JPH05122778A - Receiver for remote control system - Google Patents

Abstract

PURPOSE:To decrease the cost of the receiver by discriminating a dead battery from the pulse width of a rectangular pulse signal. CONSTITUTION:A high frequency voltage signal from a photoelectric conversion means 1 is demodulated to a pulse signal by a demodulator 2, the pulse signal from the demodulator 2 is waveform-shaped to a rectangular pulse signal by a means 3. A pulse width of the signal from the means 3 is operated by an arithmetic means 5. A dead battery judging means 6 judges whether or not this operated pulse width is narrower than the regular width. When it is judged to be narrower, a detection signal indicating a dead battery of a sender is sent to an alarm means 7 from which an alarm is sounded. Thus, the increase of the cost of the device can be prevented without providing the battery voltage measuring function and the dead battery detection function on the sender.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiver in a wireless remote control system.

[0002]

2. Description of the Related Art A wireless remote control system includes a transmitter for outputting an infrared signal and a receiver for converting the infrared signal into an electric signal for decoding and controlling a control target. Immediately before the battery of the transmitter reaches the end of its life, the output of the infrared signal becomes unstable, and if the control target is controlled based on this, it may cause malfunction or failure of the control target.

Therefore, in the wireless remote control system disclosed in Japanese Utility Model Laid-Open No. 58-76992, a comparison circuit which compares the battery voltage of the transmitter with a reference voltage and outputs a dead battery detection signal when the voltage is lower than the reference voltage. Is equipped on the transmitter. The dead battery detection signal of the comparison circuit is output to the receiving device as an infrared signal, and an alarm is displayed on the display unit of the receiving device.

Further, in the wireless remote control system disclosed in Japanese Patent Application Laid-Open No. 62-41552, a transmitter is equipped with a microcomputer and an AD converter. The battery voltage of the transmitter is input to the microcomputer via the AD converter, and the battery voltage is constantly monitored by the microcomputer. Then, when the microcomputer detects a decrease in the battery voltage, a detection signal is output, and an alarm is displayed on the display unit of the transmitting device in response to the detection signal.

[0005]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention Saikai 58-76
In the remote control system of Japanese Patent No. 992, since the transmitter is equipped with the comparison circuit, the cost is increased.
Also in the remote control system of Japanese Patent Laid-Open No. 62-41552, the cost is increased because the transmitter is equipped with the AD converter and the microcomputer for voltage monitoring.

[0006]

The receiver of the remote control system of the present invention is shown in FIG. That is, this receiving device, like a general receiving device, receives the high-frequency optical signal output from the transmitting device and converts it into a voltage signal, and the high-frequency optical signal from this photoelectric conversion device 1. Demodulating means 2 for demodulating a voltage signal into a pulse signal, waveform shaping means 3 for shaping the pulse signal from the demodulating means 2 into a rectangular pulse signal, and decoding and controlling the rectangular pulse signal from the waveform shaping means 3. And a decoding means 4 for outputting a control signal to the object E.

The receiving apparatus of the present invention further comprises a pulse width calculating means 5, a battery dead judging means 6, and an alarm means 7. The pulse width calculating means 5 is the waveform shaping means 3 described above.
The pulse width of the rectangular pulse signal from is calculated. The dead battery judging means 6 judges whether or not the pulse width calculated by the pulse width calculating means 5 is shorter than the regular pulse width, and when it is judged that the pulse width is shorter, a detection signal indicating that the battery of the transmitter is dead. Is output. The alarm means 7 issues an alarm in response to the battery dead detection signal from the battery dead determination means.

[0008]

In the receiving device of the present invention, the battery of the transmitting device is judged to be dead based on the pulse width of the rectangular pulse signal from the waveform shaping means, and an alarm is issued. Therefore, in the transmitter,
Since it is not necessary to provide the battery voltage measuring function and the dead battery detecting function, it is possible to prevent the cost of the transmitter from increasing.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 2, the remote control system includes a transmitter 10 and a receiver 20.

The transmitting device 10 has a resistor 11, a light emitting diode 12 and a transistor 13 which are connected in series to a battery V, a switch operating portion 14 and an IC1.
5 (signal generation control element). IC15 is
The transistor 13 is controlled on the basis of a switch signal from the switch operating section 14 to cause the light emitting diode 12 to output an infrared signal. This infrared signal has a time width T ₁ = 1.28 msec or a time width T ₂ = 0.42 mse 12 times in a constant cycle (T ₀ = 1.68 msec).
A high frequency (38 KHz) pulse is output by c. The infrared signal can represent the control information corresponding to the switch signal by the combination of the time widths T ₁ and T ₂ .

