JPS6013205B2 - Power supply method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power supply system for small electronic devices using battery power, such as electronic wristwatches and electronic desktop calculators.

Conventionally, small electronic devices that use batteries as a power source, such as electronic wristwatches and electronic desktop calculators, have been equipped with lighting devices to illuminate the display section as necessary, or sound alarm devices such as buzzers. There are things like that.

The above-mentioned lighting devices, sound alarm devices, etc. require a large operating current, and this causes the Kameike output voltage to drop during operation, causing problems such as malfunction of the logic circuit and stoppage of oscillation of the oscillation circuit, as shown in Figure 1 below. A specific example will be explained. FIG. 1 shows an example of the configuration of a secondary electronic wristwatch. A battery 1 has a terminal voltage of, for example, 1.5V, and its output voltage is supplied to an oscillation/logic circuit 2 and via a booster circuit 3. After being boosted to a predetermined level, for example, to a fence, it is supplied to the liquid crystal display section 4 that displays the time. Further, the output voltage of the battery 1 is coupled to a heavy load circuit, for example, a lighting device 5. This illumination device 5 is for illuminating the liquid crystal display section 4 at night to make it easier to see the time, and is made up of a switch 6 and an illumination lamp 7. In the above configuration, the oscillation/logic circuit 2 is
It operates using the output voltage from the battery 1 as the operating voltage, performs oscillation and timekeeping operations, and sends the timekeeping output to the liquid crystal display section 4 to display the time.

The oscillation/logic circuit 2 and the liquid crystal display section 4 have low power consumption, and when the lighting device 5 is not operating, the output voltage of the battery 1 is kept almost constant, that is, 1.5M. However, in order to illuminate the liquid crystal display section 4 at night, etc., the second
When the switch 6 is turned on as shown in the figure, the lighting lamp 7
A large current flows through the As the load current increases, the internal resistance of the battery 1 increases, and the output voltage ySS gradually decreases over time as shown in FIG. Then, the output voltage VSS of the battery 1 is at a certain level, for example 1.3.
If it falls below y, an error will occur in the logic operation of the oscillation/logic circuit 2, or the oscillation operation of the oscillation section will stop. Furthermore, when the output voltage VSS of the battery 1 decreases, the output voltage VSS2 of the booster circuit 3 decreases as shown in FIG. 2 and generates ripples. In conventional small electronic devices that use batteries as a power source, the voltage supplied to the logic circuit decreases when a heavy load such as a lighting lamp is driven, and the voltage drop is particularly noticeable at low temperatures. As a result, there were cases where the system malfunctioned or stopped functioning. The present invention has been made in view of the above points, and the present invention has been made in small electronic devices that use batteries as a power source. It is an object of the present invention to provide a power supply method that can reliably prevent malfunctions, functional stoppages, etc. of logic circuits by suppressing changes in voltage supplied to the logic circuits within a predetermined range.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 shows a case in which the output voltage VSS of the battery 11 is supplied to a heavy load circuit, for example, a lighting device 12, and is also supplied to a heavy load circuit, such as a lighting device 12, through a booster circuit 13, in the same way as in FIG. The voltage is boosted to a predetermined level voltage VSS2 and supplied to the time display liquid crystal display section 14. Also, battery 1
1 output voltage VSS, and the output voltage VS of the booster circuit 13
S2 is connected to the oscillation/logic circuit 16 via the voltage switching circuit 15.
supplied to This oscillation/logic circuit 16 performs a reference signal oscillation operation and a timekeeping operation based on this reference signal, and also monitors the operating state of the lighting layer 12 by a control circuit 16A and responds to the operation contents of the lighting device. A switching signal is sent to the voltage switching circuit 15. This exposure pressure switching circuit 15 is
The oscillation/logic circuit 16 operates according to a switching signal from the control circuit 16A, and when the lighting device 12 is not operating, the output voltage ySS of the battery 11 is selected and supplied to the oscillation/logic circuit 16, and the lighting device 12 is activated, the output voltage VSS2 of the booster circuit 13 is selected as an auxiliary power source and is supplied to the oscillation/logic circuit 16. That is, the booster circuit 13
is an auxiliary voltage circuit that obtains a voltage higher than the output voltage of the battery power supply, and normally supplies the output voltage VSS of the battery 11 to the oscillation/logic circuit 16 to operate the heavy-load lighting device 12. When the voltage VSS of the battery 11 decreases, the output voltage VSS2 of the booster circuit 13 is used as an auxiliary power source to lower the voltage to a predetermined voltage level and supply it to the oscillation/logic circuit 16, thereby preventing malfunction or malfunction of the oscillation/logic circuit 16. This is designed to prevent stoppage, and the detailed configuration will be explained below with reference to FIG. 4. As shown in FIG. 4, the lighting device 12 includes resistors 121, 122 and a switch 123.
An illumination lamp 124 is connected in parallel to the series circuit of the transistor 25 through the collector and emitter of the transistor 25.
The connection point of 21 and 122 is connected to the base of transistor 125.

