JPS6333184B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to an electronic device with a built-in memory that prevents the contents of a volatile memory such as a CMOS memory from being stolen.

Prior Art and Problems Various electronic devices are provided with memories for writing and reading control data and various data. This memory includes read-only memory (ROM)
There are two types of memory: memory (RAM) that can be written to and read from, and is generally constructed from a semiconductor integrated circuit. In addition, writable and readable memory (RAM) is a volatile memory that cannot retain its stored contents when the power is turned off.If it is necessary to retain written data even when the power is turned off, it is necessary to use batteries. Backup is common. Furthermore, CMOS memories with low power consumption are often used so that the capacity of backup batteries can be small.

In this way, volatile memory backed up by batteries retains its stored contents even when the electronic device is in a dormant state, so there is a risk that it may be stolen. For example, in a CATV system where you can watch programs provided for a fee by signing a contract in advance,
A volatile memory such as a CMOS memory is provided to store data for determining whether or not to provide pay programs to the CATV converter. If the contents of this memory are stolen, the system will be analyzed and paid programs will be viewed secretly.

Therefore, it has been devised that if an attempt is made to steal the contents of the memory, the backup battery will be disconnected and the stored contents will be destroyed. However, even if the power source of the electronic device or the backup battery is turned off, the stored contents are retained for several seconds due to the charge caused by the capacity of the memory contents. During the few seconds that this stored content is retained, power could be supplied to the memory from another battery or the like, and the stored content could be stolen. Although it is conceivable to connect a discharge resistor to speed up the discharge of the charged charge, this has the disadvantage that the life of the battery will be shortened since current is constantly supplied from the backup battery.

OBJECTS OF THE INVENTION It is an object of the present invention to ensure that the contents of a volatile memory equipped with a backup battery can be prevented from being stolen.

Structure of the Invention The present invention provides an electronic device including a volatile memory, a power source for supplying an operating voltage to an electronic circuit including the volatile memory, and a battery for backing up the volatile memory. When the container containing the volatile memory is closed, the power supply terminal of the volatile memory is switched and connected in parallel to the power supply and the battery,
In addition, a switch is provided which connects the power supply terminal of the volatile memory to ground when the container is opened.The following embodiments will be described in detail.

Embodiment of the Invention FIG. 1 is a block diagram of the main parts of an embodiment of the present invention, in which 1 is a volatile memory such as a CMOS random access memory, 2 is a switch, 3 is a backup battery, and 4 is each part. 5 and 6 are diodes for backflow prevention. The switch 2 switches the power supply terminal of the volatile memory 1 between a contact a on the power supply side and a contact b on the ground side, and is normally connected to the contact a. Therefore, the operating voltage of the volatile memory 1 is supplied from the power supply 4 through the diode 6 to the volatile memory 1, enabling operations such as writing and reading, and when the power supply 4 is turned off, backup is possible. Volatile memory 1 is supplied with a voltage for retaining stored contents from battery 3 via diode 5.

If a cover or the like is removed in order to steal the stored contents of the volatile memory 1, this is detected and the switch 2 is switched to contact b, and the power terminal of the volatile memory 1 is grounded. Therefore, volatile memory 1
Since the charged charge is rapidly discharged, the stored contents will be rapidly erased. In other words, plagiarism will no longer be possible.

FIG. 2 shows an example of the configuration of the switch 2, where a shows the normal usage state and b shows the state when an attempt is made to steal the stored contents. switch 2
and the volatile memory 1 are fixed on the substrate 10,
It is completely surrounded by a cover 11 and fixed to a base 12 with screws or the like. Alternatively, the cover 11 is fixed by means such as a seal so that it cannot be easily removed. The switch 2 is constructed as a so-called micro switch, and the protrusion 13 inside the cover 11 presses the operating piece 14 of the switch 1, and the switch 2 is connected to the contact a as shown in FIG. , an operating voltage is supplied to the volatile memory 1 from a power source 4 or a battery 3.

When the cover 11 is removed, the protrusion 13 that was pressing the operating piece 14 of the switch 2 moves upward, as shown in FIG.
It will be switched and connected to. Therefore, the power supply terminal of the volatile memory 1 is grounded, the charge is rapidly discharged, and the stored contents of the volatile memory 1 are erased. In this way, when the cover 11 is removed, the stored contents of the volatile memory are erased, so it is possible to prevent theft.

Effects of the Invention As explained above, the present invention provides MOS type,
A random access memory (RAM) such as a CMOS type or a bipolar type, that is, a volatile memory 1, a power supply 4 that supplies an operating voltage to an electronic circuit including the volatile memory 1, and a power supply 3 for backing up the volatile memory 1. In an electronic device having the above, the power source 4 and the battery 3 are connected in parallel, and the power terminal of the volatile memory 1 is switched to be connected to the power source and the power source or to the ground. switch 2
The switch 2 is configured to switch and connect the power terminal of the volatile memory 1 to ground when the container (cover 11) is opened, so when the container (cover 11) is opened, the volatile memory When an attempt is made to steal the memory contents of volatile memory 1, the power terminal of volatile memory 1 is switched to ground by switch 2,
The stored charge will be rapidly discharged and the stored contents will be erased. Therefore, theft of stored contents can be reliably prevented. Furthermore, since the backup battery 3 does not increase consumption, it is possible to guarantee that the stored contents can be retained for a long time even if they are not stolen.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a main part of an embodiment of the present invention, and FIGS. 2A and 2B are diagrams illustrating an example of the configuration and operation of a switch according to the present invention. 1 is a volatile memory, 2 is a switch, 3 is a backup battery, 4 is a power source, 5 and 6 are backflow prevention diodes, 11 is a cover, 12 is a base, 13 is a protrusion, and 14 is an operating piece.

Claims (1)

[Claims] 1. In an electronic device that includes a volatile memory, a power supply that supplies operating voltage to an electronic circuit including the volatile memory, and a battery for backing up the volatile memory, the container containing the electronic circuit is closed. a switch that connects the power supply terminal of the volatile memory in parallel to the power supply and the battery when the container is opened, and switches the power supply terminal of the volatile memory to ground when the container is opened; An electronic device with a built-in memory, characterized in that it is provided with a memory.