US 4,542,339 A · Cathode ray oscilloscope with a waveform storage capability

Abstract

A CRO comprising a scan converter storage tube for storing the input waveform, and a CRT for displaying the input waveform received either directly from the signal input of the instrument or via the storage tube. As the center-to-center distance between the vertical and horizontal deflection plates of the storage tube unavoidably differs from the center-to-center distance between the vertical and horizontal deflection plates of the CRT, the input waveform is displayed in horizontally different positions on the CRT screen depending upon whether it is fed directly from the signal input or has been stored in the storage tube. In order to minimize this horizontal positional difference a position corrector circuit is provided which puts out a correction signal in proportion with a horizontal sweep speed determined by a sweep speed selector switch built into a sweep generator in a horizontal deflection circuit. In a preferred embodiment the correction signal is added to the sawtooth sweep signal put out by the sweep generator when the input waveform is being written on the storage tube. Additional embodiments are disclosed.

A cathode ray oscilloscope with a waveform storage capability, comprising:

(a) a signal input;
(b) a scan converter storage tube for storing a waveform received from the signal input, the scan converter storage tube comprising:
(1) a storage target;
(2) an electron gun for emitting an electron beam directed toward the storage target;
(3) a first pair of deflection plates for deflecting the electron beam from the electron gun in a first direction;
and
(4) a second pair of deflection plates for deflecting the electron beam from the electron gun in a second direction, the first and second directions being at right angles with each other;
(c) a cathode ray tube for displaying the waveform received either directly from the signal input or via the scan converter storage tube, the cathode ray tube comprising:
(1) a display screen;
(2) an electron gun for emitting an electron beam directed toward the display screen;
(3) a first pair of deflection plates for deflecting the electron beam from the electron gun of the cathode ray tube in the first direction;
and
(4) a second pair of deflection plates for deflecting the electron beam from the electron gun of the cathode ray tube in the second direction;
(d) a first deflection circuit for applying a deflection voltage in the first direction, representative of the input waveform, at least to the first pair of deflection plates of the cathode ray tube in displaying the input waveform directly on the display screen of the cathode ray tube and at least to the first pair of deflection plates of the scan converter storage tube in writing the input waveform on the storage target of the scan converter storage tube, and for applying a deflection voltage in the first direction both to the first pair of deflection plates of the scan converter storage tube and to the first pair of deflection plates of the cathode ray tube for the purpose of raster scan in reading the waveform from the storage target of the scan converter storage tube and displaying the waveform on the display screen of the cathode ray tube;
(e) a second deflection circuit for applying a sawtooth deflection voltage in the second direction at least to the second pair of deflection plates of the cathode ray tube in displaying the input waveform directly on the display screen of the cathode ray tube and at least to the second pair of deflection plates of the scan converter storage tube in writing the input waveform on the storage target of the scan converter storage tube, and for applying a deflection voltage in the second direction both to the second pair of deflection plates of the scan converter storage tube and to the second pair of deflection plates of the cathode ray tube for the purpose of raster scan in reading the waveform from the storage target of the scan converter storage tube and displaying the waveform on the display screen of the cathode ray tube;
(f) sweep speed selector means associated with the second deflection circuit for selecting a speed at which the electron beams are swept in the second direction in the scan converter storage tube and the cathode ray tube in response to the sawtooth deflection voltage;
(g) a beam control circuit for applying an intensity signal to the electron gun of the cathode ray tube in displaying the input waveform directly on the display screen of the cathode ray tube, for applying a signal to the electron gun of the scan converter storage tube to cause the same to emit the electron beam in writing the input waveform on the storage target of the scan converter storage tube, and, in reading the waveform from the storage target of the scan converter storage tube and displaying the waveform on the display screen of the cathode ray tube, for applying an intensity signal representative of the waveform being read from the scan converter storage tube to the electron gun of the cathode ray tube;
and
(h) a position corrector circuit associated with the sweep speed selector means for producing a correction signal in proportion with the selected sweep speed in order to eliminate the difference between the positions in the second directions of the input waveform displayed on the display screen of the cathode ray tube directly from the signal input and of the waveform displayed thereon after having been stored in the scan converter storage tube, the position corrector circuit delivering the correction signal to the second deflection circuit.

16 more elements

Cathode ray oscilloscope with a waveform storage capability

Life of this patent

Cathode ray oscilloscope with a waveform storage capability

Life of this patent

Abstract

Claims8