JP2024005139A - wireless receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that desktop type wireless communication equipment cannot secure a mount region for an internal speaker in the front, so the internal speaker is built in on the back side of a sound wave output hole formed in a top and a reverse surface, but a middle- or low-pitched sound with high directivity is deficient in the front, and driving of an internal speaker is stopped during audio reproduction with an external speaker connected.

SOLUTION: A switch circuit 17 is provided which switches by connection/disconnection of an external speaker unit 30, and an audio signal of a receiving demodulation part 13 is output to an amplifier 18 for driving an internal speaker 19 through a signal adjustment part 14 (a phase converter 15 and an LPF 16) in the connection state, or directly in the disconnection state. The LPF 16 uses the internal speaker 19 for low-pitched range compensation and high tone quality reproduction accompanied by a rich low-pitched sound is provided in cooperation with an external speaker 32. The phase converter 15 corrects a group delay of a phase at the LPF 16 to prevent deterioration in sound quality. It is preferred that the signal adjustment part 14 is composed of a DPS, and more free sound quality adjustments can be made.

SELECTED DRAWING: Figure 2

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to the configuration of a wireless receiver for improving the quality of reproduced sound when an external speaker is connected to a wireless receiver having a built-in speaker and the received audio is reproduced by both speakers.

In tabletop and stationary wireless communication devices, a large number of knobs and buttons are densely arranged on the front panel of the main body housing along with the liquid crystal display, making it possible to place an internal speaker of the required size on the front. Have difficulty.

Therefore, in conventional wireless communication devices, slits or openings are provided in some regions of the upper or lower surface of the main body housing, and an internal speaker is attached to the back side of the region.
In that case, the output direction of the sound waves is naturally above or below the main body casing, making it difficult for sound waves in the middle and high frequency ranges, which have relatively high directivity, to propagate forward of the main body casing.

Therefore, as shown in FIG. 4, an external speaker unit 53 is arranged on the side of the main body casing 51 in addition to the internal speaker 52 (not shown because it is built-in) of the main body casing 51 of the wireless communication device. When the speaker unit 53 is connected to the audio signal output terminal of the wireless communication device, the operation of the internal speaker 52 is stopped.

As prior art related to this technology, the following proposals can be found in patent documents.
Patent Document 1 listed below discloses that in a wireless communication device that switches and outputs audio output to the outside, one or both of the audio signal switching means provided before and after the input audio signal amplification means are switched. An external selection method for audio output has been proposed in which the audio output is arbitrarily selected and switched by controlling with a control means.
Patent Document 2 below describes a wireless device having an internal speaker and an external speaker, which includes a switching means for switching between the internal speaker and the external speaker, and a switching means for automatically switching to the selected speaker according to the operator's selection. A radio device has been proposed that is equipped with a control means for controlling.
Patent Document 3 below describes a wireless device that selectively uses an internal speaker and an external speaker, in which the output level of an audio IC is switched between when the internal speaker is used and when the external speaker is used, so that the speaker can be quickly switched. A wireless device has been proposed.
Patent Document 4 below discloses that when audio is played back using built-in speakers and external speakers in a TV receiver, a time difference occurs in the reproduced sound due to the difference in distance from the viewer to each speaker, impairing the clarity of the sound. A speaker device has been proposed in which the problem is solved by inserting a delay line having a delay time corresponding to the time difference in a signal transmission path to an external speaker.

Japanese Patent Application Publication No. 10-336786 Japanese Patent Application Publication No. 2000-253485 Japanese Patent Application Publication No. 2000-312160 Utility Model Publication No. 3-16798

By the way, in a wireless communication device to which an external speaker unit 53 can be connected as shown in FIG. 4, the operation of the internal speaker 52 is automatically stopped when the external speaker unit 53 is connected.
On the other hand, in general, low-frequency sound waves have relatively low directivity and the intensity of the sound waves is difficult to attenuate, and the intensity of the sound waves generally tends to be proportional to the sum of the diameters of multiple speakers. It is said that

Therefore, if the sound reproduced by the external speaker 53a of the external speaker unit 53 in FIG. This makes it possible to play audio.

Therefore, in a wireless receiver equipped with an internal speaker, when an external speaker unit is connected, the internal speaker as well as the external speaker can operate as a low frequency compensation speaker to reproduce received audio with high sound quality. The purpose is to provide a wireless receiver.

