Cordless telephone apparatus with a speakerphone operation mode cordless
This application is a continuation of application Ser. No. 07/802,485 filed Dec. 5, 1991, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a cordless telephone apparatus having a handset with a radio communication function, and a stand for the handset. 
     2. Description of the Related Art 
     FIG. 3 is a diagram showing the schematic configuration of a conventional cordless telephone apparatus. In FIG. 3, there is shown a base set 1. A telephone line 3 is connected to the base set 1. An antenna 5 performs transmission/reception of radio signals with a handset 7. The base set 1 performs interface control with the telephone line 3 during conversation by the handset 7. 
     An antenna 9 performs transmission/reception of radio signals with the base set 1. The handset 7 comprises a microphone and a receiver operation unit, and is used by the operator for actual conversation. 
     When the operator engages in conversation, communication of data signals is first performed between the base set 1 and the handset 7 to confirm an ID (identification) code, to determine a channel to be used, and the like. According to this communication, a voice channel to be used is determined from among a plurality of voice channels, and voices are transmitted and received through the determined channel. 
     The operator&#39;s voice is transmitted from the handset 7 to the base set 1 through the transmitting voice channel, and is coupled from the base set 1 to the telephone line 3. A voice received from the telephone line 3 is transmitted from the base set 1 to the handset 7 through the receiving voice channel, and is heard by the operator. 
     Thus, the operator can engage in conversation over the telephone line 3 via a radio signal using the handset 7. 
     A charger 11 also functions as a stand for the handset 7. When the handset 7 is not used, a battery, serving as a power-supply unit for the handset 7, is charged by placing the handset 7 on the charger 11. 
     In the above-described conventional apparatus, since a radio signal is transmitted between the base set 1 and the handset 7, no cord curling occurs, and the handset 7 can be freely moved. However, it is always necessary to lift the handset 7 from the stand and to engage in conversation with the handset 7 close to the ear. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to improve the operability of a cordless telephone apparatus. 
     It is another object of the present invention to reduce electric power consumed in a handset of a cordless telephone apparatus. 
     It is still another object of the present invention to reduce the weight of a handset of a cordless telephone apparatus. 
     The invention is directed to a stand for a handset that receives voice signals via a radio network. The stand includes a voice signal receiver in the handset and a speaker that reproduces the received voice signal. 
     These and other objects and features of the present invention will become more apparent from the following detailed description of the preferred embodiment taken in connection with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention; 
     FIG. 2 is a flowchart illustrating processing in the embodiment shown in FIG. 1; and 
     FIG. 3 is a block diagram of a conventional apparatus. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 is a block diagram showing the configuration of a cordless phone according to an embodiment of the present invention. 
     In FIG. 1, there are shown a base set 2, a handset 30, and a stand 80 for the handset 30. Solid lines represent paths of voice signals, and broken lines represent paths of contol signals. 
     In the base set 2, a telephone line 4 is connected to the base set 2. A call-reception detection unit 5 detects call reception from the telephone line 4. A speech network 6 functions as an interface for voice to be transmitted and received voice with the telephone line 4. A dialer 8 generates a dial signal when calling is performed for the telephone line 4. A voice signal processing unit 10 performs modulation/demodulation of voice to be transmitted and received voice. A transmission unit 12 transmits data and voice to the handset 30. A reception unit 14 receives data and voice from the handset 30. A modem 16 performs modulation/demodulation of data communicated with the handset 30. A duplexer 18 separates voice to be transmitted to the handset 30 from signals received from the handset 30. A control unit 20 contols respective units within the base set 2. An antenna 22 performs transmission/reception with the handset 30. 
     In the handset 30, a transmission unit 32 transmits data and voice to the base set 2. A reception unit 34 receives data and voice from the base set 2. A duplexer 36 separates signals to be transmitted to the base set 2 from signals received from the base set 2. A voice signal processing unit 38 performs modulation/demodulation processing of voice to be transmitted and received voice. A modem 40 performs modulation/demodulation of data exchanged with the base set 2. A speaker phone voice control unit 42 performs voice control when conversation is performed in a speaker-phone (hands-free) state. A switch 44 switches a voice signal from a microphone 48. A switch 46 switches the received voice processed in the voice signal processing unit 38. The microphone 48 is used for voice transmission. A receiver 50 is used fop voice reception. An operation unit 52 is operated by the operator. A state detection unit 54 detects whether the handset 30 is placed on the stand 80 or is lifted therefrom. A control unit 56 controls respective units within the handset 30. An antenna 58 performs transmission/reception with the base set 2. A battery 60 serves as a power supply for the handset 30. A ringer 62 notifies the operator of a call from the telephone line 4. 
     In the stand 80, a charging circuit 82 charges the battery 60 within the handset 30. A speaker amplifier 84 amplifies a received voice during conversation in a speaker-phone (hands-free) state. There is also shown a speaker 86. 
     The handset 30 and the stand 80 are connected via contacts for a voice signal, a control signal and charging. 
     The operation in the above-described apparatus will now be explained with reference to FIG. 2. 
