner device is also composed of the same block circuit as in FIG. 1, and the predetermined pulse width is 1 μS and the clock frequency is 10 M.
Hz.

Before the measurement is started, the control unit 6 first clears the counter 10 (S1). The pulse-modulated infrared light radiated from the other device (not shown) is received by the light receiving element 2, converted into an electric signal, and sufficiently amplified by the amplifier circuit 3, and then converted into a pulse signal of a desired level by the waveform shaping section 4. When shaped (S2), that is, when the EN signal shown in FIG. 4 changes from low level to high level, the counter 10 starts counting (S3). The pulse signal is input to the EN terminal of the counter 10 as well as to the demodulation unit 5, and is demodulated by the demodulation unit 5 from the pulse signal to data, for example, an NRZ signal according to a predetermined method (S4).

As shown in FIG. 4, the counter 10 continues counting while the EN signal is at a high level, and when the EN signal changes from a high level to a low level, that is, when reception of one pulse signal is completed (S5). The counter 10 stops counting (S
6), the control unit 6 knows the change of the EN signal from the high level to the low level by interruption or the like, and reads the count values (QA, QB, QC, QD) of the counter 10 (S7, S8). If the count value is equal to or larger than the first predetermined value and equal to or smaller than the second predetermined value that is larger than the first predetermined value, the control unit 6 determines that this pulse signal is normal and is demodulated by the demodulation unit 5. The stored data is stored (S9) and the counter 10 is cleared to prepare for the subsequent signal reception.

On the other hand, when the count value is less than the first predetermined value (S7) or exceeds the second predetermined value (S8),
The control unit 6 determines that this pulse signal is a noise or an abnormal signal, discards the data demodulated by the demodulation unit 5 (S10), and at the same time sends it to the other device through the modulation unit 7, the drive circuit 8, and the light emitting element 9. A predetermined retransmission request signal is transmitted (S11).

In the embodiment shown in FIG. 4, the counter 1
The count value by 0 is “9”, and the pulse width of the received pulse signal is 900 nS. Actually EN signal and CL
Since it is asynchronous with the K signal, it has a value between 800 and 1000 nS. Here, for example, if the first predetermined value is programmed to "8" and the second predetermined value is programmed to "12" in the control unit 6,
A pulse width of 800 nS or more and 1.2 μS or less is judged to be normal, and a pulse width of less than 800 nS or more than 1.2 μS is judged to be abnormal.

FIG. 5 is a block circuit configuration diagram of an infrared communication device of the second embodiment, and the same reference numerals as those in FIG. 1 indicate members having the same functions. In the infrared communication device 1 ′, the output of the counter 10 includes a first comparator 13 that determines whether the count value is equal to or more than a first predetermined value, and a second comparator 13 that has a count value larger than the first predetermined value. These comparators 1 are connected to a second comparator 14 that determines whether the value is a predetermined value or less.
The outputs of 3 and 14 are connected to the control unit 6. FIG. 6 shows a circuit configuration diagram of the counter 10, the first comparator 13, and the second comparator 14. The counter 10 is a circuit similar to that of FIG. 2, and the first comparator 13 and the second comparator 14 are provided. General purpose 14
A C comparator is used.

FIG. 7 shows a flow chart, and in the first embodiment, the control unit determines whether the count value of the counter 10 is greater than or equal to the first predetermined value and less than or equal to the second predetermined value. 6 makes a judgment by directly reading the count value, but in the present embodiment, the judgment by the hardware of the two comparators 13 and 14 reduces the load on the software of the control unit 6.

As shown in FIG. 6, the first comparator 13 has a P
= 8 (PD = 1, PC = 0, PB = 0, PA = 0) and the count value Q of the counter 10 is less than P = 8, a high-level signal from the P> Q terminal, that is, a logic When "1" is output and the count value Q is P = 8 or more, a low level signal, that is, a logic "0" is output. Similarly, the second comparator 14 has P = 12 (PD = 1, PC = 1, PB = 0, PA
= 0) and the count value Q of the counter 10 is P
= 12 or less, a low-level signal is output from the P <Q terminal, and when the count value Q exceeds P = 12, a high-level signal is output from the P <Q terminal.

Therefore, the control unit 6 uses the general-purpose IC counter 12
It is not necessary to read the count value of the counter 10 when the EN terminal input signal of the signal changes from the high level to the low level, and only the output signals of the first comparator 13 and the second comparator 14 are seen, and both are If the level is low (S26, S27),
It can be seen that the count value is not less than the first predetermined value and not more than the second predetermined value, that is, not less than “8” and not more than “12”.