The present invention provides a radio receiver that has a built-in internal speaker for reproducing and outputting received audio, and is connectable to an external speaker unit that has a built-in external speaker and an audio signal amplifier for the external speaker. a reception demodulation section that demodulates a carrier signal modulated with an audio signal and outputs an audio signal, a connection terminal for the external speaker unit to which an output signal line of the reception demodulation section is connected, and the reception demodulation section a signal adjustment section that uses an output signal of the input signal as an input signal, adjusts the input signal using a phase converter and a low-pass filter, and outputs the resultant signal; and an output signal of the reception demodulation section and an output signal of the signal adjustment section. a switching circuit for outputting an audio signal for the internal speaker to an amplifier; a detection means for detecting whether or not the external speaker unit is connected to the connection terminal; and a detection means for detecting a disconnection state of the external speaker unit. If the detection means detects the connection state of the external speaker unit, the switching circuit is set to the output state of the output signal of the reception demodulator, and when the detection means detects the connection state of the external speaker unit, the switching circuit is set to the signal adjustment state. and a control means for controlling the output state of the output signal of the radio receiver.

According to the present invention, when the external speaker unit is not connected to the connection terminal, the audio signal output by the reception demodulator is amplified as is and reproduced by the internal speaker, but when the external speaker unit is not connected to the connection terminal. When connected, the audio signal output from the reception demodulation section is adjusted by the phase converter and low-pass filter of the signal adjustment section and reproduced by the internal speaker, and the audio signal output from the reception demodulation section is output from the connection terminal. It is also played back through the external speakers of the external speaker unit.
In that case, the demodulated audio signal is directly played back by an external speaker to output the middle and high range to the front, and at the same time, the low range signal that has passed the low pass filter is played back by the internal speaker. By making low-frequency sound waves with low directivity spread forward, the overall sound quality of the reproduced sound is improved. However, when passing through a low-pass filter, there is a phase lag (group delay) in the audio signal within the passband. delay), and when the sounds played by the external and internal speakers are combined, the sound tends to be unnatural and unclear.
That is why in the present invention, a phase converter is inserted in the signal path together with a low-pass filter, and the phases of the sounds reproduced by both speakers are matched so that a natural and clear sound can be heard.

Therefore, in the present invention, the cutoff frequency and phase change amount of the low-pass filter and phase converter of the signal adjustment section can be set variable, respectively, but the detection means detects the connection state of the external speaker unit. In this case, it is desirable that the control means be able to adjust the cut-off frequency of the low-pass filter and the amount of phase change of the phase converter based on a signal generated by an adjustment operation of the operation section.
This can be more easily realized by configuring the signal adjustment section with a digital signal processing circuit.

Further, in the present invention, the detection means detects the external speaker based on the impedance change between the signal terminal of the connection terminals and the ground circuit, regardless of whether the detection method is electrical or mechanical. By detecting whether or not the unit is connected, it can be constructed as a simple and reliable means.
Although the present invention relates to a wireless receiver, it naturally includes a wireless receiver that is integrated with a wireless transmitter as a wireless communication device.

According to the present invention, in a wireless receiver having a built-in internal speaker and to which an external speaker unit having a built-in external speaker and an amplifier can be connected, when the external speaker is connected, the internal speaker is not stopped. It is used for low frequency compensation and driven together with external speakers. By correcting the group delay of the phase of the audio signal caused by the low-pass filter used for this purpose using the phase converter, a rich and clear audio reproduction is realized as a whole.

1 is a block diagram of a wireless receiver according to an embodiment of the present invention, showing a state in which an external speaker unit is not connected. FIG. 1 is a block diagram of a wireless receiver according to an embodiment of the present invention, showing a state in which an external speaker unit is connected. FIG. 7 is a flowchart showing a control procedure for the switch circuit when connecting and disconnecting an external speaker unit in the wireless receiver according to the embodiment of the present invention. FIG. 2 is a perspective view of an external speaker unit disposed on the side of a main body casing of a wireless communication device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a wireless receiver of the present invention will be described with reference to the drawings.
In the block diagram of the radio receiver in FIG. 1, 11 is the main body casing of the radio receiver 10, 12 is an antenna, 13 is a reception demodulation section, 14 is a signal adjustment section, 15 is a phase converter in the signal adjustment section 14, 16 is a low-pass filter (LPF) in the signal adjustment section 14, 17 is a switch circuit, 18 is an amplifier, 19 is an internal speaker, 20 is a control section, 21 is an operation section, 22 is a liquid crystal display section, and 23 is for an external speaker. It is a connection terminal.

