JPH0216849A - Method and device for detecting state of handset in codeless telephone system - Google Patents

Abstract

PURPOSE:To attain automatic restriction with a charge current by judging whether a system is in a holding mode or a call mode in accordance with whether the micro voltage drop of both ends voltages in a secondary battery repeats in a prescribed period. CONSTITUTION:A micro voltage drop circuit 20 supervises the voltages of both ends of charge output terminals T<+> and T<->. When a handset connected to both ends of the secondary battery 10 is in the holding mode as an accurate state in the terminals T<+> and T<->, a micro voltage drop component appears in both ends of the secondary battery 10 at a prescribed period with an intermittent reception state since the handset is in the intermittent reception state. When the component is inputted to the base input P1 of an npn transistor Q3 through a differential capacitor 18, the waveform shaping output of a corresponding period appears in the output of an invertor 19. With the output, the output of a mode decision circuit 21 becomes L, and an alarm circuit 22 is prevented from operating. When a user who has terminated a call forgets to return the response switch of the handset to a holding position, and the switch is left in a call position as it is, a micro voltage drop pulse waveform cannot be obtained and an alarm sound occurs.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is particularly applicable to a cordless telephone system, which is a type of communication system that utilizes full-duplex communication using a D-mode line. In situations where the set is placed on a cradle 1- equipped with a base unit or a dedicated charger, and charging current is supplied from the built-in charging circuit to the rechargeable battery built into the handset. The present invention relates to a method and apparatus for detecting whether the handset is in standby mode or talk mode.

[Prior Art] In order to be able to make calls without being restricted by the length of the connection cord, a main unit or base unit corresponding to the telephone main body and a transmitter are connected to the telephone main body connected to the telephone line by the L+ line. A handset or handset (remote/
In recent years, cordless telephones that communicate with a mobile phone unit (also called a portable unit) via an antenna have become popular on the market.

However, one of the basic functions of such cordless telephone systems is to connect the handset to the base in order to charge the built-in rechargeable battery in the handset.
When the unit is placed in a predetermined position, such as a so-called cradle, the charging output terminal on the base unit 1~ side and the charging input terminal on the handset side are connected, automatically connecting the secondary The battery will now start charging. However, recently, due to the connection with the wired telephone line, even the permanently installed base unit 1.1 has to be set up every time it is used. Even if I return it to the 1, 17 river charger 1- which I placed near the user, I try to charge the primary battery built into this hand set when it is not in use. There are also some suggestions.

In order to prevent such over-discharge or wasteful consumption of the secondary 11L battery and to extend its life as much as possible, it should be used when the handset is on standby, that is, waiting for a call to come in. When you are in a state of
A method is preferred in which power is supplied intermittently at a predetermined period to all or at least part B of the circuit system in the entire circuit system, which is related to at least A1 and B. .

The power consumption of secondary batteries over time:
The purpose is to reduce the burden by reducing the power consumption.3 Therefore, as a general rule, it is not necessary to supply power to the transmitter circuit system during this standby state (standby mode). That's not the point.

However, as a matter of course, the handset
1 (There is a presence from the telephone line through the base unit, and after confirming this bell signal on the handset,
After the bell sounds, or when the user calls this call
'1 and operate the answer switch or talk switch on the handset to switch from the standby position to the talk position, or to make a call from the user's side for the first time. After switching the response switch to the talking position, power is continuously supplied from the next battery to the transmitting circuit from the handset side and to the circuit parts that had previously been supplied with power only intermittently. Power is supplied to the

In such a system configuration, conventionally, when the handset is placed on a predetermined position on the base unit,
``7+Note: Hand charging circuit from built-in Heath unit.
A predetermined amount of charging current is automatically and uniquely supplied to the secondary battery built into the set.

Also, there was no determination as to whether the handset returned to the base unit was currently in standby mode or talk mode.

[Problems to be Solved by the Invention] As mentioned above, cordless telephones themselves are very convenient, and measures for the rechargeable battery built into the handset, including its usability, have been made to a certain extent satisfactory. It has become to.

However, for Nagisa, who is used to using a regular telephone, the operation of switching the response switch on the handset felt somewhat unusual.

