JPH04138598A - Device for detecting opening of box body - Google Patents

Abstract

PURPOSE:To accurately detect the opening of a box body without being influenced by the ON/OFF of a power supply by providing this box body opening detecting device with a real time clock and a control part for periodically inputting the time data of the real time clock, comparing the input data with the preceding data, and when both the data are the same, generating an alarm. CONSTITUTION:When the box body is opened, switches 8, 9 are simultaneously turned off and power supply to the real time lock 3 is interrupted. Thereby, the clock 3 is reset and does not count up time thereafter. After impressing power to a microcomputer 1, the time data of the clock 3 are periodically inputted and compared with the precedently inputted time data. When the time data of the same time are continuously inputted, the cover of the box body is opened, an alarm indicating the temporary power supply interruption is generated and the contents of the alarm are displayed on a display device 4. Even when the box body is opened in the OFF state of the power supply in addition to the sure case of a power ON state, the opening can be detected.

Description

[Detailed description of the invention] [Industrial application field]

TECHNICAL FIELD The present invention relates to a case opening detection device capable of detecting that a case is opened.

[Conventional technology]

For example, in a CATV terminal capable of receiving paid broadcasting, a decoder (descrambler) for paid satellite broadcasting, etc., it is important that the case is opened so that the inside cannot be manipulated or tampered with. Therefore, a method can be considered in which a switch is provided to detect the opening of the case, and an internal microcomputer detects the operation of the switch and stores it.

[Problem to be solved by the invention]

However, this method has a problem in that it cannot be applied when the power is turned off and the case is opened. SUMMARY OF THE INVENTION An object of the present invention is to provide a case opening detection device that uses a battery-backed real-time clock to accurately detect the opening of a case without being affected by power on/off.

[Means to solve the problem]

To this end, the present invention provides a switch that turns off when the case is opened, and a real-time clock that counts time by being supplied with voltage from a built-in battery and an external power supply when the switch is on, and that is reset and maintains that state when the switch is turned off. and a control section that periodically takes in the time data of the real-time clock, compares it with the previous data, and issues an alarm when the data is the same.

【Example】

Examples of the present invention will be described below. FIG. 1 is a block diagram of a case opening detection device according to one embodiment. 1 is a microcomputer (
A voltage of 5V is supplied from a power supply circuit (not shown) that rectifies, smoothes, and adjusts the voltage of the commercial power supplied from the outlet. The microcomputer 1 is equipped with a memory 2 containing a control program, a real-time clock 3, a display 4, and the like. 5 is a battery for backing up the real-time clock 3; Reference numeral 6.7 denotes a switching diode for selectively applying the voltage of the battery 5 or the voltage of 5cm supplied from the power supply circuit to the real-time clock 3. In this embodiment, the power supply 5 of the real-time clock 3
A switch 8 is interposed in the path of V, and a switch 9 is interposed in the path of the battery 5 of the real-time clock 3. Both switches 8.9 are interlocked and have actuating pieces in contact with the housing so that they open when the lid of the housing is opened. In this embodiment, the memory 2 also includes a program shown in the flowchart of FIG. Further, in this embodiment, when the case is opened, the switch 8.
9 are turned off at the same time, and the power supply to the real-time clock 3 is cut off. As a result, the real-time clock 3 is reset, and thereafter, unless initialized, the reset state is maintained and time counting is not performed. Now, after power is applied to the microcomputer 1, the time data of the real-time clock 3 is periodically fetched into the microcomputer 1, and compared with the previously fetched time data. If the same time data is continuously captured, the real-time clock 3 is in the reset state, that is, the lid of the box has been opened and the power supply has been temporarily cut off, and an alarm is generated to inform the user that the real-time clock 3 has been reset. is displayed on the display 4. In this way, in this embodiment, regardless of whether the power is on or off, if the lid is opened, it will be accurately detected when the power is turned on later. In addition, here, two switches 8.9 were used, but
It is also possible to have a configuration in which only one switch is provided between the common connection point of the real-time clock 3 and the diode 6.7.

【Effect of the invention】

From the above, according to the present invention, it is detected not only when the power is on, but also when the case is opened when the power is off, so that it is suitable for CATV terminals and satellite broadcast decoders that can receive paid broadcasting. .

[Brief explanation of drawings]

FIG. 1 is a block diagram of a case open detection device according to an embodiment of the present invention, and FIG. 2 is a flowchart of case open detection. DESCRIPTION OF SYMBOLS 1...Microcomputer, 2...Memory, 3...Real-time clock, 4...Display device, 5...Backup battery, 6.7...Diode, 8.9...Switch. Agent Patent Attorney Tsuneaki Nagao Figure 1 Figure 2

Claims (1)

[Claims] (1) A switch that turns off when the box is opened; a real-time clock that counts the time by being supplied with voltage from the built-in battery and an external power source when the switch is on, and is reset and maintains that state when the switch is turned off; A box opening detection device comprising: a control section that periodically takes in time data from a real-time clock, compares it with the previous data, and issues an alarm when the data is the same.