JP2530719Y2 - Power supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a power supply device for supplying a power supply voltage for driving, for example, a liquid crystal display device.

[Conventional technology and its problems]

Conventionally, a dot matrix liquid crystal display device has been dynamically driven with a high bias. In such a case, a plurality of voltages are required. For example, in a drive with 1/6 bias 1/32 duty, the reference voltage V ₀ is required.
Requires five voltage of _{V 1, V 2, V 3} , V 4, V 5 in addition, also in the case of, for example, 1/4 bias 1/16 duty, V _1, V ₂ in addition to the V ₀ , V ₃ and V ₄ are required. However,
In the case where a battery is used as a power source, directly extracting these required voltages from the battery itself has a disadvantage that the number of batteries must be increased, and therefore, for example, Japanese Patent Application Laid-Open No. Sho 57-142128 discloses As described in (1), it is considered to provide a voltage circuit that uses a large number of capacitors and a large number of transistor switches to obtain a plurality of voltages by switching the connection state of the capacitors.

On the other hand, in a dot matrix type liquid crystal display device, a large number of data can be displayed by using the above-mentioned drive method of, for example, 1/6 bias 1/32 duty, but the above-mentioned drive method is necessary depending on display contents. And sometimes not. For example, when displaying a large number of characters, numeric data, etc., the above-described drive method is necessary because ON / OFF must be controlled for each pixel, but instead of the large number of character, numeric data, When extremely small data, for example, hour and minute time data, is displayed on a display device in a large size, a plurality of adjacent pixels may be turned ON / OFF at the same time. It is preferable in terms of power consumption to drive by a low-order drive method in which both the bias and the duty are lower than in the next drive method. Therefore, for example, it is conceivable to switch the drive system when displaying a large number of data in detail and when displaying data with a small time or the like in large characters. In such a case, since the voltages used are different, for example, a voltage suitable for each drive system is output from a voltage circuit that obtains a plurality of voltages by switching the connection state of the capacitor described above.

However, when switching from the higher-order drive system to the lower-order drive system in this way, it has been found that there is a defect that the display screen is abnormal for about one second. That is, when switching from the high-order drive system to the low-order drive system, the entire pixel is displayed (lighted) for about one second, and data cannot be displayed immediately.

[Purpose of the invention]

This invention was made in order to solve the above-mentioned drawbacks, and eliminates display errors when switching the drive system.
It is an object of the present invention to provide a power supply device capable of immediately displaying the switched data.

[Summary of the invention]

The drawback mentioned above is that the voltage circuit obtains the voltage from the capacitor, so even if the drive mode is switched from high to low, the high-order drive voltage remains in the capacitor, Focusing on the point where an abnormality occurs, the gist of the present invention is that the charge remaining in the capacitor is discharged when the drive method is switched.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram of an electronic wristwatch to which the present invention is applied. In the figure, reference numeral 1 denotes a control unit (CPU),
Is for controlling each unit described later based on the microprogram stored in the. Reference numeral 3 denotes a RAM, a current time register 3a for storing a current time counted under the control of the control unit 1, and input data input from a key input unit 4, which will be described later, such as name and telephone number data and schedule data. Data storage unit that stores many character data
3b etc. The key input unit 4 includes a character input key and a display switching key 4a for switching the display content from the data display of the storage unit 3b to the time display or vice versa. The control unit 1 switches the data supplied to the segment drive circuit 5 from the current time of the register 3a to the storage data of the storage unit 3b every time the operation signal of the display switching key 4a is input,
Alternatively, the switching is alternately performed. When the data supplied to the segment drive circuit 5a is switched from the current time data of the register 3a to the storage data, the segment drive circuit 5, a voltage circuit 6, and a common driver 7 described below are connected to the dot matrix liquid crystal display device. 8 to 1/6
When the data supplied to the segment drive circuit 5a is switched from the stored data to the current time data, the dot matrix liquid crystal display device is driven at 1/4 bias 1/16 duty. The control signal a to be driven is output. Further, when the data is switched from the stored data to the current time data, a signal b which is at a high level for about 10 ms is also output.

On the other hand, Bat. Is a 1.5 V or 3.0 V battery, the + terminal is connected to the reference potential V ₀ (this potential V ₀ is supplied to each unit), and the − terminal is supplied to the constant voltage circuit 9. The constant voltage circuit 9 converts the battery voltage into a constant voltage to generate a voltage V of about 1.25 V.
Outputs ₁ (-1.25V). This voltage V ₁ is sent to a voltage circuit (voltage conversion circuit) 6. Further, the output voltage of the constant voltage circuit 9, the signal b is connected to the reference potential V ₀ which through the transistor 10 and the resistor R to be ON when a high level.

The voltage circuit 6 divides a reference signal oscillated from the oscillation circuit 11 and outputs a timing signal for controlling each unit to a timing signal of, for example, 256 Hz signals A, B, and C described later from the timing generation circuit 12. It is a circuit that obtains a plurality of voltages by changing the connection state of a capacitor based on the voltage. That is,
For details of the voltage circuits have not shown a number of switch transistor capacitor C ₁ to C ₇ are shown in Figure 2, similar to the technique described in JP-A-57-142128 described above The connection of the capacitor is switched according to the principle described above.

