JP2000124723A - Communication device and small-sized portable communication device provided with range finding means - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform optimum communication by measuring a distance from an object positioned near an antenna and adjusting matching conditions corresponding to antenna characteristic change. SOLUTION: A portable telephone set 30 is provided with an antenna 1, a matching circuit 3 for matching impedance with the antenna 1, a distance measurement means 7 for measuring the distance between the antenna 1 and the object 10 by ultrasonic waves and a control means 5 as a circuit condition adjustment means for adjusting the matching circuit conditions of the matching circuit 3 corresponding to the distance measured in the distance measurement means 7. The ultrasonic waves reduce influence on the head part of a human body and measure the distance. The control means 5 sets the matching conditions calculated beforehand to the antenna matching circuit 3 corresponding to a distance measured result by the ultrasonic distance measurement means 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication apparatus having an antenna for measuring a distance of an object located near an antenna and adjusting an antenna characteristic which changes according to the measured position. Further, the present invention relates to a small portable communication device having a distance measuring means.

[0002]

2. Description of the Related Art As a communication device, a small portable communication device, for example, a portable telephone will be described as an example. Since the mobile phone is used close to the head of the person who talks, the antenna provided on the mobile phone and the human head approach. As a result, in addition to radio wave absorption in the human head,
The reflected power at the antenna feed point increases or decreases due to the coupling relationship between the human head, the antenna, and the head, and the antenna characteristics change.

[0003]

SUMMARY OF THE INVENTION In a portable telephone,
It is assumed that the human head and the antenna are used close to each other, and a circuit design has been made in consideration of the change in antenna characteristics as described above.

However, a standard circuit design is made under the condition that the distance between the human head and the antenna is within a certain range, and the standard circuit design changes according to the change in the distance between the antenna and the human head. There is no design to operate the mobile phone under optimal circuit conditions taking into account the change in antenna characteristics.
Therefore, when making a call of better quality, it is desirable to adjust the circuit conditions in consideration of antenna characteristics according to the distance between the antenna and the human head.

[0005] In the above, a case where a telephone call is performed using a mobile phone has been described. However, a similar problem occurs when data communication is performed using a mobile phone. In that case, it is not limited to the antenna of the mobile phone and the human head. For example, the presence of a metal object that absorbs radio waves near the antenna affects communication quality. In such a case, it is desirable to adjust the circuit conditions of the mobile phone according to the change in the antenna characteristics.

In such an adjustment, it is necessary to measure the distance between the antenna and an object in the vicinity of the antenna and adjust circuit conditions according to the measured distance. There is no known distance measuring means that has little influence, is inexpensive, is small, can operate stably for a long period of time, and can mount (store) a mobile phone.

[0007] In the above example, a mobile phone is illustrated as a communication device. However, other fixed transmission devices that perform communication using an antenna also encounter the same problem as described above.

[0008] In order to overcome the above-mentioned problems, an object of the present invention is to provide a small-sized communication device such as a portable telephone, which has a small effect on the human body, is inexpensive, small-sized and can operate stably for a long period of time. Another object of the present invention is to provide a communication device which has a distance measuring means which can also be mounted, and which can adjust circuit conditions based on the distance measured by the distance measuring means. It is another object of the present invention to provide a small portable communication device having a distance measuring means.

[0009]

According to the present invention, an antenna, a matching circuit for matching impedance of the antenna, a distance measuring means for measuring a distance between the antenna and an object by ultrasonic waves, There is provided a communication apparatus having circuit condition adjusting means for adjusting a matching circuit condition of the matching circuit according to a distance measured by a distance measuring means.

Preferably, the circuit condition adjusting means adjusts the matching circuit condition only when the distance measured by the distance measuring means is within a predetermined distance.

Preferably, the distance measuring means includes a transmitting ultrasonic sensor provided in the communication device, a receiving ultrasonic sensor provided in the communication device, and a transmitting ultrasonic sensor provided in the communication device. Exciting means for exciting the ultrasonic sensor, provided in the communication device, the ultrasonic wave emitted from the transmitting ultrasonic sensor is reflected by the object, the reflected ultrasonic wave by the receiving ultrasonic sensor Ultrasonic distance measuring means for receiving and measuring the time from transmission of ultrasonic waves to reception of ultrasonic waves, and measuring the distance from the ultrasonic sensor for transmission or the ultrasonic sensor for reception to the object from the measurement time And

More specifically, the communication device is a small portable communication device, for example, a mobile phone.