Then, the voltage generated at the connection point P between the resistor 122 and the switch 123 is sent to the oscillation/logic circuit 16 as a signal indicating the operating state of the lighting device 12. This oscillation/logic circuit 16
is an oscillation circuit 161 equipped with a crystal oscillator 160, and the output of this oscillation circuit 161 is frequency-divided to, for example, 256Hz, 32Hz.
A frequency dividing circuit 162 for obtaining signals such as Day 2, Day 2, IHZ, etc.
The clock unit 163 includes a clock unit 163 that counts the IH2 signal output from the frequency dividing circuit 162 to obtain time information.
The clock information outputted from 63 is sent to display section 14 and displayed. Therefore, the 2 output from the frequency dividing circuit 162
The 56 Hz signal is sent to the boost circuit 13 as a boost clock signal, and the 32 Hz and 2 Hz signals are sent to the cascaded flip-flops 16AI to 16A in the control circuit 16A.
16A5 to clock terminal C. That is, a 32Hz signal is applied to the clock terminals C of the flip-flops 16AI, 16A2, and 16A5, and a 32Hz signal is applied to the clock terminals C of the flip-flops 16A3 and 16A4. In addition, the first stage flip-flop 16
The voltage generated at point P in the lighting device 12 is applied to the set terminal S of AI via the inverter 16A6. The outputs of the flip-flops 16A2 and 16A4 are sent to the voltage switching circuit 15 via an OR circuit 16A7, and the outputs of the flip-flop 16A5 and inverter 16A6 are sent to the voltage switching circuit 15 via an OR circuit 16A8 and an inverter 16A9. The box compression cutting circuit 15 is composed of N-channel MOS transistors 151, 152 and a smoothing capacitor 153, whose gates are controlled by the outputs of a switching element, for example, an inverter 16A9 and an OR circuit 16A7, and a smoothing capacitor 153.
The output voltage ySS of the battery 11 is supplied to the source electrode of the MOS transistor 152, and the output voltage ySS2 of the booster circuit 13 is supplied to the source electrode of the MOS transistor 152. The drain electrodes of the MOS transistors 151 and 152 are connected together, and a smoothing capacitor 153 is connected between this collective connection point A and the reference side terminal, that is, the positive terminal of the battery 11, so that the voltage across this capacitor 153 is V is supplied to the oscillation/logic circuit 16. The on-resistance of the MOS transistor 151 is small, and the MOS transistor 15 to which the output voltage VSS2 of the booster circuit 13 is supplied
In No. 2, the operating conditions are set to have a large on-resistance. That is, the on-resistance of the MOS transistor 152 is set so that the output voltage VSS2 of the booster circuit 13 drops to the vicinity of the operating voltage VSS of the oscillation/logic circuit 16. Next, the operation of the present invention configured as described above will be explained.

When the lighting device 12 is operated and not in use, that is, when the switch 123 is open, the connection point P between the resistors 122 and 123 is in the "1" signal state, and the output of the inverter 16A6 is "0". ”. Therefore, flip-flops 16AI to 16A5 are all in a reset state, and their Q side outputs are all "0". Therefore, the output of the OR circuit 16A8 is "0" and the inverter 6
The output of A9 becomes "1", and the MO of tortoise pressure cutting gate circuit 15
S transistor 151 is turned on. At this time, the MOS transistor 152 has its gate input, that is, the OR circuit 16
Since the output of A7 is "0", it is in an off state.
In this way, when the lighting device 12 is in the non-operating state, M
The OS transistor 151 is in an on state, and the output voltage VSS of the battery 11 is supplied to the oscillation/logic circuit 16 via the MOS transistor 151. In this state, when the switch 123 is turned on as shown in FIG. 5c, the base potential of the transistor 125 is applied, the transistor 125 is turned on, the illumination lamp 124 is turned on, and the display section 14 is illuminated.

