JPH0349511Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention relates to a pulse insertion circuit, particularly for remote control transmission used to remotely control electronic equipment such as color television receivers and video tape recorders. The present invention relates to a pulse insertion circuit that is integrated into a machine and inserts another pulse into a pulse position modulated signal.

[Prior Art] A remote control transmitter used in a color television receiver or the like transmits a binary code signal consisting of a combination of logical 0s or 1s by pulse position modulation. It consists of a burst signal with a specific frequency. That is, for example, if the pulse interval of the pulse signal is 2m
sec, it is logic 0 and the pulse interval is 4m
sec is defined as logic 1, and a binary code signal combining such pulse intervals is transmitted by ultrasonic waves or light.

[Problems to be solved by the invention] By the way, in a typical home, not only a color television receiver but also audio equipment and an air conditioner are often installed in one room, and each room has its own dedicated A remote control transmitter and receiver are provided.
Each manufacturer independently distinguishes between these devices by changing the number of bits in the binary code, by providing bits to indicate the device code that specifies the device, or by changing the frequency that makes up the pulse. Malfunctions are unlikely to occur with equipment from the same manufacturer, but malfunctions may occur when equipment from different manufacturers are combined.

Usually, a bandpass filter is configured on the receiver side with a certain degree of selectivity to discriminate differences in the frequencies of the burst signals that make up the pulses. However, if the performance of the bandpass filter on the receiver side is poor, malfunctions may occur, such as audio equipment being operated by a signal transmitted by a transmitter for a color television receiver, for example.

On the other hand, in remote control receivers, the binary code is determined so that it does not operate when the binary code signal is a continuous signal of logic 0 or logic 1, so that it does not malfunction under light such as fluorescent lights. .

Therefore, the main purpose of this invention is to apply it to remote control transmitters and the like used near devices equipped with remote control receivers such as those mentioned above, and to operate not only the devices to be controlled but also bandpass filters. It is an object of the present invention to provide a pulse insertion circuit that does not cause malfunctions in non-controlled equipment whose performance is inferior.

[Means for Solving the Problems] This invention is a pulse insertion circuit that includes a pulse signal generating means for generating a pulse signal having a first frequency, a DC power source, and a pulse signal generating means that generates a pulse signal according to the output of the pulse signal generating means. a current source that flows current from a DC power supply;
A light emitting diode connected between a DC power supply and a current source, a capacitor connected in parallel to the light emitting diode, a resistor connected in parallel to the light emitting diode, and a connection point between the current source and the light emitting diode. a threshold voltage detection means that outputs a signal at a time delayed from the pulse signal when the voltage at the connection point exceeds a predetermined threshold voltage, and a signal output from the threshold voltage detection means. The apparatus includes a pulse signal inserting means for inserting a pulse having a second frequency between the pulse signal output from the pulse signal generating means and the pulse signal.

[Function] The pulse insertion circuit according to the invention causes a current to flow through a current source in response to a generated pulse signal to light up a light emitting diode, and also charges a capacitor connected in parallel to the light emitting diode, so that the pulse signal is When the charge is exhausted, the charge stored in the capacitor is discharged, and when this discharge voltage exceeds a predetermined threshold voltage, another pulse signal is generated and inserted at a position delayed by a predetermined time from the pulse signal. .

[Embodiments of the invention] This invention will be described in more detail below with reference to embodiments shown in the drawings.

FIG. 1 is a schematic block diagram of an embodiment of this invention, FIG. 2 is a specific electric circuit diagram of the current source 2 included in FIG. 1, and FIG. 3 is a threshold voltage detection circuit. 3 is a specific electrical circuit diagram of circuit 7. FIG.

First, the configuration of the pulse insertion circuit shown in FIG. 1 will be explained. The remote control signal generator 1 uses a pulse position modulation method to repeatedly generate a signal consisting of binary codes 0 and 1 as a pulse train at a constant period. A remote control signal output from the remote control signal generator 1 is given to a current source 2. The current source 2 is connected to the resistor 2 from the input terminal 21 as shown in FIG.
When a remote control signal is applied to the base of the transistor 23 via the current input terminal 24, the resistor 2
5 and transistor 23.
A light emitting diode 3 is connected between the current source 2 and the DC power source 6, and a capacitor 4 and a resistor 5 are connected in parallel to the light emitting diode 3, respectively.

The connection point between the light emitting diode 3 and the current source 2 (A
point) is connected to the threshold voltage detection circuit 7. The threshold voltage detection circuit 7 outputs a detection voltage when the voltage at point A exceeds a predetermined threshold voltage, and is constructed as shown in FIG. 3.
For example, threshold voltage detection circuit 7 includes resistors 72 and 75 and transistor 73. A detection voltage is applied to the base of a transistor 73 via a resistor 72, and a DC voltage is applied to an emitter of the transistor 73 via a power input terminal 74. The collector of transistor 73 is grounded via resistor 75 and connected to output terminal 76 .

The detection signal output from the output terminal 76 of the threshold voltage detection circuit 7 is given to the insertion signal generator 8. When the insertion signal generator 8 receives the threshold voltage detection output, it generates a pulse signal having a predetermined frequency for a predetermined time. The pulse signal generated by the insertion signal generator 8 is inserted into the pulse signal output from the remote control signal generator 1 and is applied to the transmitter 9.

