JPS6080785A - Supplying method of power source - Google Patents

Abstract

PURPOSE:To eliminate malfunction of a logical circuit and liquid crystal display circuit by providing a constant voltage circuit and supplying selectively a constant voltage when the output voltage of a battery power sources drops considerably on account of heavy load driving of a lamp or the like. CONSTITUTION:When an outside switch SW of an electronic wristwatch or the like is turned on, a ligical circuit 12 outputs a lighting command signal l. Then a lamp 14 is lighted and a VHD circuit 16 acts as a voltage increasing to turn off the 1st voltage selecting circuit 15 and to turn on the 2nd voltage selecting circuit 18. The constant voltage (1.5V) outputted by a constant voltage circuit 17 is impressed as a voltage Vss1 to the circuit 12 and the 1st terminal of a liquid crystal display part 13 and the constant voltage (1.5V) is increased to 3V by the circuit 16 and is impressed as Vss2 to the 2nd terminal of the part 13. The output voltage Vc of a lithium battery 1 drops from ordinary 3V to about 2.5V, but the circuit 12 and the part 13 operate normally.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to a power supply system.

[Prior art]

FIG. 1 is a circuit diagram illustrating an example of a conventional power supply system used in electronic wristwatches and the like.

In the figure, 1 is a lithium battery with an output voltage of 3V, and this output voltage [3V] is reduced to 1.5V by the saving circuit 2.
(voltage Vss,), and then passes through the switching circuit 3 to the logic circuit 4 that constitutes the time ff1 circuit, liquid high drive circuit, etc.
supplied to The logic circuit 4 also includes the output voltage of the lithium battery 1 (voltage Vss
, ) are supplied via the switching circuit 3. Further, the liquid crystal display unit 5, which is supplied with display data from the logic circuit 4, is supplied with the stepped-down voltage v881 and the output voltage (voltage Vssffi) of the lithium battery 1, and displays a liquid crystal display with, for example, % bias and % duty. Data is displayed according to the driving method. ! 1. The lamp 6 is used to illuminate the liquid crystal display section 5 at night, etc., and this lamp 6 is equipped with the output m pressure of the lithium battery 1 (v88!). is directly supplied, and when the lighting command signal e output from the logic circuit 4 becomes, for example, a "1" level by operating an external switch (path shown), the light is turned on. Note that this lighting command signal e is also applied to the switching circuit 3.

With the above configuration, when the lamp 6 is lit, the lighting command signal l is outputted as 0" and applied to the switching circuit 3 and the lamp 6. Therefore, the switching circuit 3 The step-down circuit 2 selects the stepped-down voltage V B Bl and supplies it to the logic circuit 4. As a result, the logic circuit 4 is driven by a voltage of 1.5 cm, and its clock circuit and liquid crystal drive circuit operate. Display data such as time is supplied to the liquid crystal display section 5. During this normal time, the liquid crystal display section 5 displays the voltage V output from the step-down circuit 2.
s 1111 (1.5 V) and the output voltage VB+12 (g, ov>) of the lithium battery 1 are applied, and the above display data is displayed using a field bias, % duty liquid crystal drive system.

On the other hand, when lighting the lamp 6 at night, etc.,
By operating an external switch, the lighting command signal ehs is inverted to the "l" level and is applied to the switching circuit 3 and the lamp 6. Therefore, the switching circuit 3
Output voltage V8E of lithium battery l instead of s1!
, is selectively output and applied to the logic circuit 4. That is, when the lamps of four logic circuits are turned on, the voltage Ves, (
The output of the lithium battery 1 changes from the normal 6V to 2.5V, for example, when the lamp 6, which has a heavy load, is lit.
As a result, the output voltage of the step-down circuit 2 also drops below the threshold level of the logic circuit 4, thereby preventing malfunctions from occurring. Further, the liquid crystal display section 5 has a voltage Vs s,
, Ve s2 are applied to display the data, and furthermore, the lamp 6 is turned on by applying the voltage v8B2.

[Problems with conventional technology]

In the case of the conventional circuit described above, it is possible to prevent the logic circuit 4 from malfunctioning even if the voltage drop of the lithium battery 1 becomes large when driving a heavy load such as a lamp or when the ambient temperature is close to 0°C. However, since the voltages Vg s, s Ve 81 are directly applied to the liquid crystal display section 5, the display condition of the liquid crystal display section 5 may deteriorate depending on the degree of decrease in these voltages Vas, , Vs 8fi, and the display may deteriorate. Sometimes it became obvious.

[Purpose of the invention]

This invention was made to solve the above-mentioned drawbacks of the conventional power supply system.The purpose of this invention is to prevent logic circuits and liquid crystal display even if the output voltage of a battery power supply drops significantly due to driving a heavy load such as a lamp. It is an object of the present invention to provide a power supply system that can power a display circuit without malfunctioning.