As is clear from the above explanation, for example, when you hear a ringing bell, you press this response switch from the standby position to make a call.
The operation of switching to the device is originally equivalent to picking up the handset on a normal telephone, or because the hook switch is automatically raised on normal telephones when the handset is lifted. For those who use cordless phones, it is easy to feel that what they have done is simply to lift the handset, and nothing else has been done. No. 1 often happens when you pick up a handset that was listed on a computer, and it doesn't do anything, and you think something is wrong because the line won't connect, and only after a while do you realize that you forgot to press the response switch. :do.

Similarly, after a call is over, just as with a normal telephone, it is possible to forget to return the answer switch after returning the handset to the base unit 1-.

In fact, the latter case is particularly likely to cause problems.

That is, as mentioned above, in the cordless telephones developed to date, when the handset is returned to a predetermined position, such as on the cradle of the base unit, the handset is automatically and uniquely activated. - Charging of the built-in secondary battery of the set starts, and the charging current at this time is generally a constant current.

On the other hand, with today's cordless telephones, various controls are required.
Many handsets have a built-in microcomputer, so if you forget to return the response switch and charging starts, the microcomputer is automatically set to protect the circuit. There is.

These countermeasures themselves are preferable in terms of preventing product failures, and can even be called a failure, but for this reason, as mentioned above, when charging starts without returning the response switch, the microcomputer If it is reset, you will not be able to enter standby mode, let alone call mode, and simply put, you will no longer be able to answer or answer calls.

And when this happens, the battery inside the handset actually shows an evil +, 16M.

This is because rechargeable batteries have an optimal charging current value, and therefore, as mentioned above, charging circuits are generally designed around this value, even though it may not always be the optimal value. Constant current countermeasures are taken to maintain an appropriate value.

However, this design standard has conventionally been established only under the condition of -F under normal use, and even in the case of misuse as mentioned above, in other words, if the response switch is forgotten to be returned and the base unit is Even when the handset is returned to the original position, the charging current value is not set to the optimum value for the secondary battery. In fact, in the past, it was never considered that in such a case, the preset charging current value might become inappropriate for the secondary battery.

However, when charging starts while the phone is still in the call mode as described above, the circuit system is protected and the microcomputer is reset, causing the entire circuit system to go into the body 11-1 state. The power consumption within the handset is significantly lower than even in standby mode with intermittent reception;
The amount of charging current supplied to the 71st battery in the handset is (He turns into a human at 11.

In other words, for the above-mentioned reasons, the charging current value from the charging circuit, which is often preferably configured as a constant current type, is not sufficient to charge the rechargeable battery built into the handset in standby mode with intermittent reception. Under the normal IF condition of starting from jl, this predetermined charging current is uniquely set to be the appropriate amount for charging the secondary battery, so when charging starts while in call mode, this predetermined charging current Even if the secondary battery is currently being charged, the amount of power 111 that should normally be borne by the intermittent reception becomes excessive due to the loss.

This excessive charging will significantly shorten the lifespan of the secondary battery.
Needless to say, this is undesirable.

The motive of the present invention is to solve such a problem, but in reality, upon careful consideration of this problem, conventionally, a base unit is equipped with a III+ or a river charger. However, the charging output terminal provided on them is the charging input terminal provided on the handset.
The cause of this can be seen to be that the handset simply starts charging automatically when connected to the device, but does not pay any attention to the current state of the handset. .

Then, when the charging output terminal on the charging side and the charging Oat terminal on the handset side are connected, the handset at that time is in standby mode by some method, or If it can be determined whether the phone is still in call mode (or whether the response switch has been forgotten to return), it will be easier to come up with a solution to the above problem.

The present invention has been developed based on these viewpoints, and is intended to specifically disclose the above-mentioned "some method".

In other words, the object of the present invention is that when the charging output terminal of the base unit or a dedicated charger is connected to the charging input terminal of the handset, another separate detection line and an antenna are connected to each other. In other words, without requiring major modifications to current cordless telephone systems,
It is an object of the present invention to provide a method and apparatus for reasonably detecting whether the set is in standby mode or in talk mode, and furthermore, to provide an alarm when charging or starting is started while the set is in talk mode. The system requests the user to return the response switch, or attempts to automatically limit the charging current thereafter.

