JP4619856B2 - Infrared signal selector - Google Patents

Description

  The present invention relates to an infrared signal switching device, and is applicable to, for example, an infrared wireless microphone system, a remote control device such as a television, and other infrared transmission / reception devices.

  Conventionally, infrared transmission / reception devices have been widely used as signal transmission means for wireless microphone systems, remote control devices such as televisions, and other various devices. In remote control devices such as televisions used at home, the infrared reception range is not a problem, but in wireless microphone systems used for business purposes, infrared signals are transmitted so that signals can be transmitted wherever the microphone is located. The device is designed to widen the reception range. In order to expand the infrared reception range, first of all, it is possible to use a plurality of light receivers and mix the light reception signals from the respective light receivers.

However, even if multiple receivers are used, depending on the location of the receiver, it may not be able to receive light depending on the position of the microphone, and a receiver that cannot receive infrared light is connected to the receiver. As a result, the reception state may be deteriorated. This is because a light receiver that cannot receive infrared rays generates only a noise component, so that it affects a light reception signal by other light receivers that receive infrared rays and deteriorates sensitivity.
In order to solve such a problem, it is conceivable to adopt a so-called diversity method. This is a method of selecting a light receiver having a good reception state from a plurality of light receivers and adopting the output thereof. However, the conventional diversity system cannot cope with a case where a single light receiver is intended to receive infrared rays having a plurality of frequencies.

  FIG. 5 shows a conventional example of an infrared signal switching device that is considered to cut a frequency band that has a poor reception state and causes noise. This conventional example uses a band-pass filter that passes a signal in a predetermined frequency band, divides the signal for each frequency, switches the band filter, and mixes the signal that has passed through the switched filter. In FIG. 5, an infrared receiver 10 receives infrared rays having a plurality of frequencies, converts them into electrical signals, and outputs them. The output signals are three band filters 51, 52, 53 and three level detectors 41, 42. , 43 to be input. The band filter 51 passes a signal in the frequency band corresponding to channel A, the band filter 52 passes the signal in the frequency band corresponding to channel B, and the band filter 53 passes the signal in the frequency band corresponding to channel C. . The three band filters 51, 52, 53 are connected in parallel. The level detector 41 detects the signal level of the frequency band corresponding to channel A, the level detector 42 detects the signal level of the frequency band corresponding to channel B, and the level detector 43 is the frequency band corresponding to channel C. The signal level of is detected.

  Open / close switches 31, 32, 33 are connected to the output terminals of the band-pass filters 51, 52, 53, respectively. These open / close switches 31, 32, 33 are opened / closed (on / off) by corresponding level detectors 41, 42, 43. ) Is controlled. More specifically, when the level detected by each level detector 41, 42, 43 is higher than a predetermined level, the corresponding open / close switch 31, 32, 33 is turned on, and each level detector 41, 42 is turned on. , 43 is configured to turn off the corresponding open / close switches 31, 32, 33 when the detection level is lower than a predetermined level. When the open / close switches 31, 32, 33 are turned on, the output signals of the bandpass filters 51, 52, 53 that have passed through these switches are mixed by the mixer 35 and output to the multi-channel receiver 20. It is configured. For example, the invention described in Patent Document 1 is based on the same idea as the conventional example shown in FIG.

  According to the conventional infrared signal switching device shown in FIG. 5, a signal with a low signal level that causes noise is cut, and only a signal with a high signal level is synthesized and output. A received signal is obtained. However, since the output signals of the band filters 51, 52 and 53 are mixed, there is a problem that the amount of signal attenuation is large and the sensitivity is lowered.

JP 2004-80121 A

An object of the present invention is to solve the problems of the conventional infrared signal switching device described above and to provide an infrared signal switching device that is efficient and does not have a decrease in sensitivity.
Another object of the present invention is to provide an infrared signal switching device which can obtain a good characteristic with a simple filter structure and is inexpensive.
Another object of the present invention is to provide an infrared signal switching device in which light receivers can be installed in multiple spaces.

An infrared signal switching device according to the present invention includes an infrared receiver that receives a plurality of infrared rays having different frequencies, converts them into electrical signals, and outputs them, and a signal other than a frequency signal to be used among the electrical signals output from the infrared receivers. possess a blocking means for selectively blocking the the said blocking means, the frequency of the signal by attenuating a signal level for each electrical signal corresponding to the plurality of infrared having different frequencies output from the infrared receiver A plurality of serially connected attenuation filters, and a plurality of level detectors for detecting the signal level for each of the electrical signals corresponding to a plurality of infrared rays having different frequencies output from the infrared receiver. Each level detector selects the attenuation filter corresponding to the signal of the frequency when the electrical signal of the corresponding frequency is below a predetermined level. To function Te, and most important, comprising a switching means for switching to attenuate the signal level of the frequency.

