JPH01196614A - Memory card - Google Patents

Abstract

PURPOSE:To confirm the condition of an internal battery with the simple substance of a memory card by detecting whether the voltage of the internal battery is higher or lower than a reference voltage and causing an LCD display to be a driving condition or a non-driving condition. CONSTITUTION:A comparator circuit CMP 7 builds-in the reference voltage in an internal part. An input to the CMP 7 is given with being pressure-divided by resistances R1 and R2 so that as to be the same value as the reference voltage, which is built-in the CMP 7, when the voltage of an internal battery BAT 5 goes to be a voltage which is determined in advance. The function of an exclusive OR circuit EXOR 9 is changed to an inverter or to a simple buffer according to the output signal level of the CMP 7. For an LCD display 2, the outputs of an oscillator OSC 8 and the EXOR 9 are added to respective electrodes and the LCD display is caused to be the driving condition or non- driving condition according to a phase. Thus, the voltage condition of the internal battery can be confirmed by the single substance of the memory card.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a memory card, and more particularly to a memory card with a backup battery voltage drop warning display.

[Conventional technology]

Figure 4 is a circuit diagram showing an example of a conventional memory card, which includes a volatile semiconductor memory (hereinafter referred to as MEM) 4, a backup battery (hereinafter referred to as BAT) 5, and a connecting connector (hereinafter referred to as C0N).
3, a backup voltage is supplied from BAT5 to MEM4 via a resistor and a diode, and both poles of BAT5 are wired to pins 6a and 6b of C0N3. An external bag W (not shown) inserted into C0N3 monitored the voltage between pins 31 and 32, and displayed a voltage drop alarm when it became lower than a predetermined voltage.

[Problem that the invention seeks to solve]

With the conventional memory cards mentioned above, it is not possible to check the voltage status of the internal battery on the memory card itself, so unless it is connected to an external device, the voltage may drop without you noticing and the written content may be damaged or lost. It might not have been saved.

In addition, since it is cumbersome to connect an external device to check the voltage, there is a drawback that there is a lot of waste, such as periodically replacing the battery regardless of the voltage state.

[Means for solving problems]

The memory card of the present invention includes a readable and writable volatile semiconductor memory, an internal battery for holding data written in the volatile semiconductor memory, and a readable and writable volatile semiconductor memory.
In a memory card that includes a connector for connection between a control circuit that performs switching control between an externally supplied power source and the internal battery during writing, and a connector for connection with other devices, the voltage of the internal battery is predetermined. a detection circuit for detecting whether the voltage is higher or lower than the predetermined voltage; an LCD display; and when the detection circuit detects that the voltage of the internal battery is higher than the predetermined voltage, the LCD display is set to a driving state. and a display control circuit that controls the LCD display to be in a non-driving state when a low level is detected.

〔Example〕

Next, the present invention will be explained with reference to FIGS. 1 to 3.

FIGS. 1 and 2 are a partial circuit diagram and an external view, respectively, showing an embodiment of the memory card of the present invention.

As shown in Fig. 2, there is an LCD in a part of the memory card body 1.
A display device (hereinafter referred to as LCD) 2 is incorporated. In FIG. 1, a comparator circuit (hereinafter referred to as CMP) 7 is constituted by a known dedicated IC for voltage comparison, and has an accurate reference voltage built therein. The input to CMP7 is divided by resistors R, , R2 so that when the voltage of BAT5 reaches a predetermined voltage, it becomes the same value as the reference voltage built into CMP7. The oscillator (hereinafter osc>s is an inverter, a timer function IC, and a capacitor. It is composed of resistors, etc. The exclusive OR circuit (hereinafter EXOR) 9 is the CMP7
The function changes depending on the output signal level of the inverter or a simple buffer. The outputs of oscs and EXOR9 are applied to each electrode of the LCD 2, and the LCD 2 is in a driven state or a non-driven state depending on the phase thereof.

FIG. 3 is a time chart of the embodiment shown in FIG. V7H is a reference voltage inside CMP7.

Here, when the input voltage of CMP7 is higher than the reference voltage VTI+, the output of CMP7 is low level L'''cEXOR
Reference numeral 9 has an inverter function, and since the voltages applied to both electrodes of the LCD 2 are in opposite phases to each other, a driving voltage is generated between the electrodes, resulting in a driving state. On the other hand, the reference voltage VT)! When it becomes lower, the output of CMP7 becomes high level H and EXO
R9 serves as a mere buffer function, and the voltages applied to both electrodes of the LCD 2 are in the same phase, so no driving voltage is generated between the electrodes, resulting in a non-driving state. Moreover, this state is the same as when the voltage of BAT5 disappears completely.

〔Effect of the invention〕

As explained above, the present invention provides an LC in the memory card body.
Equipped with a D display, it detects whether the voltage of the internal battery is higher or lower than the reference voltage, and depending on the result, the LCD display is activated or deactivated, allowing you to constantly check the internal battery status with a single memory card. There is an effect that can be done. Moreover, since the LCD display is brought into a non-driving state even when the internal battery runs out of power, it is possible to accurately display the voltage drop state of the internal battery.

[Brief explanation of the drawing]

1 and 2 are a partial circuit diagram and an external view showing an embodiment of the memory card of the present invention, FIG. 3 is a time chart of the embodiment shown in FIG. 1, and FIG. 4 is a conventional memory card. FIG. 3 is a circuit diagram showing an example of a card. 1...Memory card body, 2...LCD display (L
CD), 3... Connection connector (CON), 4...
Volatile semiconductor memory (MEM), 5... Backup battery (BAT), 6a, 6b... Pin, 7... Comparison circuit (CMP), 8... Oscillator (○SC), 9...
Exclusive OR circuit (EXOR).

Claims (1)

[Claims] A readable and writable volatile semiconductor memory, an internal battery for holding data written in the volatile semiconductor memory, and switching between an externally supplied power source and the internal battery during reading and writing. In a memory card comprising a connector for connection between a control circuit that performs control etc. and other equipment, a detection circuit that detects whether the voltage of the internal battery is higher or lower than a predetermined voltage;
an LCD display; and when the detection circuit detects that the voltage of the internal battery is higher than the predetermined voltage, the LCD display is driven, and when the voltage of the internal battery is lower than the predetermined voltage, the LCD display is driven, and when the voltage is lower than the predetermined voltage, the LCD display is driven. A memory card characterized by comprising a display control circuit that performs control.