JPH0612579A - Device for monitoring removal of electronic equipment - Google Patents

Abstract

PURPOSE:To maintain the high contact stability of the contact point of a detection switch for a long time and to prolong the service life of a battery for back-up required for a permanent removal monitoring operation. CONSTITUTION:The detection switch 20 is kept ON when the electronic equipment is installed at a prescribed place and is switched OFF when the electronic equipment is removed. By making a minute current flow from the battery 28 for the back-up through a current limit resistor 30 between the contact points 20a and 20b of the detection switch 20, a microcomputer 24 detects the ON/OFF signals of the detection switch 20 and monitors the presence of the removal of the electronic equipment. Then, the microcomputer 24 starts a contact point activation circuit 34 every time when an activation trigger signal is inputted from an IC card insertion detection sensor 48 to the microcomputer 24, a relatively large current is made to flow from the battery 26 for a main power source between the contact points 20a and 20b of the detection switch 20 and the contact points 20a and 20b are activated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic device removal monitor for monitoring whether or not an electronic device fixedly installed at a predetermined place has been removed due to theft or the like.

[0002]

2. Description of the Related Art In recent years, for example, in an electronic device fixedly installed at a predetermined place, a detection switch for detecting whether or not the electronic device is removed in order to prevent unauthorized use due to theft or the like. There is one that has. This detection switch maintains an ON state when the electronic device is installed in a predetermined place, and switches to an OFF state when the electronic device is removed. When removal is detected,
After that, for example, the data in the internal memory is destroyed or erased so that the electronic device does not operate normally.

[0003]

By the way, many small electronic devices use a battery as a power source. In such an electronic device equipped with the above-mentioned removal monitoring function, a minute current is constantly passed from the battery between the contacts of the detection switch to monitor the removal of the electronic device.

However, if a minute current continues to flow between the contacts of the detection switch for a long period of time, the contact stability of the contacts may deteriorate due to deterioration of the contacts over time, resulting in erroneous detection.
To prevent this, it is possible to increase the current that flows between the contacts of the detection switch, but if the current is increased, the life of the battery required for the removal monitoring operation will be shortened, and the durability of the removal monitoring operation is called Cannot meet the original demand.

The present invention has been made in consideration of such circumstances, and an object thereof is to maintain good contact stability of contact points of a detection switch for a long period of time and prevent erroneous detection. An object of the present invention is to provide a removal monitoring device for an electronic device, which can also prolong the life of a battery required for a permanent removal monitoring operation.

[0006]

In order to achieve the above object, an apparatus for monitoring removal of electronic equipment according to the present invention includes a detection switch that switches to an off state when the electronic equipment is removed from a predetermined place, and the detection switch. A backup battery that keeps a minute current flowing between its contacts when the switch is in an on state, a monitoring unit that monitors whether the electronic device is removed by detecting an on / off signal of the detection switch, and an electronic device Of the main power source, which is a replaceable main power source, and a relatively large current from the main power source battery between the contacts of the detection switch when an activation trigger signal is input to the monitoring means from the outside. It has a configuration including a contact activation circuit that allows time to flow.

[0007]

When the electronic device is normally installed at a predetermined place, the detection switch is maintained in the ON state, and a minute current is continuously supplied from the backup battery to the contact of the detection switch. As a result, the ON signal of the detection switch is detected by the monitoring means, and it is detected that the electronic device is normally installed in the predetermined place.

In this state, when an activation trigger signal is input to the monitoring means from the outside, the contact activation circuit is activated each time, and a relatively large current flows from the main power source battery between the detection switch contacts. For a short period of time to activate the contact of the detection switch and maintain good contact stability. Here, the battery that allows a relatively large current to flow between the contacts of the detection switch is not the backup battery but the replaceable main power supply battery, so the backup battery required for permanent removal monitoring operation can be consumed quickly. Can be prevented.

On the other hand, when the electronic device is removed from the predetermined place, the detection switch is turned off. The off signal of the detection switch is detected by the monitoring means to detect that the electronic device has been removed from the predetermined place.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The electronic device 10 is, for example, an IC card reading device that reads data stored in the IC card 12, and as shown in FIG. 2, a lid 14 for inserting and removing the IC card 12.
And a display unit 16 for displaying various information. The electronic device 10 is fixedly installed on a predetermined installation surface 18 (see FIG. 4) by adhesion or screwing.

