JPH0316827B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrostatic deflection circuit for an electron tube such as an electrostatic deflection type image pickup tube or a cathode ray tube.

Deflection defocus occurs in electron tubes such as image pickup tubes and cathode rays. This is due to the fact that the surface containing the focal point of the scanning electron beam is a curved surface with a certain curvature, whereas the electron beam arrival surface, such as a photoelectric conversion surface or a fluorescent surface, is a flat surface or a curved surface close to a flat surface.
Therefore, the spot diameter of the electron beam becomes larger at the periphery of the electron beam arrival surface than at the center, resulting in deterioration of image quality. Therefore, in order to correct the deflection differential focus, it is necessary to perform dynamic focusing using a parabolic wave signal.

Therefore, with reference to FIGS. 1 and 2, a conventional method of dynamic focusing in an electromagnetic focusing image pickup tube will be explained.

FIG. 1 shows an electromagnetic focusing/electromagnetic deflection type image pickup tube.
1 is a tube, 2 is an electron gun, 3 is a deflection coil, 4
is a focusing coil. Then, a parabolic wave signal (voltage) 5 having a horizontal period and a vertical period is supplied to the accelerating electrode _G3 of the electron gun 2 to perform dynamic focusing.

FIG. 2 shows an electrostatic focusing/electromagnetic deflection type image pickup tube.
A parabolic wave signal (voltage) 5 having a horizontal period and a vertical period is supplied to the focusing electrode G ₄ of the electron gun 2 to perform dynamic focusing.

Now, with an electrostatic deflection type image pickup tube, dynamic focusing cannot be performed using the same means as with an electromagnetic deflection type image pickup tube.

In view of this point, the present invention provides an electrostatic deflection type image pickup tube,
The purpose of this invention is to propose a circuit that can easily perform dynamic focusing on an electrostatic deflection type electron tube such as a cathode ray tube.

The present invention includes a sawtooth wave signal generation circuit and a means for superimposing a parabolic wave signal of the same period synchronized with the sawtooth wave signal from the sawtooth wave signal generation circuit, and the sawtooth wave signal and the parabolic wave signal are synchronized with the sawtooth wave signal. This is an electrostatic deflection circuit for an electron tube in which a signal superimposed on a wave signal is supplied to a deflection electrode as a deflection signal.

Embodiments of the present invention will be described below with reference to FIG. 3 and subsequent figures. FIG. 3 shows an electromagnetic focusing/electrostatic deflection type image pickup tube, where 1 is a tube, 2 is an electron gun, and 4 is a focusing coil. Then, the horizontal and vertical deflection electrodes (also serving as acceleration electrodes) G' ₃ of the electron gun 2 are supplied with horizontal and vertical periodic parabolic wave signals ( A superimposed signal (voltage) with the deflection signal (voltage) is respectively supplied as a deflection signal (voltage). This deflection electrode G' ₃ consists of two pairs of comb-shaped electrodes deposited on the inner surface of the tube 1, namely horizontal and vertical deflection electrodes, to which horizontal and vertical superimposed signals (voltages) of opposite polarity are respectively applied. Supplied as a deflection signal (voltage). FIG. 3 shows a case where superimposed signals 6, 6' of opposite polarity are supplied to a pair of electrodes g, g' for horizontal or vertical deflection.

Next, referring to FIG. 4, such superimposed signals 6,
An example of the generating circuit (horizontal or vertical deflection circuit) 6' will be explained. STK indicates the sawtooth signal generation circuit as a whole. 10 is one current source circuit;
Reference numeral 11 is a current source transistor. The emitter of the transistor (PNP type) 11 is connected to the power supply +B through the feedback resistor 12.
Transistors 11, 1 are connected between the power supply +B and ground.
1' is connected to the base bias circuit 13. The bias circuit 13 is composed of resistors 14 to 17 connected in series from a power supply +B to ground.

The collector of the transistor 11 is then grounded through the integrating capacitor 18. Further, a switching transistor (npn type) 19 is provided, the collector of which is connected to the collector of transistor 11, and the emitter of which is connected to ground. Then, a horizontal or vertical pulse 21 of positive polarity is applied to the input terminal 20 derived from the base of the transistor 19.
is supplied. Furthermore, a horizontal or vertical sawtooth wave signal 23 of positive polarity is applied to another input terminal 22 derived from the midpoint of the connection between the resistors 15 and 16 of the bias circuit 13.
is supplied. As a result, a positive horizontal or vertical superimposed signal 6 is outputted to the output terminal 24 derived from the collector of the transistor 11.

