JPH02165311A - Ic card - Google Patents

Abstract

PURPOSE:To reduce the size of a solar battery and to provide an IC card with many functions by providing the IC card with an accumulating element and a solar battery as power supplies, using power accumulated in the accumulating element to drive a CPU and charging the accumulating element with power obtained from the solar battery. CONSTITUTION:The solar battery 13 is mounted on the IC card 5 so as to be exposed to the surface of the IC card 5, and even when the IC card 5 is not used, charges an electric double layer capacitor 12 acting as the accumulating element by always receiving peripheral light. At the time of using the IC card 5, power accumulated in the capacitor 12 is supplied to the CPU 6, a non-volatile memory 7 and a display element driving circuit 8. Thereby, the solar battery 13 generating electro motive force extremely smaller than the maximum power consumption required at the time using the IC card 5 is sufficient for charging the capacitor 12. Consequently, the size of the solar battery 13 can be reduced and the solar battery 13 can be allowed to easily correspond to the multifunction of the IC card 5.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention independently provides a method for reading, erasing, and erasing memory contents.
It concerns IC cards that can be used for operations such as writing.
In particular, it is aimed at improving power supplies built into IC cards.

[Prior Art] As described above, an IC card having many functions usually includes a CPU, a memory, a display element, a keypad, a power source, and a means for communicating with the outside. As memory,
Electrically programmable and erasable non-volatile memory (EE
PROM) is mainly used, and contact-type input/output terminals are often provided as communication means. In addition, the power source is the CPU
It is used to supply power required for driving display devices and writing and erasing memory. Note that since non-volatile memory is used, a power supply is not required for memory retention.

Conventionally, the power supply built into this type of IC card was
Paper lithium batteries or solar cells were used. FIG. 3 schematically shows an IC card 2 with a built-in lithium battery 1, and FIG. 4 schematically shows an IC card 4 with a built-in solar cell 3.

[Problem to be solved by the invention] A paper-shaped lithium battery has an output voltage of 2.5 to 3.
．． However, since a voltage of 4 V or higher is required for erasing and writing in general non-volatile memory, the lithium battery 1 is usually used with two cells connected in series, as shown in FIG. Therefore, when these lithium batteries 1 are built into the IC card 2, the volume occupied by the lithium battery 1 becomes large, which is an obstacle to making the IC card 2 multifunctional.

Note that when a lithium battery is made smaller, its electric capacity becomes smaller, which may result in a situation where it cannot be put to practical use. Further, even if a relatively large lithium battery as described above is used, since it is a secondary battery, there is a restriction in electric capacity, and the battery life is currently about 1 to 3 years. In particular, IC cards usually have a major drawback in that the battery cannot be replaced, which limits the lifespan of the card.

On the other hand, when using solar cells as a power source, there are no lifespan restrictions like with lithium batteries, but since IC cards do not have a means of storing power, solar cells have a limited lifespan when using IC cards at their maximum power consumption. It must be designed to be able to supply more power at all times. For this reason,
As shown in FIG. 4, a solar cell 3 with a large area is required. Further, since IC cards generally require flexibility, as the solar cell becomes larger, this solar cell also needs to have flexibility. For this reason, conventionally, usable solar cells have been limited to thick-film or amorphous types, but these types of solar cells require a larger area due to their low conversion efficiency. This poses a dilemma. Moreover, such a solar cell naturally has an I
It is necessary to mount it on the surface of a C card, but as IC cards become more multifunctional, it is necessary to mount or form large display elements, multiple keypads, input/output terminals, embossing, etc. on the surface. However, large-area solar cells have been a major obstacle in achieving multifunctionality.

Therefore, the present invention provides an IC card with a power source, an I.
The purpose is to reduce the occupancy rate on the surface of the C card or the surface area of the IC card, and furthermore, it is intended to provide a long-life and highly reliable power source for the IC card.

[Means for Solving the Problems] The present invention is directed to an IC card that includes a CPU, a nonvolatile memory, a display element, a keypad, a power source, and means for communicating with the outside such as an input/output terminal. , is characterized by adopting the following configuration in order to solve the above-mentioned technical problems.

That is, the power supply includes a power storage element and a solar cell, and the CPU uses the power stored in the power storage element.
The power storage element is configured to be charged by electric power obtained from the solar cell.

