KR970008367B1 - Screen protection device of oscilloscope - Google Patents

Abstract

A screen protecting device of the oscilloscope includes an analog/digital converter 18 for converting a series of waveforms displayed on the screen of the oscilloscope into digital signals in order to cut off the electron beam of the oscilloscope screen when the oscilloscope is not used after a predetermined reference period of time, a storage 20 configured of a plurality of memories for sequentially storing the digital signals, a waveform variation detector 22 for comparing the output signals of the memories to detect whether the waveform displayed on the oscilloscope screen is changed, a counter 24 for starting counting at a predetermined initial state whenever the waveform is changed, and a comparator 26 for comparing the output value of the counter 24 with the reference period of time to generate a signal for cutting off the electron beam of the screen when the output value is larger than the reference period of time.

Description

Oscilloscope Screen Protectors

1 is a block diagram of a conventional oscilloscope screen protector,

2 is a block diagram of an oscilloscope screen protector according to the present invention,

3 is a circuit diagram of the storage unit and the change detection unit shown in FIG.

* Explanation of symbols for main parts of the drawings

10: switching signal detection unit 12, 24: counter

14, 26: comparator 18: A / D conversion unit

20: storage unit 22: waveform change detection unit

30-40: Memory 42-48: Subtractor

50-56: Absolute value calculator 60: Adder

TECHNICAL FIELD The present invention relates to an oscilloscope, and more particularly, to an oscilloscope screen protection device capable of automatically blocking an electron beam of a screen by using a change of a waveform displayed on an oscilloscope.

Oscilloscopes are used to observe or record waveforms of current or voltage and display signal waveforms on the screen.

Such oscilloscopes are widely used as equipment for testing various circuits in assembly lines and laboratories of various electronic products.

In general, oscilloscopes have a device that automatically blocks the electron beam of the screen in order to protect the circuitry of the oscilloscope that requires precision when the user does not use it.

As a method of protecting a screen of a conventional oscilloscope, if the user does not operate various switches of the oscilloscope for a predetermined time, the electron beam of the screen is automatically blocked.

As shown in FIG. 1, a conventional oscilloscope screen protector includes a switching signal detection unit 10 for detecting a switching operation of a switch box (not shown), and counting a clock signal every time the switching operation is performed. The electron beam blocking signal (the screen off signal) is compared with the counter 12 indicating the unused time and the output signal from the counter 14 and the preset reference time (the unused time of the oscilloscope to turn off the electron beam on the screen). It consists of a comparator 14 generating ().

The operation of the screen protector of the oscilloscope shown in FIG. 1 is as follows.

By detecting various key signals of the switch box provided to the control unit (not shown) in the middle and inputting them to the switching signal detecting unit 10, the state of the switch is continuously monitored, and when any key is pressed, the counter 12 is zeroed. Reset it. The counter 12 starts counting again from this moment and outputs the signal to the comparator 14. The comparator 14 compares this signal with the reference time (the unused time of the oscilloscope to turn off the electron beam of the screen). When this value is longer than the reference time, the comparator 14 outputs a signal to block the electron beam of the screen. Protect the screen.

The conventional screen protector described above puts the time when the oscilloscope is not used in the operation of switching, so if the user keeps observing several waveforms by moving only the probe without switching operation, even if the user is using the oscilloscope, This caused a problem that the electron beam of the screen is blocked.

The present invention provides an apparatus for blocking the electron beam of the screen through the waveform on the screen instead of detecting the switching operation in order to solve the above problems.

The apparatus for turning off the screen according to the present invention is analog / digital for converting a series of waveforms displayed on the screen of the oscilloscope into a digital signal in order to block the electron beam of the oscilloscope screen when the oscilloscope is not used for a predetermined reference time or more. Waveform change detection means for detecting whether or not the waveform displayed on the screen of the oscilloscope by comparing the conversion means, the storage unit consisting of a plurality of memories to sequentially store the digital signal, and the output signal of the memory And counting means for starting counting at a predetermined initial state whenever there is a change in waveform, and comparing the output value of the counting means with the reference time to block the electron beam of the screen when the output value is greater than the reference time. Generating a signal Comparing means are included.

Hereinafter, with reference to the accompanying drawings the present invention will be described in detail.

2 is a block diagram of a screen protector of an oscilloscope according to the present invention.

An analog / digital (A / D) converter 18 for converting and storing a series of waveforms input through a probe and displayed on a screen into digital signals. And a storage unit 20, a waveform change detection unit 22 that detects whether or not a series of signal waveforms are stored in the storage unit 20, and reset each time a waveform change occurs to start counting. The counter 24 indicating the time not to be compared with the preset time (reference time) from the input unit (not shown) and the output time of the counter 24, and the screen off signal when the counted time exceeds the reference time. It consists of a comparator 26 for generating a.

3 is a circuit diagram of the storage unit 20 and the waveform change detection unit 22.

3 is a circuit diagram of the storage unit 20 and the waveform change detection unit 22.

Memory (30) (32) (34) (36) (38) (40) of a plurality of (2n in this embodiment) sequentially storing the input converted from the A / D converter 18 into the digital signal And subtracting the output values of the n + i-th memory from the output value of the i-th memory to generate a difference value of the n memory outputs, and taking out and adding the absolute values of the plurality of subtractors to detect whether or not the waveform changes. 42) (44) (46) (48), absolute value calculation unit (50) (52) (54) (56) and adder (60). Although not shown in FIG. 3, data in the memory is sequentially applied to the next memory by a clock signal input when a waveform appears on the sprinkler in the oscilloscope.

The waveform displayed on the screen of the oscilloscope is input through the probe, and this signal is converted into digital through the A / D converter 18 and then stored in the storage unit 20 (memory 30-40 in FIG. 3). Stored. The storage unit 20 stores only the necessary portion of the signal, and the change detection unit 32 observes the signal stored in the storage unit 20 to detect whether there is a change in waveform.

Whether or not the waveform changes is determined by the following equation.

Where 2n = memory number

m (i) = output value of the i th memory

That is, by subtracting the output value of the n + i-th memory from the output value of the i-th memory, taking the absolute value of these values, and adding them, it is detected whether the waveform is changed.

Each time there is a change in waveform, the counter 24 is reset and counting begins again. The counted signal is compared with a preset reference time from a reference time input unit (not shown) in the comparator 26 to determine whether the signal exceeds the reference time, and when the reference time is exceeded, a screen off signal is generated to generate a screen off signal. Block the electron beam.

The screen electron beam blocking according to the present invention described above can prevent the screen from turning off even if the user moves only the brob in the absence of the switching operation and continues to work, and also automatically stops the screen only when the oscilloscope is not actually used. By blocking the electron beam, you can protect the oscilloscope's screen.

Claims (1)

Analog / digital conversion means (18) for converting a series of waveforms displayed on the screen of the oscilloscope into a digital signal in order to block the electron beam of the oscilloscope screen when the oscilloscope is not used for a predetermined reference time or more; A storage unit 20 comprising a plurality of memories to sequentially store the digital signals; Waveform change detection means (22) for detecting whether or not the waveform displayed on the screen of the oscilloscope is changed by comparing an output signal of the memory; Counting means 24 for starting counting at a predetermined initial state each time there is a change in waveform; And an comparing means (26) for comparing the output value of said counting means (24) with said reference time to generate a signal for blocking the electron beam of said screen if said output value is greater than said reference time.