Thus, when the 1/6 bias 1/32 duty is designated by signal a, the capacitor C ₁ -C ₇ when the timing signal indicating the timing generating circuit 12 in FIG. 5 A is supplied by switching the switching transistor The connection state shown in FIG. 2 is established, and when the timing signals B and C are respectively supplied, the connection state is configured as shown in FIG. 3 and FIG. 4, respectively. Therefore, the output terminal V ₁
V, the output terminals _{V 2, V 3, V 4} , from V ₅ respectively 2.5V, 5V, 6.25
V and 7.5V are output. And the voltage V
₁ is supplied to each section as a voltage for operating each circuit described above, and the voltages V _{1 to} V ₅ are supplied to the segment drive circuit 5 and the common driver 7, whereby the dot matrix liquid crystal display device 8 has a 1/6 bias. It will be driven at 1/32 duty. The liquid crystal display device 8 has a 32 × 64 dot matrix pixel composed of 32 X-direction electrodes and 64 Y-direction electrodes.

Also, the signal a from the control unit 1 causes a 1/4 bias 1/16
When the duty is designated, the voltage circuit 6 is brought into the connection state as shown in FIG. 6 at the timing of the timing signal A, and the voltage circuit 6 is set at the timing of the timing signals B and C, respectively.
The connection state is as shown in FIG. 8 and FIG. Therefore, the output terminal V ₁
3.75 from 2.5V, V ₄ from 1.25V output terminal V ₂ and V ₃ from
A voltage of 5 V is output from V and V ₅ and sent to the segment driver circuit 5 and the common driver 7. The segment driver 5 and the common driver 7 have a 1/4 bias 1
Since the drive is designated by / 16 duty, the liquid crystal display device 8 is driven based on the designation.

In the above configuration, when the current time display is designated by operating the display switching key 4a, the control unit 1
The current time data of the register 3a is supplied to the segment drive circuit 5, and a 1/4 bias 1/1
Since 6 duty is specified, 1.25
V, 2.5 V, 3.75 V, and 5 V are output, and the drive circuit 5 and the common driver 7 output the liquid crystal display device 8 based on these voltages.
Is driven with 1/4 bias and 1/16 duty, and the current time is displayed. In this case, the time display is displayed as a large numerical value. When the display switching key 4a is operated in this state, a large number of character data such as names and telephone numbers from the storage unit 3b are sent to the segment drive circuit 5, and the signal a is
Since the drive method of 1/6 bias 1/32 duty is specified, the voltage circuit 6 outputs voltages of 1.25 V, 2.5 V, 5 V, 6.25 V and 7.5 V, and the liquid crystal display device 8 outputs 1/6 bias 1/32 It is driven with a duty. When the display switching key 4a is operated again, the liquid crystal display device 8 returns to the time display again. However, when the display is switched to the time display, the capacitors C ₅ and
Charges of 5 V, 6.25 V, and 7 V still remain in C ₆ and C _7, and do not immediately become 2.5 V, 3.75 V, and 5 V used in a quarter bias. However, when the mode is changed to the time display is connected to a reference potential V ₀ which through is ON the signal b is the output transistor 10 from the control unit 1 resistor R. This allows
While the connection of the capacitors repeats the states shown in FIGS. 6 to 8, the charge of each capacitor is sequentially discharged, so that the charge of each capacitor is discharged very quickly. And signal b is 10ms
During the ec output, the values of the capacitors C ₅ , C ₆ , and C ₇ become about 2 V, and after that, the transistor 10 is turned off.
The bias voltage is correctly output. Therefore, it took more than one second until a correct voltage for 1/4 bias was output in the prior art.
The correct voltage value is obtained by the degree, and the time can be displayed immediately.

In the above embodiment, the transistor 10 and the resistor R are provided on the output voltage side of the constant voltage circuit 9. However, they may be provided on the output side of the voltage circuit 6, and the capacitors C ₅ , C ₆ , and C ₇ may be provided. Each may be provided correspondingly.

In the above embodiment, the example of switching between 1/6 bias and 1/4 bias has been described.
The number of output voltages and the values of the voltages are not limited to the above embodiment.

Further, in the above embodiment, the drive voltage of the liquid crystal display device has been described. However, the present invention can be applied to any circuit or device that immediately requires a different voltage by switching the voltage. It is not limited to use.

Further, the present invention is not limited to a wristwatch but can be applied to various devices such as a computer, a word processor, a personal computer, a handy terminal, and a remote controller.

[Effect of the invention]

As described above in detail, according to the present invention, in a device in which various voltages are obtained by using a capacitor, the electric charge previously charged in the capacitor is discharged when the voltage is switched, so that a desired voltage can be obtained immediately. A voltage can be obtained, and a power supply device that does not malfunction can be provided.

[Brief description of the drawings]

1 is a circuit diagram of an electronic wristwatch to which the present invention is applied, FIGS. 2 to 4 are diagrams showing connection states of capacitors of a voltage circuit used in the above circuit diagram, and FIG. 5 is a timing generation circuit. 6 to 8 are diagrams showing connection states of capacitors of the voltage circuit. DESCRIPTION OF SYMBOLS 1 ... Control part, 2 ... ROM, 3 ... RAM, 4 ... Key input part, 6 ...
Voltage circuit, 9: constant voltage circuit, 12: timing generation circuit.

Claims (1)

(57) [Scope of request for utility model registration] 1. A battery power supply means, voltage circuit means for supplying a voltage from the battery power supply means, switching a plurality of capacitors in a predetermined connection state, and outputting a specific voltage, and said voltage circuit means. Control signal output means for switching a connection state of the capacitor in a connection state different from the predetermined connection state and outputting a control signal for outputting a voltage smaller than the specific voltage from the voltage circuit means; A power supply device comprising: discharge means for discharging the charge of the capacitor for a predetermined time when the control signal is output from the signal output means.