[F-stage to solve the problem] In order to achieve the object described in item L, the present invention intermittently connects all or at least one part of the receiving circuit system to the secondary 1-1, each time power is supplied from the battery, a small voltage drop F occurs in the voltage across the secondary battery due to the influence of inrush current and the like.

In fact, after confirming this, in cordless telephones currently on the market that use a secondary '1IF battery with a rated voltage of 5V in the handset, the A detectable voltage drop of approximately 100 mV occurred. The intermittent reception operation at this time is one second on, one second off type. If you look at it as a supply voltage pulse from a secondary battery, the pulse interval is 2 seconds, the pulse width is 1
It is a pulse of seconds (therefore, the duty ratio is 50%).

On the other hand, in a call mode in which power is continuously supplied from the secondary battery to all circuits involved in transmission and reception (1), the voltage across the secondary battery has a period as shown in F. It was also confirmed that no small voltage drop occurred. (Actually, under this call mode, power consumption is almost constant.

For these reasons, the present inventor discovered that when the charging input terminal of the handset is connected to the charging output terminal of the base unit or the dedicated charger, the charging output terminal of the handset ends up being connected to the charging output terminal of the base unit or the dedicated charger.・In conjunction with the knowledge that it is possible to obtain information on the voltage across the secondary battery built into the set, by monitoring the voltage across the secondary 'heavy oil over time via the 5-way charging output terminal, it is possible to determine the hand A configuration has been disclosed that determines whether the set is in standby mode or in call mode.

To explain in more detail, when the charging input terminal on the handset side is connected to the charging output terminal of the base unit or dedicated charger, the secondary battery built in the handset Monitor the voltage across the battery,
When in standby mode, power is intermittently supplied to not only the entire CJ circuit system related to reception, but also the circuitry, which causes a small voltage drop. If this minute voltage drop recurs at a predetermined cycle, it is determined to be in standby mode. Otherwise, if this minute voltage drop does not occur even after a predetermined cycle, it is determined to be call mode. 1
- We will disclose a method to do so.

In this way, if the base unit or dedicated charger knows whether the handset placed on it is in standby mode or talk mode, the base unit or dedicated charger can also If necessary, a circuit can be built on the unit or Q River charger side to issue an audible alarm or a visual alarm, or both, when it is determined that the call mode is selected, or instead of or in addition to this. It also becomes easy to automatically limit the charging current output by the charging circuit.

Of course, there is a minute voltage drop detection circuit for these, a mode judgment circuit that takes into account the period of occurrence of the minute voltage drop, and a setting current value change (limitation) in the alarm circuit and constant current charging circuit that operate based on the mode judgment circuit output. The physical circuit configuration itself, such as a circuit, is an optional problem for those skilled in the art.

[Operations and Effects] According to the configuration of the present invention, when the response switch provided in the handset is returned to the base unit or dedicated charger while remaining in the talking position without being returned to the standby position, However, there is a mode judgment circuit on the base unit or dedicated charger side that judges whether a minute voltage drop appears at a predetermined period in the voltage across the secondary battery built into the handset. At the output of this circuit, a specific decision signal can be obtained indicating that the handset is currently in talk mode, e.g., labeled as the "talk mode signal."

Of course, on the other hand, when the response switch is correctly returned to the standby position, by confirming the existence of a minute voltage drop that occurs at a predetermined period across both ends of the secondary battery, it is possible to separate the signal from the call mode signal. A second signal can also be obtained in a form that is identifiable and labeled as "standby mode signal".

Generally, these call mode signals and standby mode signals are
When one signal is defined as high level "H" or logic "1", the other is defined as low level "°L" on the same route 111.
or logic "0" and definition 1 is valid.

Due to the existence of such a J, L effect, the present invention can be used to protect a secondary battery built into a handset.

In other words, when the mode determination circuit in L outputs the call mode signal, the alarm circuit is configured to generate at least one or both of an audible alarm and a visual alarm in response to the signal. I can do it,
Furthermore, if necessary, during the call mode, the constant current setting of the charging circuit can be set by No. 411! 1'1 or install a circuit that limits the maximum current that can be supplied (including selectively changing the standard resistance value in the constant current charging circuit by applying an analog switch). You can also do that.

