JPH10276486A - Reception equipment for remote control signal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To deal with carrier wave frequencies over a wide range through one integrated circuit by providing the selection resistor of central frequency control circuit with a resistor number and a resistance value which can correspond to the maximum carrier wave frequency of a remote control signal for transmitting the center frequency of a band filter. SOLUTION: One terminal of a control resistor 31 is commonly connected with one-side terminals of a resistor 17 and control resistors 21-25, and the other terminal is grounded through a Zener diode 32 for zapping. The resistance value of control resistor 31 is set at a value with which the central frequency of band filter 3 can be corrected higher just for 16 kHz, for example. Therefore, the selection width of control resistors 21-25 and 31 becomes 64 ways (the sixth power of '2'), namely, is expanded double in comparison with the conventional one, the correction width for the central frequency of band filter 3 becomes 0.5 to 31.5 kHz, and the central frequency of band filter 3 can be corrected up to 26 to 57.5 kHz. Namely, a high voltage is impressed to both terminals of any one of Zener diodes 26-30, 32 by one integrated circuit and its PN bonding is destroyed and short-circuitted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiver for reliably receiving a remote control signal.

[0002]

2. Description of the Related Art FIG. 2 is a block diagram showing a general remote control signal receiving apparatus, which is assumed to be integrated. In FIG. 2, reference numeral (1) denotes a light-receiving diode (reception circuit), which is operated by operating a remote controller, and which is intermittently transmitted on a carrier wave of a predetermined frequency (for example, 38 KHz). It receives a signal and converts it from an optical signal to an electrical signal.
An amplifier (2) primarily amplifies a small current flowing through the light receiving diode (1) in accordance with the remote control signal so that it can be recognized by a microcomputer or the like at a subsequent stage. (3) is a bandpass filter for extracting a frequency component of the carrier wave, that is, a content portion of the remote control signal. Here, FIG. 4 shows the main part of the bandpass filter (3) equivalently. That is, the bandpass filter (3)
As shown in FIG. 4, differential amplifier (4), capacitor (5)
(6) It operates by connecting a resistor (7) and a buffer (8).

Meanwhile, the center frequency of the bandpass filter (3) fluctuates under the influence of variations in element characteristics of the integrated circuit. Once the center frequency of the bandpass filter (3) deviates from the expected frequency (38 KHz), the bandpass filter (3) cannot reliably remove the carrier,
The microcomputer may erroneously recognize the remote control signal and cause the controlled system to malfunction. Therefore, if the center frequency of the bandpass filter (3) changes, it is necessary to correct the change. The center frequency f0, conductance gm, and capacitance C of the bandpass filter (3) in FIG. 4 have a relationship of f0 = gm / 2πC, and the conductance gm is proportional to the size of the current source of the differential amplifier (4). Therefore, if the current amount of the current source of the differential amplifier (4) is adjusted, the center frequency f0 of the bandpass filter (3) can be adjusted.
Can be corrected. This correction means will be described later.

[0004] A detection circuit (9) detects the carrier wave extracted by the bandpass filter (3) and outputs only the component of the remote control signal. An output circuit (10) secondary-amplifies the output of the detection circuit (9) to a level that can be sufficiently recognized by the microcomputer. A center frequency control circuit (11) adjusts the current amount of the current source of the differential amplifier (4) constituting the bandpass filter (3), and as a result, changes the center frequency of the bandpass filter (3). Things.