When the switch 123 is turned on, the potential at the connection point P between the resistor 122 and the switch 123 changes to the reference potential VDD.
In other words, the signal level becomes "0", and the output of the inverter 16A6 becomes "1". When the output of the inverter 16A6 becomes "1", the output of the OR circuit 16A8 becomes "1" and the output of the inverter 16A9 becomes "0" as shown in FIG. 5i.
As a result, MOS transistor 1 5 1 is turned off. When this MOS transistor 1 51 is turned off, the battery 1
1 output voltage VSS. Instead of capacitor 15
3 is supplied to the oscillation/logic circuit 16. The output voltage VSS of the battery 11 is determined by the switch 123.
When the current is turned on, a current flows through the illumination lamp 124, so it fluctuates greatly as shown by curve A in FIG. At this time, since the MOS transistor 1 5 1 is off, the potential at point A is not affected by voltage fluctuations of the battery 11 . Further, when the output of the inverter 16A6 becomes '1', the flip-flops 16A1 and 16A2 output 32H shown in FIG. 5A from the frequency dividing circuit 162 as shown in FIGS.
It is set in synchronization with one falling edge of the Z signal. This flip-flop 16A2 is set and its Q side output is “
1”, the OR circuit 16A7 outputs a “1” signal as shown in FIG. 5i, and the MOS transistor 152
is applied to the gate electrode of As a result, the MOS transistor 152 is turned on, and the output voltage VSS2 of the booster circuit 13 is outputted via the MOS transistor 152. At this time, the output voltage VSS2 of the ascending circuit 13 is higher than the output voltage VSS of the battery 11, as shown at the beginning of FIG.
Also, since VSS, has decreased, the waveform is unstable and includes ripples, but since the on-resistance of the MOS transistor 152 is set large, the fluctuation is within the allowable voltage range of the oscillation/logic circuit 16, that is, the waveform is unstable. This can be suppressed to a low level as shown by A in Figure 5h. In addition, the above frit flop 16A
2 is set, then flip-flop 16A
3, 16 A4 is the frequency dividing circuit 16 as shown in FIG. 5 f, g.
The signals of 2 and 2 shown in FIG.
6A5 is set in synchronization with the 32Hz signal as shown in FIG. 5h. Flip flop above. 16A3-1
While 6A5 is set, OR circuits 16A7, 16A8
There is no change in the output.

While the lighting device 12 is operating in this way, the output voltage ySS2 of the booster circuit 13 is fed to the oscillation/logic circuit 16 as an auxiliary power source via the MOS transistor 152, so that the voltage of the battery 11 is ~SS, oscillates even if it decreases.
The connection voltage to the logic circuit 16 is maintained within a predetermined level range. Therefore, the oscillation/logic circuit 16 continues to operate normally. Therefore, the switch 12 in the lighting device 12
When 3 is opened, the transistor 125 is turned off and the illumination lamp 124 is turned off. Further, by opening the switch 123, the output of the inverter 16A6 becomes "0", and the flip-flops 16AI and 16A2 are sequentially reset as shown in FIGS. 5d and 5e in synchronization with the fall of the 32Hz signal. When flip-flop 16A2 is reset, flip-flops 16A3 and 16A2 are reset.
A4 is sequentially reset in synchronization with the fall of the signal 2 on the 2nd, as shown in FIGS. 5f and 5g. When the flip-flop 16A4 is reset and its output becomes "0", the output of the OR circuit 16A7 becomes "0", and the MOS transistors 152 of the voltage switching circuit 15 are turned off.
When this MOS transistor 52 is turned off, the voltage previously stored in the capacitor 153 is supplied to the oscillation/logic circuit 16. In addition, the above flip-flop 1
When 6A4 is reset, the flip-flop 16A5 is reset by the 32Hz signal as shown in FIG. The signal becomes "1", and the MOS transistor 151 is turned on again to return to the initial state. There is a delay time caused by the flip-flops 16AI to 16A5 after the operation of the lighting device 12 stops until the MOS transistor 51 turns on, and during this time the output voltage of the battery 11 reaches the curve C in FIG. 5h. Recover as shown. Furthermore, until the output voltage of the battery 11 is recovered, the MOS transistor 52 is held in the on state, and the output voltage VSS2 of the booster circuit 13 is passed through the MOS transistor 152 to the oscillation/logic circuit 16.
, the oscillation/logic circuit 16 continues to operate normally. Although the above-mentioned embodiment shows the case where the present invention is implemented in an electronic wristwatch, the present invention can also be implemented in other small electronic devices using batteries as a power source, such as an electronic desktop calculator.

Further, in the above embodiment, a lighting device is used as the heavy load circuit, but a sounding device such as a buzzer or other heavy load circuit may also be used. As described above, according to the present invention, in a small electronic device that uses a battery as a power source, even when a heavy load such as a lighting lamp is driven and the battery voltage decreases, the change in the voltage supplied to the load circuit can be controlled within a predetermined range. It is possible to reliably prevent malfunctions, functional outages, etc.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a power supply system for an electronic wristwatch in a subsidiary, Fig. 2 is a time chart for explaining the operation of Fig. 1, and Fig. 3 is a schematic configuration diagram showing an embodiment of the present invention. , FIG. 4 is a block diagram showing the details of FIG. 3, and FIG. 5 is a time chart for explaining the operation of the same embodiment. 11... Battery, 12... Lighting device (heavy load circuit), 13
... Shosho circuit, 14 ... Display section, 15
・・・・・・Voltage switching circuit. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. A battery power source, an auxiliary voltage circuit that obtains an output voltage higher than the output voltage of the battery power source, a load circuit to which the output voltage of the battery power source is normally supplied as an operating voltage, and a load circuit that provides the output voltage of the battery power source when driven. a heavy load circuit for reducing an output voltage; a means for switching and supplying a high output voltage of the auxiliary voltage circuit to the load circuit when the heavy load circuit is driven; 1. A power supply system comprising: delay means for delaying the supply of output voltage from the battery power source to the load circuit for a predetermined period of time when the load circuit is powered on.