Since these alarm circuits and charging current value changing (limiting) circuits are installed in the base unit or the dedicated charger, conversely speaking, the dedicated charger can be installed in a convenient location for the user. Learn more about recent proposals
The present invention can also be used in layered reality.

In any case, particularly preferred in the present invention are:
A separate X+ is required to determine the internal mode of the handset.
In order to clear the R river detection line, or the handset side must always transmit a mode signal that conforms to a specific data format, the circuit becomes complicated, costs increase, and specifications change, etc. There is no place for it at all.

As is clear, from the results of the present invention, the present invention can be applied to the external equipment side of the handset.
yl=<, detect the internal mode state of the handset 1:? Therefore, claim 1 discloses the most basic configuration of the present invention among the retention chamber configurations.
, 4, the present invention not only relates to the protection of the primary battery as described above, but also includes, in addition to or in place of, the protection of the hand battery on the heat unit or the 417 charger. It can be seen that it is quite applicable to other applications where it is necessary to determine the current mode I of a handset when the set is loaded.

[Embodiment] FIG. 1 shows a preferred embodiment of a method for detecting the state of a handset in a cordless telephone system of the present invention and a device used therefor.

Although the figure only shows the main parts of the present invention and omits the overall configuration of the cordless telephone system, the cordless telephone set to which the present invention is applied is capable of intermittent reception (7E) at least in the standby state. Any known existing form may be used as long as it is suitable.

Broadly summarized, the pace unit includes a pace unit connected to a telephone line and a handset capable of being coupled by radio frequency to the base unit, the handset including at least the circuitry involved in reception. Power is supplied only intermittently to a part of the system from the secondary battery built into the Ei handset (in standby mode, where power is not supplied), and to all circuit systems that are connected to telephone calls, the rechargeable battery A call mode is set in which power is continuously supplied from the base unit or t+/.
- It may be defined as a cordless telephone system or a cordless telephone cellar l-J in which a charging circuit for charging the secondary battery built in the handset is provided in the charging machine.

As mentioned in advance, in the case shown in the figure, only the secondary battery 10 shown by the phantom line is built into the handset, and the other circuit parts are built into the pace unit or not.
Alternatively, if a dedicated charger is provided separately from the base unit, it is a part built into the charger.

Therefore, the terminals T" and T- shown at both ends of the secondary battery 10 in the figure become charging output terminals when viewed from the base unit or dedicated charger side, and these terminals
When viewed from the side of the handset placed on a predetermined position, such as a cradle provided in a unit or a dedicated charger, a geometrical shape that is mechanically or electrically connected or in contact with the 5-e charging output terminal. It also serves as an input terminal on the handset side of the engagement relationship. In the following, whether the explanation is about the base unit or the dedicated charger,
Or, depending on whether the instructions are about a handset,
These ends -f-T", T- to the corresponding ones above, l
Replace and use once.

The base unit or the dedicated charger is provided with a power supply circuit (not shown), from which the curved power supply electrification +11h) is connected. In the illustrated case, an electrolytic capacitor 12, which is a final stage filter element, and a light emitting diode 1: (having a current limiting resistor in series as a pilot lamp indicating that the power is turned on) are shown.

The power supply voltage line +It and the ground line are connected to a commercially available three-terminal regulator ((;, including control transistor 01, etc., -1
The - barrel components are connected to charging output terminals T+ and T- via a constant current charging circuit II using a well-known circuit configuration.

However, in the case of this embodiment, the standard resistors that determine the constant current setting value are the resistor 1 (1 and the resistor [(, Togara), which is selectively inserted in series with this resistor R by the operation described later. First, the resistor R2 is short-circuited by an analog switch 33, which will be described later, and the constant current value is set only by the resistor R1, as in a normal constant current circuit of this type. Suppose there is.

where the handset or base unit or -V
The charging input terminals T" and T are placed on the charger for
- comes into contact with the charging output terminals T+ and T- on the base unit or dedicated charger side, the secondary battery 10 built into the handset automatically becomes constant current according to the value of the standard resistor R3. charging current is supplied.