According to the present invention, the transmitting ultrasonic sensor, the receiving ultrasonic sensor, the exciting means for exciting the transmitting ultrasonic sensor, and the ultrasonic wave radiated from the transmitting ultrasonic sensor are provided. The ultrasonic wave reflected by the object is received by the ultrasonic sensor for reception, the time from transmission of ultrasonic wave to reception of ultrasonic wave is measured, and the ultrasonic sensor for transmission or the reception is measured from the measurement time. A compact portable communication device having an ultrasonic distance measuring means for measuring a distance from the ultrasonic sensor for use to the object is provided.

In the communication device according to the present invention, the distance between an antenna mounted on the communication device and an object located near the antenna is measured using ultrasonic waves. Ultrasound has little effect on the human body. Therefore, for example, even if the communication device is a mobile phone and the object is the head of the human body used close to the mobile phone, the distance between the antenna and the head of the human body is measured with little effect on the human body. it can. Ultrasonic waves are also suitable for detecting objects in communication devices other than mobile phones. The circuit condition adjusting means changes the matching condition of the matching circuit of the communication device based on the measured distance between the antenna and the object. As a result, even if the antenna characteristics change, communication can be performed under matching conditions in accordance with the characteristics.

The circuit condition adjusting means adjusts the matching circuit according to the change in the antenna characteristic only when the distance measurement result is within a predetermined range. This is because, when the distance between the antenna and the object is more than a certain distance, it is substantially unnecessary to change the circuit conditions according to the change in the antenna characteristics. In other words, since the specific range of the distance measuring means described above may be short, a small ultrasonic sensor can be used.

The transmitting ultrasonic sensor, the receiving ultrasonic sensor, the exciting means for exciting the transmitting ultrasonic sensor, and the ultrasonic distance measuring means are small and can be easily mounted (accommodated) in a small communication device such as a mobile phone. ). The use of an integrated transmission ultrasonic sensor and reception ultrasonic sensor further reduces the size and weight.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic configuration diagram of a small portable communication device as an example of a communication device of the present invention, for example, a transmitting portion of a portable telephone. The mobile phone illustrated in FIG. 1 includes an antenna 1, a matching circuit 3 that performs impedance matching with the antenna, a control unit 5, and an ultrasonic distance measuring unit 7. The mobile phone further includes an input filter 11 and a high-frequency amplifier circuit 13 as a receiving system.
And a frequency conversion circuit 15 and a data reproduction circuit 17. The mobile phone also has an output filter 21 as a transmission system.
, A high-frequency amplifier circuit 23, a frequency conversion circuit 25, and a data generation circuit 27. Figure 1 shows an actual mobile phone.
1 has various circuits and means, but FIG. 1 illustrates only parts related to the present invention.

The portable telephone is, for example, a widely used portable telephone 30 as illustrated in FIG. 2, and an antenna 1 mounted on the portable telephone 30 is telescopic and can be accommodated in the portable telephone 30. This is a transmission / reception rod antenna used for both transmission and reception.

The data reception operation of the circuit illustrated in FIG. 1 will be described. The high frequency signal received by the antenna 1 is matched (impedance matching) in the antenna matching circuit 3 and is input to the input filter 11 to remove a noise component. The output signal of the input filter 11 is amplified in the high-frequency amplifier circuit 13 and converted to an intermediate frequency signal in the frequency conversion circuit 15. Thereafter, the frequency may be further converted, but is omitted in the illustrated mobile phone. Thereafter, the data is demodulated by a demodulation circuit (not shown), and the data is reproduced by the data reproduction circuit 17.
The voice is output from the voice output unit of the mobile phone as voice.

The data transmission operation of the circuit illustrated in FIG. 1 will be described. After the audio signal from the microphone of the mobile phone is converted into an electric signal, the data generation circuit 27 generates a call signal. Further, the signal is modulated in a modulation circuit (not shown), converted into a high frequency signal in a frequency conversion circuit 25, and amplified to a transmittable power level in a high frequency amplifier circuit 23. Further, the noise component is removed by the output filter 21 and applied to the antenna 1 via the antenna matching circuit 3 and radiated into the air.

The present inventor has found that the distance between the portable telephone and the head of the human body and the ratio of the high-frequency absorbed power of the human body can be represented as a graph illustrated in FIG. Further, as illustrated in FIG. 3, the inventor of the present invention differs in the power absorption ratio depending on the distance between the antenna 1 (mobile phone 30) and the head of the human body. It has been found that by appropriately adjusting the matching condition, it is possible to maintain high communication quality.