Next, the receiver 20 will be described in detail. The receiving device 20 includes a light receiving diode 21 (photoelectric conversion means). The light receiving diode 21 converts a high frequency infrared signal from the light emitting diode 12 of the transmitter 10 into a high frequency voltage signal. This voltage signal is sent to the amplification circuit 22 and amplified. A bias controller 23 is connected to the amplifier circuit 22. The bias controller 22 adjusts the amplification factor according to the level of the voltage signal from the light-receiving diode 21 to bring the level of the voltage signal to an appropriate level. The ideal voltage signal from the amplifier circuit 22 is shown in FIG.

The high frequency voltage signal from the amplifier circuit 22 is sent to a band pass filter 24 to remove noise and then sent to a demodulation circuit 25 (demodulation means) where it is converted into a pulse signal. Figure 3 shows the ideal pulse signal
As shown in (B), in reality, this pulse signal is distorted. This pulse signal has a pulse width substantially equal to the time widths T ₁ and T ₂ .

The pulse signal from the demodulation circuit 25 is waveform-shaped by the waveform shaping circuit 26 (waveform shaping means), as shown in FIG.
A rectangular pulse signal as shown in (C) is obtained. That is,
In the waveform shaping circuit 26, as shown in FIG. 3 (B), the threshold level L is compared with the pulse signal from the demodulation circuit 25, and when the level of the pulse signal is higher than the threshold level L, the output becomes a high level, When it is lower than the level L, the output is low level. As a result, a rectangular pulse signal is obtained. As will be described later, when the life of the battery V of the transmission device 10 is sufficiently left, the pulse width of this rectangular pulse signal is T ₁ , T ₂
Should be either.

The rectangular pulse signal from the waveform shaping circuit 26 is sent to the microcomputer 27 and controls the controlled object E based on the decoding result here. That is, the pulse widths of the 12 rectangular pulse signals from the 1st to the 12th that are output in a constant cycle are detected, and the switch operation unit 14 of the transmitter 10 operates from the combination of the pulse widths T ₁ and T _2. The control object E is controlled by decoding the control information instructed by.

Next, the function of detecting the expiration of the battery V of the transmitter 10 will be described. When the life of the battery V is sufficiently left, the amount of infrared light output from the light emitting diode 12 is constant, and the level of the voltage signal from the amplifier circuit 22 is also constant as shown in FIG. .. Therefore, the level of the pulse signal from the demodulation circuit 25 is
As shown in FIG. 3B, the threshold level L is exceeded over the entire pulse width, so that the pulse width of the rectangular pulse signal from the waveform shaping circuit 26 becomes smaller than that in FIG.
As shown in (C), it almost coincides with either T ₁ or T ₂ .

When the life of the battery V is exhausted, the light quantity of the infrared signal gradually decreases. The method of this reduction will be described in detail. In the first time width (T ₁ or T ₂ ), the amount of infrared light gradually decreases. The initial amount of infrared light in the second time width is larger than that in the last time in the first time width. This is because the infrared output is stopped between the first time width and the second time width, and the battery V is recovered during that time.
However, the amount of infrared light at the beginning of the second time width is smaller than that at the beginning of the first time width. This is because the recovery period of the battery V is not sufficient because the infrared output stop period is short. Even in the second time width, the amount of infrared light gradually decreases, and the amount of infrared light at the end is smaller than that at the end of the first time width. In this way, the amount of infrared light decreases.

As the amount of infrared light decreases, the voltage signal level from the amplifier circuit 22 also gradually decreases, as shown in FIG. The adjustment of the amplification factor by the bias control 23 connected to the amplification circuit 22 cannot sufficiently compensate for this gradual decrease phenomenon. As a result, the pulse signal from the demodulation circuit 25 has a pulse width almost equal to the time width T ₁ or T _{2 as} shown in FIG. Moreover, the lower the pulse output later, the lower the pulse. The relationship between the level of the preceding pulse and the level of the subsequent pulse is similar to the above discussion regarding the amount of infrared light, and therefore its explanation is omitted.

When the pulse signal from the demodulation circuit 25 is compared with the threshold level L in the waveform shaping circuit 26, as shown in FIGS. 4 (B) and 5, the level of a certain pulse reaches the threshold level in the middle of the pulse width. It will be lower than the level. Therefore, the rectangular pulse from the waveform shaping circuit 26 does not have the regular pulse widths T ₁ and T ₂ , but has a shorter pulse width. FIG. 4C shows a pulse having a pulse width T ₁ ′ shorter than the regular pulse width T ₁ .
The pulse shorter than the regular pulse width may be one of the 12 pulse groups or may be a plurality of pulses.