On the back side of the electronic device 10, a detection switch 20 for detecting whether or not the electronic device 10 has been removed.
Is provided, and the actuator 2 of this detection switch 20
2 is urged by the spring force so as to project toward the installation surface 18 side. Then, when the electronic device 10 is normally installed on the installation surface 18, the actuator 22 is pushed on the installation surface 18 and the detection switch 20 is maintained in the ON state. On the other hand, when the electronic device 10 is removed from the installation surface 18, the actuator 22 projects by the spring force and the detection switch 20 is switched to the off state.

The operation of the electronic device 10 is controlled by the microcomputer 24 shown in FIG. Further, a replaceable main power supply battery 26 and a backup battery 28 are built in the electronic device 10. in this case,
The main power source battery 26 is composed of, for example, four 1.5 V dry batteries connected in series, and applies a direct current voltage of 6 V to the microcomputer 24, the display unit 16 and the like as a main power source for driving them. Has become.

On the other hand, the backup battery 28 is composed of, for example, a 3.6 V thionyl chloride battery, and functions as a backup power source for the microcomputer 24.
The (+) side of the backup battery 28 is also connected to the fixed contact 20a of the detection switch 20 via the current limiting resistor 30 and the diode 32, and the movable contact 20b thereof is connected to the ground side. As a result, the detection switch 2
When 0 is in the on state, a minute current flows from the backup battery 28 through the current limiting resistor 30 having a large resistance value between the contacts 20a and 20b of the detection switch 20.

Further, the fixed contact 20a of the detection switch 20.
The ON / OFF signal output from the side is input to the input port I1 of the microcomputer 24. As a result, the microcomputer 24 turns on the detection switch 20.
It functions as a monitoring unit that monitors whether or not the electronic device 10 is removed by detecting the off signal. When the removal of the electronic device 10 due to theft or the like is detected,
To prevent unauthorized use, the microcomputer 24
Automatically destroys or erases security data such as a password stored in an internal RAM (not shown).

On the other hand, a contact activation circuit 34 is connected to the output port P of the microcomputer 24. The contact activation circuit 34 includes an NPN first transistor 36 that is turned on when a high level signal is output from the output port P of the microcomputer 24, and the first transistor 36.
And a PNP type second transistor 38 which is turned on when the transistor 36 is turned on. The emitter side of the second transistor 38 is connected to the (+) side of the main power source battery 26 via the resistor 40. Has been done. Further, the base side of the second transistor 38 (collector side of the first transistor 36) is also connected to the (+) side of the main power supply battery 26 via the resistor 42, whereby the first transistor 36 is turned off. In the state, the second transistor 38 is maintained in the off state. A pull-down resistor 44 is connected to the base side of the first transistor 36.

In the contact activating circuit 34 having the above-described structure, the collector of the second transistor 38, which serves as a current output terminal, is connected to the fixed contact 20a side of the detection switch 20 via the diode 46. As a result, when the second transistor 38 is turned on, the main power source battery 26
From the contact 20 of the detection switch 20
It flows between a and 20b.

On the other hand, at the input port I2 of the microcomputer 24, the power source of the backup battery 28 is I.
A C card insertion detection sensor 48 is connected. This I
The C card insertion detection sensor 48 is composed of, for example, an electronic sensor such as a mechanical switch or a photocoupler.
When the C card 12 is inserted into the electronic device 10, the C card 12 is turned on to input the activation trigger signal to the input port I2 of the microcomputer 24. As a result, the microcomputer 24 sets the output of the output port P to the high level for a short time and activates the contact activation circuit 34 for a short time.

Next, the operation of the above configuration will be described.
When the electronic device 10 is normally installed on the installation surface 18, the actuator 22 of the detection switch 20 is pushed by the installation surface 18 and the detection switch 20 is maintained in the ON state. In this state, the minute current limited by the current limiting resistor 30 having a large resistance value from the backup battery 28 continues to flow between the contacts 20a and 20b of the detection switch 20,
ON signal (low level signal) from this detection switch 20
Is input to the input port I1 of the microcomputer 24. Based on the ON signal of the detection switch 20, the microcomputer 24 detects that the electronic device 10 is normally installed on the installation surface 18.

By the way, the contact 20 of the detection switch 20
If a minute current is continuously applied between a and 20b for a long time, contact 2
The contact stability of the contacts 20a, 20b may be deteriorated due to the deterioration of 0a, 20b with time, and erroneous detection may occur.