Then, as illustrated in FIG. 2, the inventor of the present application measures the distance between the antenna 1 and the measured object (object) 10 such as a human body by the ultrasonic distance measuring means 7,
The control means 5 changes the matching condition of the antenna matching circuit 3 based on the distance measurement result by the ultrasonic distance measuring means 7 so that an appropriate matching condition can be adjusted according to the distance between the antenna 1 and the object 10 to be measured. And

For this reason, the inventor of the present application previously obtains circuit conditions of the antenna matching circuit 3 according to the distance between the antenna 1 and the measured object (object) 10 based on the characteristic curve of FIG. The result was stored in the means 5. The control means 5 has a built-in computer, preferably a microcomputer, and stores the results in a ROM. The antenna matching circuit 3 includes a plurality of switches and a plurality of matching circuits. One matching circuit selected by operating a switch according to a switching command from the control unit 5 can be connected to the antenna 1. It is configured in. Control means 5
Determines which matching circuit in the antenna matching circuit 3 is to be selected according to the distance measurement result of the ultrasonic distance measuring means 7,
One of a plurality of switches in the antenna matching circuit 3 is selectively driven. As a result, the selected matching circuit and the antenna 1 are connected.

As shown in FIG. 2, the ultrasonic distance measuring means 7 is incorporated (mounted) in the portable telephone 30. FIG. 4 is a schematic configuration diagram of the ultrasonic distance measuring means 7 mounted on the mobile phone 30, and FIG. 5 is a configuration diagram of the receiver 72 illustrated in FIG.
(E) is a graph illustrating the operation of the ultrasonic distance measuring means 7 illustrated in FIGS. 4 and 5.

The ultrasonic distance measuring means 7 illustrated in FIG.
A transmitting side having an ultrasonic transmitter 71, a transmitting ultrasonic sensor 73, and a transmitting horn antenna 75; a receiving side having an ultrasonic receiver 72, a receiving ultrasonic sensor 73, and a receiving horn antenna 74; 77.

In the illustrated configuration, a transmission horn antenna 75 and a reception horn antenna 76 are used to minimize noise around the distance measurement environment. Further, the reflected ultrasonic waves are focused using the receiving horn antenna 76. However, since the distance between the mobile phone 30 and the head of the human body is short, the antennas 75 and 76 can be omitted.

Since the ultrasonic sensor can be used for both transmission and reception, the ultrasonic sensor 73 for reception and the horn antenna 74 for reception can be used as one ultrasonic sensor. In that case, the transmission mode and the reception mode may be used separately in time. However, in the following description, an example in which the receiving ultrasonic sensor 73 and the receiving horn antenna 74 are separately provided will be described. The center axis of the transmitting ultrasonic sensor 73 (or the central axis of the directivity of the transmitting horn antenna 75) and the central axis of the ultrasonic sensor 74 for receiving (or the central axis of the directivity of the receiving horn antenna 76) are aligned. Is preferably as close to 0 as possible.

As the transmission ultrasonic sensor 73, a piezoelectric ceramic ultrasonic sensor, for example, a piezoelectric sensor such as lithium niobate can be used. Similarly to the transmission ultrasonic sensor 73, the reception ultrasonic sensor 74 can use a piezoelectric ceramic ultrasonic sensor, for example, a piezoelectric sensor such as lithium niobate.

A distance measuring method in the ultrasonic distance measuring means 7 illustrated in FIG. 4 will be described. The control unit 77 controls the transmission timing of the ultrasonic transmitter 71 and the reception timing of the ultrasonic receiver 72. The control unit 77 first sets the transmission mode. At the transmission timing, the ultrasonic transmitter 71 excites the transmission ultrasonic sensor 73 to generate ultrasonic waves from the transmission ultrasonic sensor 73. The ultrasonic wave from the transmission ultrasonic sensor 73 is transmitted to the transmission horn antenna 75.
Is directed toward the object (object) 10 to be measured, and hits the object (object) 10 to be measured. The control unit 77 sets the reception mode. At the reception timing, the ultrasonic wave reflected by the object to be measured (object) 10 is incident on the ultrasonic sensor for reception 74 via the horn antenna 76 for reception, and the ultrasonic sensor for reception 74 detects the level of the incident ultrasonic wave. And outputs an electric signal corresponding to. The ultrasonic receiver 72 includes a transmitting ultrasonic sensor 73 that emits ultrasonic waves and a receiving ultrasonic sensor 74.
The time until reception is measured in step (1), and the distance between the measured object (object) 10 and the transmission ultrasonic sensor 73 is calculated from the measurement time. The distance L1 to be measured can be calculated based on the following equation.