In the microcomputer 27, the pulse width of the rectangular pulse signal from the waveform shaping circuit 26 is constantly monitored, and when it is determined that the pulse width is shorter than the specific time widths T ₁ and T ₂ , the battery of the transmitter 10 is discharged. When it is determined that the life of V has expired, the display unit 28 (alarm means) is caused to display an alarm indicating that the battery has run out.

Next, a battery dead detection program executed by the microcomputer 27 will be described with reference to FIG. First, every time a pulse signal is input from the waveform shaping circuit 26, its pulse width T is calculated (step 100). Next, it is determined whether or not this pulse width T substantially matches the specific time width T ₁ (step 101). Strictly speaking, the allowable range α is taken into consideration to determine whether T ≧ T ₁ −α. When a negative determination is made in step 101, it is determined whether the pulse width T substantially matches the specific time width T ₂ (step 102). Strictly speaking, taking into account the tolerance range beta, it is determined whether T ₂ over _{β ≦ T ≦ T 2 + β} .
When a negative determination is made in step 102, an alarm is displayed because the battery has run out (step 103).

The present invention is not limited to the above-mentioned embodiment and various modes are possible. For example, the pulse widths of a plurality of pulse groups forming a rectangular pulse signal are equal to each other, their periods,
The pulse width may represent control information corresponding to the switch signal from the switch operation unit of the transmitting device. Further, in the rectangular pulse signal from the waveform shaping circuit, the pulse widths of the preceding pulse and the succeeding pulse may be compared, and when the succeeding pulse becomes short, it may be determined that the battery is dead. In this case, the pulse width of the preceding pulse is treated as a regular pulse width.

[0022]

According to the receiving apparatus of the present invention, the battery of the transmitter is judged to be dead and an alarm is issued based on the pulse width of the rectangular pulse signal from the waveform shaping means. It is not necessary to provide the battery dead detection function, and it is possible to prevent the cost of the transmitter from increasing.

[Brief description of drawings]

FIG. 1 is a block diagram showing an essential configuration of the present invention.

FIG. 2 is a block diagram showing a control system including a receiving device according to the present invention.

FIG. 3 (A) is an output of an amplified light receiving diode in a state where the battery life of the transmitter is sufficient.
FIG. 6B is a diagram showing the output of the demodulation circuit, and FIG. 7C is a diagram showing the output of the waveform shaping circuit.

FIG. 4A is an output of an amplified light receiving diode, and FIG. 4B is a state in which the battery life of the transmitter is exhausted.
FIG. 4C is a diagram showing the output of the demodulation circuit, and FIG. 7C is a diagram showing the output of the waveform shaping circuit.

FIG. 5 is an exaggerated view of a part of FIG.
It is a figure which clearly shows the relationship between the output of the demodulation circuit and the threshold level of the waveform shaping circuit.

FIG. 6 is a flowchart showing a program executed by the microcomputer of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Photoelectric conversion means 2 ... Demodulation means 3 ... Waveform shaping means 4 ... Decoding means 5 ... Pulse width calculation means 6 ... Battery exhaustion determination means 7 ... ) 25 ... Demodulation circuit (demodulation means) 26 ... Waveform shaping circuit (waveform shaping means) 27 ... Microcomputer 28 ... Display unit (alarm means) E ... Control target V ... Battery

Claims (1)

[Claims] 1. A photoelectric conversion means for receiving a high-frequency optical signal from a transmitter and converting it into a voltage signal; and (b) a high-frequency voltage signal from this photoelectric conversion means into a pulse signal. Demodulation means for demodulating, (c) waveform shaping means for shaping the pulse signal from this demodulation means into a rectangular pulse signal, and (d) decoding the rectangular pulse signal from the above waveform shaping means to provide a control signal to a control target. A receiving device in a remote control system, comprising a decoding means for outputting, further comprising the following configuration. (E) A pulse width calculating means for calculating the pulse width of the rectangular pulse signal from the waveform shaping means. (F) The pulse width calculated by the pulse width calculating means is
A battery dead determining means that determines whether the pulse width is shorter than the regular pulse width, and outputs a detection signal indicating that the battery of the transmitter is dead when it is determined that the pulse width is short. (G) Alarm means for issuing an alarm in response to the battery dead signal from the battery dead determination means.