JPS63220726A - Electric source circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a power supply circuit that can selectively supply voltage supplied from an external power supply and voltage of a rechargeable power supply to each circuit of an electronic device. Regarding.

[Summary of the invention]

The present invention provides a power supply circuit in which a DC voltage supplied from the outside and an output voltage of a rechargeable power source can be selectively supplied to each circuit of an electronic device by a DC voltage supply means. is supplied to the charging circuit and each circuit of the electronic device through separate contacts provided in the input terminal section, thereby reducing component costs and simplifying the circuit configuration.

[Conventional technology]

Conventionally, as this type of power supply circuit, there is a circuit as shown in FIG. 3, for example.

In FIG. 3, 41 is an AC adapter for converting AC voltage supplied through the outlet 50 into DC voltage. When the plug 42 of this AC adapter 41 is attached to the DC1 source jack 40 provided in an electronic device 49 such as a word processor, the contact 40a of the terminal 32 of the jack 40 comes into contact with the positive electrode 42a of the plug 42, and the terminal 34 Contact 40b contacts negative electrode 42b of plug 42, and contact 40a and contact 40c of terminal 33 are separated.

Then, the DC voltage supplied from the plug 42 is applied to the contact 40
In addition to the nickel-cadmium storage battery 44, which is added to each circuit of the electronic device 49 via the terminal 32, the diode D, and the power switch 46, and which is chargeable via the charging timer 43, the charging circuit 45, and the diode D, The battery 44 is then charged.

The DC output voltage of this battery 44 is always supplied to the memory circuit of the electronic device 49 as a backup voltage.

When the DC voltage supply from the plug 42 is cut off, such as when the plug 42 is removed from the jack 40, the DC output voltage of the battery 44 is passed through the diode D2 and the power switch 46 to each circuit of the electronic device 49. Added.

As described above, this circuit consists of an AC adapter 41 and a battery 44.
It is configured such that direct current voltage can be selectively supplied to each circuit of the electronic device 49 from the above.

In the above-described circuit, the diode D is necessary to prevent the direct current from the battery 44 from flowing into the charging timer 43 and the charging circuit 45. That is, if the DC current from the battery 44 flows into the charging timer 43 while the voltage supply from the AC adapter 41 is cut off, the charging timer 43 will not turn off, and therefore the battery 4
4 continues to flow into the charging circuit 45. For this reason, the charge of the battery 44 is wasted unnecessarily, and
The usable time of the battery 44 will be shortened. Therefore, a diode DI is provided to prevent the direct current from the battery 44 from flowing into the charging timer 43 and the charging circuit 45.

In addition, the diode D2 is required in the above circuit because the AC
This is to prevent the battery 44 from being destroyed if the DC voltage from the adapter 41 is directly applied to the battery 44 through the supply lines 48 c, 48 b, and 48 a without passing through the charging circuit 45.

[Problem that the invention seeks to solve]

However, according to the conventional circuit described above, the diode D
1 and D2 are required, which increases the cost. Further, the voltage supplied from the AC adapter 41 is lost due to the voltage drop caused by the diode D1, and the voltage supplied from the battery 44 is lost due to the voltage drop caused by the diode Dt.

Therefore, it is necessary to increase the DC voltage supplied from the AC adapter 41 accordingly, and it is also necessary to use a battery 44 with a high voltage.

SUMMARY OF THE INVENTION Therefore, the present invention seeks to provide a power supply circuit that can eliminate the drawbacks of the conventional circuits described above.

[Means for solving problems]

The present invention includes an input terminal section to which a DC voltage supply means for supplying a DC voltage from the outside is connected, and a charging circuit that supplies the DC voltage input from the input terminal section to a chargeable power source as a charging voltage. In the power supply circuit, the DC voltage supplied from the DC voltage supply means and the output voltage of the power supply can be selectively supplied to each circuit of an electronic device. A supply circuit is provided for supplying voltage from the voltage supply means to each circuit of the electronic device without passing through the charging circuit, and a first contact connected to the charging circuit and the supply circuit are connected to the input terminal portion. and means for supplying the output voltage of the power source to each circuit of the electronic device through the supply circuit when the supply of DC voltage from the DC voltage supply means is cut off. It was established.

[Effect]

According to the present invention, the DC voltage supplied from the DC voltage supply means is applied to the charging circuit through the first contact of the input terminal section, and the power source is charged.

Further, the DC voltage is applied to the supply circuit through the second contact of the input terminal section, and is supplied from the supply circuit to each circuit of the electronic device. When the supply of DC voltage from the DC voltage supply means is cut off, the output voltage of the power supply is supplied to each circuit of the electronic device through the supply circuit.

〔Example〕

An embodiment in which the present invention is applied to a power supply circuit of an electronic device will be described below with reference to FIGS. 1 and 2.

Note that parts corresponding to those in FIG. 3 are designated by the same reference numerals, and their explanations will be omitted.

First, the outline of the circuit configuration and operation will be explained with reference to FIG. It is located opposite.