L1 = (V × S) / 2 (1) where V is the propagation speed of the ultrasonic wave in the air at the temperature t. V = 331.5 + 0.6t (m / sec) S is the time from the start of the oscillation of the transmitting ultrasonic sensor 73 to the time when the receiving ultrasonic sensor 74 receives the first reflected wave.

The temperature at the time of this measurement is measured with respect to a reference temperature, for example, the propagation speed of the ultrasonic wave at t = 20 ° C. The propagation velocity V of the ultrasonic wave at t = 20 ° C. is 3
32.7 (m / sec).

In the ultrasonic distance measuring apparatus of the transmission / reception separation type reflection type illustrated in FIG. 4, the transmission ultrasonic sensor 73 and the reception ultrasonic sensor 74 are drip-proof ultrasonic sensors to withstand outdoor wind and rain. It is preferable to use Since the drip-proof type ultrasonic sensor is provided with a cover, when passing through the cover, attenuation occurs to reduce the overall gain. Therefore, the transmission ultrasonic sensor 73
When a drip-proof ultrasonic sensor is used as the receiving ultrasonic sensor 74, the distance measurement range becomes short. However,
When the measured object (object) 10 is a human body, that is sufficient. Usually, the object to be measured (object) 10 and the mobile phone 3
This is because the distance from 0 is about several cm to about several tens cm. However, it is desirable to perform more accurate distance measurement, and it is preferable to perform sensitivity correction.

The following describes the ultrasonic receiver 72 which also performs such sensitivity correction. FIG. 5 is a diagram mainly illustrating the circuit configuration of the ultrasonic receiver 72 in the ultrasonic distance measuring means 7. The ultrasonic receiver 72 includes a preamplifier circuit
Buffer circuit 720, high frequency signal filtering circuit 722, ranging sensitivity correction circuit 724, low frequency signal filtering circuit / buffer circuit 726, detection circuit 728, buffer circuit / comparison circuit 7
30 and a distance measurement arithmetic control circuit 732.

Prior to the actual distance measurement operation, the distance measurement operation control circuit 732 generates ultrasonic sensor sensitivity correction data for sensitivity correction in the distance measurement sensitivity correction circuit 724, and based on the ultrasonic sensor sensitivity correction data. In the distance measurement sensitivity correction circuit 724, the sensitivity of the received ultrasonic signal is corrected. Therefore, ultrasonic sensor sensitivity correction data used in the distance measurement sensitivity correction circuit 724 is collected in advance. The method is described below. Driving the transmission ultrasonic sensor 73,
In a state where the sensitivity correction is not performed in the distance measurement sensitivity correction circuit 724, a temporary distance is measured in the distance measurement calculation control circuit 732 from the reception signal of the reception ultrasonic sensor 74. The distance measurement arithmetic control circuit 732 generates the obtained temporary distance and the ultrasonic sensor sensitivity correction data to be performed by the distance measurement sensitivity correction circuit 724, and sets the data in the distance measurement sensitivity correction circuit 724. The transmission ultrasonic sensor 73 is driven again. The signal received by the receiving ultrasonic sensor 74 is a distance measurement sensitivity correction circuit 724.
Is subjected to sensitivity correction. The reception signal whose sensitivity has been corrected is detected by a detection circuit 728, and the detection signal is passed through a buffer circuit / comparison circuit 730 to a distance measurement calculation control circuit 7.
32, and the distance measurement calculation control circuit 732 calculates the actual distance from the time from transmission of the ultrasonic wave from the transmission ultrasonic sensor 73 to reception of the reflected wave by the reception ultrasonic sensor 74 according to Equation 1.

The distance measurement calculation control circuit 732 performs a calculation control unit (CPU) 7320 to perform the above-described processing.
A crystal oscillation circuit 7321 as a clock oscillator of the arithmetic and control unit 7320;
, A NAND gate 7325, a reset pulse generation circuit 7327, a latch pulse generation circuit 7329, and a distance measurement pulse generation circuit 7331. Ultrasonic receiver 72
Further includes a carrier generation circuit 7242, a timing pulse generation circuit 7244, and a power amplification circuit 7246. In this example, the carrier generation circuit 7242
Generates a 40 KHz carrier.