In the wireless communication device 10, a carrier wave signal modulated with an audio signal is received by an antenna 12, demodulated by a receiving demodulator 13, and the demodulated audio signal is sent to a terminal a on the input side of a switch circuit 17 and an external speaker. In addition to being output directly to the connection terminal 23, it is also output to the signal adjustment section 14, and is outputted to the input side terminal b of the switch circuit 17 via the phase converter 15 and LPF 16 of the signal adjustment section 14. It has become.
On the other hand, the audio signal output from the output terminal c of the switch circuit 17 is amplified by the amplifier 18 and drives the internal speaker 19.

The entire system of this radio receiver 10 is controlled by a control unit 20, which includes a reception demodulation unit 13, a signal adjustment unit 14, a switch circuit 17, a liquid crystal display unit 22, an amplifier 18, and a connection terminal 23 provided in the previous stage. A volume adjustment circuit (not shown) and the like are controlled based on operation signals from the operation unit 21 and signals obtained from each module.

Here, the audio playback operation is performed with the external speaker unit 30 not connected to the external speaker connection terminal 23 of the wireless receiver 10 as shown in FIG. 1, and with the external speaker unit 30 connected as shown in FIG. I will explain about it.
FIG. 3 shows the switching procedure of the switch circuit 17 executed by the control unit 20 in response to changes in the disconnected state/connected state of the external speaker unit 30 to the connection terminal 23. First, in the disconnected state of FIG. The circuit 17 is placed in an a-c connection state (S1).

In this state, the audio signal output from the reception demodulator 13 is directly output to the amplifier 18 via the switch circuit 17, and the audio signal is power amplified by the amplifier 18 and drives the internal speaker 19.
In that case, the internal speaker 19 is built into the main body casing 11, but as explained in the background technology section, many knobs and buttons of the operation section 21 are located on the front of the main body casing 11, and the liquid crystal display section 22 Since the internal speakers 19 cannot be placed in front because they are arranged in a high density, a slit that is an audio output hole is formed on the top (or bottom) of the main body housing 11, as shown in FIG. 4. Then, an internal speaker 19 is arranged inside the slit forming area.
Therefore, there is a problem in that it is difficult for sound waves in the middle and high frequency ranges, which have relatively strong directionality, to propagate forward.

Therefore, as shown in FIG. 2, when the external speaker unit 30 is connected to the connection terminal 23, the control unit 20 determines the connection state based on the impedance change between the signal line connection at the connection terminal 23 and the ground circuit. Based on the detection, the switch circuit 17 is switched from the a-c connection state to the b-c connection state (S2, S3).

Therefore, in the connection state after the switching, the audio signal output from the reception demodulator 13 is output as is to the newly connected external speaker unit 30, is power amplified by the amplifier 31 built in the unit 30, and is output to the external speaker 32. On the other hand, due to the b-c connection state of the switch circuit 17, the audio signal output from the reception demodulation section 13 is outputted to the amplifier 18 via the signal adjustment section 14, and the internal speaker 19 is driven. .

In the audio reproduction state, a cutoff frequency is set in the LPF 16 of the signal adjustment section 14 in consideration of the frequency characteristics of the internal speaker 19, and only the audio signal in the low frequency range is output to the amplifier 18. When the signal passes through the LPF 16, the phase of the signal rotates and a group delay occurs, so if the LPF 16 alone outputs the audio signal as it is, the combined sound of the internal speaker 19 and external speaker 32 will be distorted. It becomes natural and unclear.
Therefore, a phase converter 15 is provided before the LPF 16, and by advancing the phase in advance, the phases of the audio signals that drive both the speakers 19 and 32 are matched.
Therefore, the sound reproduced by the external speaker 32 is compensated for by the low-frequency sound reproduced by the internal speaker 19 that is in phase with the sound reproduced by the external speaker 32, making it possible to listen to high-quality received audio.