Regarding the start of this charging, in the case of this embodiment, a charging detection circuit electrically separates the case where the secondary battery is connected between the charging output terminals 'r' and 1' and the case where it is connected. 1
4, which informs the user that the 11th battery 10 built into the handset is being charged.

However, the specific circuit configuration of this charging detection circuit 14 is simple! Hayashi uses a pnp switching transistor (2) to detect a drop in base voltage when a secondary battery is connected between charging output terminals T+ and T-, and when this turns on, A light emitting diode 15, which serves as a charging indicator, lights up.

However, the collector of this transistor Q2 is the NOR gate (that is, the inverter) used in the inverter connection.
i is also given, and the output of the inverter 16 has a low level when the transistor q2 is turned on. This occurs only when this low level signal (↓) is given to the Noah gate 17 in the mode judgment circuit 21, which will be described in detail later, that is, the secondary battery 10 is connected between the terminals T" and Only when connected, the judgment output of the mode judgment circuit 21 is enabled.

In other words, the NOR gate 17 shown in the mode judgment circuit 21 is configured to output the judgment output of the mode judgment circuit 21 only after the start of charging of the primary battery 10. The alarm circuit 22 is configured to prevent the alarm circuit 22 from being erroneously activated by the output of the mode judgment circuit 21 even when the secondary battery IO is not connected between the terminals T'' and T-. In other words, the secondary battery 10 is not connected between the charging output terminals T" and T-, and the transistor Q2 in the charging detection circuit 14
is off and the light emitting diode 15 is off, the output from the inverter 16 is at a high level, so the output from the NOR gate 17 is high or low regardless of the level of the external power. , is necessarily fixed at logic "L", and such logic "L" does not drive the alarm circuit 22, which will also be described later.

The voltage across the charging output terminals T" and T- as seen from the base unit or a dedicated charger is monitored by a minute voltage drop detection circuit 20.

Therefore, when the secondary battery 10 is connected between the charge output terminals T+ and T-, these terminals T'' and T
- can be used as an intermediary to monitor the voltage across the secondary battery 10.

The small voltage drop detection circuit 20 in the illustrated case consists of two cascaded npn transistors Q3. Q.

and a NAND gate 19 connected to an inverter to invert and use the detection output for convenience of the circuit.This configuration itself can be easily assembled by a designer of ordinary electronic circuit technology. It is essentially an amplifier configuration that also serves as a differential pulse waveform shaping circuit.

If the handset is currently connected to both ends of the secondary battery IO to the charging output terminals T+ and T-, or if it is in standby mode as described above, that is, if the handset has finished using If the user is ready to set up the handset,
When the handset is placed in the specified position I on the base unit or dedicated charger after one response switch has been correctly returned to the standby position, the handset will enter the intermittent reception state. Therefore, for the reasons already mentioned, a minute voltage drop component appears at both ends of the secondary battery 10 at a predetermined period accompanying this intermittent receiving operation each time.

When this is received by the base power P1 of the NPN transistor 03 via the differential capacitor 18, the waveform-shaped output is amplified to an appropriate amplitude value at the corresponding period and finally becomes the output of the inverter 11. appear.

In FIG. 2, the waveform at the human power base terminal P1 of the transistor ( ) 3 is also shown schematically.
Of course, in reality, the waveform is not as beautiful as this.

Rather, the waveform obtained by inverting this waveform P with respect to the level is
This can be seen as the waveform finally obtained at the output of the inverter 19.

However, when a pulse train of a predetermined period is obtained at the output of the inverter 19, which is the output of the detection circuit 20,
For each pulse force, primarily at its rising edge,
The medium-stable multi-vibrator 23 provided in the mode judgment circuit 21 is triggered.

Here, among these, the pulse width of the output waveform P2 of the stable multi-vibrator 23 is as shown in FIG.
Although it is shorter than the period of the differential pulse train P1 detected above,
Set it so that it is longer than the pulse width of the person's caballus.

In this way, as long as the monostable multi-vibrator 2:1 is triggered periodically and the output P2 has a waveform like the one shown in the second figure, the handset can be correctly set to standby mode. The secondary battery 1 is returned to
When charging starts to 0, this monostable multi-voltage
With respect to the output of the vibrator 23, the voltage 11 across the electrolytic capacitor 26 connected via a parallel circuit of a diode 24 and a resistor 25 for closing the discharge path is also shown in FIG. The capacitance value and resistance 25
By appropriately setting the time constant associated with the value of Eth, etc., it is possible to maintain at least a predetermined value Eth over time.