The contact 1 is provided on the terminal 3, and the contact 4 of the terminal 2 is in contact with the contact 1 in a separable manner.

Connect the AC adapter 41 to the jack 40 configured in this way.
When the plug 42 is attached, the contacts 40a and 40c are separated, and the contacts 1 and 4 are separated. and plug 4
DC voltage is applied from the positive electrode 42a of No. 2 to the contact 40a and the terminal 32.
and is supplied to each circuit of the electronic device via the power switch 46.

On the other hand, contact! From the side, a DC voltage from the positive electrode 42a of the plug 42 is applied to the charging timer 43 and the charging circuit 45 via the terminal 3.

The charging circuit 45 outputs a charging voltage by applying the DC voltage from the plug 42 . This charging voltage is then applied to the nickel cadmium storage battery 44 via the diode Ds, and the battery 44 is charged.

The charging timer 43 starts counting when DC voltage is applied from the plug 42, and sends a charging off signal to the charging circuit 45 when eight hours have passed since the start of counting. As a result, the supply of charging voltage from the charging circuit 45 to the battery 44 is cut off, and charging of the battery 44 is completed.

A switch 15 that operates in conjunction with the power switch 46 is connected to the charging timer 43, and when this switch 15 is turned on,
When this occurs, the count of the charging timer 43 is temporarily stopped, and the supply of charging voltage from the charging circuit 45 to the battery 44 is temporarily cut off. That is, when the power switch 46 is turned on, the switch 15 is also turned on in conjunction with this, and thereby the charging timer 43 and the charging circuit 45 become inactive. And power switch 4
6 is turned off, the switch 15 is also turned off, the charging timer 43 starts counting again, and the charging circuit 4
5 supplies charging voltage to the battery 44 again.

Next, when the plug 42 is removed from the jack 40, the contacts 40a and 40c and the contacts 1 and 4 of the jack 40 come into contact with each other. Then, the DC output voltage of the battery 44 is applied to each circuit of the electronic device through the terminal 33, the contact 40C140a, the terminal 32, and the power switch 46. Further, the voltage of the battery 44 is always supplied to the memory circuit.

Next, based on FIG. 2, the charging timer 43 and the charging circuit 4
5 will be explained in detail.

The charging timer 43 includes a timer IC 20, a time constant circuit 24 consisting of a resistor 18 and a capacitor 22, a ripple removal capacitor 23, a resistor 17, and a Zener diode D4 for ensuring constant voltage.

The time constant circuit 24 is connected to the 1st pin and 5th pin of the IC 20, and is configured to operate the rc2Q for 8 hours.
A value of H is selected.

The second pin of the IC 20 is connected to the contact 15a of the switch 15, and by turning the switch 15 ON or OFF, the IC 20 is switched between a non-operating state and an operating state. Also, resistance 1
The 3rd bin connected to 7 is a count reset pin, and the 7th bin is a power supply pin. Bin number 6 is diode D.

It is connected to and performs switching of diode D. Moreover, the 4th pin is connected to ground.

The charging circuit 45 includes transistors Q, SQ atmosphere, Qs,
It consists of resistors 12-14 and 27-29 and a diode D. Note that the resistors 27 to 29 are bias resistors.

Next, the operations of the above-mentioned charging timer 43 and charging circuit 45 will be explained.

First, when the plug 42 is attached to the jack 40 and a DC voltage from the AC adapter 41 is applied to the contact 1 of the jack 40, a DC voltage V1 appears at the terminal 3 of the jack 40. This voltage V, is applied to the resistor 13.

On the other hand, the voltage V appearing at terminal 3 is applied to the base of transistor Q3 through resistor 12, and
It is applied to the 3rd and 7th bins of 0 as a reset voltage and a power supply voltage, respectively.

IC2Q resets the count by applying voltage vI to pin 3 and bin 7, and enters the operating state. At this time, the 6th bin of IC20 becomes H level,
Set the cathode side of diode DS to H level. Therefore, even if the voltage (2) at terminal 3 is applied to the anode side of diode D through resistor 12, diode D does not become conductive, so the base voltage of transistor Q increases and transistor 3 becomes conductive.

When the transistor Q3 becomes conductive, the base potential of the transistor Q1 decreases and the transistor Q1 becomes conductive, which causes a current to increase! , flows through the resistor 13, the transistor Q1, and the diode D to the battery 44. As a result, the battery 44 is charged.

Note that the voltage applied to the battery 44 is kept constant by the resistor 13 and the transistor Q. That is, if the current Q increases, the voltage drop across the resistor 13 increases and the transistor Q! The base potential of decreases. Therefore, the current flowing through transistor Q increases,
The base potential of transistor Q increases. Therefore the current 1
1 is held constant.