[Key points of the invention]

A logic circuit to which a step-down voltage of a battery power source is supplied as a driving voltage, a liquid crystal display means to which an output voltage from the battery power source and the step-down voltage are supplied as a driving voltage and display information from the logic circuit, an output of the battery power source. A heavy load circuit that drops a voltage, a constant voltage circuit that obtains a predetermined constant voltage from the battery power source, and a constant voltage circuit that switches and supplies the constant voltage to the logic circuit when driving the heavy load circuit, and boosts the constant voltage and the battery power source. This power supply system is provided with voltage switching means for switching and supplying voltage to the liquid crystal display means.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 2 and 3. FIG. 2 is a circuit diagram applied to, for example, an electronic wristwatch. In the figure, 11 indicates that the output voltage (Vc) is normally 3.
This is a lithium battery (2), one end of which is grounded and connected to one end of each of the logic circuit 12, external switch SW, liquid crystal display section 13, and lamp 14.

The other end of the lithium battery 1 is a first voltage switching circuit 15.1
-1D (VOETAGE I-T &
It is connected to the first terminal of the other end of the logic circuit 12 and the other end of the liquid crystal display section 13 via the (lower/lower) circuit 16, and is further grounded via the capacitor C8. . The other end of the lithium battery 1 is connected to the second terminal on the other end of the liquid crystal display section 13 via the 111'j pressure switching circuit 15, and is also grounded via a capacitor C8. Furthermore, the other end side of the lithium tank 11 is connected to a constant voltage circuit (VR) 17 and a second voltage switching circuit l8.
V HD circuit 1
6 to the second terminal on the other end side of the liquid crystal display section 13. In addition, the other end of the lithium battery 11 is equipped with a lamp 14.
is connected to the other end.

The logic circuit 12 is composed of a clock circuit, a liquid crystal drive circuit, etc., and supplies display data such as time to the liquid crystal display section 13, and displays the display data using a liquid crystal drive method of, for example, % bias and % duty.

Further, the lamp 14 is used to make the display illuminated on the liquid crystal display section 13 easier to see at night, and has a heavy load. The external switch SW is a switch that is turned on when lighting this lamp 14, and when it is turned on,
A lighting command signal e at the '1'' level is output from the logic circuit 12 and supplied to the lamp 14.

The first voltage switching circuit 15 is made up of N-channel and P-channel MO3 type transistors 15N and 15P connected in series.・Ran resistor 15N.

The gates 15P are commonly connected and applied with the lighting command signal e, and are controlled to open and close. Also, the second voltage switching circuit 18
It also consists of N-channel and P-channel MO8 type transistors connected in series, both transistors 18N and 18N.
The gates P are connected in common and the lighting command signal e is applied through input 7<-gate 9 to control opening and closing.

The V l-ID circuit 16 utilizes, for example, the circuit described in the specification of the patent application (Japanese Patent Application No. 56-1869161) proposed by the present applicant, and a capacitor C3 is connected between both terminals of the circuit. The lighting command signal e is also applied, and the output voltage VC of the lithium battery 1 is the first
When input through the voltage switching circuit 15, the voltage VC
is stepped down at t5Vt and supplied to the first terminal on the other end side of the logic circuit 12 and the other end side of the liquid crystal display section 13. The output voltage Vc of the switched lithium battery 1 is converted to a constant voltage of 1.5 V by the constant Fff and pressure circuit 17, and when this constant voltage of 1.5 V is input via the second voltage switching circuit 18, it is changed to 3.
The voltage is increased to V and supplied to the second terminal on the other end side of the liquid crystal display section 13. Then, the voltages applied to the capacitors C8 and C3 are -'+'F4g and s Ves, respectively.

I'll leave it as that.

Next, the FLR11 operation of the above embodiment will be explained with reference to the time chart of FIG. Now, in normal times when the lamp 14 is not lit, the external switch SW is turned off, so the logic circuit 12 outputs the "o" level lighting command signal l, and the lamp 14, VTTI) circuit 16, and first voltage switching circuit 15 are turned off. It is applied to each gate of the transistors 15N and 15P and to each gate of the transistors 18N and 18P of the second voltage switching circuit 18. Therefore, the lamp 14 is off, and the V HD circuit 16 is connected to the step-down circuit (i(a l v
er circuit), the first voltage switching circuit 15 is turned on, and the second voltage switching circuit 18 is turned off. Then, the output voltage Va of the lithium battery I is
', 1L voltage switching circuit 15 is input to the VHD circuit 16 and is stepped down to the voltage Veil, (%Vc), and the logic circuit 12
It is supplied to the other i'lAt side and the first (#1^1 child) on the other end side of the liquid crystal display ff1s13.
The output voltage Vc of the lithium battery 1 is supplied to the second terminal on the other end side via a first voltage switching circuit 15. Therefore, since the logic circuit 12 is driven by the voltage Vs, (y2Vc), when the output voltage Vc of the lithium battery is 3V, it operates normally with a voltage of 1.5V.
Display data is supplied to the liquid crystal display section 13. Further, the liquid crystal display section 13 displays the voltage Ves+, (lVc) and the voltage VIl.
s, (Vc) [, J: Therefore, when the voltages V and O are 6V, voltages of 1.5V and 6V are applied to IJ11, and the above display is performed by, for example, a % bias, % duty liquid crystal driving system. Display data correctly.