FIGS. 6A to 6E are signal waveform diagrams for explaining operations related to the buffer circuit / comparison circuit 730, the distance measurement operation control circuit 732, and the ultrasonic transmitter 71.

The timing pulse generation circuit 7244 generates a timing pulse at a predetermined cycle as illustrated in FIG. 6A, and the carrier generation circuit 7242 generates a carrier of 40 KHz according to the timing pulse. This carrier is illustrated in FIG. However, FIG.
Is applied from the carrier generation circuit 7242 to the buffer circuit 7323, and the buffer circuit 732
3 shows a waveform gated by the gate signal from the buffer circuit / comparison circuit 730. The power amplification circuit 7246 amplifies the carrier from the carrier generation circuit 7242 to a level at which the transmission ultrasonic sensor 73 can be driven. The carrier amplified by the power amplification circuit 7246 drives the transmission ultrasonic sensor 73 and emits an ultrasonic wave toward the measured object (object) 10 (FIG. 6C).

The ultrasonic wave reflected by the measured object (object) 10 is received by the receiving ultrasonic sensor 74 via the receiving horn antenna 76 (FIG. 6C shows the waveform of the reflected wave). Are applied to the ultrasonic receiver 72. The preamplifier / buffer circuit 720 amplifies a weak electric signal from the receiving ultrasonic sensor 74 to a predetermined level at which signal processing can be performed by a subsequent circuit. The high-frequency signal filtering circuit 722 allows the high-frequency component of the signal corresponding to the reflected ultrasonic wave amplified by the pre-amplifier / buffer circuit 720 to pass, and removes the low-frequency component. Thereby, the measured object (object) 10
The low frequency noise included in the reflected ultrasonic wave from can be removed.
The ranging sensitivity correction circuit 724 has a variable gain amplifier circuit and corrects the sensitivity of the signal from the high frequency signal filtering circuit 722. This will be described in detail below. The low-frequency signal filtering circuit / buffer circuit 726 includes a detection circuit 7 in the subsequent stage.
The low frequency signal component of the output signal from the ranging sensitivity correction circuit 724 is passed so that detection can be performed at 28. The detection circuit 728 includes a low-frequency signal filtering circuit / buffer circuit 726.
The output signal from is detected. As detection in the detection circuit 728, for example, envelope detection is performed. In this example, double detection is performed. The buffer circuit / comparison circuit 730 sequentially stores the continuous signal detected by the detection circuit 728 as digital data, and compares it with a predetermined level signal, and when the received reflected wave is higher than a predetermined level, a desired reflected wave is output. It outputs a signal indicating that it has been received.

The distance measurement calculation control circuit 732 receives the ultrasonic oscillation from the transmission ultrasonic sensor 73,
The time until the reception of the reception wave by the comparison circuit 730 is measured, and the distance is calculated according to Equation 1. Further, the distance measurement calculation control circuit 732 performs the distance measurement sensitivity correction in cooperation with the distance measurement sensitivity correction circuit 724. The details are described below.

When the transmission ultrasonic sensor 73 oscillates, the reset pulse generation circuit 7327
The reset pulse Rp is output to the arithmetic and control unit 7320 based on the timing pulse from the H.323,
The counter in 320 is reset. The reset counter then starts counting the gated carrier pulse (FIG. 6B) obtained by logically operating the carrier output from the distance measuring pulse generation circuit 7331 with the timing pulse from the buffer circuit 7323 by the NAND gate 7325. I do. When the buffer circuit / comparison circuit 730 determines that the received wave is a valid reflected wave, the buffer circuit / comparison circuit 7
30 outputs the pulse signal illustrated in FIG. 6E to the arithmetic control unit 7320 and the buffer circuit 7323.
The latch pulse generation circuit 7329 includes a buffer circuit 7323.
The latch pulse Lp in response to the pulse signal from the CPU.
7320 to stop counting by the counter. The count value of this counter is the time required for the transmission ultrasonic sensor 73 to oscillate ultrasonic waves toward the measured object (object) 10 and for the reception ultrasonic sensor 74 to receive a reflected wave. Distance measurement is performed based on Equation 1 using the measurement time.
Note that the CPU 7320 performs a correction process in cooperation with the distance measurement sensitivity correction circuit 734 in addition to the above-described distance measurement process. Further, the CPU 7320 can be shared with the control means 5 illustrated in FIG.