Therefore, if the voltage across this capacitor 26 is applied to the manual power of the Noah gate 17 mentioned above, and the predetermined value PLh is set above the manual power threshold of the Noah gate 17, as described above, Since the logic level "L" from the inverter 16 has already been applied to the external power of this NOR gate 17, its output can be kept at the "L" level over time.

As long as the output of the NOR gate 17, and thus the output level of the mode determination circuit 21, is L'', which is a significant standby mode signal, as will be clear from the operation described below,
Alarm circuit 22 does not operate. The alarm circuit 22 operates in the following cases.

After finishing a call, the user forgets to return the response switch of the handset to the standby position, and while the handset is in the talking position, connects the secondary battery 10 between the charging output terminals T+ and T- as shown in the figure. At this time, of course, the handset remains in the call mode, and as described above, the minute voltage drop pulse waveform P1 that repeats at a predetermined period cannot be obtained at both ends of the secondary battery 10.

Therefore, periodic trigger pulses are not generated in the output of the inverter 19, which is the output of the minute voltage drop detection circuit 20, and the medium-stable multi-vibrator 23 in the mode judgment circuit 21 is also operated as shown in the second figure. Periodic waveform l)2 is not output.

Therefore, if the voltage across the summing capacitor 26 remains red for at least the time corresponding to the discharging time constant after the last charge pulse is collected, the voltage across the summing capacitor 26 will be the same as the waveform ``3'' in FIG. It becomes below the threshold value Eth of simultaneous display.

Eventually, such a condition will cause the output of the Nor-Kate 17 as the output of the mode determination circuit 21 to be pulled to a high level. This is because both the powers of the Noah gate 17 are at logic "L".

The high level obtained at the output of this NOR gate 17 is 1-
This is the call mode signal in this embodiment.

In this way, when a significant high-level talk mode signal is output to the output of the mode judgment circuit 2I, the manual control stage of the alarm circuit 22 is equipped with a・Since this call mode -J is set to the other power of the gate 27, from then on, the output of the NOR gate 27 becomes '1'+. arise.

This generates an appropriate output signal via a pair of inverters 28 and 29 obtained by NAND gate inverter connection.
"Since it is applied to the piezoelectric sounding element 30, which is one of the whole,
This activates and a warning sound is emitted to the user.

At the same time, in this embodiment, a visual alarm means is also used, and a light emitting diode 326 as a visual alarm means is driven to blink through the PNP driver transistor 05.

However, since the alarm sound may be too noisy and inappropriate at night, a switch 31 is also provided that allows the user to selectively turn on or off the alarm sound generator.

Of course, the specific configurations of these alarm sound generators and alarm light generators are not limited to the illustrated embodiments, but are a matter left to the design of those skilled in the art, and other circuit configurations are also possible. However, only one of the alarm sound and the alarm light may be used.

However, as explained above, in the actual product, an alarm will be issued if you accidentally start charging the secondary battery without returning the handset to standby mode. If you configure it like this, it is often sufficient. This is because the user will immediately notice that he or she has forgotten to operate the device.

However, if it is desired to further automate the function, the charging current may be automatically reduced in addition to or instead of issuing such an alarm. In other words, the secondary battery can be protected even if charging starts accidentally and the user does not notice it.

This embodiment also shows such a case.

That is, when the output of the NOR gate 17 appears at a high level and a significant signal (No. 8) as described above, this signal activates the analog switch 33 shown in the constant current charging circuit. This acts to open the equally curved signal line.Then, as mentioned above, the charging current of a constant current value determined only by the standard resistor R4 is supplied to the secondary battery. However, the set current value is now changed to a value determined by the series circuit of resistors R3 and R2, and becomes substantially smaller.

As a result, even though the alarm circuit 22 has issued an alarm, the user ignores it or does not notice it and does not return the response switch of the handset. Even if you omit this in the first place, there is a risk that the entire circuit system will go into the 11-state because it remains in the call mode, which may result in supplying an excessive charging current to the secondary battery. Even at certain times, the optimal
It is possible to keep the charging current value within an allowable range and is safe.