FIG. 3 shows a conventional circuit of the center frequency control circuit (11). In FIG. 3, a PNP transistor (1
2) (13) forms a current mirror circuit, and the emitter is connected to the power supply VCC. The resistors (14) and (15) are connected in series between the power supply VCC and the ground. The base of the NPN transistor (16) is a series resistor (14) (1
5), the collector is connected to the collector of the PNP transistor (12), and the emitter is connected to the resistor (1).
7) is grounded. That is, when the power supply VCC is in a steady state, the NPN transistor (16) is driven at a constant current. The base collector of the NPN transistor (18) is connected to the collector of the PNP transistor (13),
The emitter is grounded. NPN transistor (1
The base of 9) is connected to the collector of the PNP transistor (13), the collector is connected to the current source of the differential amplifier (4) constituting the bandpass filter (3), and the emitter is grounded via the resistor (20). ing. According to the center frequency control circuit of FIG. 3, the center frequency of the bandpass filter (3) is N
Depending on the collector current of the PN transistor (19), N
The collector current of the PN transistor (19) is the resistance (1
7). Therefore, the center frequency of the bandpass filter (3) can be corrected by adjusting the resistance value of the resistor connected to the emitter of the NPN transistor (16).
Note that the resistance value of the resistor (17) depends on the frequency at which the center frequency of the bandpass filter (3) is lower than the expected frequency (for example, 29 KH).
z). Therefore, the adjustment resistor (21)
(25) to adjust the resistance of the resistor connected to the emitter of the NPN transistor (16).
The adjusting resistors (21) to (25) are connected in parallel with the resistor (17), but one end thereof is grounded via zener zener diodes (26) to (30).
The Zener diodes (26) to (30) have a structure in which a PN junction is destroyed and short-circuited when a high voltage (for example, 40 V) is applied to both ends. Specifically, when at least one of the Zener diodes (26) to (30) is turned on, the resistor (17) and at least one of the adjusting resistors (21) to (25) are connected in parallel, and are connected to the emitter of the NPN transistor (16). The resistance value of the connected resistor decreases, and the collector current of the NPN transistor (19) increases with an increase in the collector current of the NPN transistor (16), whereby the center frequency of the bandpass filter (3) becomes higher. It will be corrected.

[0006] From the above, Zener diode (26) ~
By selectively shorting any one of (30), the center frequency of the bandpass filter (3) has been corrected to be the expected frequency.

[0007]

In the case where the remote control signal receiving device shown in FIG. 2 is integrated, a bandpass filter (3) is used.
It has been experimentally confirmed that the center frequency varies within a range of ± 3 KHz. On the other hand, it is desirable that the center frequency of the bandpass filter (3) is suppressed within a range of ± 0.5 KHz from the expected frequency. Therefore, the adjustment resistors (21) to (2)
When setting the resistance value of 5), it is necessary to select a resistance value such that the center frequency of the bandpass filter (3) can be adjusted to 38 KHz with a width of at least 0.5 KHz with reference to the theoretically lowest frequency of 26 KHz. Specifically, when the Zener diodes (26) to (30) are short-circuited, the center frequencies of the bandpass filters (3) are 8 KHz, 4 KHz,
The value is set to a value corrected to a higher side by 2 kHz, 1 kHz, and 0.5 kHz. From this, the adjustment resistance (21) to
By the combination of (25), the center frequency of the bandpass filter (3) can be adjusted within the correction range of 0.5 to 15.5 KHz, that is, the center frequency of the bandpass filter (3) is adjusted to 26 to 4 kHz.
It can be 1.5 KHz, and the center frequency of the bandpass filter (3) can be matched to the carrier frequency.

However, the frequency of the carrier on which the remote control signal is superimposed is set to a different value for each electronic device, and its frequency width ranges from 32 to 57 KHz. This is to eliminate the inconvenience that the remote control transmitter of one electronic device operates the other electronic device, or to determine the carrier frequency independently by the manufacturer of the electronic device. Therefore, there is a problem that it is impossible to cope with a remote control signal having a carrier frequency in the range of 42 to 57 KHz as it is. In order to cope with the problem, another integrated circuit in which the resistance values of the adjustment resistors (21) to (25) are changed to different values has to be manufactured, and there is a problem that manufacturing cost is high and production efficiency is low. .

SUMMARY OF THE INVENTION It is an object of the present invention to provide a remote control signal receiving apparatus which can support a wide range of carrier frequencies with one integrated circuit.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a receiving circuit for receiving a remote control signal transmitted while being superimposed on a carrier wave of a predetermined frequency. A bandpass filter for extracting a frequency component of the carrier from an output of a receiving circuit, wherein a center frequency of the filter changes when a current amount of a current source of a differential amplifier constituting the filter is adjusted; A detection circuit for detecting an output of the differential amplifier, a circuit for changing a center frequency of the bandpass filter, a transistor for adjusting a current amount of a current source of the differential amplifier, and a plurality of selection resistors for adjusting a control current amount of the transistor. A remote frequency signal receiving apparatus that has a central frequency control circuit including: a central frequency control circuit that adjusts a central frequency of the band-pass filter to a carrier frequency of the remote frequency signal. Oite, select resistance of said center frequency control circuit is characterized by having a number of resistors and the resistance value can be adjusted to the maximum carrier frequency of the remote control signal may be transmitted to the center frequency of the bandpass filter.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be specifically described with reference to the drawings. FIG. 1 is a circuit block diagram showing a remote control signal receiving apparatus according to the present invention, which is applied to the entire block diagram of FIG. 2 and integrated. Note that, in the configuration of FIG. 1, the same components as those of FIG. 3 are denoted by the same reference numerals, and description thereof is omitted.