The crystal oscillation circuit 7321 includes a CPU 7320
Is a signal source of the clock CLK. Therefore,
When the CPU 7320 is shared with the control means 5, an existing crystal oscillator of a microcomputer in the control means 5 can be used as the crystal oscillation circuit 7321.

The ultrasonic distance measuring means 7 illustrated with reference to FIGS. 4 and 5 can accurately measure the distance to the object to be measured (object) 10. In particular, since the ultrasonic distance measuring means 7 corrects the sensitivity, the distance can be accurately measured without increasing the power applied to the ultrasonic sensor 73 for reception. In particular, the inventor of the present application has found that changing the pulse width of the carrier substantially changes the power of the transmitting ultrasonic sensor. Therefore, it is possible to substantially change the applied power of the transmitting ultrasonic sensor without using a power amplifier circuit as a variable amplifier circuit or the like. In the present invention, optimally set the pulse width of the carrier according to the distance,
The transmission ultrasonic sensor is driven by the power according to the pulse width.

Preferably, the pulse width of the carrier is set up to the object to be measured (object) 10, for example, at a distance in the middle of the measurement range, and the transmission ultrasonic sensor is driven by the carrier. Perform distance measurement. Next, from the result of the approximate distance measurement, a pulse width of a carrier most suitable for the distance measurement is determined, and the transmission ultrasonic sensor is driven by the carrier having the pulse width to perform the distance measurement. This second distance measurement is an accurate distance measurement.

Although the above-described processing of the ultrasonic distance measuring means 7 has been described for the case where accurate distance measurement is performed, as described with reference to FIG. 4, the antenna 1 and the object to be measured (object ) It is also possible to measure the distance to 10. In that case, the antenna 76, the sensitivity correction circuit 724, and the antenna 75 illustrated in FIG. 5 are removed, and the processing of the CPU 7220 is simplified. Further, the receiving ultrasonic sensor 73 and the receiving horn antenna 74 may be one ultrasonic sensor for both transmission and reception.

Referring again to the circuit illustrated in FIG.
As described above, based on the result of measuring the distance between the antenna 1 and the measured object (object) 10 by the ultrasonic distance measuring means 7, the control means 5 determines the matching condition of the antenna matching circuit 3,
In the above-described example, a matching circuit according to the distance measurement result is selected, and impedance matching between the antenna 1 and the antenna matching circuit 3 is performed under optimal conditions. If transmission and reception are performed under such optimal impedance matching conditions, the mobile phone 30 can always talk in a good state.

The adjustment of the antenna matching circuit 3 by the control means 5 is performed by adjusting the antenna 1 and the object to be measured (object) 10.
It is preferable to perform this only when the distance from the object is within a predetermined range. The reason for this is that it is not normal to make a call when the distance between the measured object (object) 10 and the antenna 1 is longer than a predetermined distance, and that the measured object (object) 10 is very far from the antenna 1 This is because the influence on the antenna 1 is small.

In the above example, the case where the antenna 1 and the head of the human body as the object to be measured (object) 10 are located in the vicinity has been described. The object to be performed is not limited to the head of the human body, but may be an object located near the antenna 1, for example, a metal object.

The adjustment of the matching condition of the antenna matching circuit 3 by the control means 5 can be performed not only in the above-described stepwise manner by switching, but also continuously. In that case, the antenna matching circuit 3 is constituted by a variable resistance element, a variable capacitance element and the like, and the control means 5 changes the values of the variable resistance element and the variable capacitance element.

The condition change of the antenna matching circuit 3 by the control means 5 can be prevented from being performed by, for example, setting a mode switch in the mobile phone 30.

Note that the portable telephone 30 is shown in FIGS.
In the case where the ultrasonic distance measuring means 7 described with reference to FIG. 7 is mounted and operated, the mobile phone 30 itself is equipped with various electronic circuits and a power supply (battery) for operating the electronic circuits. There is no electrical problem in operating the means 7. Further, since the circuit configuration of the ultrasonic distance measuring means 7 is not particularly complicated and is small,
0 can be easily accommodated.