Note that as the power storage element, for example, an electric double layer capacitor or a secondary battery is used.

[Function] In the IC card according to the present invention, a power source consisting of a combination of a power storage element and a solar cell is used. Here, C
The PU is driven by electric power stored in a power storage element,
The power storage element is charged by a solar cell. therefore,
It is sufficient that the solar cell has sufficient performance to charge the electricity storage element.

[Effects of the Invention] Therefore, according to the present invention, compared to the case where only a conventional paper-type lithium battery is used or only a solar cell is used, when viewed as a whole, the power supply occupies less space in an IC card. The volume can be reduced. In particular, since the solar cell that must be mounted exposed on the surface of the IC card can be significantly downsized, the ratio of ml to the surface of the IC card can be reduced. Therefore, it becomes possible to increase the size of the display element and the keypad, and also to mount other elements, making it easier to respond to multifunctional IC cards. Furthermore, the degree of freedom in terms of circuit design and design increases.

In addition, if solar cells become smaller, flexibility will no longer be necessary, so single crystal solar cells with excellent conversion efficiency can be used, so in that sense as well,
This solar cell can be further downsized.

In addition, if a paper-type lithium battery is used as a power source, it is not possible to replace the battery with an IC card.
The lifespan of the C card is determined by the lifespan of the battery. However, in this invention, since the power supply is composed of only semi-permanent elements, it is possible to eliminate the restriction on the lifespan of the IC card based on the power supply.

[Embodiment] FIG. 1 shows an IC card 5 as an embodiment of the present invention.
The external appearance is shown in a plan view. FIG. 2 shows a block diagram of electrical elements included in the IC card 5 shown in FIG.

In FIGS. 1 and 2, 6 is a CPU, which is connected to a non-volatile memory 7, which is a main memory, via a data address bus or the like. A display element drive circuit 8 drives the liquid crystal display element 9 based on data sent from the CPU 6. 10 is a keypad formed of a membrane, a switch, etc., and 11 is an input/output terminal serving as a means of communication with the outside. Further, 12 is a paper-like electric double layer capacitor (for example, 5.5V; 0.3F) that acts as a storage element, and 13 is a small solar 7.
Indicates substitute land.

The solar cell 13 is mounted so as to be exposed on the surface of the IC card 5, and even when the IC card 5 is not in use,
It is configured to constantly receive ambient light and charge the electric double layer capacitor 12.

Furthermore, when the IC card 5 is used, the CPU 6, nonvolatile memory 7, and display element drive circuit 8 are powered by the electric power stored in the electric double layer capacitor 12. ISR supplied.

Therefore, in this embodiment, it is sufficient that the solar cell 13 generates an electromotive force that is much smaller than the maximum power consumption when the IC card 5 is used (for example, the power consumption when rewriting the memory). Therefore, it is possible to downsize the solar cell 13. Furthermore, if the solar cell 13 is made smaller, flexibility is not required so much, and a single crystal solar cell with excellent conversion efficiency can be used, which allows for further miniaturization.

When the IC card 5 is used with the electric double layer capacitor 12 in this embodiment fully charged, it is possible to supply power for one hour or more, depending on the usage conditions, and the usage time per day under normal conditions. is quite satisfactory.

In addition, in the above-mentioned example, an electric double layer capacitor was shown as a power storage element, but a secondary battery can also be used.
It is clear that similar effects can be obtained even when a secondary battery is used.

Furthermore, the present invention is not limited to the configuration of the embodiments described above, and various modifications are possible within the scope of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an IC card 5 as an embodiment of the present invention. FIG. 2 is a block diagram showing electrical elements included in the IC card shown in FIG. 1. 3 and 4 are plan views schematically showing conventional IC cards. In the figure, 5 is an IC card, 6 is a CPU, 7 is a nonvolatile memory, 8 is a display element drive circuit, and 9 is a liquid crystal display element (
10 is a keypad, 11 is an input/output terminal (means for communicating with the outside), 12 is an electric double layer capacitor (power storage element), and 13 is a solar cell.

Claims (1)

[Scope of Claims] An IC card comprising a CPU, a non-volatile memory, a display element, a keypad, a power source, and a means for communicating with the outside, comprising a power storage element and a solar cell as the power source, and a power storage element and a solar cell as the power source. The CPU is driven using the stored power, and the power storage element is configured to be charged by the power obtained from the solar cell.
IC card.