  The plurality of filters are attenuation filters, and the level detector that detects that the electrical signal of the corresponding frequency is equal to or lower than the predetermined level among the plurality of level detectors operates the filter corresponding to this to detect the frequency of the frequency detector. Attenuate signal level. Other filters that do not function will pass signals of the corresponding frequency. Therefore, the mixer used in the conventional example shown in FIG. 5 is not required, the circuit configuration can be simplified, and an infrared signal switching device having no signal attenuation and good sensitivity can be obtained. .

Embodiments of an infrared signal switching device according to the present invention will be described below with reference to the drawings.
In FIG. 1, an infrared receiver 10 receives infrared rays having a plurality of frequencies, converts them into electrical signals, and outputs them. The output signals are input to blocking means 30 for selectively blocking signals other than the frequency signals to be used. Connected to be. The blocking means 30 has three attenuation filters 11, 12, 13 connected in series. The attenuation filter 11 attenuates the signal of the frequency corresponding to the channel A and blocks the passage of the signal, and the attenuation filter 12 attenuates the signal of the frequency corresponding to the channel B and blocks the passage of the signal. 13 attenuates the signal in the frequency band corresponding to channel C and blocks the passage of the signal. The frequencies corresponding to the order of A channel, B channel, and C channel are higher.

  The output signal of the infrared receiver 10 is connected to be input to three level detectors 16, 17 and 18. The level detector 16 detects the signal level of the frequency band corresponding to channel A, the level detector 17 detects the signal level of the frequency band corresponding to channel B, and the level detector 18 is the frequency band corresponding to channel C. The signal level of is detected. The operation of the attenuation filters 11, 12, 13 is controlled by the detection outputs of the level detectors 16, 17, 18. More specifically, when the level detected by each level detector 16, 17, 18 is higher than a predetermined level, the corresponding attenuation filter 11, 12, 13 is prevented from functioning. When the level detected by each level detector 16, 17, 18 is lower than a predetermined level, the level detector 16, 17, 18 causes the corresponding attenuation filter 11, 12, 13 to function, and the corresponding frequency is detected. The signal is attenuated by bypassing, and a signal having a frequency other than that is passed. The output of the blocking means 30 is configured to be input to the multi-channel receiver 20. The circuit portion including the attenuation filters 11, 12, 13 and the level detectors 16, 17, 18 constitutes an infrared signal switch 15.

  FIG. 2 shows the configuration of the blocking means 30 more specifically, and shows its function or operation example. As shown in FIG. 2A, the three attenuation filters 11, 12, and 13 are connected in series, and the input side of the attenuation filter 11, between the attenuation filters 11, 12, and 13 and the attenuation filter 13. Buffer amplifiers 21, 22, 23, and 24 are connected to the output side, respectively. Therefore, the output signal of the infrared receiver 10 is input to the buffer amplifier 21, and the output signal of the blocking means 30 is output from the buffer amplifier 24.

  FIG. 4 representatively shows a specific circuit configuration example of the attenuation filter as an attenuation filter 11. The output terminal of the buffer amplifier 21 is connected to the input terminal of the buffer amplifier 22 through a parallel connection of the coupling capacitor C1 and the coupling coil L1, and is attenuated between the parallel connection of the coupling capacitor C1 and the coupling coil L1 and the buffer amplifier 22. There is a connection point of the filter 11. The attenuation filter 11 includes a capacitor C2 connected in series, a coil L2, and a switching transistor 16. One end of the capacitor C2 is connected between the parallel connection of the coupling capacitor C1 and the coupling coil L1 and the buffer amplifier 22, and the emitter of the transistor 16 is grounded. The capacitor C2 and the coil L2 constitute a filter that passes a signal having a specific frequency, that is, a frequency corresponding to the A channel in this example. The detection signal of the level detector 16 is input to the base of the transistor 16, and when the level of the detection signal of the level detector 16 is lower than a predetermined level, a signal is input to the base of the transistor 16 to turn on the transistor 16 , A signal having a frequency corresponding to the A channel is dropped to the ground. Accordingly, the blocking means 30 blocks the passage of a signal having a frequency corresponding to the selected A channel and allows a signal having a frequency other than that corresponding to the A channel to pass. In other words, the signal of the frequency corresponding to the A channel is a signal of a frequency that is not used, the signal of the other frequency is a signal of the frequency that is used, and the blocking means 30 is a signal other than the signal of the frequency that is used. Operates to selectively block. The configurations of the other attenuation filters 12 and 13 included in the blocking unit 30 are the same as the configuration of the attenuation filter 11. However, in the attenuation filters 12 and 13, the values of the capacitor C2 and the coil L2 are different, and are set so as to attenuate the signal of the frequency corresponding to the B channel and the signal of the frequency corresponding to the C channel, respectively.