     First, the path of a data signal communicated between the base set 2 and the handset 30 will be explained. 
     That is, when a data signal is transmitted from the base set 2 to the handset 30, in the base set 2, the data signal is transmitted to the outside via the control unit 20, the modem 16, the transmission unit 12, the duplexer 18 and the antenna 22. This data signal is received by the control unit 56 of the handset 30 via the antenna 58, the duplexer 36, the reception unit 34, and the modem 40. 
     When a data signal is transmitted from the handset 30 to the base set 2, in the handset 30, the data signal is transmitted to the outside via the control unit 56, the modem 40, the transmission unit 32, the duplexer 36 and the antenna 58. This data signal is received at the control unit 20 of the base set 2 via the antenna 22, the duplexer 18, the reception unit 14 and the modem 16. 
     Next, the paths of voice signals between the base set 2 and the handset 30 will be explained. 
     That is, in the base set 2, voice received from the telephone line 4 is transmitted to the outside via the telephone line 4, the speech network 6, the voice signal processing unit 10, the transmission unit 12, the duplexer 18 and the antenna 22. This voice signal reaching the handset 30 is received via the antenna 58, the duplexer 36, the reception unit 34 and the voice signal processing unit (reception) 38. 
     A voice from the handset 30 is transmitted to the outside via the voice signal processing unit (transmission) 38, the transmission unit 32, the duplexer 36 and the antenna 58. This voice signal reaching the base set 2 is transmitted to the telephone line 4 via the antenna 22, the duplexer 18, the reception unit 14, the voice signal processing unit 10 and the speech network 6. 
     In this apparatus, when there is a call reception from the telephone line 4 (step S1), the call-reception detection unit 5 detects the call, and a data signal indicating &#34;call reception from the telephone line&#34; is transmitted via the above-described path of the data signal from the base set 2 to the handset 30. In recognizing this transmission, the control unit 56 rings the ringer 62 to notify the operator of the call reception. 
     When the operator requests conversation by operating the operation unit 52 (step S3), a data signal indicating the &#34;conversation request&#34; is transmitted via the aforementioned path of the data signal from the handset 30 to the base set 2. In recognizing this transmission, the control unit 20 performs inquiry of an ID code and determination of a voice channel to be used by communicating data signals with the base set 2 (step S4). 
     The processing of the conversation request from operating the operation unit 52 to the determination of a voice channel to be used is the same as when the operator arbitrarily requests calling and operates the operation unit 52 (step S2). 
     When the channel to be used has been determined, a voice conversation state is provided (step S5). In the voice conversation state, if a state wherein the handset 30 is lifted from the stand 80 (a usual state of use wherein the operator brings the handset 30 close to the ear) is detected by the state detection unit 54 (step S6), the control unit 56 sets the switches 44 and 46 to a No (normal) side, and conversation is performed (step S7). 
     That is, the voice of the operator is transmitted from the microphone 48 to the voice signal processing unit 38 via the switch 44, is further transmitted through the above-described path of the voice to be transmitted from the handset 30 to the base set 2, and is coupled to the telephone line 4. 
     A received voice from the telephone line 4 is transmitted to the voice signal processing unit 38 through the above-described path from the base unit 2 to the handset 30, and reaches the receiver 50 via the switch 46. Thus, the operator engages in conversation with a communication partner on the telephone line. 
     If the state detection unit 54 detects a state wherein the handset 30 is placed on the stand 80 in step S6, the control unit 56 sets the switches 44 and 46 to SP (speaker phone) side in step S8, and conversation is performed. 
     That is, the voice of the operator is transmitted from the microphone 48 to the speaker phone voice control unit 42 via the switch 44, and the voice received from the telephone line 4 is transmitted from the voice signal processing unit 38 to the speaker phone voice control unit 42 via the switch 46. The speaker phone voice control unit 42 compares the levels of the voice to be transmitted and the received voice, and determines the state of conversation. That is, if the level of the voice of the operator is higher than the level of the received voice, the received voice is muted (or reduced to a very low level) to provide a voice transmitting state, and the voice of the operator is transmitted from the speaker phone voice control unit 42 to the voice signal processing unit 38. The voice of the operator is transmitted to the outside via the antenna 88. If the level of the voice of the operator is lower than the level of the received voice, the voice of the operator is muted (or reduced to a very low level) to provide a voice receiving state, and the received voice from the antenna 88 is transmitted from the speaker phone voice control unit 42 to the speaker driver 84, where the voice is amplified to ring the speaker 86. 
     Thus, it becomes possible to perform a speaker-phone conversation (hands-free conversation) by an amplified received voice while howling is prevented. 
     The conversation is terminated according to an instruction from the operation unit 52 (step S9). 
     In the present embodiment, a handset-conversation mode and a speaker-phone-conversation mode are altenatively selected when the handset 30 is lifted from the stand 80 and when the handset 30 is placed on the stand 80, respectively. That is, the handset-conversation mode and the speaker-phone-conversation mode may be repeated any times. 
     While the present invention has been described with respect to what is presently considered to be the preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiment. The present invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.