In FIG. 1, reference numeral (31) denotes an adjusting resistor, one end of which is connected to the resistor (17) and the adjusting resistors (21) to (2).
5), and the other end is grounded via a zener zener diode (32). That is, the adjusting resistor (31) is connected in parallel with the resistor (17) and the adjusting resistor (32). The resistance value of the adjustment resistor (31) is set so that the center frequency of the bandpass filter (3) is 16 kHz.
Is set to a value that can be corrected to the higher side. As a result, the selection range of the adjustment resistors (21) to (25) and (31) is 64 ways (2 to the sixth power), which is twice as large as the conventional range, and the correction range of the center frequency of the bandpass filter (3) is 0. 0.5-31.5KH
z, and the center frequency of the bandpass filter (3) is 26 to 5
Correction is possible up to 7.5 KHz.

Therefore, the frequency of the carrier on which the remote control signal is superimposed is set to the frequency range 32 currently used in the market.
Applying a high voltage to either end of the Zener diodes (26) to (30) and (32) to break the PN junction and short-circuit it in any one integrated circuit at any frequency of up to 57 kHz This makes it possible to respond. The zener diodes (21) to (25) and (31) are short-circuited before the periphery of the chip is molded with resin or the like.

As described above, the conventional problem of 42 KHz
The inconvenience of not being able to cope with the above-described carrier frequency and the inconvenience of recreating a new integrated circuit can be solved. Therefore, on the manufacturing side of the integrated circuit, the production efficiency is improved and the price of the integrated circuit can be reduced. On the other hand, on the side of using the integrated circuit, the delivery time of the integrated circuit is accelerated, and the electronic device is quickly manufactured. It can be put on the market.

In the embodiment of the present invention, the adjusting resistors (21) to (25) and (31) are connected in parallel to the resistor (17). However, the present invention is not limited to this. (21) to (25) and (31) are connected in series to the resistor (17), and the Zener diodes (26) to (30) (3)
2) may be connected in parallel to the adjustment resistors (21) to (25) and (31).

[0016]

According to the present invention, even if the frequency of the carrier on which the remote control signal is superimposed is in any of the frequency ranges currently used in the market, one integrated circuit can cope with the problem. The inconvenience of not being able to cope with a carrier frequency higher than a predetermined value and the inconvenience of recreating a new integrated circuit can be solved. Therefore, on the manufacturing side of the integrated circuit, the production efficiency is improved and the price of the integrated circuit can be reduced. On the other hand, on the side of using the integrated circuit, the delivery time of the integrated circuit is accelerated, and the electronic device is quickly manufactured. It has the advantage of being able to go to market.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing a main part of a remote control signal receiving device of the present invention.

FIG. 2 is a block diagram showing the whole of a general remote control signal receiving device.

FIG. 3 is a circuit block diagram showing a main part of a conventional remote control signal receiving device.

FIG. 4 is an equivalent view showing the inside of a bandpass filter.

[Explanation of symbols]

 (1) light receiving diode (3) bandpass filter (9) detection circuit (10) output circuit (11) center frequency control circuit (17) resistor (19) NPN transistor (21) to (25) (31) adjustment resistor (26) )-(30) (32) Zener diode

Claims (1)

[Claims] 1. A receiving circuit for receiving a remote control signal transmitted in a state of being superimposed on a carrier having a predetermined frequency, and a filter for extracting a frequency component of the carrier from an output of the receiving circuit. A band filter whose center frequency of the filter changes when the current amount of the current source of the dynamic amplifier is adjusted, a detection circuit that detects an output of the band filter, a circuit that changes the center frequency of the band filter, A center frequency control circuit including a transistor for adjusting a current amount of a current source of the differential amplifier and a plurality of selection resistors for adjusting a control current amount of the transistor, wherein a center frequency of the bandpass filter is set to a carrier frequency of the remote control signal; In the remote control signal receiving apparatus, the selection resistance of the center frequency control circuit is set at the center of the bandpass filter. Receiver of remote control signals, characterized in that it comprises a number of resistors and the resistance value can be adjusted to the maximum carrier frequency of the remote control signal may be transmitted wave number.