Therefore, in this embodiment, the detection switch 20
The contacts 20a, 20b of the above are occasionally activated as follows. That is, when the user inserts the IC card 12 into the electronic device 10, the IC card insertion detection sensor 48 turns on,
The activation trigger signal is input to the input port I2 of the microcomputer 24. In response to this activation trigger signal, the microcomputer 24 sets the output of the output port P to high level for a short time, and turns on both transistors 36 and 38 of the contact activation circuit 34 for a short time. As a result, a relatively large current from the main power source battery 26 is passed through the diode 46 for a short time and the contact 20 of the detection switch 20 is connected.
flows between a and 20b, and this current causes the detection switch 20
The contacts 20a, 20b of are activated to maintain good contact stability and prevent erroneous detection.

Here, the contacts 20a of the detection switch 20,
Since the power source for supplying a relatively large current between the 20b is the replaceable main power source battery 26, not the backup battery 28, it is possible to prevent early consumption of the backup battery 28 necessary for the permanent removal monitoring operation. As a result, the life of the backup battery 28 can be extended, and the original requirement of the durability and stability of the removal monitoring operation can be satisfied.

On the other hand, when the electronic device 10 is removed from the installation surface 18 due to theft or the like, the actuator 22 of the detection switch 20 projects by the spring force and the detection switch 20 is switched to the off state. The microcomputer 24 detects the off signal of the detection switch 20 to detect that the electronic device 10 is removed from the installation surface 18. In this case, the microcomputer 24 automatically destroys or erases security data such as a password stored in an internal RAM (not shown) in order to prevent unauthorized use. At this time, the reason why only the security data such as the password is destroyed or erased without destroying or erasing all the data in the RAM is to enable the restoration by a service person or the like.

Further, since the main power supply battery 26 is replaceable, if the main power supply battery 26 is consumed and the voltage drops, it may be replaced with a new battery. At this time, even if the main power source battery 26 is removed (or even if the consumable battery is left without being replaced), the detection switch 20 and the microcomputer 24 continue to have the backup battery 2
Since the electric power is supplied from 8, even if the main power supply battery 26 is removed (or the consumable battery is left without being replaced), the presence or absence of the removal of the electronic device 10 can be accurately detected. The data in RAM will not be erased.

In this embodiment, the electronic device 10 is I
Although the C card reading device has been described as an example, it goes without saying that the present invention can be applied to various electronic devices that are fixedly installed at a predetermined place. In this case, the generation source of the activation trigger signal may be, for example, a power switch or the like according to the type of electronic device to which the present invention is applied.

In addition, the present invention provides a backup battery 2
It is needless to say that the voltages of the battery 8 and the battery 26 for the main power source may be appropriately changed according to the type of electronic device, and various changes may be made without departing from the scope of the invention.

[0026]

As is apparent from the above description, the present invention activates the contact activation circuit every time an activation trigger signal is input from the outside, and the main power source battery is activated between the contacts of the detection switch. Since a relatively large current is made to flow for a short time, the contact of the detection switch can be activated each time, and the contact stability can be favorably maintained and erroneous detection can be prevented. Moreover, since the battery that allows a relatively large current to flow between the contacts of the detection switch is not the backup battery but the replaceable main power battery, it is possible to prevent early consumption of the backup battery required for removal monitoring operation. As a result, the backup battery can have a long life, and in combination with the activation of the contacts as described above, it is possible to satisfy the essential requirement of the durability and stability of the detachment monitoring operation.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram showing an embodiment of the present invention.

FIG. 2 is a perspective view of the electronic device viewed from the front side.

FIG. 3 is a perspective view of the electronic device viewed from the back side.

FIG. 4 is an enlarged vertical sectional view of a detection switch portion.

[Explanation of symbols]

10 is an electronic device, 12 is an IC card, 16 is a display unit, 1
8 is an installation surface, 20 is a detection switch, 24 is a microcomputer (monitoring means), 26 is a main power supply battery, 28 is a backup battery, 30 is a current limiting resistor, 34 is a contact activation circuit, and 48 is an IC card insertion It is a detection sensor.

Claims (1)

[Claims] 1. A device for monitoring whether or not an electronic device fixedly installed at a predetermined place is removed, the electronic device maintaining an ON state when the electronic device is installed at the predetermined place and A detection switch that switches to an off state when the detection switch is removed from the predetermined location, a backup battery that keeps a minute current flowing between its contacts when the detection switch is on, and an on / off signal for the detection switch. A monitoring means for detecting whether or not the electronic device has been detached by detecting, a replaceable main power source battery serving as a main power source of the electronic device, and an activation trigger signal input to the monitoring means from outside thereof. A detachment monitoring device for an electronic device, comprising: a contact activation circuit for flowing a relatively large current from the main power source battery for a short time between the contacts of the detection switch.