On the other hand, when lighting the lamp 14, the external switch S
Turn on W. Therefore, the lighting command signal e at the 1'1'' level is output, and in response to this, the lamp 4 is lit, and the V
T (D circuit 16 booster circuit (er circuit in Doub), the first voltage switching circuit 15 is turned off, and the second voltage switching circuit 18 is turned on. Therefore, the constant voltage circuit 17
The constant 'l■ pressure (1,5V) outputted by it! is passed through the second ηL pressure switching circuit 18. A voltage V s s is applied to the first terminal on the other end side of the logic circuit 12 and on the other side of the liquid crystal display section 13, respectively, and a voltage V s s is applied to the first terminal on the other end side of the liquid crystal display section 13, respectively. , upper W constant '71 pressure (t 5V-Vs s,
) is RrX 27Lf, V HD via pressure switching circuit 18
Circuit 16 [input - 1r3V [boosted, voltage Vss2
and °C is applied. 141J When the lamp 14 is lit, the output voltage Vc of the battery 1 drops from the normal 3V to around 2.5V because the lamp 14 is under heavy load, but the logic circuit 12 indicates that the lamp 14 is turned off. Time,
Similarly, a voltage of 1.5v is supplied and it will operate normally. In addition, in the liquid crystal display section 13, the constant voltage 1.5
V is the voltage V s s I , and this constant voltage 1.
The voltage Vase, which is boosted from 5V to 3V, is applied, and the display operation is performed normally during the time when the lamp 14 is turned off, and the display condition does not deteriorate and become difficult to see.

Then, when the external switch SW is turned off and the lamp 14 is turned off, the output voltage Vc of the lumen battery 1 returns to 6V.
Return to the initial state.

Although the above embodiment is an electronic wristwatch, the present invention can also be applied to other electronic devices equipped with a liquid crystal display device. Further, an external n'l regulator may be provided in the constant voltage circuit to cope with fluctuations in battery voltage.

Further, as a heavy load circuit, in addition to a lamp, a buzzer, a motor, etc. may be used.

〔Effect of the invention〕

As described above, the present invention includes a battery ill source, a logic circuit to which the step-down voltage of the battery power source is supplied as a driving voltage, and a logic circuit to which the output voltage from the battery power source and the step-down voltage are supplied as the driving voltage. a liquid crystal display means for displaying information obtained by the circuit; a heavy load circuit that reduces the output voltage of the battery power source during operation; a constant voltage circuit that obtains a predetermined constant voltage from the output voltage of the battery power source; 11
When driving the U circuit, the circuit pressure is turned off (+ supplied) to the t'Nj'n logic circuit as a driving power source, and the constant ?L(
This power supply method is characterized by comprising a voltage switching means that switches and supplies the + voltage and the ``boosted voltage of the battery power source'' to the liquid crystal display means as the L voltage, so that it can be used for heavy loads such as lamps. Even if the battery voltage drops significantly during operation or when the ambient temperature is low, near 0°C, a stable power supply voltage is always supplied to the logic circuit and liquid crystal display, preventing malfunctions. There are advantages. It also has advantages such as simple circuit configuration and low power consumption.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram explaining the conventional power supply system, and Figure 2 is the fruit of this invention! The circuit diagram of the example shown in FIG. 3 is a time chart for explaining the operation. 11...Lithium tube pond, 12...Logic circuit, 13...Liquid crystal display means, 14...
... Lamp, 15.18 ... Voltage switching circuit, 1
6... Step-down world "E circuit, 17... Constant voltage circuit 〇 Patent applicant Casio Computer Co., Ltd. $1 Figure

Claims (1)

[Claims] A battery power source, a logic circuit to which the step-down voltage of the battery power source is supplied as a driving voltage, and a liquid crystal displaying information that the output 1π voltage from the battery power source and the step-down electrician are supplied as the driving voltage and is F5 in the logic circuit. a display means; a heavy load circuit that lowers the output voltage of the battery power source during driving;
a constant voltage circuit that obtains a predetermined constant voltage from the output voltage of the battery power source; and a constant voltage circuit that switches and supplies the constant voltage as a driving power source to the logic circuit when driving the heavy load circuit, and boosts the constant voltage and the battery power source. A power supply system comprising: voltage switching means for switching and supplying a voltage as a driving voltage to the liquid crystal display means.