Next, when charging the battery 44 using the above-mentioned AC adapter 41, if the power switch 46 is turned on and the DC voltage from the AC adapter 41 is supplied to each circuit of the electronic device, the Switch 15 is turned on. As a result, the second pin of IC20 is connected to the ground and becomes L level, 1C20 becomes inactive and charging timer 430 counts are temporarily stopped, and the base potential of transistor Q3 decreases and transistor Q becomes inactive. Becomes conductive. Then, as the transistor Q becomes non-conductive, the base potential of the transistor Q1 increases, so that the transistor Ql also becomes non-conductive, and the supply of the current 2 to the battery 44 is cut off.

However, at this time, the battery 44 has a resistor 13 and a resistor 14.
Since a small current I2 is always supplied through the memory circuit and the diode D, a decrease in the charge of the battery 44 caused by constant voltage application from the battery 44 to the memory circuit is replenished.

Next, when the power switch 46 is turned off, the switch 15 also becomes 0FFL, which causes the second bin of the IC 20 to go to H level, the IC 20 enters the operating state again, and the counting of the charging timer 43 is restarted, and the transistor Q ,
The base potential of J- increases and transistor Q becomes conductive. As transistor Q3 becomes conductive, transistor Q+ also becomes conductive, and a current of 1. supply will start again.

Next, when a predetermined time (eight hours in the above example) determined by the time constant circuit 24 has elapsed, the sixth bin of the IC 20 becomes L level. As a result, diode D5 becomes conductive, so the base potential of transistor Q falls, transistor Q becomes non-conductive, transistor Q9 also becomes non-conductive, and charging of battery 44 ends. Note that even in this case, the current (2) is always supplied to the battery 44 through the resistor 14.

Next, when the plug 42 is removed from the jack 40, the output voltage v2 of the battery 44 is supplied to each circuit of the electronic device through the above-described path.

As described above, according to this embodiment, the contact 4 for supplying DC voltage from the AC adapter 41 to each circuit of the electronic device
0a, and a contact 1 for supplying charging timer 43 and charging circuit 45 are provided separately. and battery 4
The contact 40c for applying the output voltage v2 of No. 4 to each circuit of the electronic device does not contact either the contact 40a or the contact No. 1 while the plug 42 is attached to the jack 40, and the contact 40c applies the output voltage v2 from the jack 40 to the plug 42. Contact 4Qc is disconnected when
is in contact with the contact 40a, and is configured to apply the output voltage v2 of the battery 44 to each circuit of the electronic device through the contact 40a. Therefore, when applying the DC voltage from the AC adapter 42 to each circuit of the electronic device, the DC voltage can be prevented from passing through the charging circuit 45 (directly being applied to the battery) without using a diode or the like. When the output voltage V of the battery 44 is supplied to each circuit of the electronic device, this output voltage V8 can be prevented from being applied to the charging timer 43 and the charging circuit 45 without using a diode or the like.

Note that the present invention is not limited to the above-described embodiments (and various effective changes can be made based on the technical idea of the present invention).

〔Effect of the invention〕

According to the present invention, when a DC voltage is supplied from the DC voltage supply means to each circuit of an electronic device, a diode is provided to prevent this DC voltage from being directly applied to a rechargeable power source without passing through a charging circuit. There is no need to provide

Also, when supplying the output voltage of the power supply to each circuit of an electronic device, this output voltage powers the charging circuit! There is no need to provide a diode to prevent this from occurring.

Therefore, since these diodes are not required, component costs can be reduced and the circuit can be simplified. Moreover, voltage loss in the DC voltage supplied from the DC voltage supply means and the output voltage of the power supply can be prevented by these diodes.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a circuit diagram showing details of each part, and FIG. 3 is a block diagram showing a conventional example. In addition, in the symbols used in the drawings, 1-・-・
−・−・−−−−−・−・Contact 40−・−・・・・−
・・・・・・・・・・DC power jack 40a, 40
b, 40c ・=Contact 41−・−・−・−・−・−・AC adapter 4
2-・-・−−−−1−−・−・・−・−・Plug 42
a-・・-・−・−・・・Positive electrode 42b・・−・
・・−・・−・−・−・・Negative electrode 43−・−・・−
・−・−−−−−−・・−Charging timer 44−・・−−
−111−・−・−・Nickel cadmium storage battery 45−
・・・・・−・・−・−・−・・・It is a charging circuit.

Claims (1)

[Scope of Claims] An input terminal portion to which a DC voltage supply means for supplying a DC voltage from the outside is connected, and a charging circuit that supplies the DC voltage input from the input terminal portion to a chargeable power source as a charging voltage. In a power supply circuit that is capable of selectively supplying the DC voltage supplied from the DC voltage supply means and the output voltage of the power supply to each circuit of an electronic device, the DC voltage is A supply circuit is provided for supplying the DC voltage from the DC voltage supply means to each circuit of the electronic device without passing through the charging circuit, and a first contact connected to the charging circuit and the supply circuit are provided at the input terminal portion. means for supplying the output voltage of the power source to each circuit of the electronic device through the supply circuit when the supply of DC voltage from the DC voltage supply means is cut off; A power supply circuit characterized by being provided with.