On the other hand, if the output signal of the first comparator 13 is at high level (S26), the count value is the first predetermined value "8".
If the output signal of the second comparator 14 is at a high level (S27), it can be seen that the count value exceeds the second predetermined value "12". That is, according to the present embodiment, the control unit 6 checks the levels of the two signals so that the received pulse width is equal to or larger than the first predetermined value 800 nS
It is possible to easily determine whether or not the predetermined value of 1.2 μS or less.

FIG. 8 is a block diagram of the third embodiment.
The outputs of the comparator 13 and the second comparator 14 are OR gate 1
5 and is configured to input the logical sum of the P> Q output signal of the first comparator 13 and the P <Q output signal of the second comparator 14 to the demodulation unit 5 ′. Then, the demodulation unit 5 ′ has the function of the demodulation unit 5 of the first and second embodiments, and OR
Based on the output signal of the gate 15, the pulse signal from the waveform shaping unit 4 is determined, for example, by setting a bit "1" or ignoring the pulse signal, and a signal for clearing the counter 10 after the determination. The function to output is added. Therefore, the load of the control unit 6 can be further reduced by the second embodiment.

FIG. 9 shows a flow chart diagram, 800n.
The pulse signal having a pulse width of S or more and 1.2 μS or less is used for demodulation only when the demodulation unit 17 receives the pulse signal,
Since a pulse signal having a pulse width of less than 800 nS or more than 1.2 μS is ignored by the demodulation unit 5 ′, demodulation is performed only by the normally received pulse signal.

As described above, if the pulse width of the received pulse signal is equal to or longer than the first predetermined time and equal to or shorter than the second predetermined time longer than the first predetermined time, the pulse signal is normally received. Can be judged. On the other hand, when the pulse width of the received pulse signal is less than the first predetermined time or exceeds the second predetermined time, it can be determined that the received pulse signal is a signal due to noise or other abnormality.
Therefore, it is possible to use only the pulse signal determined to be normally received for demodulation, ignore the pulse signal determined to be abnormal and not use it for demodulation.
The reliability of the demodulated data is further improved.

Further, since the pulse width measuring circuit can be realized by a general-purpose logic circuit, it becomes a simple and inexpensive measuring circuit, and the faster the clock signal, the more the number of bits of the counter 10 increases.
More precise discrimination is possible. Furthermore, when a pulse signal with an abnormal pulse width is received, the partner device can be prompted to retransmit, and the reliability of mutual communication is also improved.

[0026]

As described above, since the infrared communication apparatus according to the present invention can discriminate the normally received pulse signal based on the pulse width of the received pulse signal, only the correct pulse signal is demodulated and the abnormal pulse signal is detected. Since the signal can be ignored and not demodulated, the reliability of the data is improved and efficient and highly accurate communication becomes possible.

[Brief description of drawings]

FIG. 1 is a block circuit configuration diagram of a first embodiment.

FIG. 2 is a flowchart.

FIG. 3 is a circuit configuration diagram of a counter.

FIG. 4 is a timing chart.

FIG. 5 is a block circuit configuration diagram of a second embodiment.

FIG. 6 is a circuit configuration diagram of a counter and a comparator.

FIG. 7 is a flowchart.

FIG. 8 is a block circuit configuration diagram of a third embodiment.

FIG. 9 is a flowchart.

FIG. 10 is a timing chart of a conventional example.

[Explanation of symbols]

 1, 1'infrared communication device 2 light receiving element 4 waveform shaping section 5, 5'demodulation section 6 control section 9 light emitting element 10 counter 13, 14 comparator 15 OR gate

Claims (3)

[Claims] 1. A conversion means for converting transmission data into a pulse signal having a predetermined pulse width, a light emitting means for converting the pulse signal into infrared rays and transmitting the infrared rays to a space, and an infrared ray received from the space into an electric signal. In an infrared communication device having a light receiving means for converting, an amplifying means for amplifying the electric signal, and a restoring means for restoring the pulse signal amplified by the amplifying means to a predetermined data format, a received pulse signal from the amplifying means Measuring means for measuring the pulse width of, a first judging means for judging whether or not the measurement result by the measuring means is equal to or longer than a first predetermined time, and the measurement result is longer than the first predetermined time. An infrared communication device, comprising: a second determination means for determining whether or not the second predetermined time is long or less. 2. The counting means counts with a clock signal having a cycle sufficiently shorter than a predetermined pulse width.
Infrared communication device according to. 3. The first determining means determines that the pulse width of the received pulse signal is less than the first predetermined time, or the second determining means determines the second width.
The infrared communication device according to claim 1 or 2, which transmits a retransmission request signal when it is determined that the predetermined time has been exceeded.