As described above, the embodiments of the present invention have been described with respect to a small portable communication device, in particular, a mobile phone. Will be easy to understand. For example, in a fixed communication device, an obstacle located near the antenna, in particular, a metal object that absorbs and reflects radio waves, and the position of the antenna are measured by the same method as the ultrasonic distance measuring means 7 described above. Then, by adjusting the matching condition of the antenna matching circuit 3 in the same manner as the control means 5 described above, optimal communication becomes possible.

[0052]

According to the present invention, the influence on the human body is small,
It has a low-cost, compact, stable operation for a long period of time and, for example, has a distance measuring means that can be mounted on a small communication device such as a mobile phone. To provide a communication device capable of adjusting the threshold value.

Further, according to the present invention, a small portable communication device having a distance measuring means can be provided.

[Brief description of the drawings]

FIG. 1 is a partial configuration diagram of a small portable communication device as an embodiment of a communication device of the present invention.

FIG. 2 is a diagram illustrating a positional relationship between a mobile phone as an embodiment of the present invention and a head of a human body as an object to be measured (object).

FIG. 3 is a graph illustrating that power absorption changes in accordance with the distance between the antenna 1 of the mobile phone 30 and the head of the human body in FIG.

FIG. 4 is a schematic configuration diagram of an ultrasonic distance measuring unit illustrated in FIG. 1 mounted on a mobile phone.

FIG. 5 is a detailed circuit configuration diagram of the ultrasonic distance measuring means illustrated in FIG. 4;

6 (a) to 6 (e) are signal waveform diagrams for explaining the operation of the ultrasonic distance measuring means illustrated in FIGS. 4 and 5. FIG.

[Explanation of symbols]

 1 Antenna 3 Antenna matching circuit 5 Control means 7 Ultrasonic distance measuring means 71 Ultrasonic transmitter 72 Ultrasonic receiver 73 Ultrasonic sensor 74 for reception 74 Ultrasonic sensor 75 Transmitting horn antenna 76 Receiving horn antenna 10 Measurement object (object) 30 Mobile phone

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) H04B 1/40 H04B 1/40 5K062 7/26 7/26 B 5K067 F term (reference) 2F024 AA16 AB07 AF03 5J046 AA02 AA04 AB06 TA03 5J083 AA02 AD04 AE08 AF04 CA01 CA03 5K011 AA01 DA02 JA01 KA00 LA01 5K060 AA02 BB00 CC04 CC12 DD04 JJ21 LL07 LL28 PP05 5K062 AA01 AB12 AC01 AE02 AF04 5K067 AA13 BB04 EE02 EE32 EE38 EE38 KK

Claims (6)

[Claims] An antenna; a matching circuit for impedance matching with the antenna; distance measuring means for measuring a distance between the antenna and an object by ultrasonic waves; and the matching in accordance with the distance measured by the distance measuring means. A communication device having circuit condition adjusting means for adjusting a matching circuit condition of a circuit. 2. The communication apparatus according to claim 1, wherein said circuit condition adjusting means adjusts the matching circuit condition only when the distance measured by said distance measuring means is within a predetermined distance. 3. An ultrasonic sensor for transmission provided in the communication device, an ultrasonic sensor for reception provided in the communication device, and an ultrasonic sensor for transmission provided in the communication device. Exciting means for exciting an acoustic wave sensor, provided in the communication device, ultrasonic waves emitted from the transmitting ultrasonic sensor are reflected by the object, and the reflected ultrasonic waves are received by the receiving ultrasonic sensor. Ultrasonic distance measurement means for measuring the time from transmission of ultrasonic waves to reception of ultrasonic waves, and measuring the distance from the ultrasonic sensor for transmission or the ultrasonic sensor for reception to the object from the measurement time. The communication device according to claim 1, comprising: 4. The communication device according to claim 1, wherein said communication device is a small portable communication device. 5. An ultrasonic sensor for transmission, an ultrasonic sensor for reception, excitation means for exciting the ultrasonic sensor for transmission, and ultrasonic waves emitted from the ultrasonic sensor for transmission are reflected by an object, The reflected ultrasonic wave is received by the ultrasonic sensor for reception, the time from transmission of the ultrasonic wave to reception of the ultrasonic wave is measured, and the ultrasonic wave sensor for transmission or the ultrasonic sensor for reception is measured from the measurement time. A small portable communication device having an ultrasonic distance measuring means for measuring a distance to the object. 6. The small portable communication device according to claim 5, wherein said transmitting ultrasonic sensor and said receiving ultrasonic sensor are integrally formed.