Of course, the circuit configuration for changing (limiting) the set current value in the case illustrated schematically represents an example of the simplest case.
Those skilled in the art can also adopt various change control methods based on arbitrary design judgment, and as mentioned above, the output of the mode judgment circuit 21 can be selectively obtained. The possible handset status detection signals can also be further developed into arbitrary applications.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an embodiment of a handset status detection circuit in a cordless telephone system constructed according to the present invention, and FIG. 2 schematically shows waveforms at each circuit point in FIG. FIG. In the figure, 10 is a secondary battery built into the handset, 11 is a constant current charging circuit, 14 is a charging display circuit, I5 is a charging display means, and 17 is a device that selectively enables the output of the so-called judgment circuit. Condition gate, 20 is a minute voltage drop detection circuit, 21 is a mode judgment circuit, 22 is an alarm circuit, 23 is a monostable multi-voltage
Vibrator, 30 is a sounding body as an audible alarm means, 3
1 is a light emitting diode as a visual alarm means; 33 is an analog switch in the constant current setting value changing (limiting) circuit;
n, , R, are standard resistances for setting the constant current value. Applicant Unison Co., Ltd.

Claims (6)

[Claims] (1) includes a base unit connected to a telephone line and a handset capable of coupling to the base unit by radio frequency; the handset includes at least a portion of the circuitry involved in reception; On the other hand, there is a standby mode in which power is only intermittently supplied from the rechargeable battery built into the handset, and a call mode in which power is continuously supplied from the rechargeable battery to all circuits involved in the call. In a cordless telephone system, the base unit or a dedicated charger is provided with a charging circuit for charging the secondary battery built in the handset. Whether the hand set is in the standby mode with the input terminal connected to the charging output terminal of the base unit or the dedicated charger, and charging current flowing from the charging circuit to the secondary battery. A method for detecting the state of a handset for determining whether the handset is in the call mode on the side of the base unit or the charger; monitoring the voltage across the secondary battery; The micro voltage drop caused by the intermittent supply of power to at least a part of the circuit system involved in reception is detected, and if the micro voltage drop occurs repeatedly at a predetermined period, the micro voltage drop is set to standby mode. Determining that the call mode is present when a voltage drop does not occur even after exceeding the predetermined cycle;
Set status detection method. (2) The method according to claim 1, further comprising: emitting an audible alarm, a visual alarm, or both when the call mode is determined;
Set status detection method. (3) The method according to claim 1 or 2, further comprising: limiting the charging current output from the charging circuit when the call mode is determined;
Set status detection method. (4) includes a base unit connected to a telephone line and a handset capable of radio frequency coupling to the base unit, the handset including at least a portion of the circuitry involved in reception; On the other hand, there is a standby mode in which power is only intermittently supplied from the rechargeable battery built into the handset, and a call mode in which power is continuously supplied from the rechargeable battery to all circuits involved in the call. In a cordless telephone system, the base unit or a dedicated charger is provided with a charging circuit for charging the secondary battery built in the handset. Whether the hand set is in the standby mode with the input terminal connected to the charging output terminal of the base unit or the dedicated charger, and charging current flowing from the charging circuit to the secondary battery. A state detection device of the handset for determining whether the handset is in the call mode on the side of the base unit or the charger; , a circuit for detecting a minute voltage drop appearing across both ends of the secondary battery built into the handset; determining whether or not the minute voltage drop occurs in accordance with a predetermined cycle; a determination circuit that generates a standby mode signal when the signal is generated in accordance with the above-mentioned conditions, and generates a call mode signal when the signal is not generated in the base unit or the dedicated charger; A device for detecting the status of a handset in a system. (5) The device according to claim 4, further comprising an alarm circuit that issues one or both of an audible alarm and a visual alarm based on the call mode signal output from the determination circuit. A device for detecting the status of a handset in a cordless telephone system. (6) The device according to claim 4 or 5, further comprising a circuit that limits the charging current output from the charging circuit based on the call mode signal output from the determination circuit. A device for detecting the status of a handset in a cordless telephone system.