Define the deflection sensitivity of CRT?

Answer 1

There is basically two cases:

(It is recommended to read about Cathode Ray Tube Deflection prior to read this)

1 - Electrostatic Deflection:

Is the voltage necessary to move the electronic beam by a unit of lenght. Usually is V/cm or V/in.

Since there is no significant current flowing on the deflection plates, and these kind of CRTs (Cathode Ray Tubes) are using on measuring devices (on wich the lenght of the trace on the screen will be measured in a way or another), only the voltage is relevant

on the specification of the CRT, and its effect on the moving of the bean.

CRT manufacturers made a tremendous effort to make the relationship between the Voltage on the plates and the beam deflection to be linear.

2 - Magnetic Deflection:

Used on most popular CRTs, as TVs, Monitors (now being replaced by LCDs).

Is the product of the square of the total (Ap-p)current needed to deflect the beam tottaly on the screen (from left to right - horizontal deflection, or top to bottom - vertical deflection), and the inductance of the coil.

It is understood as the minimum energy that the inductor (the deflection coil) must store to generate the magnetic field and move the beam totally on the screen.

Magnetic is the most complicated deflection since there are several factor affecting the performance of the circuit, i.e. coil resistance, geometric limitations, core saturation, variation of core permeability.

Is the product of the inductance of the coil by the peak-to-peak current, squared.

Most of the time is given in mHApp^2, but less often found in OhmsApp^2

Needless to say that the CRT using this kind of deflection uses several types of correction of linearity, because now the beam does no move in a linear way with the surface of the screen. The most popular are East-West correction, Pin-Cushion correction, and S-correction. There is basically two cases:

(It is recommended to read about Cathode Ray Tube Deflection prior to read this)

1 - Electrostatic Deflection:

Is the voltage necessary to move the electronic beam by a unit of lenght. Usually is V/cm or V/in.

Since there is no significant current flowing on the deflection plates, and these kind of CRTs (Cathode Ray Tubes) are using on measuring devices (on wich the lenght of the trace on the screen will be measured in a way or another), only the voltage is relevant

on the specification of the CRT, and its effect on the moving of the bean.

CRT manufacturers made a tremendous effort to make the relationship between the Voltage on the plates and the beam deflection to be linear.

2 - Magnetic Deflection:

Used on most popular CRTs, as TVs Monitors (now being replaced by LCDs).

Is the product of the square of the total (Ap-p)current needed to deflect the beam tottaly on the screen (from left to right - horizontal deflection, or top to bottom - vertical deflection), and the inductance of the coil.

It is understood as the minimum energy that the inductor (the deflection coil) must store to generate the magnetic field and move the beam totally on the screen.

Magnetic is the most complicated deflection since there are several factor affecting the performance of the circuit, i.e. coil resistance, geometric limitations, core saturation, variation of core permeability.

Is the product of the inductance of the coil by the peak-to-peak current, squared.

Most of the time is given in mHApp^2, but less often found in OhmsApp^2

Needless to say that the CRT using this kind of deflection uses several types of correction of linearity, because now the beam does no move in a linear way with the surface of the screen.

Answer 2

The displacement of the electron beam at the target or screen of a cathode-ray tube per unit of change in the deflection field; usually expressed in inches per volt applied between deflection electrodes or inches per ampere in a deflection coil.