FIG. 4 is a waveform diagram of each part shown in FIG. 1.

Next, the operation of one embodiment of this invention will be described with reference to FIGS. 1 to 4. In this example, the pulse width is 500 mm, as shown in FIG.
μsec, it is determined to be logical 0 when the pulse interval is 2 msec, and determined to be logical 1 when the pulse width is 500 μsec and the pulse interval is 4 msec. A 500 μsec pulse consists of a 50 μsec repetitive pulse. And remote control signal generator 1
A binary code signal 100100 of a pulse train consisting of a combination of logic 0s or 1s as described above is generated. This binary code signal is applied from the input terminal 21 of the current source 2 to the base of the transistor 23 via the resistor 22. Therefore, the transistor 23 allows a DC current to flow from the DC power supply 6 through the light emitting diode 3, the resistor 25, and the collector and emitter of the transistor 23. For this purpose, light emitting diode 3
lights up only for a period of 500μsec pulse width. At this time, the capacitor 4 is charged to the forward voltage V _F of the light emitting diode 3. When the output from the remote control signal generator 1 falls between pulses, the transistor 23 is cut off and the light emitting diode 3 is turned off.

At the same time, the charge stored in the capacitor 4 is discharged through the resistor 5, and the potential at point A gradually increases. A threshold voltage detection circuit 7 determines whether or not the potential at point A exceeds a predetermined threshold voltage. Here, the timing at which the threshold voltage detection circuit 7 detects that the voltage at point A exceeds the threshold voltage is approximately at the center of the pulse period representing logic 1.

Therefore, the threshold voltage detection circuit 7 has logic 0.
A voltage that becomes high level at the rising edge of the pulse representing the period of logic 1 and falls to low level approximately at the center of the logic 1 pulse period is output as a detection signal. The insertion signal generator 8 generates an insertion signal having a pulse width of, for example, 500 μsec at the timing when the threshold voltage detection signal falls to a low level.

This insertion signal has a pulse width of 500μsec and
It consists of a 25 μsec pulse signal, which is inserted into the remote control signal and given to the transmitter 9. The transmitter 9 transmits the remote control signal into which the insertion signal has been inserted using light or ultrasonic waves. The receiver receives the transmitted signal and removes the inserted signal to obtain a regular transmitted signal. On the other hand, in a device that is subject to malfunction, since it receives all the transmitted signals, a series of logical 0 signals occurs, so no malfunction occurs.

As described above, according to this embodiment, by inserting another insertion signal into the remote control signal, normal remote control is possible even in the vicinity of electronic equipment whose receiver has poor ability to eliminate interference signals. Therefore, even if a color television receiver, video tape recorder, air conditioner, etc. are arranged in one room, malfunctions can be prevented.

Further, the pulse insertion circuit included in the above embodiment lights up the light emitting diode 3 in response to a remote control signal, and charges the capacitor 4, so that when the pulse signal disappears, the discharge voltage from the capacitor 4 is increased. Since the insertion signal is generated when a predetermined threshold voltage is exceeded, the position of the inserted pulse can be kept constant over time even when the voltage of the DC power source changes.

Furthermore, the light emitting diode 3 lights up when a remote control signal is output, but does not light up when an insertion signal is generated, so power consumption can be reduced, and when a battery is used as the DC power source 6, the battery It can extend the lifespan. Furthermore, since a transistor 73 as shown in FIG. 3 is used as the threshold voltage detection circuit 7, the temperature characteristics of the light emitting diode 3 and the temperature characteristics of the transistor 73 cancel each other out, so that the inserted pulse The insertion position will not change.

[Effects of the invention] As described above, according to this invention, current flows through the light emitting diode in response to a pulse signal to light it up, and the capacitor is charged, and when the pulse signal disappears, the charge in the capacitor is discharged. However, since a signal is output when this discharge voltage exceeds a predetermined threshold voltage, a stable insertion signal can be generated at a predetermined time delay from the pulse signal with a relatively simple configuration. .

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram of an embodiment of this invention. FIG. 2 is a specific electrical circuit diagram of the current source included in FIG. 1. FIG. 3 is also a specific electrical circuit diagram of the threshold voltage detection circuit. Fourth
The figure is a waveform diagram of each part shown in FIG. 1. In the figure, 1 is a remote control signal generator, 2 is a current source, 3 is a light emitting diode, 4 is a capacitor, and 5 is a
6 is a resistor, 6 is a DC power supply, 7 is a threshold voltage detection circuit, 8 is an insertion signal generator, and 9 is a transmitter.

Claims (1)

[Claims for Utility Model Registration] Pulse signal generating means for generating a pulse signal having a first frequency; a DC power source; a current source for supplying power from the DC power source in accordance with the output of the pulse signal generating means; A light emitting diode connected between a DC power supply and the current source, a capacitor connected in parallel to the light emitting diode, a resistor connected in parallel to the light emitting diode, and a connection between the current source and the light emitting diode. a threshold voltage detection means connected to a point connected to the connection point and outputs a signal at a time delayed from the pulse signal when the voltage at this connection point exceeds a predetermined threshold voltage; and an output from the threshold voltage detection means. A pulse insertion circuit comprising a pulse signal insertion means for inserting a pulse having a second frequency between the pulse signal outputted from the pulse signal generation means and the pulse signal.