10' is the other current source circuit, and 11' is its current source transistor (NPN type). The emitter of transistor 11' is grounded through negative feedback resistor 12'. The midpoint between the resistors 16 and 17 of the bias circuit 13 is connected to the base of the transistor 11'. 18' is another integrating capacitor, which connects the collector of transistor 11' and the power supply +
B. Another switching transistor (PNP type) 19' is provided, the emitter of which is connected to the power supply +B, and the collector of which is connected to the collector of the transistor 11'. Input terminal 2 derived from the base of transistor 19'
0' is supplied with a horizontal or vertical pulse 21' of negative polarity. Then, a horizontal or vertical superimposed signal 6' of negative polarity is outputted from an output terminal 24' derived from the collector of the transistor 19'. The superimposed signals 6, 6' from the output terminals 24, 24' are supplied to the electrodes g, g' (FIG. 3) as described above.

Thus, in the circuit of FIG.
1, 11', currents I ₀ +αt, −I ₀ +αt, which are constant DC currents I ₀ , −I 0 and horizontal or vertical sawtooth wave current αt ( _where α is a constant and t is time), are obtained. is,
This is supplied to a parallel circuit of integrating capacitors 18, 18' and transistors 19, 19', and the transistors 19, 19' are turned on and off by horizontal or vertical pulses 21, 21' to generate a horizontal or vertical sawtooth waveform. Superimposed signal (voltage) of signals I ₀ t, -I ₀ t and horizontal or vertical parabolic wave signal 1/2 αt ² V = I ₀ t + 1/2 αt ² , V' = -I ₀ t + 1/2 αt ² (integration constant omitted) )6, 6' are output to output terminals 24, 24'. This circuit has good stability because the entire circuit can be grounded in an alternating current manner. Note that the average value of the voltages V and V' is 2/V + V' = αt ² , and the potential difference is V - V' = 2I ₀ t, so both the electron beam deflection and the correction of the deflection defocus can be performed reliably. It will be done.

In addition, as shown in FIG.
By connecting the collector of 0' to the midpoint between the resistors 15 and 16 of the bias circuit 13 through the resistor 25, it is necessary to create a new horizontal or vertical sawtooth signal 23 as shown in FIG. It disappears.

In addition, in the conventional deflection circuit that supplies a sawtooth wave signal (voltage) to the electrodes G ₃ ′ (g, g ¹ ) in FIG. 3, a known parabolic wave signal generation circuit is provided, and its integrating capacitor A horizontal or vertical parabolic wave voltage may be supplied between the cold end side of the converter and ground to be superimposed on the horizontal or vertical sawtooth signal (voltage).

According to the present invention described above, an electrostatic deflection type image pickup tube,
It is possible to obtain an electrostatic deflection circuit for an electron tube that can easily perform dynamic focusing on an electrostatic deflection type electron tube such as a cathode ray tube.

Furthermore, in the present invention, in a deflection circuit that supplies sawtooth wave signals having phases opposite to each other to a pair of deflection electrodes, a common parabolic wave signal having the same phase is superimposed on these sawtooth waves having phases opposite to each other. Therefore, the average value of the voltage supplied to both electrodes becomes a parabola component, and the difference between them becomes a sawtooth wave, which has the great advantage that both the deflection of the electron beam and the correction of deflection defocus can be performed reliably. There is.

[Brief explanation of drawings]

1 and 2 are schematic diagrams showing a conventional image pickup tube, FIG. 3 is a schematic diagram showing an example of an image pickup tube as a preferred electron tube to which the present invention is applied, and FIGS. 4 and 5
The figure is a circuit diagram showing one embodiment of the present invention. STK is a sawtooth wave signal generation circuit, and G ₃ ', g, g' are electrostatic deflection electrodes.

Claims (1)

[Claims] 1. A sawtooth signal generation circuit that generates sawtooth wave signals having opposite phases to each other; and a correction parabola having the same period synchronized with each of the sawtooth wave signals having opposite phases from the sawtooth signal generation circuit. an electrostatic tube for an electron tube, comprising means for superimposing a wave signal, and a pair of superimposed signals of the sawtooth wave signal and the parabolic wave signal are supplied as a deflection signal to a pair of deflection electrodes. Deflection circuit.