JPH0574148U - Cordless phone - Google Patents

Abstract

(57) [Abstract] [Purpose] A cordless telephone that can fully discharge the battery of the cordless handset to prolong the life of the battery and can operate the cordless handset even when the battery is completely discharged. provide. [Composition] The comparator 13 of the charging device 10 compares the voltage of the nickel cadmium battery 22 of the slave unit 20 between the charging terminals 12a and 12b with a specified value, and when the voltage of the nickel cadmium battery 22 is less than or equal to this specified value, turns on the switch SW2. Charge it. The comparator 26 of the child device 20 uses the nickel-cadmium battery 22
When the voltage of the voltage is less than or equal to the drop detection voltage, the common terminal of the switches SW11 and SW12 of the interlocking electronic switch is switched to the terminal B side to start the operation of the DC-DC converter 24.
Is supplied to the DC-DC converter 24 via the switch and is boosted, and this voltage is supplied to the load 23 via the switch SW11.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a cordless telephone in which a cordless handset is driven by a battery.

[0002]

[Prior Art]

 Generally, a cordless telephone handset is equipped with a rechargeable nickel-cadmium battery (so-called Ni-Cd battery) 1 as shown in FIG. 2, and the power supply of the battery 1 allows wireless communication with the parent device. . Both ends of the battery 1 are connected to +/- charging terminals 2a and 2b for receiving a charge from a charger (not shown) or charging means of a master unit, and a load 3 which is various circuits for wireless communication. The load 3 can also be supplied with DC power from the outside via the DC voltage input terminal DCin.

[0003]

[Problems to be solved by the device]

 However, the life of the nickel-cadmium battery 1 generally becomes shorter as the number of times of charging increases, so that there is a problem that the life of the nickel-cadmium battery 1 becomes short if the call state and the standby state are repeated and the battery 1 is frequently discharged and charged. is there.

Here, in order to reduce the number of times of charging, a method of integrating the time when the slave unit is set in the charger and performing charging after a lapse of a predetermined time considering the power consumption of the battery load Is possible. However, since this method charges the battery taking into account the discharge time of the battery, the voltage of the battery will not change as in the case where the battery is relatively new and the performance has not deteriorated, or the performance of the battery itself is good. Even if it is not so low, the battery will be charged, which will shorten the life of the battery.

Therefore, the present invention is capable of completely discharging the battery of the cordless handset to prolong the life of the battery, and also allows the cordless handset to operate even when the battery is completely discharged. The purpose is to provide.

[0006]

[Means for Solving the Problems]

 In the present invention, in order to achieve the above object, the charging unit does not perform charging until the voltage of the first battery of the child device becomes equal to or lower than a predetermined voltage, and the child device includes the auxiliary second battery. The first battery is switched to the second voltage when the battery is below a predetermined voltage. That is, according to the present invention, in the cordless telephone in which the slave unit wirelessly communicates with the master unit by the first battery and the first battery is rechargeable, the voltage of the first battery of the slave unit is set. The slave unit includes a charging unit that detects and charges the battery when the voltage is equal to or lower than a predetermined voltage. The slave unit detects the voltage of the first battery and the second battery that assists the first battery. There is provided a cordless telephone characterized by having switching means for switching from the first battery to the second voltage when the voltage is equal to or lower than a predetermined voltage.

[0007]

[Action]

 Since the present invention has the above-mentioned configuration, charging is not performed until the voltage of the first battery of the slave unit falls below a predetermined voltage, and thus the first battery is completely discharged to reduce the number of times of charging. Therefore, the life of the first battery can be extended. Further, since the slave unit includes the auxiliary second battery and the first battery is switched to the second voltage when the first battery has a voltage equal to or lower than the predetermined voltage, the voltage of the first battery is equal to or lower than the predetermined voltage. It can work even if it becomes.

[0008]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a charging device 10 and a mobile device 20 which are an embodiment of a cordless phone according to the present invention. The charging device 10 includes a charger 11 that rectifies a commercial power source (AC100V) to generate a DC voltage (for example, DC3.6V) for the slave unit 20, and a +-for supplying the DC voltage to the slave unit 20. Charging terminals 12a and 12b, and the charger 11 and the charging terminal 12a are connected via a switch SW2.

The charging device 10 also has a switch SW 1 for detecting whether or not the charging terminals 21 a, 21 b of the slave 20 are connected to the charging terminals 12 a, 12 b, for example, by the weight of the slave 20. When the charging terminals 21a and 21b of the device are connected to the charging terminals 12a and 12b, the comparator 13 compares the voltage of the nickel cadmium battery 22 of the child device 20 between the charging terminals 12a and 12b with a specified value (for example, about 3.3V). Then, when the voltage of the nickel-cadmium battery 22 is less than or equal to this specified value, the switch SW2 is turned on. That is, when the charging terminals 21a and 21b of the child device 20 are not connected to the charging terminals 12a and 12b of the charging device 10, and when the voltage of the nickel-cadmium battery 22 is equal to or more than the specified value even when connected. Switch SW2 is not turned on, and thus charging is not performed.