Incidentally, the signal adjustment section 14 may incorporate the phase converter 15 and the LPF 16 as independent modules, but in this embodiment, the entire signal adjustment section 14 is configured with a digital signal processing circuit (DSP). It realizes phase conversion function and LPF function.
That is, by configuring the DSP, the audio signal output by the reception demodulator 13 is AD converted (the AD converter is not shown), and the phase conversion process and LPF process are performed on the digitized audio signal. The processed digital data is DA-converted (DA converter not shown) and output to the amplifier 18, allowing high-speed and highly accurate signal adjustment.
The signal adjustment unit 14 configured with this DSP not only adjusts the phase with respect to the group delay, but also adjusts the amount of phase change of the phase converter 15 and the LPF 16 via the control unit 20 by adjusting the adjustment operation from the operation unit 21. The cutoff frequency can be set freely, and the playback sound can be output that matches the usage environment of the wireless receiver and the user's preference for sound quality (S4).

When the external speaker unit 30 is removed from the connected state of the external speaker unit 30 shown in FIG. Based on the detection, the control unit 20 switches the switch circuit 17 from the b-c connection to the a-c connection (S5→S6).
Therefore, the state returns to the original state shown in FIG. 1, and the audio signal output from the receiving demodulator 13 is reproduced only by the internal speaker 19 via the amplifier 18.

It goes without saying that the switch circuit 17 is switched each time the external speaker unit 30 is connected and disconnected, resulting in the states shown in FIGS. 2 and 1.
A feature of the wireless receiver 10 according to this embodiment is that when the external speaker unit 30 is connected and the external speaker 32 reproduces audio, the operation of the internal speaker 19 is not stopped, but a speaker for low frequency compensation is used. The advantage is that it is possible to effectively utilize the received and reproduced sound in combination with the reproduced sound from the external speaker 32 to produce a received and reproduced sound with a natural and rich bass sound.

INDUSTRIAL APPLICABILITY The present invention can be applied to a desk-top or stationary wireless receiver (or wireless communication device) to which an external speaker unit can be connected.

10...Radio receiver, 11...Main body housing, 12...Antenna, 13...Receiving demodulator, 14...Signal adjustment unit, 15...Phase converter, 16...Low pass filter (LPF), 17...Switch circuit, 18...Amplifier , 19...internal speaker, 20...control unit, 21...operation unit, 22...liquid crystal display unit, 23...connection terminal, 30...external speaker unit, 31...amplifier, 32...external speaker, 51...main body case, 52... Internal speaker, 53...external speaker unit, 53a...external speaker.

By the way, in a wireless communication device to which an external speaker unit 53 can be connected as shown in FIG. 4, the operation of the internal speaker 52 is automatically stopped when the external speaker unit 53 is connected.
On the other hand, generally speaking, sound waves in the low frequency range have relatively low directivity, the intensity of the sound waves is difficult to attenuate, and the intensity of the sound waves tends to be proportional to the sum of the diameters of multiple speakers. There is.

Claims (4)

In a wireless receiver that has a built-in internal speaker for reproducing and outputting received audio, and is connectable to an external speaker unit that has a built-in external speaker and an audio signal amplifier for the external speaker,
a reception demodulator that demodulates a carrier signal modulated with the audio signal obtained from the antenna side and outputs the audio signal;
a connection terminal for the external speaker unit to which an output signal line of the reception demodulation section is connected;
a signal adjustment unit that takes the output signal of the reception demodulation unit as an input signal, adjusts the input signal using a phase converter and a low-pass filter, and outputs the adjusted signal;
a switching circuit that selectively selects the output signal of the reception demodulation section and the output signal of the signal adjustment section and outputs the selected signal to the audio signal amplifier for the internal speaker;
detection means for detecting whether the external speaker unit is connected to the connection terminal;
When the detection means detects the disconnection state of the external speaker unit, the switching circuit is set to the output state of the output signal of the reception demodulator, and the detection means detects the connection state of the external speaker unit. a control means for controlling the switching circuit to an output state of the output signal of the signal adjustment section when the signal adjustment section is in an output state. The low-pass filter and phase converter of the signal adjustment section can each have a cut-off frequency and a variable phase change amount, and when the detection means detects the connection state of the external speaker unit, the adjustment of the operation section can be performed. 2. The radio receiver according to claim 1, wherein the control means adjusts the cutoff frequency of the low-pass filter and the amount of phase change of the phase converter based on a signal from an operation. The radio receiver according to claim 1 or 2, wherein the signal adjustment section is comprised of a digital signal processing circuit. Claim 1, 2 or 3, wherein the detection means detects whether or not the external speaker unit is connected based on a change in impedance between a signal terminal of the connection terminals and a ground circuit. The radio receiver described in .

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