  FIG. 2B shows the operation of the blocking means 30 when signals of frequencies corresponding to the B channel and the C channel are used, and therefore when the signal level of the frequency corresponding to the A channel is equal to or lower than a predetermined level. ing. In this case, the attenuating filter corresponding to the A channel operates to block the signal of the corresponding frequency, and operates so that the signal of the other frequency passes. FIG. 2 (c) shows the operation of the blocking means 30 when a signal having a frequency corresponding to the C channel is used and the signal level of the frequency corresponding to the A channel and the B channel is low and not used. Attenuation filters corresponding to the A channel and the B channel operate to block signals having frequencies corresponding thereto, and operate so that signals having frequencies corresponding to the other C channels pass. (D) shows the operation of the blocking means 30 when a signal having a frequency corresponding to the B channel is used and the signal level of the frequency corresponding to the A channel and the C channel is low and not used. Attenuation filters corresponding to the A channel and the C channel operate to block signals having frequencies corresponding thereto, and operate so that signals having frequencies corresponding to other B channels pass.

  The table shown in FIG. 3 summarizes the relationship between the combinations of the operations of the three attenuation filters 11, 12, 13 included in the blocking means 30 described above and the output of the blocking means 30 at that time. FIG. 3 shows “large” when the signal level of the frequency corresponding to each channel of A, B, and C is equal to or higher than a predetermined value, and “small” when the signal level is lower than the predetermined value. It is shown whether the signal of is output. As can be seen from the top of the chart of FIG. 3, when the signal level of the frequency corresponding to the A channel is equal to or higher than a predetermined value, the signal of the A channel is used, and the signal of the frequency corresponding to the A channel is used. Only the other channel is selected, and signals of other channels are blocked. As shown at the bottom of the chart of FIG. 3, when the signal level of the frequency corresponding to all channels A, B, and C is “high”, the signal of the frequency corresponding to all channels A, B, and C is output. Is done. FIG. 3 does not describe the case shown in FIGS.

  According to the embodiment of the present invention described above, it is configured to selectively block signals other than the frequency signal to be used and pass only the signal having the frequency to be used, so that it can be found in a conventional infrared signal switching device. It is not necessary to use a mixer, and the circuit configuration can be simplified. Further, a signal to be used among the signals received and converted by the infrared light receiver 10 is not used to mix signals of a plurality of frequencies by using a mixer, but passes through the blocking means 30 and directly into a multi-channel. Since it is transmitted to the receiver 20, there is no signal attenuation, and an infrared signal switch with good sensitivity can be obtained.

  In the illustrated embodiment, the attenuation filter constituting the blocking circuit 30 has a three-channel configuration, but the number of channels may be increased by increasing the number of attenuation filters. Even if the number of channels is increased, a signal having a frequency to be used is directly transmitted to the multi-channel receiver 20 as described above, so that it is possible to obtain an infrared signal switching device with no signal attenuation and high sensitivity. . The number of channels may be two.

  One or a plurality of infrared receivers used in the infrared signal switching device according to the present invention may be installed in the same space, or a plurality of infrared receivers may be installed dispersed in multiple spaces. By using the infrared signal switching device according to the present invention, it is possible to realize an infrared cordless microphone used in a wide space or multiple spaces, or to apply to an infrared position detection system, an infrared tracking system, or the like. .

It is a block diagram which shows the Example of the infrared signal switching device concerning this invention. The attenuation filter in the said Example is shown more concretely, (a) is a block diagram, (b), (c), (d) is a graph which shows each example of various operation | movement of an attenuation filter with a frequency versus signal level, respectively. . 6 is a chart summarizing an operation example of the attenuation filter. It is a circuit diagram which shows one of the said attenuation | damping filters more concretely. It is a block diagram which shows the example of the conventional infrared signal switching device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Infrared light receiver 11 Attenuation filter 12 Attenuation filter 13 Attenuation filter 15 Infrared signal switch 16 Level detector 17 Level detector 18 Level detector 20 Multichannel receiver 30 Blocking means

Claims (2)

An infrared receiver that receives a plurality of infrared rays having different frequencies, converts them into electrical signals, and outputs them;
Have a, and blocking means for selectively blocking the other frequency of the signal used among the electric signals outputted from the infrared receiver,
The blocking means attenuates a signal level for each electrical signal corresponding to a plurality of infrared rays having different frequencies output from the infrared light receiver, and can block a signal having that frequency in series. A plurality of level detectors for detecting a signal level for each electrical signal corresponding to a plurality of infrared rays having different frequencies output from the attenuation filter and the infrared receiver;
Each level detector selects and functions the attenuation filter corresponding to the signal of the frequency when the electric signal of the corresponding frequency is equal to or lower than a predetermined level, and switches to attenuate the signal level of the frequency. An infrared signal switching device comprising switching means . Infrared signal switching unit according to claim 1, wherein that are arranged buffer amplifiers between a plurality of filters connected in series.

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