The charging terminals 21a and 21b of the child device 20 are connected to a DC 3.6V nickel cadmium battery 22, and the + charging terminal 21a is connected to a terminal A of one switch SW11 of the interlocking electronic switch. The common terminal of the switch SW11 is connected to the load 23, and the terminal B is connected to the output terminal of the DC-DC converter 24. The Manganese alkaline battery 25 is, for example, a 1.5V AAA or AA auxiliary battery for the NiCd battery 22, and the + terminal of this battery 25 is connected to the common terminal of the other switch SW12 of the interlocking electronic switch. Has been done. The terminal B of the switch SW12 is connected to the input terminal of the DC-DC converter 24, and the terminal A is a free terminal.

The common terminal of the switch SW11 is also connected to the − side via the current limiting resistor R, the switch SW21, and the light emitting diode LED. The comparator 26 detects the voltage across the nickel-cadmium battery 22 to disable communication. For example, when the voltage is 3.3 V to 3.0 (referred to as “drop detection voltage”) or more, the interlocked electronic switches are commonly used. The terminal is controlled so as to be connected to the terminal A side, and the switch SW21 is turned off. The drop detection voltage differs depending on the circuit characteristics of the load 23.

When the voltage of the nickel-cadmium battery 22 becomes the drop detection voltage or less, the comparator 26 switches the common terminal of the switches SW11 and SW12 of the interlocking electronic switch to the terminal B side to start the operation of the DC-DC converter 24. And switch SW21 on. Therefore, the voltage of the dry cell 25 is supplied to the DC-DC converter 24 via the switch SW12 and boosted, and this voltage is supplied to the load 23 via the switch SW11, so that the load 23 can operate. Further, since this voltage is supplied to the light emitting diode LED via the resistor R and the switch SW21, it is possible to inform the user that the light emitting diode LED is turned on to charge the nickel-cadmium battery 22.

The comparator 26 also monitors a voltage slightly higher than the drop detection voltage (referred to as “rising detection voltage”) to detect the start of charging, and the slave unit 20 is set in the charging device 10 to charge the battery. When started, the common terminal of each switch SW11, SW12 of the interlocking electronic switch is switched to the terminal A side to stop the operation of the DC-DC converter 24, and the switch SW21 is turned off. Therefore, the dry battery 25 is disconnected from the load 23, the charging from the charging device 10 is continued, and the light emitting diode LED is turned off.

Therefore, according to the above-described embodiment, when the voltage of the nickel-cadmium battery 22 becomes lower than the drop detection voltage, the power of the dry battery 25 is supplied to the load 23, so that the load 23 can operate and the charging can be performed. Since the device 20 does not charge when the voltage of the nickel cadmium battery 22 is equal to or higher than the specified value, the number of times the nickel cadmium battery 22 is charged can be reduced, and thus the life of the nickel cadmium battery 22 can be extended.

Further, since a 1.5 V AAA or AA dry battery 25 of 1.5 V is used as the auxiliary battery, it is possible to prevent an extreme increase in the mounting volume. The capacity of the AAA dry battery 25 is generally about 400 mA · h, and the current consumption of the slave unit 20 is usually about 80 mA / h, so that the dry battery 25 alone operates continuously for about 4 to 5 hours. be able to. Further, since the light emitting diode LED lights up to notify the user that the battery should be charged, it is possible to prevent the dry battery 25 from being worn out by the user performing the charging operation.

[0016]

[Effect of the device]

 As described above, according to the present invention, charging is not performed until the voltage of the first battery of the child device becomes equal to or lower than the predetermined voltage, so the first battery is completely discharged and the number of times of charging is reduced. It can be reduced and thus the life of the first battery can be extended. In addition, since the slave unit includes the auxiliary second battery and the first battery switches from the first battery to the second voltage when the first battery has a predetermined voltage or less, the voltage of the first battery is set to the predetermined voltage. It can operate even below pressure.

[Brief description of drawings]

FIG. 1 is a block diagram showing a charging device and a handset as an embodiment of a cordless telephone according to the present invention.

FIG. 2 is a block diagram showing a slave unit of a conventional cordless telephone.

[Explanation of symbols]

10 Charger 11 Charger 13,26 Comparator 20 Handset 22 Nickel / Cadmium Battery (NiCd Battery) 25 Manganese Alkaline Battery SW1, SW2, SW11, SW12, SW21 Switch

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical indication H04M 1/00 N 7117-5K

Claims (2)

[Scope of utility model registration request] 1. A cordless telephone in which a slave unit wirelessly communicates with a master unit by using a first battery, and the first battery of the slave unit detects a voltage of the first battery in the cordless telephone. And a charging unit that charges the battery when the voltage is equal to or lower than a predetermined voltage, and the slave unit detects a voltage of the second battery that is an auxiliary of the first battery and a voltage of the first battery that is a predetermined voltage. A cordless telephone having switching means for switching from the first battery to the second voltage in the following cases. 2. The switching means detects the voltage of the first battery and switches from the second battery to the first voltage when the voltage is slightly higher than the predetermined voltage. Cordless phone as described.